Impossible To Fix Overheating Problem

Eldobroken · #1 (**permalink**) 02-02-04, 03:26 AM

Hi i have a 1994 Eldo Touring coupe that is on its way to getting the sledgehammer if this problem persists

. Well here is the problem and the results. Car runs fine for 10 minutes or so heat works. Then after about 10 minutes or so heat cuts out and car begins to overheat this has happened over the corse of a week of me trying to fix it most of the time now it just overheats with no heat but sometimes i get heat and no overheating for a little while. Waterpump was replaced and car converted to Dex cool 2 years ago. Things i have done over the last week are. Fixed all leaks 100% changed radiator cap and thermostat filled and purged system so many times i cannot count. Also pressure tested cooling system while removing spark plugs one by one as to eliminate the head gasket possibility no pressure loss at all at 16 lbs for 10 minutes or more. Radiator is one year old bought from a repuitable shop off DPA. Anyone with any knowledge in this area help would be greatly appriciated as i am at the end of my rope with this car. Seems like airlock but i do not know anymore Thanks in advance.

Ralph · #2 (**permalink**) 02-02-04, 03:56 AM

I wonder if it could be the heater core, could be plugged up with muck and stuff? I had to replace it on my Pontiac and it made a difference. Do you ever get a foggy mist on your windshield? Have you tried one of those "10 minute rad flushes" You add it to your rad, run the car for 10 mins and flush, rinse, refill with coolant. If you drained the coolant, was there any scale or chunks of corrosion that came out? How often have you drained and flushed your system? Maybe the thermostat is sticking. Are you using at least a 50/50 mix of coolant to distilled water? Personally, I go 60% coolant, 40% water.

Eldobroken · #3 (**permalink**) 02-02-04, 04:14 AM

Quote:

Originally Posted by Ralph

I wonder if it could be the heater core, could be plugged up with muck and stuff? I had to replace it on my Pontiac and it made a difference. Do you ever get a foggy mist on your windshield? Have you tried one of those "10 minute rad flushes" You add it to your rad, run the car for 10 mins and flush, rinse, refill with coolant. If you drained the coolant, was there any scale or chunks of corrosion that came out? How often have you drained and flushed your system? Maybe the thermostat is sticking. Are you using at least a 50/50 mix of coolant to distilled water? Personally, I go 60% coolant, 40% water.

Thanks Ralph i have eliminated the heater core no smell or dampness there at all. Lol i have done a heater core in a 88 mustang 2 times in 2 days bad core learned to always use a dealer core the hard way that was the heater core from hell had to take out entire dashboard.

Anyway the tstat is new but i am going to try to take it out all together and see if it still overheats. And the antifreeze is a perfect 50/50 i make 2 bottles from 1 when i get it. This is really turning into a mystery here for me. Only thing i havent done this week is water pump but i have not heard of a water pump sometimes working without leaking. For instance i ran car yeaterday it overheated at 250 turned it of and open up recovery cap spilled all over the place so i let car cool all the way down but i had to go home. so i was going home suddenly the heat works and temp is 201 so i took car up to 145 no sweat runs fine did it again car is even spinning second gear. Temp outside was like 15 degrees F. So i go home top it off and drive around slowly getting on it only a little bit. Heat cuts off and next thing overheating again. I am so fed up with this car cooling should be simple i diagnosed and put a new fuel rail and fuel pump in this car faster than i am fixing this problem. Thanks for your reply.

Ralph · #4 (**permalink**) 02-02-04, 04:22 AM

Quote:

Originally Posted by Eldobroken

Thanks Ralph i have eliminated the heater core no smell or dampness there at all. Lol i have done a heater core in a 88 mustang 2 times in 2 days bad core learned to always use a dealer core the hard way that was the heater core from hell had to take out entire dashboard.

Anyway the tstat is new but i am going to try to take it out all together and see if it still overheats. And the antifreeze is a perfect 50/50 i make 2 bottles from 1 when i get it. This is really turning into a mystery here for me. Only thing i havent done this week is water pump but i have not heard of a water pump sometimes working without leaking. For instance i ran car yeaterday it overheated at 250 turned it of and open up recovery cap spilled all over the place so i let car cool all the way down but i had to go home. so i was going home suddenly the heat works and temp is 201 so i took car up to 145 no sweat runs fine did it again car is even spinning second gear. Temp outside was like 15 degrees F. So i go home top it off and drive around slowly getting on it only a little bit. Heat cuts off and next thing overheating again. I am so fed up with this car cooling should be simple i diagnosed and put a new fuel rail and fuel pump in this car faster than i am fixing this problem. Thanks for your reply.

How about the thermostat switch on the rad fans? Mind you, if the fans weren't working, you would only overheat in slow, city driving, not on a freeway or HW. One time on my old car, I added a temp gauge and I somehow switched the sensors for fan switch, and temp sensor for the gauge display!! Needless to say, thankgoodness it was in the winter so the fan was never needed. In the spring it overheated and I promptly reversed them! Oh ya,

So my next Q would be, "are your rad fans working?"

growe3 · #5 (**permalink**) 02-02-04, 10:36 AM

Is there any chance that your water pump belt is slipping?

Maybe had Armor All or such get on the pulleys?

Have you cleared the air purge line from the water pump bolt to the surge tank?

Eldobroken · #6 (**permalink**) 02-02-04, 01:38 PM

Quote:

Originally Posted by growe3

Is there any chance that your water pump belt is slipping?

Maybe had Armor All or such get on the pulleys?

Have you cleared the air purge line from the water pump bolt to the surge tank?

Hi Growe the air purge line? Now that is what i have been looking for a Purge line valve ETC.... I was thinking mabye there is a broken keyway in the water pump if there is one at all. If you could tell me exactly where that line is i will be gratefull. I will go look for it now. Time to heat the garage back up

. Thanks for the responces i will let you guys know how i make out.

BeelzeBob · #7 (**permalink**) 02-02-04, 03:57 PM

Quote:

Originally Posted by Eldobroken

Hi Growe the air purge line? Now that is what i have been looking for a Purge line valve ETC.... I was thinking mabye there is a broken keyway in the water pump if there is one at all. If you could tell me exactly where that line is i will be gratefull. I will go look for it now. Time to heat the garage back up

. Thanks for the responces i will let you guys know how i make out.

Check the water pump drive belt and the tensioner on the water pump drive belt. That is on the rear of the engine. The water pump has it's own drive belt and tensioner and the most common reason for oveheating like you describe is lack of circulation caused by the water pump belt slipping/failed or the tensioner being frozen and not tensioning. Take the guard off the water pump drive belt and check the belt for presence and condition and exercise the tensioner using a 1/4 drive rachet and the square drive lug on the tensioner arm. You may have to lube the tensioner pivot to get it to free up if it is frozen due to corrosion.

Look at the water crossover casting where the water pump is mounted. At the very top there is a hollow mounting bolt that acts as a nipple for the water pump vapor bleed. There is a 3/8 hose on the nipple that goes to the throttle body heater and then to the pressurized surge tank. Disconnect that hose at the nipple/hollow bolt. Start the engine. There should be a steady stream of coolant out of that bolt/nipple. If not, something is plugging the orifice and the bolt/nipple needs to be removed and cleaned out so that the water pump can vent vapor or it will lock up and not pump. If the nipple flows coolant then check the 3/8 line to the surge tank for obstructions. It might help to reinstall the line on the nipple and then disconnect it at the surge tank and repeat the check with the engine idling to make sure coolant flows from the 3/8 hose at the bottle.

BTW....even though you converted to DexCool you still need to drain and refresh the cooling system every 2 years or so. The engine was originally run with the green silicated conventional coolant that plated the inside of the engine with silicates. You cannot eliminate the silicates. The long life corrosion protection of the DexCool is rendered useless in the presence of the silicates so the DexCool offers no long life feature on a retrofit like yours. Change it the same as teh green stuff required. There is really no advantage at all to using DexCool in your case. It offers the same corrosion protection , length of corrosion protection and cooling capability as the conventional green silicated coolant.....so just use the green stuff. DexCool is a long life coolant IF it is the orginal installation into the new engine. An older engine that has been run with silicated (green) coolant is not a candidate for the long life function of DexCool.

Eldobroken · #8 (**permalink**) 02-02-04, 07:47 PM

Quote:

Originally Posted by bbob

Check the water pump drive belt and the tensioner on the water pump drive belt. That is on the rear of the engine. The water pump has it's own drive belt and tensioner and the most common reason for oveheating like you describe is lack of circulation caused by the water pump belt slipping/failed or the tensioner being frozen and not tensioning. Take the guard off the water pump drive belt and check the belt for presence and condition and exercise the tensioner using a 1/4 drive rachet and the square drive lug on the tensioner arm. You may have to lube the tensioner pivot to get it to free up if it is frozen due to corrosion.

Look at the water crossover casting where the water pump is mounted. At the very top there is a hollow mounting bolt that acts as a nipple for the water pump vapor bleed. There is a 3/8 hose on the nipple that goes to the throttle body heater and then to the pressurized surge tank. Disconnect that hose at the nipple/hollow bolt. Start the engine. There should be a steady stream of coolant out of that bolt/nipple. If not, something is plugging the orifice and the bolt/nipple needs to be removed and cleaned out so that the water pump can vent vapor or it will lock up and not pump. If the nipple flows coolant then check the 3/8 line to the surge tank for obstructions. It might help to reinstall the line on the nipple and then disconnect it at the surge tank and repeat the check with the engine idling to make sure coolant flows from the 3/8 hose at the bottle.

BTW....even though you converted to DexCool you still need to drain and refresh the cooling system every 2 years or so. The engine was originally run with the green silicated conventional coolant that plated the inside of the engine with silicates. You cannot eliminate the silicates. The long life corrosion protection of the DexCool is rendered useless in the presence of the silicates so the DexCool offers no long life feature on a retrofit like yours. Change it the same as teh green stuff required. There is really no advantage at all to using DexCool in your case. It offers the same corrosion protection , length of corrosion protection and cooling capability as the conventional green silicated coolant.....so just use the green stuff. DexCool is a long life coolant IF it is the orginal installation into the new engine. An older engine that has been run with silicated (green) coolant is not a candidate for the long life function of DexCool.

Thanks bbob now i have some new info to work with. I am convinced it is airlock so i am going to check all of the above tonight i was getting to the giving up point with this problem now i have some hope. Just a question the water pump was done by caddy plam beach when i was on vaca
They are the ones that told me to do the dex cool conversion and they said they had to do a special evacuation to convert it to dex cool it was very expensive for this but i said ok since i take good care of my car all AMSOIL ETC.. and change every 3000 anyway. DO you think this was just a waste of money the evac or should i still change back to regular green antifreese. Thanks in advance.

WOTMODE · #9 (**permalink**) 02-02-04, 10:54 PM

I work at a chev dealer in MN. Last week I fought a overheating cavalier. I diagnosed a bad T-stat. Still overheated. After lots of cussing and scratching my head, I put another t-stat in it. Turns out that the brand new ac delco t-stat I installed would not open. Just a thought. and its one of the easier things to try.

BeelzeBob · #10 (**permalink**) 02-02-04, 11:45 PM

Quote:

Originally Posted by Eldobroken

Thanks bbob now i have some new info to work with. I am convinced it is airlock so i am going to check all of the above tonight i was getting to the giving up point with this problem now i have some hope. Just a question the water pump was done by caddy plam beach when i was on vaca
They are the ones that told me to do the dex cool conversion and they said they had to do a special evacuation to convert it to dex cool it was very expensive for this but i said ok since i take good care of my car all AMSOIL ETC.. and change every 3000 anyway. DO you think this was just a waste of money the evac or should i still change back to regular green antifreese. Thanks in advance.

Yes, it was a waste of time and money to evaquate the system and switch to DexCool. Since you have changed over I would just stick with it. Neither the DexCool nor the green conventional coolant is better for cooling or corrosion protection....they are equivalent...just the DexCool lasts longer for the corrosion protection....if the engine was initially filled with it. In your case, the DexCool is fine, just change it frequently...it will not last for the corrosion protection due to the silicates already in the engine.

Personally I would ditch the Amsoil.....waste of money in my opinion.