SicOne

Long winded warning....

Have a 2002 3.0 auto, has 192k miles so it certainly is past its shelf life..... But I drove it about 15k miles since I got it this summer and has always lost coolant (It was summer so I mostly filled with water, never ran hot or any ill effects.) and really no oil loss (not concerning anyway) in the fall I got a low oil pressure light and accompanied by a rattle to verify just that when hot. Rattle/knock would go away when cooled down. Changed the oil with no change. Dropped the oil pan and cleaned the pump out, screen and the valley check valves.

Dove the car to work (40 miles one way) no issue no light, on the way home about 35 miles in the light is back on. but no noise, then coolant light came on. Got home no noises and ran great,Drained oil and put in heavier weight oil, Winter was coming so decided I need to fix the coolant loss issue because water is mainly if not strictly just in the system and I am in Minnesota.

Found to be bad and replaced o ring on crossover pipe and new expansion tank, vacuumed the system and held vacuum just fine so proceeded to suck the coolant in, start the car and burp anything that maybe in the system and let idle for probably 45 mins, no coolant loss and no oil light or rattle, shut the car off and it sat for maybe 15min, Went to pull it out and wouldn't start so I tried a bit as this is odd then the starter thud and no crank but could feel it try to turn the engine over,

Figured hydro locked, Pulled spark plugs and coolant in 2 cylinders on driver side a 2 on passenger side, after seeing this I said F it and went in for the night.

Next morning I walk in and seen something dripping below my car, It's the driverside middle cylinder completely filled with coolant and was dripping out of the spark plug tube (spark plugs removed) sucked the coolant out, sprayed the plugs with cleaner, dried them threw them in, started up, white smoke barreling out and just parked the car... I have had a interesting odd smell (very dry smell) when I got on it that I haver never smelled when I cut the mufflers off (was bored). Well what it was, was water burning but no smoke, no weird feeling and power seemed there so meaning that it has been leaking into the cylinders for a while but never filled a cylinder up or had hard starts after sitting days and drove fine.

The questions...... (mind you I never overheated the car)
Why would when vacuuming the cooling system did it hold vacuum just fine with coolant being in that many cylinders? (Not all the cylinders are going to be TDC or BDC!)
Why would coolant be in both banks? (Likelihood of both head gaskets going especially when it never overheated or ran hot? impossible?)
So with the likelihood of it not being head gaskets, There is no coolant ports in the intake, Then HOW?

I do not know these engines well and researching I only find info on the 3.0T Which come to find out is very common to have coolant in cylinders from the intercoolers leaking 😂

turbo510

This is the first I've heard of a problem like this on the 3.0. Engine is obviously junk now, but why? I suspect that at some point the water froze and cracked the heads or distorted the gaskets. Antifreeze always in your location I'd say.

AudiAllTheWay

Running water only with no G12 is not a good idea and certainly does not guarantee not overheating the heads, especially since the coolant temp sensors are not in the heads. Having said that, only the person who repaired the cross over pipe leak (or other repairs) would know if they misconnected a vacuum hose with a coolant hose, as this could explain how coolant gets sucked into the intake.

SicOne

no at this time it never got cold. I drove it out of the shop. It drove fine and system held vacuum. Cracked anything shouldn't hold vacuum either.

Cracked headS is another one that the likelihood of that as being the issue.

As i said, i suspect this is not exactly new as it's now evident the smell i l was smelling was water vaporizing but not at this rate. Never hydro locked for sure. But why low oil pressure alert now and all this when I have never overheated? Certainly odd.

I took the intake manifold off to clean the oil check valves and here was no coolant passage or hoses connected to the intake but it would seem the most likely way of intrusion with being in multitude cylinders in both banks. The cylinder filling up just could mean those valves were open on that cylinder I admittedly was not happy so I didn't study every cylinder well and should have looked more into it at that time.

One thing I didn't remove is the throttle body.... Does that have coolant lines going into it? I know there's a few lines going to it but i figure they are vacuum... Speaking of which, still helf -15psi vacuum for at least 2 mins while i got everything else ready.

SicOne

I didn't unhook any hoses Except pcv. As i said I suspect this issue had been on going just not to this extreme.

Head gaskets, warped heads, cracked cylinder walls still doesn't explain the holding vacuum.

Is there a coolant hose that could be mistaken for a vac line? I don't believe there is. I guess I'm seeing if there is any specific issues with these engines in particularly for me to look into fast. (It's good af out)

turbo510

The throttle body has two coolant connections and two vacuum hose connections, at least on my 2005. You could take a cylinder head off for a look, but I think that the engine has been mortally damaged. Hydro-lock often bends connecting rods.

AudiAllTheWay

Vacuum system has some check valves so in theory, if vacuum and coolant lines were cross connected, then the coolant system could still hold vacuum during your test. I am not saying 100% this is your issue, but it is a suspect.

AudiAllTheWay

Could pull the throttle body and look around, and pressure test the two coolant connections on the throttle body housing to test for an internal crack / leak. At least this is simple first checks before the significant effort of pulling intake and cylinder heads.

https://www.audizine.com/forum/showt...-Throttle-Body

SicOne

Thank you for this, I did not know there is coolant lines in the throttle body, I leave the throttle body in the car when I removed the intake so I did not see that. The only weird thing is the exhaust didn't smoke, at all! But this makes the most sense in my situation, your previous reply about the check valves makes the most logical sense with holding vacuum. but in my situation no because I did not take them off.

SicOne

I think it's fine for whatever reason it never cranked then stopped, just stopped. And after the fact it ran decent once the cylinders cleaned out.