Okay.. here's the story. My car usually runs fairly hot (230-240) because of a lack of airdam, hole in the overflow tank, possibly bad radiator cap, yatta yatta.. Anyways, today while driving into work, it did it's usual up and down cycle between 230 and 240*, but once it cooled way down, to about 200*. It sat there for a bit, then jumped up to about 230 in maybe a little over a second. It slowed it's pace, but it continued to climb until it got to 250. I could hear the fans on, but it wasn't cooling it down any and it slowly climbed up to 260. Fortunately by that time I was at work.

I opened my hood up, and the overflow tank was compeltely full, spilling radiator fluid out of the top of it. I know all about thermal expansion and what-not, but I was curious.. Maybe the radiator cap let it flow into the tank but not back into the radiator. So very carefully with a thick rag I started to open the radiator. At first fluid from the overflow tank dribbled out, and when I opened it a bit more I found that the radiator was indeed quite pressurized. I closed the cap back up before I lost too much fluid. Fortunately I didn't burn myself because of all the rags I had over the radiator cap. With all the pressure out of the radiator, it didn't take long for it to suck all the fluid back out of the overflow tank. Well.. after work I checked the level of the radiator, and it was pretty low, so I added coolant until it was full, letting the engine while doing so. But then I walked around towards the back of the car and saw two wet spots on the parking lot where the exhaust was blowing. Bending over to examine this, I put my hand near the exhaust pipes to see if I could get any of it to form on my hands, and, well.. it did. It didn't have a strong enough smell to overpower the grease that was already on my hands, nor did it have a distinguishable color. Oh yeah.. and when I started the car this morning the exhaust had a slighty whitish tint to it, which I know could be coolant.

But still.. . PLEASE PLEASE PLEASE tell me it could be something other than what I'm thinking of.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

If you're thinking head gasket, then normally you would get a huge cloud of steam and/or smoke, and it would be pretty obvious. Sometimes not, but usually. You would probably feel a loss in smoothness and power with misfires as well.
good luck
ODB

 

Any ideas what it might be then?

 

It is possible the liquid is just water that condensed in your exhaust or whatever, if it didn't smell. I'm not sure about the overheating, air in the system maybe, bad thermo, did you check the water pump? just possibilities. I'd get an airdam though and get a new cap, and whatever else you need to get the cooling system back to decent shape, maybe get the fans to come on earlier too. All this could be done for like $20, and like 30 minutes of your time.

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90 IROC 5.7l (L98)
ram air, K&N's, air foil,Flows

LIKE A ROC

 

I have had similar concerns. I overheated a few months ago and ended up blowing up my 13yr old battery. Once I got a new one, I was looking for signs of a blown head gasket (this engine isn't even a year old) and would see a good puddle of water (dipped a towel in it and tried to light it to check) under each tail pipe. It has been a few months now and it doesn't always do that... it is only condensation in the pipes.

As for your overheating... fix it or else you may indeed have a blown head gasket! I would check your thermostat ($4) and make sure you coolant is indeed flowing though your radiator.

Start it up with the cap off. After a few minutes, the liquid (which should be green ) will start to flow... and eventually overflow, so watch out. That will tell you if your water pump and thermostat are working OK.

If you want to know if you have a blown gasket, take your car to a service station and have them test the pH of the coolant. If it has CO2 in it, then the pH will be lower then normal.



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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

You said the radiator was 'pretty low'. How much did you have to add? If it was alot then thats why the temp spiked and it was running hot.
Seems like you know how to open the radiator cap and avoid burning yourself to death, so...
Easy check for a head gasket leak that has been effective on every car I've ever touched:
Do what you have to so the radiator cap is open when the car is running. I have found on a thirdgen its easier to take it off, start the car, and warm it up. Rev the engine up to around 2-3000rpm, the water level in the radiator should drop a fair amount (generally 1-2"). Dont let it back to idle quickly, it will overflow, let the rpms drop slowly and it wont overflow. If the water comes out of the radiator as the rpms increase, you have a problem. Some splashing may happen, what I am talking about is lots of water being forced out of the radiator. Blocking the heater hose inlet might not be a bad idea so you dont confuse it for water coming out of the radiator.

 

I'd look into the thrmo being stuck shut. It will still build pressure in the radiator and the fans will still come on, but will overheat anyway.

 

Well, I replaced the radiator cap and the thermostat.. It still heats up because I don't have an airdam (something I'm going to replace very soon), but it cools just fine when I switch the AC on (to make the fan come on). If only it weren't so friggin' cold around here right now I could just do that all the time. heh

 

OK, the color of smoke differs when something is burning. whit smoke from the tailpipes is gas and/or water, whit smoke from the wheelwells(well we know what's burning there) blue smoke is oil(i.e. blown head gasket, bad piston rings)and black smoke is carbon(i.e. carbon deposits)the white smoke from your tailpiep is the unburned gasoline that you get every time you start your car and the engine is cold...every car does it, young, old, fast or slow. and btw how in the hell can coolant get in you exhaust system(thats a question for enkil)

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1991 RS LO3
mods: 14" chrome air cleaner, straight-piped after cat exhaust with one chrome dual tip on the left side.
future mods: headers, removing smog equipment, and as many cheap mods as i can find
aol s/n: budman8503

 

that instant cool for a minute makes me woner... have you changed the thermostat lately?? if so is the rad. clean?? if so then re-place the airdam! if thats not it then i think you know the problem! oh yeah change the tank in question!

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1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 160 (882) heads,.447/.447 lift 222@.050 duration speed pro 327/350hp cam 350 .40 over (356) Edlebrock torker2 and a 600 edlebrock manual choke (1405)

Future mods performer rpm air gap intake (polished) comp roller cam, and way better headsa 400 defintely in the works!

[This message has been edited by burnoutrpm (edited February 12, 2001).]