Coolant in Air Filter Housing
Thread Starter
Instructor
Joined: Oct 2013
Posts: 137
Likes: 1
From: Fairborn Ohio
Coolant in Air Filter Housing
Anybody have an idea on this one? While changing the air filter housing on my 1989 coupe I found coolant in the air filter housing. Seems to be fairly recent as the coolant wasn't evaporated. Wasn't a lot - less than 1/2 a cup - but really causes me to wonder how the coolant got there. 
Drifting
Joined: Feb 2008
Posts: 1,538
Likes: 178
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
Are you loosing coolant? Pressure test the system.
Anybody have an idea on this one? While changing the air filter housing on my 1989 coupe I found coolant in the air filter housing. Seems to be fairly recent as the coolant wasn't evaporated. Wasn't a lot - less than 1/2 a cup - but really causes me to wonder how the coolant got there.
Burning Brakes
Joined: Jun 2005
Posts: 1,191
Likes: 15
From: Wallingford Vermont
Is the coolant migrating down from the throttle body? Is it in the accordion tube? Never heard of a throttle body leaking like that but who knows. The only other possibility I could think of would be some type of radiator leak that is getting sucked into the air filter, very odd.
Thread Starter
Instructor
Joined: Oct 2013
Posts: 137
Likes: 1
From: Fairborn Ohio
I hadn't thought about coolant migrating down from the throttle body! I'll check the accordian tube this evening. I did consider a radiator leak and then fluid being sucked into the filter. Yes, odd to me as well. Ken - thanks for the tip on the pressure test. Another one for me to follow up on as well.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Don't think your coolant is coming from the TB, especially when the car is running. The air flow is into the TB not reverse. It is also a long way to travel and you would be having other issues. Check coolant engine in radiator. I would expect it to be a little low. Guessing you have a radiator leak that has a small stream from the radiator shooting forward and entering the air cleaner. Pressure check the radiator as suggested above and look for the stream.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Well, it actually CAN be coming from the TB....the bottom is full of coolant that's being pulled IN as the engine is running,. BUT
when you shut down the cooling system is still pressurized for several hours and a tiny leak in the TB coolant passage could dribble a 1/2 cup down into the filter as the pressure forced liquid out of the TB and into the accordion to the filter.
If there is no coolant on the ground after letting it cool off, that has to be it. If it were an external leak that happened to spray at the filter, then it would have some evidence on the ground as well...
when you shut down the cooling system is still pressurized for several hours and a tiny leak in the TB coolant passage could dribble a 1/2 cup down into the filter as the pressure forced liquid out of the TB and into the accordion to the filter.
If there is no coolant on the ground after letting it cool off, that has to be it. If it were an external leak that happened to spray at the filter, then it would have some evidence on the ground as well...
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
I would think it (coolant from the TB) would hit the MAF sensor first and cause issues there before going to the air cleaner housing.
Next question....does the air filter show signs of coolant hitting it or is it dry and clean?
Next question....does the air filter show signs of coolant hitting it or is it dry and clean?
Burning Brakes
Joined: Jun 2005
Posts: 1,191
Likes: 15
From: Wallingford Vermont
Years ago, my FIL called me from a parking lot when his Chevy Citation died. He explained that he had gas in his airfilter 
He was not a "car-guy" so I hustled down to take a look. Sure enough the air filter was saturated. Seems the fuel pressure regulator diaphragm had ruptured and was sending fuel back up the vacuum line to the manifold and down the intake tube. And yes that raw gas went through the MAF sensor (which survived), but it certainly gave new meaning to the term "burn off module".
He was not a "car-guy" so I hustled down to take a look. Sure enough the air filter was saturated. Seems the fuel pressure regulator diaphragm had ruptured and was sending fuel back up the vacuum line to the manifold and down the intake tube. And yes that raw gas went through the MAF sensor (which survived), but it certainly gave new meaning to the term "burn off module".
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Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
yep, there is some strange stuff that can happen in cars...
just 'cause its not normal don't mean it can't happen !
Like the 1st time I saw my engine running and spraying RAW Gas out of the exhaust !
besides being scared spitless
( all I could think of was BOOM !)
....the question of how in the hell can this happen, started to echo in the vast emptiness aka my head.
**************************************** ***************
(answer to the quiz, batch-fired fuel injectors and ONE shorted to ground thus shorting that bank and sticking them ALL WFO instead of any kind of duty cycle) It gushed gas into the rt bank WITH the left bank doing all the work and running the engine !That alone was a BIG surprise.
God only knows how close it came to hydro'ng each of those 4 cylinders !
That sucked several GALLONS in just a couple minutes, with about 2 gal in the crankcase. The rest went out the tail pipe.
Strange butt true....
just 'cause its not normal don't mean it can't happen !
Like the 1st time I saw my engine running and spraying RAW Gas out of the exhaust !
besides being scared spitless
( all I could think of was BOOM !)
....the question of how in the hell can this happen, started to echo in the vast emptiness aka my head.
**************************************** ***************
(answer to the quiz, batch-fired fuel injectors and ONE shorted to ground thus shorting that bank and sticking them ALL WFO instead of any kind of duty cycle) It gushed gas into the rt bank WITH the left bank doing all the work and running the engine !That alone was a BIG surprise.
God only knows how close it came to hydro'ng each of those 4 cylinders !
That sucked several GALLONS in just a couple minutes, with about 2 gal in the crankcase.
The rest went out the tail pipe.Strange butt true....
Thread Starter
Instructor
Joined: Oct 2013
Posts: 137
Likes: 1
From: Fairborn Ohio
Well, it actually CAN be coming from the TB....the bottom is full of coolant that's being pulled IN as the engine is running,. BUT
when you shut down the cooling system is still pressurized for several hours and a tiny leak in the TB coolant passage could dribble a 1/2 cup down into the filter as the pressure forced liquid out of the TB and into the accordion to the filter.
If there is no coolant on the ground after letting it cool off, that has to be it. If it were an external leak that happened to spray at the filter, then it would have some evidence on the ground as well...
when you shut down the cooling system is still pressurized for several hours and a tiny leak in the TB coolant passage could dribble a 1/2 cup down into the filter as the pressure forced liquid out of the TB and into the accordion to the filter.
If there is no coolant on the ground after letting it cool off, that has to be it. If it were an external leak that happened to spray at the filter, then it would have some evidence on the ground as well...