car overheating!!!!

[johnathan1]

hello, everyone... today, when i was on the freeway for about an hour (moderate boosting @~10psi) i max boosted, and my check engine light came on, so I pulled over, but the car was perfectly fine, so I kept driving, and shortly after, it started overheating, the gauge would keep creeping up, and then down, up and down, etc...

it seemed like when i would rev or downshift it would temporarily make the temp go down. So i arrived at my destination when it was almost in the red, and turned it off, and the overflow resorvoir was full, and shaking. When I took out the overflow tube, steam was spraying out of it, keep in mind that the gauge started moving around 1/2 way through the trip, and up until that point it was absolutely perfect, also the coolant level was fine, as I checked it before I left. Also, I pulled codes, and got #21 (oxygen sensor):dunno: . Please help!! Thanks!

 

[IJ.]

Sounds like it leaned out and blew the head gasket......

 

[johnathan1]

Also, I dont believe my o2 sensor is even connected right now...

 

[IJ.]

Not sure how anal the Mk3 ECU is but most will limp when the 02 is dead or unconnected so maybe pushing it so hard would account for the lean condition that blew the HG?

Wait a bit and someone that knows will jump in and answer.

 

[johnathan1]

what makes you so sure that the hg is blown, it could be a million different things, like a leaking coolant hose, clogged radiator, water pump, the list goes on...

 

[Nick56289]

what makes you so sure that the hg is blown, it could be a million different things, like a leaking coolant hose, clogged radiator, water pump, the list goes on...

Yea it really could be any one of those things. When I blew my headgasket I was thinking the same thing. But with what you described and in all likelyhood its a BHG. Check out everything but save yourself some time and start with a BHG check. Sorry man.

 

[IJ.]

what makes you so sure that the hg is blown, it could be a million different things, like a leaking coolant hose, clogged radiator, water pump, the list goes on...

It's a 7M.....

 

[Joel W.]

It's a 7M.....

IJ,:yelrotflm

John. see the "how you know your a supra owner" thread...

any smoke at the time? sorry to hear it... hope ya get it fixed..

 

[Dirgle]

Also, I don’t believe my o2 sensor is even connected right now...

Why wasn't it connected, and why were you going into positive manifold pressures without being sure it was connected?

what makes you so sure that the hg is blown, it could be a million different things, like a leaking coolant hose, clogged radiator, water pump, the list goes on...

While it is possible for it to be other things, in all likely hood it is the HG. Especially running a faulty o2 sensor on a boosted engine. On a boosted engine the potential for running lean is very high, and can cause a lot of damage. For this reason the A/F ratio's must be kept in check (especially since your running over stock boost), and this cannot be accomplished with faulty equipment.

You can test for a BHG by performing a leak down test. Also before you run the car much more you need to check to make sure that there isn't coolant in your oil. Check under you oil cap and on your dipstick for any kind of milky white/brown froth (AKA milkshake)

Also, if your still convinced that it might not be a BHG you can pressurize the cooling system, and check for leaks. Most likely you won't find any. (Beware if you pressurize the cooling system, find it to be losing pressure but can see no visible leaks. It is possible that it is a BHG. This can result in coolant being forced in to the cylinders and can create hydro-lock if the car is started. Hydro-lock as we all know can destroy internals. So just be cautious of that.)

To check the water pump, take the radiator cap off and bring the car up to operating temp( the point where the thermostat opens) and see if there is flow in the radiator or check to see if you are receiving heat from the climate control. Either of which indicate a functioning water pump.

 

[shaeff]

pressure test the cooling system, and do a leakdown test.

-shaeff

 

[JesseH]

hello, everyone... today, when i was on the freeway for about an hour (moderate boosting @~10psi) i max boosted, and my check engine light came on, so I pulled over, but the car was perfectly fine, so I kept driving, and shortly after, it started overheating, the gauge would keep creeping up, and then down, up and down, etc...

it seemed like when i would rev or downshift it would temporarily make the temp go down. So i arrived at my destination when it was almost in the red, and turned it off, and the overflow resorvoir was full, and shaking. When I took out the overflow tube, steam was spraying out of it, keep in mind that the gauge started moving around 1/2 way through the trip, and up until that point it was absolutely perfect, also the coolant level was fine, as I checked it before I left. Also, I pulled codes, and got #21 (oxygen sensor):dunno: . Please help!! Thanks!

You might want to check the coolant hose that goes behind the spark plug valley, I was having oveheating problems this last summer and after the gauge got really close to red it would start to smoke, and after changing everything possible I found out that that hose had a hole in it and since it was leaking the coolant would hit the engine causeing the smoke, So you might want to check it.

 

[jetjock]

What shaeff said.

If your O2 sensor isn't cross counting the TCCS will go into a open loop and the engine will run slightly rich. And if it's not even connected it's no wonder you're getting that code. In fact the MIL should've been on the entire time.

 

[NDBoost]

blown head gasket, your temp gauge is fluctuating because your getting air in your coolant system because of the BHG. which causes it to continually push coolant out through the overflow. Ask me how i know

 

[shaeff]

blown head gasket, your temp gauge is fluctuating because your getting air in your coolant system because of the BHG. which causes it to continually push coolant out through the overflow. Ask me how i know

it's WAY too early to tell, dude. seriously. right after my rebuild i had the same symptoms (minus the o2 sensor code). it turned out to be a pinhole in the only coolant hose i didnt replace (but was already on order). dont jump to conclusions!

as little as a coupler that's not tight, or a hose clamp, or a hole in a hose can cause overheating problems. we have pressurized cooling systems. when it becomes pressurized, coolant will escape through the leaks, and air will replace it, thus boiling the coolant, causing overheating.

-shaeff

 

[jetjock]

I agree. It's always best to approach a problem with an open mind and troubleshoot so as to prove a diagnosis a minimum of two ways. Pressure testing and checking for combustion gases in the coolant for example.

That said, taking all the symptoms into consideration my money is on the head gasket too.

 

[johnathan1]

ok, update. I burped the coolant system, and refilled it, and it seemed to be smoking SLIGHTLY at idle (although it could have been steam)... then I went for a drive, for about 20 mins, boosted about 4 times at no more than 6-8psi, and the car was absolutely fine, no missing coolant, no overheating, and no smoke WHATSOEVER. I also fixed the o2 sensor... I am totally stumped...

 

[johnathan1]

So...hmmm....

 

[jetjock]

So...hmmm....

If it is the head gasket it could be fine for days before it acts up again but eventually it'll get progressively worse. I'd still either pressure test the system or put a combustion gas checker on it. The first will find any external leaks while the second will rule out the HG. And understand that if it is the HG ignoring it could be bad news depending on where it's leaking. You're rolling the dice by doing nothing.

 

[Dirgle]

Just because there is no sign of combustion gasses in the coolant doesn’t necessarily mean the HG is not screwed up. It is possible for the coolant to push its way in to the oil passages, dumping coolant in to the oil, result of an overheated and warped head.

 

[rakkasan]

ok, update. I burped the coolant system, and refilled it, and it seemed to be smoking SLIGHTLY at idle (although it could have been steam)... then I went for a drive, for about 20 mins, boosted about 4 times at no more than 6-8psi, and the car was absolutely fine, no missing coolant, no overheating, and no smoke WHATSOEVER. I also fixed the o2 sensor... I am totally stumped...

Look at the bottom of your oil filler cap. Is it coated with a milky substance?