Likely Coolant Leak Locations

[BodybyFisher]

the 4.9 can produce poor heat if:

The coolant is low

The thermostat is STUCK OPEN

The T in the heater hoses is not properly oriented

The heater core is clogged and needs flushing

Something is wrong with the temp control on the HVAC unit.

The first thing I would do is get the car to operating temp, and feel the two hoses going into the HEATER CORE, see how they feel are they the same temp or is one cold and one hot

[Cadillac Jim]

I believe in post #21 that Galcion said that he heard a noise which "sounded like air escaping" when turned on. It's possible that a vacuum hose for the temperature door is off.

[Ranger]

I believe in post #21 that Galcion said that he heard a noise which "sounded like air escaping" when turned on. It's possible that a vacuum hose for the temperature door is off.

Good point. Check all the vacuum hoses to the ACM (Air Conditioning Module) aka programmer as well as where they end up at the various door controllers.

[Tsar_of_Cows]

I believe in post #21 that Galcion said that he heard a noise which "sounded like air escaping" when turned on. It's possible that a vacuum hose for the temperature door is off.

Good point. Check all the vacuum hoses to the ACM (Air Conditioning Module) aka programmer as well as where they end up at the various door controllers.

Would they be located behind the glove compartment in the passenger's side?

[Ranger]

Yes.

[Tsar_of_Cows]

Ok I checked and there's no air blowing around in the glove compartment.

I was reading the Chilton manual and I think a reasonable possibility is the blower motor is busted...

But then I'm not sure why I don't get any air out the main vents and I only get cold air out of the floor vents and the windscreen vent. :/

[navion]

Maybe 1.75 Gallons or so. I used 1 full gallon and most of the second.

Considering the area I'd think (hope) that it had 50/50 in before hand.

What does the thermostat control? The heating system is definitely kicking in if I set up the climate control correctly, but it's just blowing cold air at me.

The thermostat regulates the engine operating temperature. It allows more or less coolant to flow through the radiator to keep the engine at operating temperature.

Thermostats can be damaged by running an engine extremely low on coolant.

As far as checking your antifreeze level of protection, don't assume, you need to KNOW!

In your area a weak mixture of antifreeze can cause your radiator to freeze up while driving & cause your engine to overheat. Worst case would be for the coolant to freeze and crack your engine block!

Buy a tester and check it!

[Ranger]

Ok I checked and there's no air blowing around in the glove compartment.

I was reading the Chilton manual and I think a reasonable possibility is the blower motor is busted...

But then I'm not sure why I don't get any air out the main vents and I only get cold air out of the floor vents and the windscreen vent. :/

If you are getting any air, blowing from any vent at any temperature, then the blower motor is fine.

[Tsar_of_Cows]

As far as checking your antifreeze level of protection, don't assume, you need to KNOW!

In your area a weak mixture of antifreeze can cause your radiator to freeze up while driving & cause your engine to overheat. Worst case would be for the coolant to freeze and crack your engine block!

Buy a tester and check it!

Surely this would have happened last winter if the last owner had only used water and no antifreeze.

The thermostat regulates the engine operating temperature. It allows more or less coolant to flow through the radiator to keep the engine at operating temperature.

If you are getting any air, blowing from any vent at any temperature, then the blower motor is fine.

Ok, Thermostat is sounding a likely culprit. Is there a way of testing it?

[lothos]

Ok, Thermostat is sounding a likely culprit. Is there a way of testing it?

I think you can take it out and put it in water and heat it, use a thermometer to see when it opens.

If you replace it, I think it's wise to use an ACDelco thermostat. RockAuto.com has good prices and there's a discount code if you click the little link on the bottom of this message.

[BodybyFisher]

If you have been driving with no coolant just replace it with an AC DELCO, get a new seal also

[navion]

As far as checking your antifreeze level of protection, don't assume, you need to KNOW!

In your area a weak mixture of antifreeze can cause your radiator to freeze up while driving & cause your engine to overheat. Worst case would be for the coolant to freeze and crack your engine block!

Buy a tester and check it!

Surely this would have happened last winter if the last owner had only used water and no antifreeze.

The thermostat regulates the engine operating temperature. It allows more or less coolant to flow through the radiator to keep the engine at operating temperature.

If you are getting any air, blowing from any vent at any temperature, then the blower motor is fine.

Ok, Thermostat is sounding a likely culprit. Is there a way of testing it?

OK, I am going to say this one more time! TEST YOUR ANTI FREEZE! You have NO WAY to know what the freeze point of your coolant is UNLESS you TEST IT!

If the previous owner found he was low on coolant during the summer he could very well have just added water, knowing that he would be selling the vehicle before cold weather set in!

Now, it is your vehicle, ignore my advice at your peril. You may find out the hard way that your engine did not, after all, contain a good antifreeze mix when you bought it!

Let me make this suggestion. Since you have NO IDEA if or when the coolant has EVER been replaced, do a complete cooling system service on your car. This entails completely draining, flushing and refilling the system with fresh coolant. This procedure, if properly done may even fix your "no heat" problem if the heater core is plugged.

BBF has suggested that you replace the thermostat & gasket with a new AC Delco thermostat! That is EXCELLENT advice! Do it and make it part of your complete cooling system service. As I said before, in your area, not having the proper freeze protection can cost you big bucks. And IF you were in a remote area when it freezes up and the engine fails, it could be deadly.

Again, Assuming that your vehicle contained a good antifreeze mix when you bought it is foolhardy. At LEAST just check it!

[BodybyFisher]

This is especially true if you are getting bad heat, flush the cooling system, flush the radiator core, replace the stat, and use the cooling supplement tablets, and refresh with a 50/50 blend of coolant and distilled water

bad heat can be caused by a stuck thermostat

what was the result of feeling the two hoses going in and out of the heater core, they should be more or less the same temp, if one is hot and one cold, you need to flush it

[Tsar_of_Cows]

This is especially true if you are getting bad heat, flush the cooling system, flush the radiator core, replace the stat, and use the cooling supplement tablets, and refresh with a 50/50 blend of coolant and distilled water

bad heat can be caused by a stuck thermostat

what was the result of feeling the two hoses going in and out of the heater core, they should be more or less the same temp, if one is hot and one cold, you need to flush it

I haven't felt the hoses. I'll do that today.

I'll take it to a garage and get them to do a coolant system service, I don't feel confident enough to do that myself.

[KHE]

Make sure the garage uses distilled water to mix with the coolant and the 4.9 engine REQUIRES the use of the supplemental sealer tablets. These are available from any GM parts counter. Install the tablets in the 4.9 engine through the radiator cap on the top, side of the radiator, not the overflow tank.

[Tsar_of_Cows]

I've booked it in for a coolant service on Monday in a local garage.

Will try and impress them with my extensive (ha-ha) knowledge of the cooling system. Last time I took a car to a garage they tried to fill me with so much bullshit it was unbelievable.

I'll ask them about using coolant supplement, if they don't have it I'll get some myself and put it in after they're done.

Also going to pull an old trick and mark the coolant hoses so if they do the good old "we had to replace it, look how bad it was" **** I can take a look and see if they really did replace it.

As you can tell I don't trust garages. At all. Ever.

[KHE]

I'll ask them about using coolant supplement, if they don't have it I'll get some myself and put it in after they're done.

/quote]

Pick up the pellets at the GM dealer and take them with you. Do not allow the garage to add ANY other sealer other than the GM sealer pellets or Bars Leaks Golden Seal (the same stuff as the GM pellets). Do not use the Bars Leaks "Powdered Aluminum" - you want the brown powder or pellets labeled as "Factory Installed" The GM pellets will need to be crushed in order to add them to the radiator.

Here is the powdered Bars Leaks: http://www.barsproducts.com/G12BP.htm

This is the pelletized bars leaks - like what the GM parts department has: http://www.barsproducts.com/HDC.htm

[rek]

It wouldn't hurt to bring two jugs of distilled water as well.

[Cadillac Jim]

Distilled water: About 50 cents a gallon at our WalMart Grocery Department.

[Tsar_of_Cows]

Well I put it in to the garage and they said that the radiator is leaking coolant as is the head gasket, and they don't want to replace the gasket as apparently it's a horrible job.

Any way I can verify these things myself? I don't see any leaks with the hood open etc. Also, there's no supplement in it at the moment, if these are minor leaks, would adding the sealent supplement possibly fix it?

Looks like my caddy adventure may be at an end, might have to trade her in for something which is in one piece. :|

[adallak]

Well I put it in to the garage and they said that the radiator is leaking coolant as is the head gasket, and they don't want to replace the gasket as apparently it's a horrible job.

Any way I can verify these things myself? I don't see any leaks with the hood open etc. Also, there's no supplement in it at the moment, if these are minor leaks, would adding the sealent supplement possibly fix it?

Looks like my caddy adventure may be at an end, might have to trade her in for something which is in one piece. :|

Head gasket failures are extremely rare on 4.9 engines. On the other hand, radiator end tanks are know sources of leaks as it was mentioned several times. Did they actually show you where on the radiator they saw the leaks? Get second opinion on the head gaskets.

[Tsar_of_Cows]

Well I put it in to the garage and they said that the radiator is leaking coolant as is the head gasket, and they don't want to replace the gasket as apparently it's a horrible job.

Any way I can verify these things myself? I don't see any leaks with the hood open etc. Also, there's no supplement in it at the moment, if these are minor leaks, would adding the sealent supplement possibly fix it?

Looks like my caddy adventure may be at an end, might have to trade her in for something which is in one piece. :|

Head gasket failures are extremely rare on 4.9 engines. On the other hand, radiator end tanks are know sources of leaks as it was mentioned several times. Did they actually show you where on the radiator they saw the leaks? Get second opinion on the head gaskets.

They didn't show me, no. I don't *think* they were stringing me along as they right up front said that they couldn't fix it, I'd expect them to try and squeeze some ridiculous amount out of me if they were playing me for a fool.

Bearing in mind I know very little about engines is it possible to look for the leaks myself?

I'll checkt he diagnosis sheet they gave me when I get home and see what it says.

[Tsar_of_Cows]

Ok, well you know, I checked the ground under the vehicle, and I saw a couple of drip-marks, but this was in a busy car park, so there usually are some.

I checked under the radiator cap, and the radiator is full of coolant, I checked the coolant tank and it's still full of coolant, I turned the engine on, revved it for about 30 seconds, then knelt down and looked under the radiator and the engine and I didn't see any ominous drips of coolant. I just don't see any leaks anywhere, it's not exactly gushing coolant all over the place.

I've bought some of that Bar's Leaks supplement (http://www.barsproducts.com/G12BP.htm found it in Wal Mart), I'm going to put that in tomorrow morning when the engine is cold, then run it for a few days, and then if the heater's still not working I'm going to take it to a different garage and tell them that the heater isn't working (and nothing at all about what the last lot said).

Oh, also, I dug through the service history, and the thermostat was replaced this year and the coolant system was flushed at the time, so it should have had decent coolant in there before hand. However, that makes me think that the heater's been broken for a while and the last owner got rid of the car ASAP after having that work done didn't fix it.

The report isn't very helpful, it just says "COOLANT LEAKS FROM CYLINDER EHAD [sic] GASKETS - WATER PUMP AND RADIATOR - POSSIBLE PROBLEMS WITH HEATER CONTROL BLEND DOOR OR ACTUATOR IN ADDITION TO COOLANT LEAKS"

Actuator is fine (I checked that). Does anyone have or know where I could find a labelled diagram of this engine so that I can try and find the water pump and the head gasket so I can do a proper check of this? The Chilton manual doesn't seem to have an overall diagram.

Oh, I did the "check the hoses temperatures" things as advised a couple of days ago (been really busy, and I kept meaning to), the one coming out of the radiator on the right side (as you look at the car from the front) was very hot, and the one going into it (?) on the left side, which passes under the radiator cap, was hot but not as hot as the other one.

As a temporary solution I bought a little 12V in-car heater.

[adallak]

Ok, well you know, I checked the ground under the vehicle, and I saw a couple of drip-marks, but this was in a busy car park, so there usually are some.

I checked under the radiator cap, and the radiator is full of coolant, I checked the coolant tank and it's still full of coolant, I turned the engine on, revved it for about 30 seconds, then knelt down and looked under the radiator and the engine and I didn't see any ominous drips of coolant. I just don't see any leaks anywhere, it's not exactly gushing coolant all over the place.

I've bought some of that Bar's Leaks supplement (http://www.barsproducts.com/G12BP.htm found it in Wal Mart), I'm going to put that in tomorrow morning when the engine is cold, then run it for a few days, and then if the heater's still not working I'm going to take it to a different garage and tell them that the heater isn't working (and nothing at all about what the last lot said).

Oh, also, I dug through the service history, and the thermostat was replaced this year and the coolant system was flushed at the time, so it should have had decent coolant in there before hand. However, that makes me think that the heater's been broken for a while and the last owner got rid of the car ASAP after having that work done didn't fix it.

The report isn't very helpful, it just says "COOLANT LEAKS FROM CYLINDER EHAD [sic] GASKETS - WATER PUMP AND RADIATOR - POSSIBLE PROBLEMS WITH HEATER CONTROL BLEND DOOR OR ACTUATOR IN ADDITION TO COOLANT LEAKS"

Actuator is fine (I checked that). Does anyone have or know where I could find a labelled diagram of this engine so that I can try and find the water pump and the head gasket so I can do a proper check of this? The Chilton manual doesn't seem to have an overall diagram.

Oh, I did the "check the hoses temperatures" things as advised a couple of days ago (been really busy, and I kept meaning to), the one coming out of the radiator on the right side (as you look at the car from the front) was very hot, and the one going into it (?) on the left side, which passes under the radiator cap, was hot but not as hot as the other one.

As a temporary solution I bought a little 12V in-car heater.

Leave the heater alone for a while. It is most likely th eclogged heater core. Not a big deal. Go back and read all the info we provided you with. Looks like you did not follow all of them. If you want to keep the car get a Factory Servica Manual oneBay. There are alway some listed for a few bucks.

[lothos]

Leave the heater alone for a while. It is most likely th eclogged heater core. Not a big deal. Go back and read all the info we provided you with. Looks like you did not follow all of them. If you want to keep the car get a Factory Servica Manual oneBay. There are alway some listed for a few bucks.

I got my FSM set on ebay for like forty bucks plus shipping. Not too bad considering what they go for new.