Overheating/Antifreeze Loss/Serious Problem...please respond

[Hayabusa630]

Disclaimer: I know enough about cars to know that I don't know enough about cars. **Any information or advice re: the car is appreciated immensely**

A brief history as to the relevant car. The car currently has 142K on it. Every thing is updated, checked, etc. on a regular basis (belts, hoses, misc. fluids, etc.). The car has accumulated plenty of miles as of late due to work (23K in the past seven months). V6, 3.3, SE. Last July, while in a traffic jam for about 2-3 hours on a record setting warm day, the car overheated in a big way, huge plume of smoke, etc. After that the water pump, thermostat, an oxygen sensor, and a hose (I believe one of the heater hoses) was replaced. A coolant flush was also done to eliminate debris from the overheating.

From that point on, as long as I did not turn the heat or AC on more than level one on the car, there were no problems (there was an instance in November where the car overheated after the defrost was turned on full blast because the car ran out of antifreeze again).

Last week the car overheated again on a day where it was -4 when I left for work. The car was pretty much out of antifreeze, so I put 3/4 of a gallon in, waited an hour, and it was OK. Today, the car struck back. When I left for work this morning it was -8 (don't know if that is relevant). The car overheated again, I tried the same thing as last week, the car readily guzzled a gallon of antifreeze, and it got me nowhere.

There hasn't been any antifreeze mixing in with the oil, that I am aware of, so that leaves me hoping/thinking I won't have to worry about the intake manifold gasket (with the mileage on the car, such a job would probably mean getting rid of the car). However, antifreeze is not dripping or leaking anywhere at all and over the past two weeks it is disappearing at an insane pace; the antifreeze has to be going somewhere, right? Putting in the gallon this morning did nothing. A mechanic recently recommended a radiator flush earlier this week, but I didn't want to mess with the car in weather like this (if relevant, boy, that paid off, huh?). It seems like whenever the car calls upon a large amount of antifreeze, the antifreeze isn't getting to the radiator, but is going somewhere else, causing the car to overheat (since this is happenening whenever the heat or air are turned up or the weather is particularly awful).

1) What tests could/should be done on the radiator and heating/cooling system to see where the problem is...&...2) What part/s might be the problem this time around (or again). Thank you in advance to those who respond.

[Jpit]

I would think you would be able to see the coolant loss, either leaking out, in your oil, or immense amount of steam from your tailpipe. If it is truly just leaking out you may just buy the prestone flush kit that you can find almost anywhere including walmart. The kit has you splice into one of your heater coolant hoses coming from your firewall and allows for a garden hose to be screwed into it. Normally you open a drain and turn on the hose and flush through your system. In your case you may want to just turn on the hose and keep the drain plug closed to simulate some pressure in your system hoping to find where it is leaking. also another thing is to park over some newspaper. Let it sit during the night and in the morning check for moisture on the paper. Good luck!

[justin0419]

You mentioned no mixing of oil and antifreeze, but you need to also consider the antifreeze could be leaking into the combustion cylinders. This would mean that you'd be losing the antifreeze by combustion. You should see that at your tailpipe, but in the cold weather you're talking about, that could easily be mistaken for water vapor from condensation in your exhaust system (the vapor you'd normally see in cold weather after a start up). One test you need to do is a pressure test. The mechanic takes a pump and hooks it in where you add your coolant. Then the system is pressurized to test for leaks. This will verify you have a leak and, unless it's internal, you'll be able to see where it's leaking out. My guess is when you overheated the car, the cylinder head got warped and now there's antifreeze passing into the combustion cylinders. That would explain why you're loosing coolant, but not seeing any visible leaks.

[Hayabusa630]

Justin & JPit, thanks for the information. I am going to take the car for another couple of opinions and estimates, but I have an update and another question. The car was taken in for an estimate and was supposed to receive a coolant pressure test (the repair shop involved was suggested by my future father-in-law). The shop said that a hose was loose running to the radiator (which they alleged to have fixed), but they also said that the exterior of the intake manifold gasket was cracked, causing the leak/s. Future father-in-law took the car for a joyride (under the guise of testing it) and, in doing so, cranked the heat in the vehicle up full-blast (live and learn, won't happen again). After the joyride, a decent amount of antifreeze pooled where such a crack or leak is conceivable.

My question: Is that really a plausible problem or is the repair shop testing me to see if I bite and give them an unnecessarily big job and big profits? (I ask because I had a $1,200 estimate given to me last July for the job I mentioned in the original post which included, you'll love this, $190 for just a rebuilt water pump, classic). As a throwaway line, the guy also said that the car had a bad converter. I didn't think anything of it.

Question Two: Does anyone have an honest estimate as to the cost of repairing an intake manifold gasket or to repair the cylinder head (cost of parts & a reasonable amount of time for labor), whichever the case may be. Thanks again.

[snowgoerx]

This is actually whats going on with your car. Your intake is more than likely cracked, but this looney that you're dealing with is giving you an outrageous estimate. It just cost me $180 for an entire replacement of my water pump and a pressure test along with a gallon of coolant and a coolant flush. Also, I thought the leak might have been coming from the intake, since the pontiac 3400 engines are notorious for having a weak intake. My reccomendation: get it fixed, shouldn't cost anymore than about $600 for an intake and $50 for a water pump, not including labor. Good Luck. and it will also stop your belt from squeaking, its the coolant drying out the bearings.

[Hayabusa630]

Thanks for the information, I really appreciate it. Shame to hear that Pontiac 3400 engines are so notoriously awful. As for the underhanded repair service (for any of you in the Chicagoland area it was the Brandy's in Rolling Meadows), they did not get any further business or money and have probably already heard from the BBB by now (I understand you mark things up to the general buying public, but $190 for a rebuilt water pump was obscene, even I know that much). I am going to get a few estimate done over the weekend.

There hasn't been any antifreeze loss coming from the tailpipe (as indicated by the nature and consistent of the discharge from the tailpipe). As of now the crack still hasn't spread to the interior of the intake manifold gasket, thank goodness, so I will hopefully have this problem solved before it kills the car. I'm thinking a coolant flush would probably be a good idea as well, in light of the recent episodes of overheating.

Would a water pump really be necessary at this point? I just got a new one 23K ago and it seems to be in fine working order. Would the debris from the episodes of overheating do that much damage?

A new car dealer spoke with my fiancee about the matter and he said that the intake manifold gasket should run about $600 for a new one and $300-$350 for a used, but properly working, gasket. I'm reflexively leery about a used or refurbished gasket...any opinions?

In closing, thank you to all of the parties who are responsible for creating, maintaining, and posting on this site. For novices like me, such a quality site is a huge benefit. Thanks to all.

[brianhsr]

In responce to loss of rediator coolant,as a victim myself of the same circumstance with a grand am.Myself just knowing the basics for automtive repairs,the anti-freeze wasnt coming out the exhaust,or leaking on the ground.It turned out the water pump was actually the culprate for loss of anti-freeze in my case.It was losing like yours 1/2
to 3/4 a gallon every 2nd to 3rd day.The water pump fix took care of it,
needless to say mine was under warranty thank god cause its a 6.5-8 hr job and can be expensive.

I hope this helps you.

[annie61]

we to have this problem with our car we put the new manifold gaskets on and since then the car over heats, it was not doing this before we did the job on the car, we know that we are loosing anitfreeze but dont see a leak anywhere, is our motor now good now and should we scrape the car

[gravis2000]

I have just replaced my water pump after about 160,000 miles on it. I was losing a great deal of fluild just as you were the damn cap was bad the seal was broken and I was losing about 1 gallon of fluild a day I replaced the cap with a new one. It fixed it. Check to make sure the seal on the cap is in one piece a new cap is cheap thing to try. Other then the intake mainfold gasket I have put 193,000 miles on the car with no other major issues.