Coolant pressure test: will it reveal PCV or IC leaks?

[Waffles_s4]

Hi all,

I am having what it seems a small or slow coolant leak.

I pressure tested it, it did not drop after 1 hour.

I did carbon cleaning about 15,000 miles ago, and at the time, the Intercooler cores were fine, no leaks. I did not notice the thermostat or water pump leaking. No signs of leaks anywhere.

The oil looks fine, level is fine, no signs of coolant in oil.

My question is: will a pressure test on the coolant reveal if the PCV is leaking coolant into the block?

[DM_CincyEast]

Not sure if a pressure test would reveal an issue.

Did you replace the o-ring on the coolant pipe that runs front to back above the PCV?

It's a stupid design, but that seal is very sensitive to leaks. It's also one that's heavily influenced by heat, so no leak in the garage but maybe while driving.

[DM_CincyEast]

It would be this pipe circled in redhttps://uploads.tapatalk-cdn.com/20240713/70301ea41cd0cd5f0e185d95f8ddb59c.jpg

[Waffles_s4]

It would be this pipe circled in redhttps://uploads.tapatalk-cdn.com/20240713/70301ea41cd0cd5f0e185d95f8ddb59c.jpg

Nope, I did not touch anything related to PCV or coolant pipes/hoses. At the time, I saw no coolant anywhere...

If I take the SC off, I could inspect pretty much everything; intercooler, coolant pipes, thermostat, water pump, PCV and what not.

[Nelson G]

No this is the pipe: https://www.fcpeuro.com/products/audi-vw-coolant-hose-genuine-audi-vw-06e121045bb

And yes if you pressurize the system you will either hear and or see where the coolant is coming from. That is how I found that the coolant hose was leaking.

[LowKeyLoki]

Yes pressurizing the system will show the leak, just did this for both my water pump and Pcv system both failed one after the other within a week. Replace all the plastic cross over pipes, the one above circled in red i would buy the URö brand. They upgraded it to a metal pipe much more durable. Might as well replace the Pcv if it’s the original still, they alll fail, mine started mixing coolant and oil. Luckily I caught it right when it happened.

[Waffles_s4]

In my case, the pressurized test wont drop the pressure, meaning as if there was no leaks. What could it be then?

[maksym]

Hi all,

I am having what it seems a small or slow coolant leak.

I pressure tested it, it did not drop after 1 hour.

I did carbon cleaning about 15,000 miles ago, and at the time, the Intercooler cores were fine, no leaks. I did not notice the thermostat or water pump leaking. No signs of leaks anywhere.

The oil looks fine, level is fine, no signs of coolant in oil.

My question is: will a pressure test on the coolant reveal if the PCV is leaking coolant into the block?

Pressure test definitely worked on my pcv, albeit not very fast - there was a tiny stream coming down the block under supercharger. I did have signs of leak before the test though- faint smell of coolant and white splotches to the left of the engine, most noticeable when driving hard (driving hard is essentially a pressure test).


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[Nillious]

In my 20 years of working as a mechanic I’ve had SEVERAL cases where a simple pressure test does not reveal a leak. Sometimes it’s hard to simulate the running temperatures and vibration of the car running. Try hot cold and warm. Wiggle and move different junctions and fittings. Remember your heat exchanger and pump are linked. Could be a leak in those hidden areas. Also the water pump vacuum diaphragm can leak and drink coolant while running. Just some things to consider if you have not checked them.

[Waffles_s4]

In my 20 years of working as a mechanic I’ve had SEVERAL cases where a simple pressure test does not reveal a leak. Sometimes it’s hard to simulate the running temperatures and vibration of the car running. Try hot cold and warm. Wiggle and move different junctions and fittings. Remember your heat exchanger and pump are linked. Could be a leak in those hidden areas. Also the water pump vacuum diaphragm can leak and drink coolant while running. Just some things to consider if you have not checked them.

My issue is that I currently do not see any leaks under the car, under the hood, or near anything coolant related. If the only choice is to remove the SC, then I would have to do so. I dont see any rise of oil level, nor weird colors under the oil cap.

[Waffles_s4]

Pressure test definitely worked on my pcv, albeit not very fast - there was a tiny stream coming down the block under supercharger. I did have signs of leak before the test though- faint smell of coolant and white splotches to the left of the engine, most noticeable when driving hard (driving hard is essentially a pressure test).


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When u mention white splotches to the left of the engine, is that after taking the SC off, or totally from the exterior?

[maksym]

When u mention white splotches to the left of the engine, is that after taking the SC off, or totally from the exterior?

No, just from driving. It drips from under SC on the belts and belts throw drops of the coolant to left. Drops dry to whitish color. Though not redlining and driving like a sane person did barely any drops in coolant level. I think I had to take pressure tester close to the limit as well, but I might be imagining things.


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[keithyo88]

No, just from driving. It drips from under SC on the belts and belts throw drops of the coolant to left. Drops dry to whitish color. Though not redlining and driving like a sane person did barely any drops in coolant level. I think I had to take pressure tester close to the limit as well, but I might be imagining things.


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I am seeing similar drips to you, with very slow coolant loss. Please update if you found the leak. Thanks.

[maksym]

I am seeing similar drips to you, with very slow coolant loss. Please update if you found the leak. Thanks.

Yes, that was many years ago. Rented pressure tester from Advanced Auto Parts, pressurized, waited for about 10 minutes and observed coolant dripping from under thr supercharger pulley, which indicated PCV valve - it sits in the valley under the supercharger. Replacing the PCV fixed the problem. Also made sure to pressure test super charger radiators - other common point of failure.


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