# Eheim Pro II Primer O-ring replacment



## partsrep

While the Eheim Pro II is one of the most reliable filters in the hobby it is subject to wear and tear just like any other. An area of concern is the primer. Often the primer may become stiff or even stuck completely or the o-ring which which seals the motor/primer may cause slight leakage after years of use. Unfortunately the o-ring is not available from Eheim separately and would require purchase of a new pump head assembly.

I found an easy fix to both problems using o-rings I have sourced from theoringstore. 
The sizes you will need are 4.5mm X 92mm for the motor/primer and a 2.5mm X 12mm for the flow control indicator.

This is what I ordered: 
N4.50X092 Metric Buna-N 70 O-ring	$2.80
2.5mm X 12mm Metric Buna-N 70 O-ring	$0.22

The replacement is simple and can be done with basic hand tools. You will need a #1 Phillips screwdriver, a #2 Phillips screwdriver, a small flat blade screwdriver and a standard pliers. You should also have some silicone grease on hand to lube the o-rings and gaskets during installation.

Here's a step by step instruction with photos

1. Remove pump head from your filter and set it on a clean work surface.

2. Remove the Eheim logo cover plate using the small flat blade screwdriver



3. Remove impeller cover and impeller assembly.



4. Turn the pump head over and using pliers to depress the retainer tabs, remove the flow control valve. It may need a little wiggling to get it free. Be gentle and patient.



5. Lift out flow control valve.



6. Turn the pump head over and remove the two Phillips head screws as shown using the #1 Phillips screwdriver.



7. Turn the pump head over and remove the four Phillips head screws as shown using the #1 Phillips screwdriver.



8. Remove the top cover to expose the motor housing, motor, and primer. (NOTE: I have already removed the flow control indicator in this photo)



9. Remove the two Phillips head screws holding the motor cord to the lower housing.



10. You can now lift out the motor/primer assembly and will see the o-ring just under the cover. *Be careful to watch the springs so they don't go flying*.



This is the flow control indicator. It just pops out when releasing the two tabs.



11. Remove the three Phillips head screws from the motor cover using the #1 Phillips screwdriver.



12. Remove the o-ring from the motor. Clean the motor as best you can being sure to clean out all the gunk (factory grease) from the o-ring land. Thoroughly clean the lower pump housing especially the areas where the o-ring will be contacting. Once clean and dry, install the new o-rings with a light coating of silicone grease. Replace the o-rings on the motor and the flow control indicator.

This is what I use.



Motor o-ring (Note: The factory o-ring is orange. The replacement from theoringstore will be black)


Flow control indicator o-ring.



13. Install flow control indicator by sliding it into place



14. Install motor cover to motor with the three screws. Just snug the screws, do not over tighten them.



14. Install the four primer springs



15. Install motor back into lower pump housing being careful to allow the o-ring to slide in smoothly.



16. Install the motor cord to the lower housing using the retainer and two screws.



17. Install the top cover over the lower housing and install the four small screws at the corners with the pump head upside down. Apply a little pressure to the primer to hold it down against the springs just enough so the top cover and the lower housing meet (a helper is handy). tighten the screws snug, not too tight as it is plastic and you don't want to strip it.



18. Turn the pump head over and install the two larger screws. Again make them snug, not too tight.



19. Install impeller and impeller cover.



20. Install Eheim logo cover plate by snapping it into place



21. Install pump head back on the filter. Connect your water lines. Depress the primer button (it should now move like new again). Let water fill the filter and turn it on. If you did everything correctly you should have years of use left in your Eheim Pro II.


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## nodima

Darn, why did you have to post this? Now my supply of cheap "leaky" pro II's will dry up!!!    

Seriously, good stuff, and a nice write up on how to do the job. May I recommend *bolding* the part about the springs?


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## rachael94

Hey, I know this was from a few months ago but does anyone know how to get the actual (green) case apart?
I'm pretty sure there's a crack somewhere on mine  I don't have this exact model but mine's just the older version of it.
I've tried sliding off the grey corner parts but I feel like I'm going to break something trying to do it that way.


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## Deeda

I think the corner guards 'snap' onto the body of the canister filter. I would try some gentle prying with a small flat blade screwdriver.


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## nodima

Deeda said:


> I think the corner guards 'snap' onto the body of the canister filter. I would try some gentle prying with a small flat blade screwdriver.


Yes, the corner clips snap onto the green canister. Gentle prying is the way to go - though it is interesting to hear you have the issue of them being difficult to get off, as mine are always falling off when I do maintenance. Simple to clip back on at least.


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## ciscokid

I'd like to thank the OP for detailing this. My 4 year old Pro II is leaking from the power cord, and this thread will (hopefully) save a lot of aggravation! I also ordered directly from the o-ring store - the Pro II is in a bucket right now (leaking slowly but running, primer button won't move).

Of course, I had just ordered a bunch of fish for this tank before this happened - fingers crossed that the o-rings come first!


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## ciscokid

I just finished replacing the O-ring on my 2028 - here are my notes and lessons learned:

- The instructions from partsrep are very well documented

- The O-ring listed from the O-ring store (N4.50X092 Metric Buna-N 70 O-ring) is perfect, IMHO. I think it is *very slightly* thicker than the original Eheim ring, and I think that's a good thing (better than the original). The O-ring store also shipped like lightning- I ordered on Thursday and got my rings on Saturday with the regular "USPS" shipping! I think the transit time will vary according to where you are, but I couldn't have been happier. I also added the Dow silicone - pretty cheap.

- The flow control valve is difficult to remove. I'd actually recommend "skipping" that step until later - it seems much easier to remove when the pump motor is completely out from the (opposite) direction because you can see the way it is being retained much better. Once you pull the valve, push the motor through the other way and then install the O-ring. You should remove the valve, though, because if you try to put the o-ring in from the "top" and push the motor/primer back in the O-ring will visibly "bunch" up. Inserting it from the other way with the valve removed prevents that from happening.

- The flow control indicator is *extremely brittle* (or it least mine was). I pulled on it very gently and it snapped the retaining clip on one side. I doubt that o-ring is the cause of any leaking anyway and I'd leave it alone if you don't have to touch it. BTW, mine is working with only one retaining clip and the original o-ring (or at least it is currently).

Thanks again partsrep!


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## Deeda

Glad you were able to find the information helpul for your filter repair. I'd also like to say thanks for the update on your particular experience and the additional info regarding the flow control indicator.


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## ciscokid

Deeda said:


> Glad you were able to find the information helpful for your filter repair. I'd also like to say thanks for the update on your particular experience and the additional info regarding the flow control indicator.


Thanks Dee.

A 2nd update: The filter was still leaking, this time apparently due to me snapping the one side of the clear tab on the flow control indicator - it just took a while before it started leaking. I ended up taking it apart again and crazy gluing the tiny piece back on with additional re-enforcement from a backing of duct tape which I also crazy glued onto one of the sides for additional strength. So far it's holding with no leaks. The flow control o-ring was also slightly thicker than the original, and once again I think that's a good thing.


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## wagsworld

Glad I finally found this group and found this thread. I have an Eheim Pro II 2126 and have had for several years now and have really enjoyed it. I had to put my fish tank in storage (3 years ago) as I was moving around, strange it was like my fish knew I was going to move and they all died off. When I pulled it out this summer to get it going again I noticed that there was a small leak around my filter. Luckily I keep it in a pan. I never could find the leak till I took it apart and water poured out of the filter top. Thought it was the sealing gasket, changed that a few times in the past, but since it wasn't leaking anywhere that I could see I thought it had to be somewhere else. That's when I figured it had to be around the priming pump. Been talking to Eheim but they are very slow with their responses, started my conversation with them June of this year. The last I heard from (Nov 11, 2013) them this what they said "If you have a white ball inside your maintenance indicator, this means your filter was manufactured before 2004. Since this unit is at least 9 years old, is possible that the priming o-ring needs replacement. This can be done free of charge if the pump is sent to our Repair Center in Montreal Canada. Please inform." Well I've written back to them twice now trying to figure out where I need to send it to but no answers, getting tired of waiting and really need to get my filter running again. Have a behind the tank filter and a heater but those don't work near as well.

Now that I'm getting tired of waiting for Ehiem to respond I was wondering if the o-ring sizes that's being mentioned is for all Pro II or is there a different sizes for different model #'s Thanks. Looking forward to getting around these boards here a getting (re)learning a few things & folk.


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## Deeda

Hi John and Welcome to C-F!!!!

The o-ring for the primer pump should be the exact same size because the pump head is physically the same size among this series canister.


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## wagsworld

Thanks Dee.


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## nodima

The most positive sign is that you actually got a reply from Eheim...

I found replacing the o-rings not to be that big a job - most difficult part was sourcing the ring itself.


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## wagsworld

Well got got the two o rings ordered. Now I was looking at my book and comparing it to the eheim site http://www.eheimparts.com/display_product.php?pid=2126 and I noticed another set of o-rings that I never noticed before. Where the hoses connect to the unit, They call it a double tap unit( part number 744578) and it has a ring on each side (part # 7444190) Has anyone noticed these leaking before? Any one know what size these are? Should I go ahead a replace them since I'm replacing the others? I've noticed Eheim is starting to run out on a few parts and beginning to wonder if I should stock up on a few things.


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## Deeda

I do keep a spare set of the double tap o-rings on hand but have never had to replace them. I've had them in the original packaging and have not noticed any visible deterioration of the parts. They are not made of pure rubber so I don't think they would be subject to 'normal' degradation like in the olden days.


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## wagsworld

ok got my o-rings today and put it back together. The small ring for the flow control went on easy and went back easy. The large one for the primer was a different mater. It went on ok but it was extremely difficult to get back together had to put a lot of force on it but it went in. Hooked everything back up and tried pushing the primer, don't know why I tries it cause when I hook up the hoses water just flows in and fills it up, and the primer stuck in the open position. So I had to take it back apart and just pushed the primer up in the closed position. Again hooked the hoses up and water flowed in so I didn't try the primer. I didn't turn on the pump or heater and let it sit about 30 min to check if it was leaking and didn't see anything. Then I started to plug in the pump and water started pouring in. Took the head off again and it was full of water. I've been checking everything but do not see any cracks anywhere. What could be causing the leak now? Thanks for any help.


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## Deeda

It's very possible that you nicked the new o-ring when you had to force it back into the housing. I used a good amount of regular vaseline to lube the housing so the pump would move smoothly prior to reassembling it. Or maybe the o-ring twisted and is causing the water to pass by the seal.

Sorry you are having trouble with it. Maybe try again and see if that fixes the problem. I think I had to do my first repair twice before it stopped leaking.


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## wagsworld

Took the o ring back off looks good can't see or feel any nicks. Ran out of the Vaseline that can w/pump, thought I had enough. Gonna go get me some new o-ring lube and try again


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## mambee

Even though Vaseline is supplied by Eheim, there is a difference of opinion as to whether it is a good idea to use Vaseline. Being petroleum based, it could eventually degrade the rubber o ring. I switched to silicone grease. Google "silicone grease scuba" to find it.


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## CrypticLifeStyle

Technically your right about the vaseline, but honestly i've never seen it actually happen in real life, or hear of it happening yet, but +1 for finding out. I have a 2028 that has a primer that likes to stick open sometimes. It'll close on it's own though when you have it running.


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## wagsworld

well I bought some vaseline, couldn't find any fish safe silicon lube locally and didn't want to wait,and really lubed it up. Got it in but couldn't get it to move. Then I noticed the o-ring was sticking out, in the area where the flow control valve is. So I pushed really hard and got it out. The ring popped back into the grove and didn't seem damaged. So this time I placed the padded envelope my o-rings came in on top of the primer and pushed it in again this time it moved fairly easily. Got it all together and hooked the hoses up and turned on the pump. Kept checking it to see if there was any leaks and didn't see any till 30 minutes of it running. Now did I damage the o-ring or is there something else that could be leaking? The head was full of water once again too. Thanks for the help


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## CrypticLifeStyle

So there's no visible cracks or damage to the plastic housing of the unit itself? Are you very sure the oring didn't slip when you out the top back on? Do the clips feel tightly secure? If you did damage the oring there would be cracking, ripping or just straight up cut open. It's pretty straight forward so if those 3 things arn't a factor then it's something else. I question pressure buildup as a last resort if everything else passes inspection.


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## wagsworld

No visible cracks. I even have the unit full of water and sitting out and no water leaks. It just dumb founds me. Wish I could see inside to see where its actually leaking. My flow control indicator was the ball instead of the floater I wander if I should change that out too.

Well I set it all back up again and this time I changed everything around and set it it front of the tank and outside the cabinet, So I can see it a little better. Again after about 20 minutes I noticed water again. This time I could see behind the filter and noticed that there was a small leak coming out behind the tank from the pump head between the two layers I must of stripped a screw or something to prevent it from tightening up. I tighten the screws up as tight as I can get them. Any idea's what to do now? Since its plastic there isn't a way to fill in the holes and rethread it is there? Or maybe put a line of silicon between the two layers. But I still can't figure out how the water is leaking into the head to begin with. Maybe I should just see if I can find a replacement head. Was really hoping to fix this thing, ain't making near the amount of money I was when I first bought the filter can't afford to get a new one.


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## CrypticLifeStyle

Is there anyway you can post pics of the area's where the problems are coming from.


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## Deeda

I'm assuming that the 2 layers you are referring to are where the top half of the pump head assembles to the lower half of the pump head, correct? If it is leaking in that section, it is either the primer pump o-ring or the clear flow indicator housing and/or o-ring.

It is possible that the clear flow indicator window has a small hairline crack, especially if the filter is pretty old. I would hate to see you buy this part and discover that isn't the problem but it is an option to consider.

Regarding the stripped screw threads for the lower half of the pump head, you might be able to use a drill-able plastic mend product to fill the hole, let it cure according to directions, carefully drill the appropriate size hole for the screw size and then reassemble it. There isn't a need to torque those screws down that tightly, just hand snug is usually sufficient.


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## wagsworld

ok I hooked it up again and watched it closer this time. This time I looked down the flow control valve with a flash light and about 10 minutes in to it running I started to see a little water. So I stuck my finger down the side and and felt water. Then where the pump motor wire comes out I saw water there. Here are a couple pics I took to try and show the 2 places. 1st one is a little blurry but you can see it.


















So maybe I just wore the o-ring out my first couple attempts and just can't see it?

The flow indicator housing I looked it over and filled it with water plugging one side and never had water anywhere or saw a crack even had my wife look at it and she couldn't find any cracks. Really wish there was a way to hook it up with the top off so I can see inside where the water is leaking at. Any one know what size the double tap o-rings to get from the o-ring store? Might as well as replace those too.

On another note Eheim finally sent me a reply on where to send it but this time it said I need to show proof of purchase. Well after having this pump for 9 years and a few moves I was surprised I had the manual for the pump but can't remember where I purchased the pump or where the receipt is.


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## wagsworld

Well I replaced the 2 o-rings once again and even used the food grade lube they sell. It slide in a little better this time but still stiff. hooked it up and turned it on and I'm still getting water in the same place. Like I showed in the pics. What else could it be? I can not see any cracks and even poured water in it before hooking it up and couldn't see any leaks. Any other things Maybe the 2 o rings for the double tap unit? So much want to use this pump but getting tired of fooling with it and might just get rid of it all together. Any suggestions?


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## Deeda

Sorry you are still having problems fixing this filter!

The only 2 places I am aware that will cause the leak at the power cord are the primer pump o-ring, the flow indicator window o-rings or the flow indicator window itself. It would be cheap enough to replace the o-rings for the double tap window to see if that could also be the problem and is what I would do just to eliminate it.


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## wagsworld

Would anyone know the size of the o rings for the double tap unit? I've pulled mine out and measured but figured if they are worn out that the size might be wrong (to thin). Mine is measuring out at 3mm x 26mm. I've been checking out places that sale them and a place called Big Al's say Replace double tap seals yearly to avoid the potential for a leak. We'll see. I'll probably order from Ehiem so far, they are the cheapest with S&H. Still searching though.


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## wagsworld

Got the new o ring for the double tap unit and still have a leak. Now I'm second guessing the primer o-ring. My red (original) one just measures almost 4mm and the ones I've been getting is 4.5mm. After I installed the new ones I can not move the primer so I'm thinking its too big. Guess I'll try a 4mm one now, don't know what else to do.


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## wagsworld

Ok I've been trying to figure out how I can find the leak so I took the top cover off and wired the top to the base. Placed the double tap unit on and then turned the water on. Well I didn't have the top tight enough to the base and water sprayed everywhere so i cut it off and tightened it up a little tighter and this time turned the water on a little slower and I saw a leak between the double tap unit and the valve where the adapter lever touches tried making a video but don't know if this group does videos will try it but I took a couple pictures to show what I did and saw. The water drop is hard to see because its more on the back side of the unit. Funny thing is it only leaks while its on.





Ok this last one is a video don't know if it will show as a video here but i think you can click on the picture and it will take you to my photobucket where you can watch the video.


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## partsrep

Deeda said:


> Hi John and Welcome to C-F!!!!
> 
> The o-ring for the primer pump should be the exact same size because the pump head is physically the same size among this series canister.


2026/2028 are the same pump head as 2126/2128 model filters. The difference is the 2100 series are heated


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## wagsworld

Happy Happy Happy. Well I got my new Double tap unit yesterday and replaced it and SO far there is no leaks PTL. Now I'll hook it back up to my under gravel filter like I used to have it and I can get rid of the hang on filter.


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## SWD40

Very good tutorial! My canister was leaking and made quite a mess. I contacted ENHEIM and they pointed me to the flow rate indicator O-Ring, quite a common problem from what I gather. They said that I needed to replace the indicator assembly as it came with the O-Ring. I saved myself a few dollars by removing the O-Ring and taking it to a local hardware store. Was able to a perfect match in a pack of two. Has not leaked a drop since I replaced it. The primer O-Ring will be my next task. One thing I would HIGHLY suggest to anyone using a canister filter, place it in plastic bin or pale under your aquarium. Doing so gives you protection and time to address the problem before water damage to the tank stand and flooring happens. Trust me, I learnt the hard way.


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## Deeda

Hey John, I missed your update on the leak problem. Is the filter still leak free?


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## wagsworld

Yes after replacing the double tap unit it hasn't leaked a bit. And my water is crystal clear


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## wagsworld

SWD40 yes that's a big help is placing your filter in a bin. I did from the begging just in case I spilled anything during filter changing. But I could only image if it wasn't in a bin when I finally noticed the leak the bin was half full. Saved the floor.


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## partsrep

wagsworld said:


> Well got got the two o rings ordered. Now I was looking at my book and comparing it to the eheim site http://www.eheimparts.com/display_product.php?pid=2126 and I noticed another set of o-rings that I never noticed before. Where the hoses connect to the unit, They call it a double tap unit( part number 744578) and it has a ring on each side (part # 7444190) Has anyone noticed these leaking before? Any one know what size these are? Should I go ahead a replace them since I'm replacing the others? I've noticed Eheim is starting to run out on a few parts and beginning to wonder if I should stock up on a few things.


The double tap O-rings are easily available at most LFS or some of the online aquarium supply sites. I keep spares of all the O-rings for all my filters all the time just in case. It's when you stock the O-rings that you don't have problems. Murphy's law will have it's way when you don't.


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## partsrep

Deeda said:


> Sorry you are still having problems fixing this filter!
> 
> The only 2 places I am aware that will cause the leak at the power cord are the primer pump o-ring, the flow indicator window o-rings or the flow indicator window itself. It would be cheap enough to replace the o-rings for the double tap window to see if that could also be the problem and is what I would do just to eliminate it.


I believe Dee is correct. Those are the only two places water could leak at the power cord.


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## partsrep

wagsworld said:


> Yes after replacing the double tap unit it hasn't leaked a bit. And my water is crystal clear


Great news, I'm glad you fixed the leak.

*It's been almost a year since I started this thread and my Eheim Pro 2026 has been leak free ever since*. I did see some posts where members used Vaseline as the lube. I suggest using a silicone based grease instead of Vaseline. It's safer for the fish and the silicone base won't expand the O-ring like a petroleum based lubricant might. The grease Eheim packs with their filters is silicone based.


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## pkut

It seems that the cross-sectional diameter of the primer button o-ring that has been specified at the beginning of this thread is at least 5 thousandths of an inch larger than the cross-sectional diameter of the original orange o-ring that comes installed in a new filter. Because of this, the black o-ring that has been specified here will take a lot of force to install and will most likely make the primer extremely hard to pump or it may even jam it. It's also potentially dangerous to put enough force on these plastic components to install it.

I hope partsrep will take another look at this o-ring and specify a different one with a cross-sectional diameter that more closely matches the original orange o-ring that came installed in this filter. I appreciate partsrep posting this information for us to make a repair but I'm afraid to force the o-ring presently being specified and possibly damaging the adjoining plastic components. It appears that other people hear have already had this problem.


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## brammn

I've given up trying to replace the primer O-Ring now (shocking design on Eheims behalf imho), I have a pair of 2128's and they're both out of action at the min, thank goodness for the wet/dry pros being pretty much indestructible, so I still have filtration! Even though I've replaced the O-rings again and again they eventually go again, so I'm looking for a permanent fix now.

I've spoken to one of the Eheim reps in the UK today and he said that the older 1228 pump head is probably the better option as a spare part (not as cheap as the O ring, but a heck of a lot cheaper than a new filter!), the main difference is it doesn't have the primer, so less to go wrong and start leaking! It means you have to manually prime it, but in reality how often does priming actually take place - I'd rather that than an empty tank!


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## partsrep

pkut said:


> It seems that the cross-sectional diameter of the primer button o-ring that has been specified at the beginning of this thread is at least 5 thousandths of an inch larger than the cross-sectional diameter of the original orange o-ring that comes installed in a new filter. Because of this, the black o-ring that has been specified here will take a lot of force to install and will most likely make the primer extremely hard to pump or it may even jam it. It's also potentially dangerous to put enough force on these plastic components to install it.
> 
> I hope partsrep will take another look at this o-ring and specify a different one with a cross-sectional diameter that more closely matches the original orange o-ring that came installed in this filter. I appreciate partsrep posting this information for us to make a repair but I'm afraid to force the o-ring presently being specified and possibly damaging the adjoining plastic components. It appears that other people hear have already had this problem.


It's been two years since I have done my original repair and still no leakage. My primer works smooth and easy and apparently doesn't put any stress on the pump head. If Pkut can actually find the exact size O-ring that Eheim uses please post it so we know where to get them. I used what I could find and that was after a lot of searching. I haven't found .005" to be extreme keeping in mind that .005" is about the thickness of a human hair.


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## jungleval

Great write up !! I am leaning to change the Orings as well coz when i prime it almost refuses to come back up..and i kinda pull it up. But no leaks at all. I love these INDESTRUCTIBLE canisters that we can still DIY service after a decade. Thanks again partsrep.


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## partsrep

My Eheim Pro 2028 finally started leaking after over 10 years of use. I had the O-rings on hand and did the repair in about an hour. I did notice the 12mm o-ring for the flow control meter fit a bit loose so it may need an 11.5mm X 2.5mm o-ring instead. http://www.theoringstore.com/index.php?main_page=product_info&cPath=368_12_45&products_id=1982
My primer was extremely stiff, rendering it all but useless but that meant I have a good seal. I can live without the primer. Once again I am leak free!


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## partsrep

***UPDATE***
It's been quite a while since I did these repairs on two of my Eheim Pro2 canister filters. While the repairs lasted well over a year, further attempts to repair the leakage have been unsuccessful and I have been forced to retire the two Pro2 filters. 
It was a easy and inexpensive fix while it lasted, but it didn't last forever. I now run Eheim Pro3e and Classics. Oh, yeah and my much older Eheim 2322 Thermofilters.


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## Belair62

Too bad that Photobucket pulled the wool over our eyes. Would have been nice to see the pics.


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## Deeda

Check out the following link Replacing the Priming o-ring from the New Jersey Aquatic Gardeners Club (NJAGC) as they have a nice tutorial.


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## nodima

Sorry to hear that, partsrep.

Knock on wood, but it's been over 5 years without issue after replacing the rings on mine.


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## Belair62

Deeda said:


> Check out the following link Replacing the Priming o-ring from the New Jersey Aquatic Gardeners Club (NJAGC) as they have a nice tutorial.


Thanks for this link Deeda. Hoping for a couple years out of these


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## Deeda

You are very welcome!! I replaced the o-ring twice on mine over a couple years but decided to stop using the priming button completely after filter maintenance to avoid having to change it again. I still have a couple spare o-rings though just in case.


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## nodima

Deeda said:


> You are very welcome!! I replaced the o-ring twice on mine over a couple years but decided to stop using the priming button completely after filter maintenance to avoid having to change it again. I still have a couple spare o-rings though just in case.


Actually I meant to say the same thing - I don't use the priming button any more either.

What I've found works best for restarting the canister after maintenance is to fill the canister with water. I add as much as possible, then install the head unit. Pour a couple additional cups down the intake in the filter head to fully fill it. Connect the quick connects, and the filter starts every time. Key seems to be eliminating as much air as possible inside the filter.


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