Hey Guys ---

My 96'z28 m6 has been in the shop the last 3 weeks for an opti install, that turned into a waterpump install, that turned into tie rod ends , ect ect.

Well the last step was changing the heater hose.

The car got REAL hot about 12 miles into my drive home, I never had a problem with overheating before. I pulled to the side of the road, and noticed if I revved the car to 3k rpm and held it there, that the temperature IMMEDIATELY (within 5 seconds ) went from the red line to under the half way point. The second I let it idle again it IMMEDIATELY (just as fast) went back up the the red line and sat there. The fans were kicking on. I also was putting antifreeze and water in the overflow tank , and it took 3 jugs. I couldnt tell if it was puking it out because just my luck it was raining on me the entire time.

Does it seem like the shop dumped the fluid for the heater hose, and forgot to replace it in the system? I am guessing with a heater hose install you wouldnt lose all the fluid, but you would lose enough for the car to overheat if you didnt replace it?

I didnt get a chance to pop the radiator cap because it was already in overheat mode, and the fact it was raining and dark out. The engine was running smooth and NO smoke from the exhaust, so I dont think I have a blown head gasket.

Could this be a stuck open thermostat? This crossed my mind because when the car is idle it may not get the fluid flowing fast enough through the radiator ... and when I give it gas it gets things flowing enough to cool everything down? Would it also open room for extra fluid in the system?

I just wanted a few opinions before I raise hell at the dealership , thanks for the help ---

 

could be an air bubble or your low on fluid...
check to see if u see any fluid in your raidator if now add some.. water and bet it will fix the prob....

 

check out shoebox.com for the air bleeding proceedure. but i would make the dealership do it. no sense in paying big bux to the dealer if they cant even bleed the cooling system right. i am a dealership tech (not gm) and if i let a car go in that condition i would be in big trouble. i would call them up and tell them what you said here and ask them to send a tow truck to come get it so they can fix it right.

 

I don't see how it's an air bubble if you can put 3 jugs of antifreeze/water into the system. And I also don't think the thermostat is stuck open. That would normally cause it to run cooler than normal.

Now that it's daytime, I'd go outside, fill up the system (if it's not already) and see if you have a leak somewhere. If you're really low on coolant, it will tend to overheat until the rpms are up, which will pull some more coolant through. Had that happen to me before. Sounds like your coolant is leaking somewhere. Maybe just a hose not on tight enough, etc. (also check around the water pump since that was just replaced) That also happened to me recently after changing the water pump...a few twists of a screwdriver tightened up the hose correctly and it stopped leaking. Let us know what happens.

 

Is the WP drive assembled correctly (gear drive)? If not, the pump will not turn.
The LT1 has a "long" type WP. It has an internal cooling media by_pass port for quick heating. If the thermostat is broke, most all the fluid will not flow thru the rad core. Car will over heat. You must plug the WP internal bypass to divert all cooling media to the rad core (I know this because I do not run a thermostat and run Evan NPG waterless).
I would start by bleading air from the system.
B.

 

Thanks guys, I will update after I investigate a little more. Its still raining, but should stop soon .

I am starting to think they didnt replace the fluid after the heater hose replacement . What a crock of ****. I paid extra at a dealership to NOT deal with this ---

 

OK, the fluid in the radiator is all the way to the cap, AND its full in the reservior. That could be from me lastnight though.

I got an emergency phone call and couldnt wait for the car to fully warm up and idle.

The oil is fresh, and the fluid in the radiator looked good.

There were NO water or other leaks (that may come with a warm temperature though)

I will update after I get it to warm up to operating temps, and let it sit for awhile running ---

 

You can do an Opti Change with minimal tools in less then an HOUR.

Try the Bleeder screws on your Coolent hoses. If you had a Electric water pump this would be much easier, it seams you have an Air bubble in the system and you need to use the bleeder screws to get the air out. OR you take it back to the dealer and say WHAT THE F did you do to my car????

 

I will bleed it when it finally stops raining, lol. I turn the 2 screws out 3 turns (not all the way) after the car warms up and the thermostat opens, right? Do I leave the radiator cap on, or keep it off so I can add fluid?

The car sat for a year and a half, so I am wondering if I have some sediment blockage in the radiator or somewhere. The water pump may be working hard enough at 3k rpm to push the fluid past it, but not hard enough at idle to keep things cool.

Do you recommend I put some kind of additive in the radiator, or will that just make things worse if there is a blockage problem?

I am worried if I go to the dealer they will "find" a problem that they didnt see the first time it was in ... and it will cost me more money (they never own up to a mistake). If I cant fix it myself, I will definately get it back to the dealership.

THANKS ---

 

Turn the screws out and if there is nothing but air that comes out at first then you have air in the lines. Turn them let some air out tighten it back up turn the other one let the air out back and forth until you get straight water, sorta like bleeding your brakes.

 

So this is with the car on, warmed up, and the cap on the radiator right?

How much fluid should I expect to come out? I dont want the new opti wet, lol

Do you have a recommended radiator additive I should use if the bleeding doesnt work? ---

 

OK, well I twisted the bleeder screws and fluid came out ... and then the car ran around 180 for a 30 minute idle with a few 3k rpm revvs.

Tonight I am going to drive it to work and see how it goes , thanks for the help ---

 

Well, I just got home from driving it to work.

Nothing but overheating problems, hahahah.

I was reading through threads, and sometimes it takes a FEW bleed cycles to get everything straight??

I opened the rad. cap and revved it to 3k ... while a friend watched. A few bubbles came out , then nothing more. I waited for it to hit 185 and then saw the thermostat open and fluid move. This engine is cold blooded, it takes a LONG time to hit operating temperature ( 15 min or more ) .

The damn car stays at 180 for as long as I want it while idling. I can revvv it to redline over and over and it wont budge while sitting still.

The second I hit the f'n highway the thing pegs 250F within a minute. I had to drive home at 3k rpm for it to stay cool. Its pretty weird, I can drive at 2500rpm and it overheats, but 3k it stays at 180F. I thought cars were supposed to overheat sitting still, not while at 70mph in 45 degree weather?!

The car SMELLS hot when I get done driving it, so I am sure the gauge is correct.... BUT it doesnt puke any fluid like I would expect (and the rad and overflow is FULL). The radiator is clean on the outside, and the fans kick on when the engine is hot. I also have a perfect front air dam.

Thank God I have a 6 speed, and can control my rpm!!! I will be bleeding it again soon. I dont see what else it could be. ---

 

Do you still have your air dam attached? And is there a plastic baggie or anything stuck in front of the radiator?

 

Its still attached, and the radiator is clean on the outside ( its the inside I may need to worry about, the car sat for a year and a half ) ---