Could he have routed the serpentine belt wrong?= i would think that if this was the case you would have more than just coolant problems. there should be a sticky under your hood that shows you how the belt is to be ran. the noise you hear near your pullies worries me...you shouldn't hear a "rattling" noise anywhere. Your fans are obviously not the issue since it only overheats when your driving...can i ask what speeds you are doing? Have you had your battery checked lately? i had a 99 Taurus that when a cell went dead in my battery it overheated and spewed coolant everywhere even tho the gauge was reading cold and also caused my fuel gauge to go all weird as well.

Could he have let all kinds of crud into the cooling system which now result in periodic blockages and reduce or even stop coolant flow? ==this is a possibility. my aunt didnt have heat in one of her cars and her boyfriend squeezed a hose where it stopped feeling warm and he heard a crunch and then she had heat again.
i dealt with bad gaskets a cpl years ago and my oil was clean, rad fluid was clean, car ran fine except it overheated during idle, or low speeds (had to be going at least 40 mph or faster to keep the engine cooled since the air pockets didnt allow the fluid to circulate properly. i had a pressure test done on my rad and it failed, and the rad cap had gunk on it ) i had no smoke coming out the exhausts, and the longer i drove it the worse the gasket got until it was leaking at the corners on both sides of the engine to confirm for real (i tend to be in denial with some things) that my intake gaskets were blown.
you say that your not sure that its actually over heating even tho the gauge says it is. in my history of overheating coolant is bubbling out of control letting you KNOW its well past its boiling point.....did you take it to have it scanned to see what temps the computer is reading based on what the gauge is actually saying? maybe that guy bumped a ground wire somewhere that's not sending proper signal for the coolant system? (not sure if there is one, i would think there would be since there is a coolant temp sensor) maybe that sensor is going bad.it ALMOST sounds like there could be a intermittent connection for proper temp control..did you figure out what was making the rattling noise?

 

this is impossible to do with the stock belt size.


this does not imply anything about the fans at all. the fans automatically turn off above ~30mph unless the a/c is on. the pcm is coded to not allow the fans to turn on when the air flowing through the raditor is more than the air the fans can pull in.




i am confused on how a dead battery would cause your car to overheat? if the car starts, the alt will still provide ~14 volts to the electrical system so the fans would have still worked.

very unlikely in his case since it had been flushed before



im pretty sure his issue is the head gasket. which most likely failed after the water pump was replaced and the coolant was not topped off properly. which allows extremely hot gases to circulate in the coolant system and overheated the heads and causing them to warp (they are aluminum and warp fairly easily), which then causes the permanent leak since the seal on the head gasket is now compromised. imo.







if its bubbling, there is a issue that has nothing to do with a sensor or a ground wire. the likelyhood that this is the issue is like 5% chance.

the rattling noise is something that very interesting twist in this story.

if there is "something" in the coolant system, it could very well cause the waterpump to not work correctly or at all. if the old one was a plastic fin version, its possible that one or more fins broke off and is now causing a partial block to happen.

 

What makes the rattling noise even more interesting is that it seems to only do it when it's cold. Engine was fully warm when I took it yesterday for the hydrocarbon test (DIFFERENT guy lol), and of course when he was doing it, ZERO noise was heard. Then of course when I started it later after engine cooled down, it was rattling. I SWEAR it's coming from the pump...

The HC test passed; I know that's still not a guarantee, but couple that with the fact that there's no oil in coolant or vice versa, no chocolate milk, no white smoke, and no bubbles watching coolant at top of rad fill neck, even when it's clear the t-stat is open. I must come to the conclusion that the head gasket is not leaking. When done he reset the tester with new blue stuff. He blew into it with his mouth and it immediately turned yellow. The head gasket is fine.

It really seems like I've gotten to the point of not being able to get any more air out. Hot lite has not come on since I was able to add that extra gallon of coolant when I first got the car back, and it's behaving "better", but still spikes as high as 3/4 - 7/8. I figured that since I was able to add another gallon of coolant, originally that volume was being taken up by air, cuz the guy didn't know what he was doing.

The guy who did the pump did not open the bleeders when he filled it, so there might be air trapped in places that will NEVER come out. He did not even know the bleeders existed - I think my pump is the first one he ever changed lol. Maybe if these bleeders had been opened when refilling, the usual methods used to "burp" these systems would have worked.

I have a theory: the system was never filled properly to begin with, so I have air in there with the coolant (duh lol). Maybe even this: the water pump, for WHATEVER reason, is not pumping as fast as the old one did, even though it was leaking, or, for whatever reason, coolant is not moving as fast as it was. This allows the air to remain trapped in the jackets longer than it normally would - contributing to overheating. It also makes it easier for air to remain in the upper hose longer, just downstream from the tstat, before it would otherwise enter the radiator and eventually make it out of the system thru the overflow tank. So it's a cascading-type effect. Since the system is closed, volume can't increase, so something's gotta give when pressures get high enough- that's when the gauge falls back to normal - usually very quickly.

The guy who did the HC test really thinks the pump is NOT pumping too slow, and that coolant is moving around fine. I'm kinda leery about draining and refilling WITH THE BLEEDERS OPEN THIS TIME, but then again nothing else is working...

Whatcha guys think? After reading literally dozens of examples on how to drain/refill/bleed air, yeah it can be a pain, but NOT THIS BAD. Had the bleeders been open when he first filled it, maybe my bleeding efforts would have been successful?

 

I should note this too: he flushed and filled three times at one point. during the second time, a piece of material about 1 1/2" long, about the diameter of a night-crawler, ended up in the tank - I saw it floating around. Looked like it could be part of a gasket or something.

I was not there when he changed the pump - maybe there is crap floating all around in there...

someone suggested trying a short drive with the thermostat completely removed. Other than maybe leaking a bit of coolant, I think that would be OK as long as I don't take the car on a cross-country road trip lol.

What would you do first? Drain and refill WITH BLEEDERS OPEN THIS TIME, or test drive it with the t-stat OUT?

 

All temps everywhere are "normal", or at least seem that way. Tested with one of those laser-pointer temp guns.

vikesfan: do you think I could prove that? Because if that's the case, I'm taking this guy to court!!!!!!!!!!!!!!!!!!!!!

But then I would come back to this: why did it pass the HC test done yesterday? I know anything is possible but....

 

no, no way to prove it, just a guess.


when you did the HC test, was it overheating? you say it doesnt do it at idle, and thats when you test for the HC. so of course, it should show up as "clean"


i say the head gasket, because i have dealt with these exact same symptoms before on my wifes old rendezvous with the 3400. it was the head gasket and it was because my wife overheated the car worse than what she "claimed" when the lower intake gasket blow out the side of the intake. there was coolant in the engine, but it was very low and the air temp and steam inside the coolant passages allowed the head to ever so slightly warp. it only was apparent when driving after a period of time and under certain acceleration levels.

after i changed the head gaskets and had the heads decked, it was fine.




for a quick "tip" to try to avoid replacing the head gaskets and decking the heads.....

take out the thermostat, drill a very very small hole in it, replace the thermostat with that hole at the 12 o'clock position and refill coolant and drive a few times.

i also do this to all of my cars.

 

Nope - not overheating. The gauge was higher than normal though (about 1/2). "Normal" is 1/3 - rock steady @ 1/3 before he changed pump.

I HAS occasionally spiked when idling - very seldom though. I'm still stuck on this idea that the pump is wrong type and not pushing enough coolant. I've read that guys did their own, got the gauge spikes, and everything returned to normal when they put a better pump in. The parts store said the guy who did mine got a pump that had sheet metal blades. The guy who did the pump said the new pump is just like the old one. Someone is mistaken, and the only way to find out is to take the pump out and look at it. If coolant is flowing at half the rate it used to, maybe that's the problem?

Here's a simple question: if I were to drain ALL coolant and remove the t-stat, and then add coolant AT the opening that's under the t-stat, won't that completely fill the engine block's "water jackets" - or whatever they're called? Then replace t-stat & housing, open bleeders, and fill the rest of the way, and "re-burp" just to be safe.

Or maybe opening the system again will just compound the problem. I just want to eliminate everything else before I say "OK: time to change the head gasket"...

 

if you fill at the thermostat neck, you are not going to fill everything. the heater core is the highest point, and the most likely place for bubbles to hide.

please refer to one of my previous posts on how to fill your system without having to "burp" the system.


if you want to be 100% sure, this is what i would do....


1. drain every ounce of coolant i could get out.
2. drill tiny hole in a NEW thermostat as mentioned above
3. install a NEW radiator cap
4. refill with proper mix of coolant and DISTILLED water using the procedure i mentioned in my other post on how to fill the system (i am not sure if i mentioned to turn the heat to defrost at high temperature). if he didnt use the proper mix, well then he is.... a. he is an idiot, or b. he is an idiot.
5. start car and let warm up and idel to full temp (~1/2 way on the gauge), top off as needed during this step (radiator cap can be open for a period of time before it starts to come out the top).
6. turn car off and let set until COMPLETELY COOL (overnight preferred)
7. top off radiator and overfill bottle
8. drive car, with heat/defrost on high, and observe the temps for 15-30 mins, in town and highway driving.
9a. if temps are normal, drive to nearest liquor store, buy a 6'er, go home, drink said beer.
9b. if temps are not normal, go buy head gaskets and have fun, because it sucks on the DOHC engine. Do the timing belts while you are at it. as a matter of fact, sell it as is, and buy a 98 z34 instead. just sayin.

 

while typing my reply above, i thought of something i dont think anyone had mentioned yet, which i assume we all may have thought that the mechanic wasnt stupid enough to put a wrong mix of coolant in.

i am the type of person that will NOT buy the premix 50/50 stuff because i can get 2 gallons from the full strength stuff for the same price, i just have to add water.

if he did put in the wrong mix, my hunch is that he may have diluted down the 50/50 stuff even more by adding more water, making it a 3parts water, to 1 part coolant, which is a big no go!

you can buy a cheap little tester to see what "range" your mix is in. however, if he used tap water, there is a chance that the additional chemicals and salt that is tap water does change the boiling point of coolant mixture.

 

The guy who did this works at a quick lube. If the mix is wrong it came from their main tank(s). The one with the whole rack of different kinds of oil, etc.

Thanks alot for your replies vikesfan - you're helping me out alot.

I wasn't suggesting only filling from the thermostat neck - I'm trying to figure out if his action of not filling it right in the first place could cause all this. I.e., if what he did resulted in air stuck in places that it can never come out of with the engine running.

This doesn't make sense to me: I made a device that works just like one of those Lisle spill-free funnels (my parts store wants $60 for it and they have to order it - screw that). With the funnel on, start car, initially nothing happens cuz tstat is closed. Then it warms up, tstat opens, fluid starts to go up & down - fills the funnel with about 1/2 quart of coolant. Then when fully warm, the up/down action stops. Rev the engine - no change in coolant level in the funnel; coolant level just sits there no matter how you rev the engine. I would assume this means the dam pump is not even pumping?

What do you think?