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Discussion Starter #1 (Edited)
So, the GLX isn’t loosing oil, but the coolant is dropping quickly. I see steam coming up around the sides of the heads. So please tell me where you think this latest leak is? Well, more like that this is the last leak? Could a leaky head gasket lose coolant? Or what else?
 

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The first places I would check, would be the CTS at the back of bank 1 head, and the heater hose "O" ring where it connects to the cross pipe.
 

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Discussion Starter #3 (Edited)
Sorry, my head is foggy.. what’s CTS? An o-ring would be awesome but could that result in steam coming the passenger side of the engine and from the back of the driver's side?

[edit] CTS coolant temp sensor?
 

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Coolant temp sensor, yes. Also, just trace the path of any coolant pipe/hose around the engine bay to where each terminates.
 

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The cross pipe is a coolant pipe that connects from one head to the other, the CTS and heater hose connect into it.
There is also a "T" off the cross pipe that runs forward under the intake manifold, that also has an "O" ring on the front connection.

They are the 3 most likely causes of steam as you described.
Also check where the cross pipe connects to the heads.
 

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Discussion Starter #6
Thanks guys! Sgt. Preston and King (@cchief22) will report back after further investigations into this matter. I fear that as I find leaks the pressure will build on other weak links causing a bit of a wack-a-mole game of leaks from hoses that were never intended to last this long...
 
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Discussion Starter #7
So if I want complete access to the back of the engine, what should I remove to get access to the 6 or 7 O-rings and old coolant hoses back there? The air intake duct from the air box, sure. But also the little platform with all the small air hose connections, the duct going into the intake manifold, the manifold itself?? The PCV parts and pieces? How much do AI need to pull out?
 

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This should help. Pics are at the end.
 

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Discussion Starter #9
This should help. Pics are at the end.
Thanks!! Wow
 

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Double check the part numbers as they may have changed over the years.
 

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Discussion Starter #11 (Edited)
So @PZ, where is the leak? What tell tale signs should I be looking for? Do I need to look more around the back of the heads?

oh - and what’s a ‘combi valve’? (This is me, remember... no clue...)

100252


driver’s side:
100253


passenger’s side:
100254
 

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I don't see a leak on that. The coolant leaves a pink-white trail where it has leaked. The heater hoses behind the engine area also a common leak area (and a pain to reach). On the writeup, there are pics like yours, but you can see the dried coolant. On my own car, you can see a leak at the back of the left head, just next to the combi valve. The black metal is the coolant pipe, the part to the left is the combi valve. The problem with this is that if you pull the pipe off, every other seal will move enough to leak if not replaced.
100256
 

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combi valve is the round metal cylinder thingy (I think V6 has 2). It is opened via vacuum under ECM control and is used to inject air into the exhaust from the SAIP to help heat up the catalytic converters after a cold start.
 

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Discussion Starter #14 (Edited)
I don't see a leak on that. The coolant leaves a pink-white trail where it has leaked. The heater hoses behind the engine area also a common leak area (and a pain to reach). On the writeup, there are pics like yours, but you can see the dried coolant. On my own car, you can see a leak at the back of the left head, just next to the combi valve. The black metal is the coolant pipe, the part to the left is the combi valve. The problem with this is that if you pull the pipe off, every other seal will move enough to leak if not replaced.
View attachment 100256
I an ordering all o-rings and gaskets (the manifold & throttle body have 5 between them - and there are 4 other o-rings for the water tubes, and for good measure, replacing the bleeder valves and throttle body water hoses too (dealer prices in CAD):

coolantN 909 125 01O-Ring
$4.80​
3​
$14.40​
N 905 607 01O-Ring
$3.20​
1​
$3.20​
WHT 006 407O-Ring
$3.10​
1​
$3.10​
078 121 188 Aheater hose
$21.85​
1​
$21.85​
078 121 188 Bheater hose
$10.40​
1​
$10.40​
intake manifold078 129 717 Jgasket
$68.30​
2​
$136.60​
to throttle body078 133 073 Bgasket
$55.90​
1​
$55.90​
to snorkle078 129 949 Cgasket
$23.30​
1​
$23.30​
bleederN 013 811 5seal ring
$0.78​
2​
$1.56​
N 016 024 3threaded plug
$5.60​
2​
$11.20​
 

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Discussion Starter #15
Yikes, why is thread lock SO expensive?!? LOL
 

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Those are great prices on the heater hoses, but they kill you on the gaskets.
 

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I an ordering all o-rings and gaskets (the manifold & throttle body have 5 between them - and there are 4 other o-rings for the water tubes, and for good measure, replacing the bleeder valves and throttle body water hoses too (dealer prices in CAD):

coolantN 909 125 01O-Ring
$4.80​
3​
$14.40​
N 905 607 01O-Ring
$3.20​
1​
$3.20​
WHT 006 407O-Ring
$3.10​
1​
$3.10​
078 121 188 Aheater hose
$21.85​
1​
$21.85​
078 121 188 Bheater hose
$10.40​
1​
$10.40​
intake manifold078 129 717 Jgasket
$68.30​
2​
$136.60​
to throttle body078 133 073 Bgasket
$55.90​
1​
$55.90​
to snorkle078 129 949 Cgasket
$23.30​
1​
$23.30​
bleederN 013 811 5seal ring
$0.78​
2​
$1.56​
N 016 024 3threaded plug
$5.60​
2​
$11.20​
I an ordering all o-rings and gaskets (the manifold & throttle body have 5 between them - and there are 4 other o-rings for the water tubes, and for good measure, replacing the bleeder valves and throttle body water hoses too (dealer prices in CAD):

coolantN 909 125 01O-Ring
$4.80​
3​
$14.40​
N 905 607 01O-Ring
$3.20​
1​
$3.20​
WHT 006 407O-Ring
$3.10​
1​
$3.10​
078 121 188 Aheater hose
$21.85​
1​
$21.85​
078 121 188 Bheater hose
$10.40​
1​
$10.40​
intake manifold078 129 717 Jgasket
$68.30​
2​
$136.60​
to throttle body078 133 073 Bgasket
$55.90​
1​
$55.90​
to snorkle078 129 949 Cgasket
$23.30​
1​
$23.30​
bleederN 013 811 5seal ring
$0.78​
2​
$1.56​
N 016 024 3threaded plug
$5.60​
2​
$11.20​
Let me guess, you work for Ernst & Young !
 

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Discussion Starter #18
Let me guess, you work for Ernst & Young !
??? Nope. I’m actually in Ag Tech and run our global engineering department. Why E&Y? I’m just a lazy paranoid SOB that doesn’t want to dig this all out again lol. Oh the grid? Just habits from project/budgeting work...
 
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Discussion Starter #19
Ok kinda frustrated on finding the leak. I’m beginning to think the ‘rust’ looking... rust... is the end result of the coolant screaming out as steam. When the leak occurs, there’s just steam and nothing drips to the road/garage floor. If ‘rust’ is the symptom then I do have to replace the temp sensor o-ring, and the o-rings to the water pipe connections at the front of the engine and the middle one at the back. The connections of the water pipe at the back of the heads are fine. It still means I have to replace those o-rings anyway...

Passenger side underneath:

100280


on top:

100284


driver’s side:

100285


back pipe:

100286


temp sensor:

100287
 

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Discussion Starter #20
I’m really tempted to just try replacing the temp sensor o-ring and the bleeder valves/seals. Then see if that fixes it. Those are the only places where it looks like stuff came out and that’s where the steam was
 
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