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Tranny heat exchanger leaking coolant!

Well guys,

I was feeling pretty good...:D I just got done replacing my radiator, all hoses, water pump, thermostat. Put everything together, started the engine, checked for leaks...and guess what...the tranny heat exchanger is dripping coolant! drip...drip..drip..drip :swear:

RealOEM.com BMW E53 X5 4.4i Oil-cooler pipe/heat exchanger

Anyone replaced this unit? Is it typical for this part to leak with only 100K on the vehicle?

Anyone have any pointers? It seems like there are two quick-connects that need to be pulled out...and it should come right off. Seems like an easy job. :dunno:

2001 X5 4.4L w/ 100KMiles

most likely it's the rubber ring(#12 in your realoem link). I did that 1-2 years ago.

I thought it was the seal, BUT....the leak is coming from between the exchanger. It doesn't look like the leak is near the seal.

Was yours leaking near the seal or in the middle of the exchanger?

Are you positive the leak is coming from the middle of the exchanger? It might just be residual coolant from the bleeding process. I've never heard of the exchanger leaking from the center. I've had mine for over 100k miles and its still fine (I assume).

Quote:

Originally Posted by vtyagi (Post 742388)

I did after I replaced my WP/thermostat back in Nov/Dec, the funny thing was the leaks continued with new heat-exchanger until about 2 days and now no leak what-so-ever. Weird indeed.

BTW, I googled the part number and found an online company in Texas who charge around $200 for it (brand new and OEM) with free shipping. The 0-rings come with it. Good luck or you can just drive run the engine until warm in the garage to see if the leak persist (never know, but it may save you a few bucks).

Quote:

Originally Posted by vtyagi (Post 742425)

I thought it was the seal, BUT....the leak is coming from between the exchanger. It doesn't look like the leak is near the seal.

Was yours leaking near the seal or in the middle of the exchanger?

I would suggest you to trace the leak when it's still wet. Put fingers around those 2 ports where the rubber seals go and see if they're wet(don't do it right after you shut the engine. it's still HOT). I have strong feeling the rubber seal is the problem.

It could be leaking from uptop

Anything leaking up by the trans thermostat will look like its leaking from the cooler. See if the leak is running down any coolant hoses from above and colloecting at the cooler.

Are you sure it is from the exchanger and not the new radiator?
You could have damaged the new radiator when putting it in. I have seen it happen before.
Take off the shroud and loosen the exchanger again so you can see if the leak is from the radiator or the exchanger

Update:

Well...weird thing...I drove the X5 around for 15 minutes, came back...no more leak! It's almost like the pressure in the system rose which caused the o-rings to seat and seal the system.

I will check tomorrow morning after it has cooled and start it to see if the leak re-appears.

Quote:

Originally Posted by vtyagi (Post 742718)

Leave the belly pan off for a few days to make sure.

Trust me I was sure the core leaks, I wrapped paper-towel around the core connectors (to the hoses) and they were dry but the core dripped; the brand new core replacement dripped also so I was WTF, wasting $$$, oh well live and learn.