Adder

Hey Guys,

I've been having overheating problems for a long while now. Blowing coolent out of the overflow tank each trip I take. Replaced the thermostat first. I ended up replacing the radiator too just in case it was clogged or something (I had put some stop leak crap in there early on thinking that there was a leak somewhere), the water pump seemed to be working fine... hot water at both hoses leading in and out of engine, and could see coolent flow when the thermostat opened. I feel like I've done everything I can but it is still overheating badly. The overflow tank bubbling and sputtering out fluid even after relativly short trips... having to refill radiator to make it from A to B.

I got my hands on a cylinder pressure tester which I screwed into the spark plug sockets and each one filled to good pressure after turning the engine over a couple times and held the pressure without leaking. I checked my oil and it did not look milky or wierd in anyway. Coolent is green and doesnt seem to have oil in it but hard to tell.

Anyway... after about a month of this I went out there to check the water pump again seamingly the one thing i'm not sure is working right. So opened the hood took off the cap and filled it to the top. Started the car and the coolent erupted like a volcano when it started up (normal?). Needing to watch the fluid I topped it off again bubbled down, filled bubbled down, filled again till it stayed full... but It kept bubbling pretty big bubbles every few seconds but fluid did not go down. After watching this for a while waiting for the thermostat to open... i got pretty suspicious of the bubbles coming out of the radiator cap, so I got my nose down there to sniff the popping bubbles and low and behold it smelled like exhaust .

Which gets me thinking about the head gaskets again... but how can this be happening if the cylindars are keeping pressure and not leaking? It seams like the hot exhaust in the cooling system is causeing the coolent temp to rise as well as causeing there to be far too much pressure in the coolent system forcing the fluid out into the overflow tank and out even before the engine has begun to overheat. Is there a way exhaust could be getting into the coolent system other than from a cracked head or gasket??

Just looking for some confirmation before I go tear into that project. This has been the first time I have ever worked on my own car and I'm learning a lot... but working on my heads scares me. Its not something I want to try unless I'm sure its the cause. I've already replaced so many parts that arent the problem that I feel like a total

Thanks a mill for any help you give!

alex_aha

wow, i have never heard of that problem.... did you check if your coolant circulating within the engine? Putting on new or used head is not that bad should take you about 5 or 6 hous by yourself if you slightly mecanically inclined... let me know how it goes.

Adder

Yeah, I would say that the fluid is circulating fine. When I have it in my garage with the cap off watching the fluid (and the bubbles) eventually when the engine heats up the thermostat opens and I see it start to gurgle and flow... the fluid level usually drops when this happens as fresh coolent is taken from the radiator into the engine. After a drive, both the top coolent hose (the one taking hot coolent from the engine into the radiator) and the bottom hose (the hose taking the cooled down fluid into the engine) are hot... meaning to me that the water pump is pumping fluid propperly in full cycles around the cooling system.

The car runs completely normally other than the overheating. Usually takes about 15 min on the freeway to overheat... and usually overheats after I exit the freeway to and from work... becuase the high speed wind is no longer helping cool what is left in the radiator by that time. I have found that the overflow tank is filling and overflowing long before the temperature guage shows signs of overheating. Uggg

Thanks for your imput Alex.

alex_aha

how about your fans, are they working properly?

Adder

Yes... sorry I forgot to include that info. Both fans work fine... when its hot they are on. I think one of the 2 fans is mainly or only for the air conditioner though.

I'm hoping some resident guru's here will see the post to give their 3 cents too.

Hope to find out what exactly is wrong and then how to get it done. I'm pretty afraid of fing something up here

kmaalfiisa

whoa, ive never herd of exoust going into a radiator. are the hoses in correctly?

i would follow the hoses up to the engine and go from there. youve got a 99 protege also?
im tearing (well not tearing) out my motor, and replacing the engine intirely, maybe i could use my motor with the info you've got, and i could find the problem.. it almost sounds like something in the engine is cracked, letting exoust leak into the coolent system... im no professional at all, but thats about my best guess..

hope you can get this problem solved

Adder

Yeah the hoses are all tight... there is no coolent leak or any other leak in the engine. Its all working properly and runs great. Which is why i dont want to shoot it to hell

I'm just tired of fixing/replacing things that are not broken and hope to get some expert guidence on what I should do next.

GNO

First off, changing the radiator sounds like a bit of overkill for the "throw parts at it until it's fixed" method.

Since your cylinder pressures aren't leaking rapidly, I doubt it's the head gasket.

What mix of antifreeze and water do you have? Ethelene-glycol does not conduct heat as well as water. If the concentration is too high, this may contribute to the problem.

Rent/borrow the pump and attachements to pressure test the system and cap. If the system does not pressurize properly, the boiling point of the coolant mixture lowers. It sounds to me more like a pressure problem.

Adder

I replaced the radiator because it had a leak in it a longish time ago... I used stop leak on it a few months ago and was afraid that it lead to a clog in the radiator blocking free flow of coolent through it. I used some "heavy duty" flush stuff to clean out the cooling system a week ago which caused the leak to reappear (eating away the stop leak i guess). So I took the radiator out to have it repaired/rebuild... but they said it could not be repaired because of where the leak was.

I did replace the radiator cap too with one of those handy lever types. And after I drive there seams to be a lot of pressure in there. When I pull up on the leaver it bubbles and sprays coolent out of the overflowing overflow tank. My biggest concern is how fast the overflow tank begins to fill up... it begins to fill and overflow long before the car overheats... and it think that its overheating because all the coolent is getting forced out of the overflow tank by exhaust or some other gases... but I really am clueless The engine temp guage looks completely normal for 90% of the drive all while the overflow tank is spraying coolent out like mad. Only after the coolent is substantially reduced in the system (either sprayed out or in the overflowing tank) does the needle rise up to indicate the overheating engine.

Thanks GNO, I'll see if I can get my hands on a pressure tester kit. I dont think its the coolent mixture, I've been using premixed 50/50 antifreeze. What do you think about the exhaust fumes bubling out of the radiator?

amrit

Hey I don't know much about these things either, I'm here to learn from others.

I'm supposed to take it to my mechanic to hear what he has to say about my car, but so far everyone's tellin' me that I should change the thermostat.

all i can really suggest is a good mechanic.

Adder

I'm hear to learn too. I'm tired of having to depend on a mechanic every time someting goes wrong. I've never been inside a car the way I have since I've decided to do things myself and it really is a lot of fun... I never thought I would ever say that. Changed my own oil for the first couple times this months, breaks, sensors and other stuff. Love this site and the things that I learn from it. This problem has had me stumped though... but cant bring myself to give in to a mechanic unless I find out that it is a job that I can't do.

I know that there are some guru's here that haven't yet had a chance to read my problem and chime in. Just hope it gets seen.

amrit

I understand what you mean about the mechanic and it's really a nice feeling to know that you've done something on your car that you never thought you could do.

Adder

Is there no other way to get exhust in the coolent system besides a head problem?

mitchman

I think it would be pretty easy for a shop to determine your problem.

1. They'll have a coolent pressure tester (attaches to radiator cap). It will detirmine if you've got a link in your coolent system.

2. They'll have a gizmo that can test your oil to see if it has coolent in it (not good).

3. They can check if your coolent is flowing. (it might be plugged up from from the stop leak)

My guess is that your engine block is plugged with stop leak. But it's just a guess.

Roddimus Prime

sounds to me like air in the system. When you get pockets of air in the cooling system it'll overheat and stop circulating properly.

on the upper rad hose neck (on the engine block) is a plug that is screwed into the neck, (with the car running) CAREFULLY start to unscrew this bleeder to vent of the air pockets.once you get a steady stream of coolant coming out you'll know the air is out of the system. Try this and let me know.