Oil cooler leaked into antifreeze, should I have the transmission flushed also?

codylent

Veteran Member
Joined
Aug 24, 2008
Location
East Millsboro, Pennsylvania
TDI
1999.5 Golf TDI, 2015 Jetta TDI
I recently found out that my oil cooler is leaking into my coolant. My transmission started shifting funny because it was low on fluid. That is how I found the problem. I flushed out my coolant, but should I also go to a VW garage and have the transmission flushed? I just changed the fluid & filter, but I am sure there is still a bunch in there? Is it worth the cost to have it flushed? I got to thinkin about it and figured that the pressure is probably much higher in the transmission, so I figured that no coolant may have gotten into the transmission, but I am not sure. Any help is appreciated. Thanks!!
 

Ski in NC

Top Post Dawg
Joined
Jul 7, 2008
Location
Wilmington, NC USA
TDI
2001 Jetta ALH 5sp stock
You've got to assume some coolant got in the tranny. When engine shuts down, tranny pressure goes to zero, but coolant system stays pressurized til it cools down. Drain a bit of fluid out of the tranny and see how it looks. Any milkiness..coolant is in there.
 

daedalus

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Aug 3, 2005
Location
Pittstown NJ
TDI
05 Variant TDI Black w/Gray
I'm sure no whiz-kid but I'm really confused by this one. The oil cooler has coolant running through lines to remove the heat from the oil. Got it. The transmission has coolant lines running through it to cool the trans fluid. I think I got that.

But... I assume the transmission fluid and the coolant are isolated systems. How would the coolant, contaminated or otherwise, mix with the transmission fluid? How would looking at or draining the transmission fluid help? Coolant mixed with transmission fluid sounds like a v-e-r-y bad thing but wouldn't it be the result of a mechanical rupture somewhere in the transmission?

Apologies to those in the know if this is a really stupid question!
 

Herm TDI

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Nov 21, 2001
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Richmond, Maine...The far side of Witsend
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2002 Golf GLS Malone Stage 3, P+520 nozzles, 11MM Inj pump, Sachs VR6 clutch, Stelth Race Pipe, Immo Deleat, EGR Deleat
....How would the coolant, contaminated or otherwise, mix with the transmission fluid?
The tranny heat exchanger (aka fluid cooler) performs the same way as the engine oil cooler (though both heat exchanges) are indepentant of each-other.
If the transmission heat exchanger has an internal leak you can get coolant into the transmission fluid..
 

daedalus

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Joined
Aug 3, 2005
Location
Pittstown NJ
TDI
05 Variant TDI Black w/Gray
Thanks, Herm. The premise then would seem to be the OP has two unconnected cooler issues?

"I was there, I can prove it! When I was a kid, you could buy meat anywhere! Eggs they had, real butter! Not this... crap!" Sometimes I feel as old as Sol!
 

codylent

Veteran Member
Joined
Aug 24, 2008
Location
East Millsboro, Pennsylvania
TDI
1999.5 Golf TDI, 2015 Jetta TDI
You've got to assume some coolant got in the tranny. When engine shuts down, tranny pressure goes to zero, but coolant system stays pressurized til it cools down. Drain a bit of fluid out of the tranny and see how it looks. Any milkiness..coolant is in there.
You make a very good point! It seemed to be ok when I drained it & changed the filter. I think that maybe I should do it once more though just to be safe. I would imagine that some would still be in there though after draining it twice! I should probably just have it flushed. Knowing how expensive the dealer can be & how expensive the fluid is, it'll probably be 500 bucks!!
 

night mission

Member
Joined
Jan 31, 2010
Location
central NJ
TDI
2005.5 Jetta, white, pkg 1, 70K
Working a simular problem but with the oil intercooler (don't have the auto trans). Parts replaced but still working on getting the oil out of the rad, removing it from the expansion tank. FWIW, no coolant/cloudy oil noted in the oil.
 

GenMan

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Dec 10, 2009
Location
Grandville MI
TDI
2011 Golf (aka Phil) 4dr 3 pedals Candy White
night mission.....Where I work the guys use Cascade liquid dishwasher soap to clean the cooling system when it has been contaminated with oil. I've never used it myself but its supposed to work great.
 

White Crow

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Joined
Mar 21, 2007
Location
Maine
TDI
2002 gls tdi
antifreeze will kill your transmission if you even think it maybe in the trans you need to get it flushed it will take the facings right off the clutch plates.
 

codylent

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Joined
Aug 24, 2008
Location
East Millsboro, Pennsylvania
TDI
1999.5 Golf TDI, 2015 Jetta TDI
Thanks guys! I really appreciate all the responses. I guess I should just have it flushed. The dealer told me between $350 and $400 and I need to drop it off the night before so the fluid is cold. In the long run it might end up saving me much more! It just sucks..haha
 

codylent

Veteran Member
Joined
Aug 24, 2008
Location
East Millsboro, Pennsylvania
TDI
1999.5 Golf TDI, 2015 Jetta TDI
1 last dumb question guys

It was $320 bucks for the tranny flush but I think it could end up saving me much more in the long run. I have one last stupid question though. As I said, I have tranny fluid in my coolant. I was trying to install one of them prestone flush & fill kits to flush it out, but there is lines going everywhere! I installed one on my Dodge truck and it was very simple, just follow it outta the firewall to the heater neck. With the TDI I'm not sure which hose to install the T onto because of all the hoses everywhere. I feel like an idiot askin this question but I just wanna be sure before I got hoses cut..haha
 
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