Coolant leak

flyboybob

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Joined
Mar 11, 2003
Location
sumwhere, oregon
TDI
'12 passat tdi se dsg
2012 Passat Tdi SE with 153,000 miles suddenly developed a 1 liter/20 miles sized coolant leak (coolant level was fine at fill up 200 miles ago).

Put the car up and removed the lower sound shield (belly pan) and oil pan insulation (both wet with coolant). Coolant is dripping off the oil pan after running down the front of the block. Leak appears to be in the area of the oil filter housing/oil cooler. Nothing above that is wet. Passenger side of the engine from the oil cooler to the belt drive area is dry. Intercooler and hoses are dry. The oil cooler itself looks dry. Hard to see up or down into that area below the oil cooler but that area of the block is wet.

Suspect a gasket tween the oil cooler and block has failed. :(

Searched (briefly) the forum for threads about coolant leaks like this and came up empty.

Anyone else heard of an issue like this on an NMS Passat?

Lots of smaller hoses in that area but they look intact. I think I'll hafta disassemble to figure this out. No time to do that tonight.

Any ideas bout how to proceed appreciated. Thanks!

bob.
 

jrm

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Jul 24, 2013
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Oregon
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2013 Passat SE with nav (totaled)
sounds like a question for 767 wrench, he is the only one of us to pull the egr cooler off
 

740GLE

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Aug 19, 2009
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NH
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2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
Does the oil look black or milky? Maybe the oil cooler may sprung a leak.
 

767wrench

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Jul 25, 2012
Location
Ohio
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1981 Rabbit Pickup
There's a seal between the aluminum oil cooler and the oil filter housing on the front side of the filter. It's easy to take apart, only 4 screws hold it on. There's another seal where the oil filter housing mounts to the block it looks like another 4 bolts hold that on. There are some hoses around there too that are extremely hard to get to. Had to mess with them when installing my frost heater.
 

flyboybob

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Joined
Mar 11, 2003
Location
sumwhere, oregon
TDI
'12 passat tdi se dsg
thanks for the help!

to be clear, the leak is a coolant leak (as in antifreeze, G13, the purple stuff). 767wrench is correct...there's a bunch of small hoses in there but i can't seem to find one that's leaking. that's why i suspected the gasket on the oil filter/oil cooler housing. but a closer look at the literature available (parts diagrams and erwin stuff i have) now has me thinking that there isn't any coolant behind those gaskets so it must be a hose.

today i should have a cooling system test setup that will let me pressurize the system without running the engine. maybe then i can find or hear the source or the leak.

any advice appreciated. thanks again!

bob.
 

767wrench

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Jul 25, 2012
Location
Ohio
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1981 Rabbit Pickup
thanks for the help!

to be clear, the leak is a coolant leak (as in antifreeze, G13, the purple stuff). 767wrench is correct...there's a bunch of small hoses in there but i can't seem to find one that's leaking. that's why i suspected the gasket on the oil filter/oil cooler housing. but a closer look at the literature available (parts diagrams and erwin stuff i have) now has me thinking that there isn't any coolant behind those gaskets so it must be a hose.

today i should have a cooling system test setup that will let me pressurize the system without running the engine. maybe then i can find or hear the source or the leak.

any advice appreciated. thanks again!

bob.

There's definitely coolant there, that aluminum block on the oil filter housing is an oil/coolant heat exchanger. The seals are like an oil ring in a groove
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
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2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
thanks for the help!

to be clear, the leak is a coolant leak (as in antifreeze, G13, the purple stuff). 767wrench is correct...there's a bunch of small hoses in there but i can't seem to find one that's leaking. that's why i suspected the gasket on the oil filter/oil cooler housing. but a closer look at the literature available (parts diagrams and erwin stuff i have) now has me thinking that there isn't any coolant behind those gaskets so it must be a hose.

today i should have a cooling system test setup that will let me pressurize the system without running the engine. maybe then i can find or hear the source or the leak.

any advice appreciated. thanks again!

bob.
My comment was geared toward and issue with the coolant to oil heat exchange, if there is a leak that's external, there may be a leak that's also internal, granted it's a slim chance.

But, you'd also see the color of the coolant turn to chocolate milk due to the oil pressure.
 

flyboybob

Veteran Member
Joined
Mar 11, 2003
Location
sumwhere, oregon
TDI
'12 passat tdi se dsg
Confirmed gasket failure.

Was able to find a coolant system pressure tester to fit and then remove/move enough stuff (air filter housing, EGR line, injector harness) to get a picture of coolant squirting from between the oil filter housing and the cylinder block.



Now I'll need to round up the parts before I remove the fans, intercooler, oil cooler and oil filter housing to fix this :/

Big PITA.

Will check the coolant reservoir cap to be sure it isn't over pressurizing the system. Can't imagine why else this gasket would fail.

Will consider it good luck if I don't find oil n coolant mixed somewhere as 740GLE suggested.

bob.
 

jrm

Veteran Member
Joined
Jul 24, 2013
Location
Oregon
TDI
2013 Passat SE with nav (totaled)
geeze, HUGE PITA, man I don't know what id do- our Passat see's 100 miles a day min. I better log in and add rental car coverage to my insurance options :(
 

flyboybob

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Mar 11, 2003
Location
sumwhere, oregon
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'12 passat tdi se dsg
Yep....I hear ya. If we didn't have other vehicles in our household I'd be on the phone to usaa about help with a rental....don't know if my rental insurance covers this kinda thing tho.

Once I have what I need (oil filter housing gasket set ordered online tonite @ $26) I should be able to knock this out in a couple of hours. Shouldn't be that tough of a job now that I know what's broke.

What gets me is why it broke in the first place....still haven't figured that out.

Will be putting this gasket back w some Hylomar as insurance it won't leak again.

bob.
 

Ol'Rattler

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Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
Is it possible to get to the 4 screws without a lot if disassembly? They just might need to be snugged up. I would try snugging up the big black nut, as well.

Best I can come up with without a pic.
 

roni024

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Joined
Mar 31, 2007
Location
Syracuse, NY
TDI
2015 Passat TDI SEL DSG
^^^^^^^^^^
Good advice!

I had a DSG leak that I fixed by tightening the mechatronics unit's cover. It's certainly worth a shot.
 

flyboybob

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Joined
Mar 11, 2003
Location
sumwhere, oregon
TDI
'12 passat tdi se dsg
That is a good idea. Those bolts that hold on the plastic oil filter housing don't take a lot of torque to begin with (14 Nm if I recall). I think I can get to them now. But it will be a couple of long work days 'fore I can get back to it. I'll try retorquing them n see what happens....might save a couple hours of wrench time.

Thanks!

bob.

Edit by bob: these bolts are spec' to be initially installed w a torque wrench, then additionally torqued to an angle (add'l 90 degrees IIRC). Check ERWIN data for correct installation.
 
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flyboybob

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Mar 11, 2003
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sumwhere, oregon
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'12 passat tdi se dsg
saga continues....

so....

it wasn't the torque on the oil filter housing mounting bolts--they didn't budge when i put a torque wrench on them. as a matter of fact they seemed over torqued when i removed them.

here is a link to a picture of my removed plastic oil filter housing:



the three oil passage areas look great but the coolant passage area has a broken gasket retaining lip (easier to see zoomed). found one small broken piece of the plastic in the mating passage of the block.

i can't think of a way to repair this so a new part is on the way.

more details later.

bob.
 
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jrm

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Jul 24, 2013
Location
Oregon
TDI
2013 Passat SE with nav (totaled)
wonder if any coolant wandered over to the oil side? Man that G13 coolant sure turns to crud :eek:
 

flyboybob

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Joined
Mar 11, 2003
Location
sumwhere, oregon
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'12 passat tdi se dsg
Hi jrm!

I don't believe that oil and coolant are mixed since the oil passages were sealed up nicely when I removed the oil filter housing. I will be pulling an oil sample to have the lab check tho. And I intend to change the oil when I'm finished putting back the new oil filter housing (still waiting for the part to arrive). The coolant color looked good (translucent and purple-ish as when new) all through this. There is a bunch of rust in that area. Doesn't seem excessive for a water cooled iron block. But I'll do a good coolant system flush too. The engine oil looks like it always looks....no signs of coolant in it.

I suspect that the new part is different than the original since the part number has changed (last letter C on original is now last letter H on replacement part). I hope that means it's improved.

Still don't understand why this broke. Plastic might have been cracked or defective since new or maybe installed incorrectly when new or maybe cracked over time from heat cycling. Just seems to me that this is a part that should never fail or need to be fussed with.

bob.
 

Pentonvb05

Member
Joined
Oct 28, 2017
Location
Denver
TDI
2012 Passat
I finally got the housing off, unfortunately I have the same issue. Only one of the walls of the gasket seat were broken. Ordered new gaskets to see if it will seat properly if not i will bite the bullet and order a new housing. That is a very expensive peice of plastic.
 

jw4free

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Joined
Aug 28, 2014
Location
NW Boston Metro
TDI
2012 Passat TDI SE
I'm not intending to stir-up negativity, or be a debbie downer, but I wonder if the factory didn't have their torque gun dialed in correctly on the installation of this engine component.

This may be a time, fatigue /vibration issue, or just random acts of bad luck. Time will tell.

I see you both have a 2012. I too have a 2012.
 

d2freeman

Veteran Member
Joined
Aug 8, 2013
Location
NC
TDI
2013 Passat SE
Add me to the list, my housing started leaking at 215k miles, luckily I had time to order the part before hand as my local dealer quoted $550 for the part, I found it on the web for $345, anyway the coolant passage was broken in the exact same place as the others and like the others the oil passages were all fine.
As stated this is a PITA to replace, then while removing the dip stick tube, the end of the plastic tube broke off in the block where the o-ring is located, Had to remove the oil pan to drive the end of the tube back out of the block. Since the dip stick tube is a special order part, no dealer stocks it. Sealed the broken tube at the block with some RTV and hope it holds until the part arrives.
 

pj_diesel

Member
Joined
Apr 17, 2020
Location
Ohio
TDI
MkIV ALH Jetta
Thanks for this thread. I did this recently for a friend, had the exact same problem. Mysterious coolant leak that I traced to the housing. Not only was the plastic broken, but the little o-ring seal came out in two pieces. I got the new part from ECS Tuning.
The triple square bolts were not so easy to get out, because the bolt heads were packed with crud and I couldn't see them to clean it out. The only difficult coolant hose was the one that attaches to the housing itself, the intercooler hoses weren't hard to get on and off.
 

hitman1985

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Joined
Apr 15, 2018
Location
Clarksville, TN
TDI
02 Jetta TDI ALH
Joining in on this ! After a few months of not using the Passat much. Omw to work 4 am... Coolant light and later that day went over our pit at work and sure enough there's that stupid filter housing...

125k miles. I went the cheapo route and bought the 37dollar eBay special just to obtain the plastic housing with 2 sets of gaskets... Hope to tackle this next weekend perhaps.

I'm going to try doing this without removing too much off the car


Sent from my SM-G965U using Tapatalk
 

joshferrer

Well-known member
Joined
Jun 6, 2018
Location
Ontario, CA
TDI
2014 VW Passat TDI SEL (CKRA)
Joining in on this ! After a few months of not using the Passat much. Omw to work 4 am... Coolant light and later that day went over our pit at work and sure enough there's that stupid filter housing...

125k miles. I went the cheapo route and bought the 37dollar eBay special just to obtain the plastic housing with 2 sets of gaskets... Hope to tackle this next weekend perhaps.

I'm going to try doing this without removing too much off the car


Sent from my SM-G965U using Tapatalk

Curious about those gaskets that came with the eBay housing. That’s a great idea! I just spent $100 in oem gaskets for mine. Let us know of the quality of those gaskets!

Also, while you’re down there, you should replace all of the oem clamps with the screw clamps to make it easier for the future. I replace all of mine just to take them off easier when I’m down there because the oem style ones are a PIA.



I have external coolers on mine but you can see how I replaced all of my oem clamps with the screw type make it easier for future times in there.


-2014 Passat TDI SEL
Malone Stage 2 "Econo" Tune.
Rawtek DPF, EGR, DEF Delete Performance Kit. Straight Pipe. No resonator and no cat.
 

hitman1985

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Joined
Apr 15, 2018
Location
Clarksville, TN
TDI
02 Jetta TDI ALH
So my nightmare of this new generation over engineered Passat oil filter housing replacement is complete.

Things I have learned:
Cooler held on with torx and housing with m8 triple squares.

Loosen the intercooler; remove all the coolant lines in nearby areas; I took off the cooler and then the housing separate from each other.

Even ended up using the cheapo housing because my original one was damaged; one of the interior walls of the upper coolant port broke / cracked.

Left all clamps because I on my personal cars, don't mess with screw clamps; I've seen plenty of screw clamps fail; not too many oe style ones tho and I grab some at the yards anytime I go to have spares in several sizes on hand meaning they are mostly free to me ;)

Made a good 2 hour job off this and the worst part was the angles of the screws to loosen without breaking or stripping.

I didn't take pics because I doubt they would have been nice quality [emoji14]



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crdouger

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Joined
Jan 16, 2010
Location
Michigan
TDI
99.5 & 06 jetta TDI's
I ended up having this exact same housing failure on my 2013 with 220,000 miles. This thread was helpful. Where have people had luck finding affordable oil filter housing replacements?
 
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flyboybob

Veteran Member
Joined
Mar 11, 2003
Location
sumwhere, oregon
TDI
'12 passat tdi se dsg
Crdouger,

sorry you're having this issue.....i still feel this is an issue that should NEVER happen....can't understand why vw would use such a crappy part in such an important spot.

i paid a small fortune ($325 iirc) for my replacement....at the time i couldn't find the oil filter housing alone without the oil cooler.

do a search for p/n 03L115389H. You can find just the plastic part + gaskets now. Some on this board have had success with those parts alone using their original oil cooler.

don't forget to torque the triple square mounting bolts correctly. The Erwin info sez replace them and torque to an initial value then torque an additional angle.

bob.
 

crdouger

Veteran Member
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Jan 16, 2010
Location
Michigan
TDI
99.5 & 06 jetta TDI's
Thanks.

Do you know what the torque sequence is for the triple square ones?
 

d2freeman

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Joined
Aug 8, 2013
Location
NC
TDI
2013 Passat SE
1. Tighten to 14 Nm, in a diagonal sequence.
2. Tighten an additional 90° (1/4)
 

wsc

Member
Joined
Jan 3, 2015
Location
Cypress Texas (Houston)
TDI
99.5 Jetta, 06 Jetta (Totaled), 14 Passat.
I chased this leak through the thermostat housing and all of the numerous pipes and hoses on the front of the engine. Wish I would have seen this thread before taking all of that stuff off, but I'm glad I saw it now because I was about to spend $600 on a bunch of parts that would not have fixed the problem. Only 70 k on the car but it had a plugged heater core before and an eroded out elbow to the heater core that left me stranded. That was related to the solids that form from either "flux left in the head" or from the "excessive heat from the egr cooler". This could be what is making the ID of the oil cooler housing fail as well.
 

dvbull

New member
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Sep 9, 2020
Location
Livingston, TN
TDI
2012 Passat TDI SEL
Well, this has certain been an enlightening thread. Thank you to all. My 2012 has the same issue. In fact, the photos looks like they were taken on my car. It has around 220K miles on it. So far, I'm having zero luck finding the URO013456 replacement part. Autozone online claims to have the part - right up until you click on the "Check Out" button, then it says "part unavailable". RockAuto, who I have used alot and trust, says "on backorder". Can someone recommend a trustworthy, online merchant? I'd rather pay a little more from a trustworthy, know supplier than plug my card number into ebay.
 

d2freeman

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Aug 8, 2013
Location
NC
TDI
2013 Passat SE
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