Overheating Help (I'm stumped)
 

I'm running out of ideas on what my problem might be. The car is overheating after only about 20-30 min of driving and the coolant is boiling and coming out of the overflow tank. I'd really appreciate any help guys. The following has been done so far.

-Yes I've spent a lot of time doing a search
-New radiator cap didn't help
-New thermostat didn't help
-Yes the system was bleed of air after it was re-filled
-Yes my fans are coming on
-No leaks anywhere besides the overflow tank
-Coolant is circulating in radiator
-No oil was mixed in with coolant
-No coolant was in my oil when changed 2 weeks ago
-Exhaust doesn't smell like burning coolant
-No debris is blocking the radiator

is that plastic air damn that is attatched to the lower radiator clip still on ?

Yes the airdam is still on. Been there done that with a thirdgen before :bang:

your sure the belts not slipping?

Nope, can't say I'm sure of that. I didn't notice it when I had the car running, but I wasn't really watching for it either. The belt doesn't seem loose at all. Should I be able to see it slip on the WP pulley?

not sure to be honest, it was just a thought. if everything else is working correctly and the radiator isnt plugged or full of crap so it cant cool then maybe it isnt circulating at higher rpms?

I'd pull the rad out and inspect it closer, service it. Flush it thoroughly with a hose. Are the fins all mashed up can it breath?

I'll check to see if the belt is slipping when I get home, if not I'll just pull the radiator and try flushing it out. I love pulling the radiator, can't wait. :barf:

LOL, its not bad. Just a few bolts and the a/c evap struggle. I have the one from my 99 sitting in my garage. I'm replacing it with a ron davis, so if yours is trashed I can sell you my used one if you want. Or find one local to save on shipping, its a big box that mine came in. If your elec system is charging fine then most likely the belt is not slipping, it was just a wild stab, I figured you had already flushed it good.

I just got home and the belt is tight, really don't think think it's slipping, plus like you said, no problems with the electrical system.

Let me know if you think the water pump could be failing. Whatever the problem is, it's progressively getting worse. I went from overheating about every two days, to once per day, to now having to pull over 3 times in a 15 mile drive from work. All of this has happened over the last 5 days btw. I'm heading out to eat now (not in my car haha) and am going to flush the radiator and put a new water pump on unless anyone thinks that's not the problem.

The therm is good? is the WP leaking or making noises? hard to believe it would just fail and not leak or something. Never heard any squealing?

blown head gasket. Were you running it hard 5-6 days ago? Have you had ANY detonation lately?

The only way the coolant will start to boil over is "air is getting into the cooling system", period. Your temp can go all the way into the red on the gauge, as long as the system is tight with NO air, it won't boil over.

To rule out the water pump just take the rad cap off when the engine is COLD, start it up and stand there until the temp gets up there and it opens the t-stat...if the water is flowing then the pump is fine.

Also, don't waste your time removing the radiator to flush it. If you open the drain on the bottom and it drains normally, the radiator is not clogged.


I think its the head gasket though. Get a leakdown check done. Sometimes if its bad enough you can rev the engine at the TB while looking into the radiator (with the rad cap off) and bubbles will come to the surface while revving, sometimes.

If the gasket(s) is blown the piston on the UP stroke will push the air into the coolant system. On the DOWN stroke it will suck it out of the coolant system into the cylinder and out the exhaust. BUT ONLY SOMETIMES if the blown part is big enough. Rev the engine pretty good and see if coolant comes out of the exhaust pipes. Or, were you losing coolant over time before the overheating got really bad, like a few months ago.

well not exactly.. it will build pressure until it blows something if the temp keeps rising. Could very well be a gasket, looked like he ruled it out but you never know. It could be weeping and he doesnt see it. Its getting hotter without cooling and is circulating, fans are on. Not leaking or making noises at the WP.

Is it losing fluid at all or just getting hot?

I lost my serpintine belt (before I put a katech tensioner on) while getting on it real hard on the highway once. Didn't realize it was getting hot until my friend looked over at it and said HOLY SHIT you're almost in the red. I let off and rolled to a stop. By the time I pulled to the side of the road it was in the red about halfway through it. I got out and popped ther hood and I couldn't put my hand on anything. Could have cooked an egg on my air lid and my STB would have burned my skin badly if I touched it. My coolant did nothing, no boil over, no bubbling, no sound at all. I let it drop down to the 155 mark, started it up and got it off the highway to an Advanced Auto and put a new belt on it. Its been perfect ever since, 4 years ago this happened. Fully built 427ci N/A, factory cooling system.

Air in the coolant is the killer. It drops the boiling point way down.

I bet when this guys coolant is boiling over his temp gauge is nowhere near the red zone.

Also, what did he do to rule out a blown gasket? Checking for coolant in the oil or coming out the exhaust is not the tell tale sign of a blown gasket. It can be a very small hole in the gasket that is getting a lot of air pushed through by the upstroke piston, but only sucking in a tiny bit of coolant on the downstroke, not enough to detect. I've seen this on more than one car.

If the entire cooing system checks out, what else can it possibly be. Boiling coolant before the temp goes into the red means air is in there.

Not true.Radiators clog from the center out to the edges.A 75% clogged radiator will still pour water out the drain and you will see the water flowing with the radiator cap off and the thermostat open.Quickest way to rule out a clogged radiator is to drive it until it reaches operating temp and the thermostat opens, park it,turn off the motor and feel the backside of the radiator in the center.If its still cold, the radiator is partially clogged.You can slowly move your hand from the center out towards the edge to see how much of it is clogged.If the center is hot like the rest of the radiator, then its something else.Possibly a blown head gasket.

If the radiator is partially clogged, while the coolant is draining from the drain plug it will start and stop and start and stop the whole time. It won't just drain smoothly the whole time. But either way if its boiling over there is air in the system and thats where the problem lies.

He needs to do a leakdown check.

May sound off topic but my moms 4.6 ford was doing the same thing. Temp would just shoot up out of nowhere. Nothing blocked, clogged, dirty, stuck, no water in the oil, no oil in the water, no coolant out the exhaust.
I just tore it down and found a blown head gasket. Not bad but bad enough.

Also check the trans temps if it's an automatic. I had a LSX work truck that would boil over. Come to find out it was a trans problem, it was boiling around the trans cooler in the side tank.

99.99% of the time you have boiling coolant, its indeed the head gasket. I pinhole sized opening is all it takes to push air into the system.

your fans coming on ?

Yes he stated that in the 1st post.

I'm more leaning to a bad headgasket, then a bad pump or radiator..good luck!