So today I took the 10 minutes to replace my expansion tank. The lower hose that goes to the water pump will not get a good seal. I can't get the reservior filled without it leaking dry now. Is there some sort of part number split with the expansion tanks and plastic female hose connector?

I even removed the new behr replacement and tried the original tank and it's a super snug fit. But the new tank requires zero effort to connect and does not seal.

Before I throw more money into parts, any advice?

 

Is it this one?

BMW E60 545i N62 4.4L Engine Cooling - 17137542986 - Coolant Expansion Tank - ES#2731801

Seems like the only thing it could be is the o-ring. You might measure the diameter of the plastic outlet on the two bodies to see if there is a difference.

Could it be you haven't seated the hose right on the new one?

 

Is it possible the o-ring might be stuck on the old tank?? At least that would explain why it fits tight on the old tank and not the new one.

 

That is the exact tank I ordered, from ecs too.

I did call pelican parts to see if there may have been some sort of split year change. They replied that there is only 1 p/n available. My next question was to know if there was any kind of gasket or o-ring. My answer was no. However they kindly offered to sell me a replacement hose haha. I'll triple check for an o-ring tomorrow on the old tank.

I know my car is an early '04 model, where some clutch stuff had different p/n's.

 

I got the same Behr Expansion Tank and had no issues.

 

Bummer town. I don't get why I am having this issue. It should've been a very straight forward swap.

Unless there is an o ring I didn't see

 

Yeah I'm missing the o-ring.

I found what looks to be some sort of liquid gasket (where the o-ring should be). It's the orange material. It's almost like a wax consistency.

 

Hate to say this, but you might want to drain the radiator since you found this crud.

 

Just drained it haha! Topped it off and used an o-ring. Sealed good, drove it to operating temps and it still held.

On the other hand I did order a replacement hose to get the correct o-ring. I'll pay the $40 for piece of mind. And keep my fingers crossed while I wait for it. I only have a 4mile drive to work, but it's hard to say how many heat cycles that o-ring will tolerate.

 

What a Bummer.....Glad you found the cause, something else for me to keep in mind when replacing that tank.