Head Gasket Diagnosis Help - Would you post a quick video of ALH coolant cap removal?

[sangretdi]

I'm having trouble diagnosing a *possible* head gasket breach. Been reading up on here regarding the amount of "normal" pressure in the cooling system. Would any kind and willing ALH owners (with good motors!) post up a quick video clip of removing your coolant pressure cap after a freeway drive? And another, if possible, after freeway driving then sitting overnight? Would like to see what amount of pressure release is "normal".
Many thanks!
Mike

 

[STDOUBT]

I'm pretty sure uncapping at full temp is not safe. Never tried it.
The test I've learned is that if you uncap after sitting overnight (stone cold), any pressure release = bad news.
Are you seeing oil in your overflow tank? Any other symptoms?

 

[Nero Morg]

Have a car in my car port at this very moment that had a head gasket breach. Had flakes of soot in the coolant ball. Lost a gallon of water every 20 miles. That's the easiest way to tell. And I second it, definitely not a good idea to remove the cap when hot. 3rd degree burns hurt.

 

[Mongler98]

When the car cools off, almost no pressure will come out. Please dknt don't when hot. Lots of hot coolant will burn your self and it comes out really fast. These systems are not ment to be opened like that.
What you need to do is a leakdown test. It could be coming from the egr cooler.

 

['lectricjeff]

Most cooling systems operate at 15 PSI. Pressurize the system with a proper tool and check for leak down. How does the oil look, if it looks like chocolate milk you have a problem. Are you seeing any smoke/steam out the exhaust while driving?

 

[Mike_04GolfTDI]

Cooling system remaining pressurized when cold is a sign of a leaking head gasket.

This is because high pressure combustion gasses can be forced through the slightest imperfection into the cooling system, which will relieve excess pressure to keep it at 15 PSI.

The 15 PSI residual pressure in the cooling system may not necessarily be enough to force itself back the other way into the combustion chamber.

So the head gasket is acting kind of like a check valve. Hundreds or thousands of PSI gasses will leak through, but 15 PSI won't go the other way, so it stays in the cooling system. It stays pressurized when cold because something has been added that isn't supposed to be there.

There can also be other reasons for this, such as a block or cylinder head that are cracked or warped.

 

[Mongler98]

Cooling system remaining pressurized when cold is a sign of a leaking head gasket.

Not all the time, if you let it cool down over night, it will actually cause a suction. You displace Coolent, LOT OF IT with steam, 1 drop of water makes about 6,000x more displacement in steam form When this all cools down this condenses back to a liquid and pulls a vacuum basically
My AHU always had the hoses sucked in after a night after driving for years with the head gasket head lift issue. It depends on how bad it is, just a little bit, yea pressure left over once cool but if you displace enough, it goes the other way.

OP, if once the engine and all are cold, and you have pressure in the system, LOTS of it, not just a tiny little psst when you open it, you probably have a head lift or EGR failure. Keep track of how much you loos and put a temp gauge on your coolent, dont trust the idiot gauge on the dash, IT WILL LIE TO YOU.

 

[sangretdi]

Hi guys,

I appreciate all the replies!

The spectrum of comments of what constitutes a "problem" or not i've read on here before (no pressure when cold is ok, some when cold is ok, oil in the coolant, no oil in the coolant, etc) that is why I am asking for a video of how much pressure release is deemed "OK"

As far as removing the coolant cap hot, totally understand if that seems too sketchy to try, but my car doesn't shoot out any scalding coolant when removed at temperature/190, but a tone of air pressure -yes! (A cold overnight video is appreciated too (and maybe more useful for diagnosis?!)

My car:
evidence of some oily soot on the inside walls of the coolant globe.

No signs of oil in coolant, no coolant in oil. Have read on here that's not always the case.

Did a diesel combustion gas in coolant test- negative. Have read on here, those test often give false negative.

Lots of pressure when coolant cap released hot.

Some pressure when released cold/next morning

did a 15lb pressure test at coolant bottle, no leak detected. Read on here not always the case. see above for 1-way valve explanation.

Did a compression test on 3 cylinders, till I got to the 4th and discovered the PO had stripped the glow plug treads and did a janky repair. didn't want to risk cross threading my tester on that cylinder. Glow plug does seal, however.

The heater core was replaced by the PO (possible sign of HG?)

o-ring in the Coolant cap was removed by the PO or just missing... (possible sign trying to vent excess pressure caused from HG?)

I discovered the PO had the flex pipe , between the EGR cooler and EGR valve, welded "closed" ... an EGR delete of sorts?

Since I want the EGR valve functioning I put a stock/open flex pipe on there.
Since I've done that I've noticed an ocational "pop" noise in the intact tract.
Not always there though and non constant by any means. (ALH motor, not worn cam from BEW)

I'm just trouble shooting the soot and popping noise- wondering if these point to a head gasket issue and/or EGR cooler issue? or not at all?

could anyone explain how a bad egr cooler could cause the cooling system to be pressurized and how to test for that? since the popping sound came after freeing up the EGR cooler...

thank you!
Mike

 

[Mongler98]

Egr passes coolant though some pipes that the exhaust passes over. If it leaks, the exhaust gasses will push into the cooler pipes but not the other way around that you will notice. Bypass the coolant loop ilto it and see how it behaves

 

[sangretdi]

Egr passes coolant though some pipes that the exhaust passes over. If it leaks, the exhaust gasses will push into the cooler pipes but not the other way around that you will notice. Bypass the coolant loop ilto it and see how it behaves

Thanks Mongler!

Is there enough slack between the two hoses to disconnect from the cooler and then connect them together with a coupler?

Or this kit from IDparts looks like it does this?
https://www.idparts.com/product_info.php?products_id=2170{3}512

 

[ghohouston]

I'd bet the water pump is shot. Remove thermostat and see if you can spin the impeller. If you can spin it/move it around, its crap. Had a metal impeller waterpump shear off within 15k miles of a tdi club recommended mechanic shop doing the timing belt. I swore it was a blown head gasket too.

Are you dealing with overheating as well?

 

[Mongler98]

Yea kinda, you need to make a part like the shape of a U to connect them. I made mine out of copper bits. Pex fittings seems to be the right size.

 

[sangretdi]

Yea kinda, you need to make a part like the shape of a U to connect them. I made mine out of copper bits. Pex fittings seems to be the right size.

Cool, i'll swing by the plumbing place and grab a couple fittings. thanks

 

[sangretdi]

I'd bet the water pump is shot. Remove thermostat and see if you can spin the impeller. If you can spin it/move it around, its crap. Had a metal impeller waterpump shear off within 15k miles of a tdi club recommended mechanic shop doing the timing belt. I swore it was a blown head gasket too.

Are you dealing with overheating as well?

I did the timing belt/water pump myself 30K ago with a quality kit from IDparts, no overheating, so think the WP is good. thanks for the suggestion though!

 

[sangretdi]

I *might* have dodged a bullet here.... My coolant flange was leaking, hard to tell 'cause it was mixing with all the oil on the back of the motor. Found it after adding uv dye to the cooling system. Will replace that coolant o-ring and the gasket in the vacuum pump that's leaking oil.

doesn't account for the oily residue on the coolant globe walls though.. or the occasional "pop" in the intake...?

 

[Mongler98]

Wait, you have a pop from the intake, like a backfire? You never mentioned this before.
That's extremely bad for both the engine and the turbo. If you actually have a detonation coming from the in intake and blowing back up into the intercooler and turbo, do not drive it one more inch. Your pulling that head, and expect burnt seats, headgasket, turbo failure soon, complete head job, etc....
I told you to do a leakdown test. If you have popping from the intake, a leakdown test would have showed you your intake valves leak and you reported no such thing
Did you actually do a proper leak down of each cylinder?

 

[sangretdi]

Wait, you have a pop from the intake, like a backfire? You never mentioned this before.
That's extremely bad for both the engine and the turbo. If you actually have a detonation coming from the in intake and blowing back up into the intercooler and turbo, do not drive it one more inch. Your pulling that head, and expect burnt seats, headgasket, turbo failure soon, complete head job, etc....
I told you to do a leakdown test. If you have popping from the intake, a leakdown test would have showed you your intake valves leak and you reported no such thing
Did you actually do a proper leak down of each cylinder?

Hi Mongler,

I did mention that in post#8. People were asking symptoms so tried to give anything that could be related to the oily residue in coolant globe, and loosing coolant. After swapping out the o-ring in the coolant flange no more loosing coolant that i can measure...

The pop is NOT constant, happens only occationaly. it showed up after I "undeleted" the EGR...

Also, I am NOT pushing coolant out of the globe. Is that a mandatory sign of head gasket?

I mentioned in #8 that I began a compression test, not leak down, but discovered PO had stripped out glow plug #4 so didn't want to risk stripping out my tester.

BTW, was your EGR cooler the cause of your problems?

 

[Mongler98]

Hi Mongler,

I did mention that in post#8. People were asking symptoms so tried to give anything that could be related to the oily residue in coolant globe, and loosing coolant. After swapping out the o-ring in the coolant flange no more loosing coolant that i can measure...

The pop is NOT constant, happens only occationaly. it showed up after I "undeleted" the EGR...

Also, I am NOT pushing coolant out of the globe. Is that a mandatory sign of head gasket?

I mentioned in #8 that I began a compression test, not leak down, but discovered PO had stripped out glow plug #4 so didn't want to risk stripping out my tester.

BTW, was your EGR cooler the cause of your problems?

oh no, my issue is 32 PSI on a engine i overheated MANYaTIME and 230 HP with some sick temps. dont worry about why my AHU is a pile of parts right now! (hint: Im doin a 350HP+ build into a Porsche 944 with it!!!!)

Pushing out coolant is not a head gasket necessarily. the EGR can also do this.

My advice on the pop issue, get the tool to remove the glow plug, there is a very specific tool to remove this, do a search on it, there is also a tool to tap and fix it if it gets worse. Compression and leak down test are going to be CRITICAL to making sure you pop is not from a leaking valve. you might want to check your timing marks and make sure its spot on, also VCDS and check your timing advance. those 2 things could also be a possibility to a poping sound. are you sure its from the intake?

 

[sangretdi]

oh no, my issue is 32 PSI on a engine i overheated MANYaTIME and 230 HP with some sick temps. dont worry about why my AHU is a pile of parts right now! (hint: Im doin a 350HP+ build into a Porsche 944 with it!!!!)

Pushing out coolant is not a head gasket necessarily. the EGR can also do this.

My advice on the pop issue, get the tool to remove the glow plug, there is a very specific tool to remove this, do a search on it, there is also a tool to tap and fix it if it gets worse. Compression and leak down test are going to be CRITICAL to making sure you pop is not from a leaking valve. you might want to check your timing marks and make sure its spot on, also VCDS and check your timing advance. those 2 things could also be a possibility to a poping sound. are you sure its from the intake?

Mongler,
Woah! I was hoping to put a chip and bigger nozzles in mine, but you're obviously on a whole OTHER level with your cars! LOL!

To clarify --- if you do *not* have coolant pushing out of the globe, does that mean you do *not* have a head gasket breach? and/or EGR issue?
If that is the case, I can rule that out now! (fingers crossed)

since i *was* loosing coolant and saw some oily residue in the globe, i was trying to decipher if that was a head gasket (or egr).
The coolant leak was the o-ring in the coolant flange. appears to no longer be loosing coolant, though haven't driven much or pushed it hard this week.

The glow plug thread -
this had some terrible "repair" done to it already by po/or po's mechanic. it must have been stripped/cross threaded and then it was "fixed" by stacking TWO helicoils... like they didn't have one long enough so did two...? never seen that before. You can thread the glow plug in just fine through the first heli-coil, but then when it gets to the 2nd helicoil, the threads don't line up, so then as you seat the plug farther, you strip the threads on the GP. It will seat and seal though! But when you remove the GP, it is then rendered unusable because the lower threads are now stripped out on it, so no way to reinstall it.

compression was good on the 3 cylinders i could test.
i could do a leak down on those 3 also...

popping sound ---

I did the belt with all the proper ALH tools, double checked timing marks etc.
I have VCDS, just checked, timing graph is spot on.
motor overall runs well. no smoke. no cold start issues.

the popping isn't constant, which i figured would rule out the valves???
sometimes it pops a lot, other times it doesn't...
pretty sure, but I'll remove the intake again at the EGR valve

I just ordered a new globe from idparts, just to see if any new soot or oil appears..

 

[Nero Morg]

A blown head gasket won't always push coolant out of the ball. It most likely will push particulates into the coolant though. Little black specs. After doing the head gasket last week on my friends car, it's been his daily with no issues. Save up for a gasket and maybe some ARPs.

 

[sangretdi]

A blown head gasket won't always push coolant out of the ball. It most likely will push particulates into the coolant though. Little black specs. After doing the head gasket last week on my friends car, it's been his daily with no issues. Save up for a gasket and maybe some ARPs.

Nero, thank you. I'm not seeing specs, like floating debris... there is some oily streaking areas on the inside of the globe, put a finger in there you can feel it. hmmmm...?

I'm going to swap out the globe, drain the old coolant (uv dye is in it) it and fill it fresh. should be easy to see if there's any new contamination/specs after that...

btw, when you run your car hard and let it cool off over night is there ANY pressure in your cooling system when you remove the cap?
I'm hearing "some" is ok and that "none" is ok...

 

[Nero Morg]

Pressure *should* be fully equalized after a cold soak, speaking you have correct coolant level, a good cap, no bad head gasket, coolant leaks, ect. Maybe a fraction of 1psi is all. But nothing significant. If it was the head, it'd be close to relief pressure (17psi iirc) after cold soaking.

 

[sangretdi]

Pressure *should* be fully equalized after a cold soak, speaking you have correct coolant level, a good cap, no bad head gasket, coolant leaks, ect. Maybe a fraction of 1psi is all. But nothing significant. If it was the head, it'd be close to relief pressure (17psi iirc) after cold soaking.

OK, thank you!

I'm gonna say my head gasket is OK then.

I pressure tested my cooling system and it held at 15 psi
(i left it for an hour, held steady)

when I removed the cap this morning after beating on it yesturday, you could feel the slight sensation of pressure as the o-ring seal broke, but no "whoosh" or anything remotely close to 17 psi

the oily reside in the globe --
maybe a PO had a leaky oil cooler at some point?
or EGR cooler has a slight leak?

occational popping noise--
egr leak?
possibly something weird with the vacuum and popping egr valve...

will swap out the globe and coolant and see if anymore new oily reside appears.