Overheating Seville

[elindsay]

I have a 2000 Seville with Northstar engine. It overheated going up a large hill, stopped let cool, then drove home 60 miles no problem. Then car started overheating slowly but when it got hot it stayed hot. Replace thermostat, drove for a week everything ok, then started overheating again temp goes up and down then overheats. Have now replaced water pump and radiator but car still over heats. Have had a blocks test done twice and both come up negative. Car can idle for hours and not overheat it seems to start when pulling a hill. Sometimes the temp comes back on its own. When this first started no coolant lose, but now when it over heats I have to add coolant. What next?

[Texas Jim]

By block test... I assume you mean checking for combustion gases in the coolant.

If you recently added coolant and then did the block test... a lot of the time it will come back negative...

[scott y]

It's such a shame that these cars seem to to have all these overheating probs. I still have my 94 STS but it's becoming riddled with problems everytime I turn around, battery,rad, fuel injectors,coilpacks,plugs,gaskets,hoses,you name it I've replaced it. However at just short of 200K miles what can one expect? It's had a damned good run. It just sits in my garage now spotless, waiting for the next time that I take it out. It's still a gorgeous looking car when I stand out here and have a few rums and just stare at it

[rockfangd]

It's such a shame that these cars seem to to have all these overheating probs. I still have my 94 STS but it's becoming riddled with problems everytime I turn around, battery,rad, fuel injectors,coilpacks,plugs,gaskets,hoses,you name it I've replaced it. However at just short of 200K miles what can one expect? It's had a damned good run. It just sits in my garage now spotless, waiting for the next time that I take it out. It's still a gorgeous looking car when I stand out here and have a few rums and just stare at it

Well It happens and with the temps we have been happening it is more of a chance. I never worry about my Deville though. having 197000 miles and nothing has gone wrong with anything major yet. But eventually things will start to happen. I like your 94 SLS. Love the color.

I am also interested to hear more about the block test

[elindsay]

The first test was done before changing coolant. I was wondering since the car only overheats while being drove and does not overheat at idle, could that be the reason the test come up negative since you cannot drive and do the test.

[BodybyFisher]

Are you saying yo

The first test was done before changing coolant. I was wondering since the car only overheats while being drove and does not overheat at idle, could that be the reason the test come up negative since you cannot drive and do the test.

Are you saying that a combustion by-products in the coolant test was done and it was NEGATIVE?

You said the car first overheated on a long uphill climb, correct?

If its not a bad head gasket as evidenced by coolant by products in your coolant, then its something else.

You changed your coolant and thermostat.

1) I trust you are sure that you have at LEAST a 50% coolant to 50% distilled water ratio correct? Lower than that, the coolant will boil when hot. Never add water to the cooling system alone, mix it at least 50/50

2) Long uphill drives put an increased strain on the cooling system as the torque converter creates a lot more heat. There is a 5 mile uphill run from Phoenix to Sedona, there are signs that say, TURN OFF YOUR AIR CONDITIONING! I thought yea right, this is a rental car, screw that, its 95 degrees out and I am on vacation! I am driving a brand new 2006 Cadillac Deville at 85 uphill! Well, all of a sudden I start seeing cars on the side with STEAM coming out of their hoods, .... I glance at the dash and the TEMP gage is at 3 fricken quarters! I was like, man the battle stations, AC OFF, ALL WINDOWS OPEN, and I slowed to 55 The point is, LONG UPHILL runs are hard on your cooling system, as you can see even in brand spanking new Northstars.

Now, it is possible that you overheated and on REFILL of coolant, your purge line did not allow AIR out of your system an your water pump is cavitating at high speeds. You need to check the purge line to see if it is flowing.

DO THIS>>> With the engine cool, gently pull the purge line off the top of the black coolant tank, easy so as NOT to break off the nipple, let the hose hand DOWN so coolant does not damage the PAINT if it spits, go and start the engine, dont rev it just let it idle, and go look at the hose, coolant should be coming out of the hose, if NOT, you found your problem, let us know the result of your test and if its not flowing we will tell you what to do.

3) Check your water pump belt, if it is going bad and slipping you will have overheating problems when the engine is labored. It is located on the RF of the engine, and is driven off the camshaft via a pulley. Look for cracks, voids looseness, shininess indicating slippage, and check for a bound up tensioner by pushing on it with your hand but be careful NOT to dislodge the belt when you do that.

let us know what you find, and good luck, we TRY around here before we CONCLUDE the worst!!

pay no attention to the gloom and doom glass is half empty spectators that offer nothing but dressed up negative statements and heart burn and negativity while they sit on the sidelines beating a dead horse offering no help at all, its amazing. These people exist to pull down the positive people in the world in everything you do whether it be your work out routine, weight loss, ideas, or your enthusiasm and to me would do better to just read and refrain from responding at all. There used to be a song years ago, Short People have No Reason for Living, I think it should be changed to Negative People have no reason for living.

[Texas Jim]

Short people got no reason

Short people got no reason

Short people got no reason

To live

They got little hands and little eyes

They walk around tellin' great big lies

They got little noses and tiny little teeth

They wear platform shoes on their nasty little feet

Well, I don't want no short people

Don't want no short people

Don't want no short people

`Round here

[Texas Jim]

But at the same time... don't forget the one about TALL PEOPLE....

Tall People got no reason

Tall People got no reason

Tall People got no reason

To live

They have huge hands and monster arms

And they can't even fit inside a car

They got giant noses and enormous teeth

They wear too tall shoes on their gigantic feet

Well, I don't want no Tall People

Don't want no Tall People

Don't want no Tall People

Round here

[rockfangd]

what the. lol.

[BodybyFisher]

Haha, Jim, I am 6'5" so I resemble that comment,

My feeling is that if you don't have something to offer to solve a problem keep your opinions and perceptions to yourself, its OLD news and beating a dead horse. We are here to help not pour salt into cuts

[Texas Jim]

Haha, Jim, I am 6'5" so I resemble that comment,

My feeling is that if you don't have something to offer to solve a problem keep your opinions and perceptions to yourself, its OLD news and beating a dead horse. We are here to help not pour salt into cuts

I am only 5'7"... so I on the other end.

I agree about the comments that help nothing... like my previous posts about tall and short people... but when you mentioned that, the lyrics popped into my head..

[elindsay]

when replacing the radiator, put 50 / 50 mix with the red stuff, had a mechanic check out water pump and he replaced the pully and belt, and that seemed to work at first but then started overheating again. Now it is overheating quicker and quicker, and loosing coolent somewhere, but not sure where it is going. Oil looks ok, no water out tail pipes. I really want to save this car, I just love this body type, there is nothing I want to repalce it with.

[elindsay]

checkd the overflow coolent came out.

[BodybyFisher]

Check the CAP to make sure that it holds the rated pressure, if it is only holding say 7 lbs she will boil and lose coolant

ALso have the cooling system pressure tested to see if it holds pressure, pressure testing will also highlight leaks

AGAIN, was the coolant tested for combustion by products? yes or no?

[elindsay]

Put new cap that is rated for 15 lbs got from dealer. The mechanic I had do the water pump did a pressure test and said there was no leaks. The 2 tests that were run are the one where the chemical changes color. Both times showed no change.

[elindsay]

I noticed when the car temp at normall is straight up and down, even when the temp only goes up a little that I start to see coolant leaking around the cap. Is this normal the cap is rated 15 lbs should this happen?

[Cadillac Jim]

No. If you see coolant leaking around the cap, wait until the car is cold, then remove the old cap, clean off the surfaces around the lip and the flat surface on the inside below the lip and put on a new radiator cap.

[ialicea]

Hi looks like misery likes company I'm having the exact same problem with my 1999 Cadillac STS

I've added a new water pump, thermostat, radiator belt and holes and I still can't stop it from overheating.

Will run for about 30 minutes to 40 minutes before overheating even at idle.

I also did the chemical test like you did and came up negative and I have nothing coming out of the tailpipe .

so you're not in this boat alone I'm trying to find an answer but also running short on money after all the work I've done .

would like to save the car so if you find an answer sending a message and and if I find one I'll send you a message.

good luck to both of us .

[Cadillac Jim]

ialicea - check the bypass hose that runs from the thermostat area on the rear of the engine to the surge tank. Take off the fitting to the surge tank and start the car; there should be a steady flow of coolant out of it. If not, the bypass is clogged. The most common place for it to be clogged is the fitting in the thermostat housing, which is a "bolt with a hole." You should be able to clear it with a paper clip.

[elindsay]

have pulled the hose and it seams to run fine.

[ialicea]

Thanks I will look at the bypass hose

[ialicea]

The bypass holes the one that is the one under overflow I pulled it at the point where it tees into the line coming from the back of the engine

turned engine on and all I could see coming out was just a small stream just like if you turn the knob on a little.

Was a lot more posted be coming out and not just like a little thin stream

thanks

[Cadillac Jim]

The bypass line on my engine goes across the top of the engine under the beauty cover. There are rubber hoses at either end, and a metal hose under the beauty cover. The line with the tee is the heater hose line, and the tee is the main input line from the surge tank.

[BodybyFisher]

If by by-pass hose you are speaking of the purge line, calling it a by-pass hose is confusing. Its the air purge hose/line, the purpose of the bolt with a hole in it is to let air out of the system at the high point of the cooling system circulating coolant through the bolt with a hole in it back to the coolant tank. You can check to see if the air purge line is flowing coolant from two places, at the bolt with a hole in it and at the tank, if it flows at the bolt but not the tank the hose/pipe is clogged somehow (rare) but its usually just something in the bolt's orfice

As a side note, the purge line is part of the throttle body pre-heater so that the throttle body does not ice up

[Cadillac Jim]

BodybyFisher, I stand corrected, it is the purge line that I am referring to.