Coolant Loss When Using Heater

[ward]

Sally is a 2001 SL2 with 87K miles on her clock.

Last year, I noticed that the coolant level dropped a bit during the winter - actually had to buy some DexCool and refill the tank sometimes. When Summer arrived (and I stopped using the heater) the problem went away.

Now winter is back, and so is the problem. Now, I notice that there is a puddle of coolant under the car after she sits for a while. There is coolant on the catalytic converter. There is NOT any coolant in the passenger compartment, so I think the heater core is OK. I've checked the hoses to the heater core, and there isn't any evidence of leakage there.

Is there a valve/valves that could be leaking when turning the heater on? If so, where is it/them?

To emphasize, I think the radiator is OK, as there is no leakage unless the heater is being used.

Any ideas?

[stocksaturn]

Hmmm... I was going to say heater core, I would double check the actual core it's self and run the heat wile looking under or over the car and try to trace down the leak. It could be a hose connection leaking when the system is under pressure but that would explain the no loss during the summer deal. Defiantly some thing with the heater. Check every thing that has to do with the hear system-run it full blast and watch where it's coming out of. I got a bet on core connection or hose.- Smell anything coming out of the vents?

[ward]

There's no smell coming out of the vents, and there's no dampness on the carpet under the console where the heater core is. All the leakage appears to be outside of the passenger compartment.

I think I'll put the car up on the ramps, run it 'till it's good and hot, and start looking at the underside. I'll do that on the weekend, as today's T-day, and tomorrow is a work day.

[madpogue]

If you can find a pressure tester that will fit the S-car reservoir cap, a pressure test (applies pressure to the cooling system) will usually reveal a leak like this without having to run/heat up the engine. Might be a better/safer way, esp. since you'll be under the car.

There's no heater control valve, but still, first guess would be, if the leak is that far back, it's one of the heater hoses, or the fitting just before it goes thru the firewall.

[Uzzy]

Was a coolant flush fitting ever installed in the heater lines? They can often leak.

[ssicarman]

Most likely leaking from the intake manifold gasket. There is a coolant passage from the head in to the intake. Check the back of the engine at the intake by the small hose from the surge tank. You will likley find coolant coming from that area. Get the gasket from Saturn.There is a redesigned two piece intake gasket instead of the original one piece.

[ward]

MadPogue: Rural Georgia doesn't know from Shinola about Saturns - so no pressure test gizmo is to be had. And... how can there be no valve? If I have the vent open to the outside air, and the air is at ambient, and cool outside air comes in through the vent, right? And then I move the temp knob from cold throuth warm to hot, and hot air starts coming out the vent??? What am I missing? I will plead ignorance, which is correctable! Educate me!!

Uzzy: No flush fittings were ever fitted to the heater lines that I can see. What would they look like? See above about ignorance and educate me!

SSICarMan: Does replacing the intake gasket involve removing the fuel injectors? And why would that gasket only leak when I'm using the heater? Not being critical, just want to know - see the two above for remarks regarding ignorance and education....

And... did everyone have a good Thanksgiving? I'm still burping.... Ò¿Ö

[ssicarman]

Originally Posted by ward

SSICarMan: Does replacing the intake gasket involve removing the fuel injectors? And why would that gasket only leak when I'm using the heater? Not being critical, just want to know - see the two above for remarks regarding ignorance and education....

It is not so much that you are using the heater it is because you have to use the heater. The leak from the intake gasket tends to leak more in cooler weather. You tend to use the heater more in cooler weather.

You don't have to remove the injectors to get the intake off of the engine. The fuel line does need to be disconnected though.

TSB

Subject: Engine Coolant Leak at Intake Manifold Gasket #01-T-15A - (04/16/2003)

Models: 2000-2001 Saturn S-Series vehicles equipped with DOHC (LL0) engines up to and including VIN IZ305500

Condition
Some customers may comment about loss of engine coolant, low coolant level, low coolant telltale illuminated and/or engine overheating.

Cause
This condition may be caused by a coolant leak at the intake manifold gasket. The leak may occur at the cylinder head-to-intake manifold coolant passage located to the rear of the number four cylinder intake port. The seal may experience a compression set allowing an external coolant leak past the seal during cold engine operating conditions.

Correction
Refer to service procedure in this bulletin to replace the intake manifold gasket with the new design 2-piece gasket.

[Uzzy]

Originally Posted by ward

Uzzy: No flush fittings were ever fitted to the heater lines that I can see. What would they look like? See above about ignorance and educate me!

It's basically a spot where the hose would be one piece, but it is cut into two, and a plastic three-way fitting is placed in-line. Two ends in the hose, and the other with a cap of sorts that can be removed to attach a garden hose to. Or it could be an intake leak. ^^^

[BarnOwl]

Originally Posted by ward

And... how can there be no valve? If I have the vent open to the outside air, and the air is at ambient, and cool outside air comes in through the vent, right? And then I move the temp knob from cold throuth warm to hot, and hot air starts coming out the vent??? What am I missing? I will plead ignorance, which is correctable! Educate me!!

Water is always flowing through the heater core. The temperature knob just routes more, less or no air through the heater core to control the temperature.

[97coupe]

Originally Posted by ssicarman

It is not so much that you are using the heater it is because you have to use the heater. The leak from the intake gasket tends to leak more in cooler weather. You tend to use the heater more in cooler weather.

You don't have to remove the injectors to get the intake off of the engine. The fuel line does need to be disconnected though.

TSB

Subject: Engine Coolant Leak at Intake Manifold Gasket #01-T-15A - (04/16/2003)

Models: 2000-2001 Saturn S-Series vehicles equipped with DOHC (LL0) engines up to and including VIN IZ305500

Condition
Some customers may comment about loss of engine coolant, low coolant level, low coolant telltale illuminated and/or engine overheating.

Cause
This condition may be caused by a coolant leak at the intake manifold gasket. The leak may occur at the cylinder head-to-intake manifold coolant passage located to the rear of the number four cylinder intake port. The seal may experience a compression set allowing an external coolant leak past the seal during cold engine operating conditions.

Correction
Refer to service procedure in this bulletin to replace the intake manifold gasket with the new design 2-piece gasket.

I think that this is the most likey cause of this senerio here.

[ward]

Just put the car up on the ramps, opened up the heater knob, and ran it until the fan cycled a couple of times, and guess what? No freakin' leak!

Grrrrr..... "A watched pot never boils", or something.

I'll keep looking until I find the leak. I really don't want to pull the intake if I don't have to - it's pretty tight quarters in there.

Thanks for the knowledge transfer about heater cores and cooling flush fittings - there aren't any fittings in the heater hoses.

[Uzzy]

Originally Posted by ward

Thanks for the knowledge transfer about heater cores and cooling flush fittings - there aren't any fittings in the heater hoses.

Good. I don't trust them, they tend to leak.

[Becca99SW1]

Hey, I have the exact same leak! It has been driving me crazy for 2 years! I can never find the darn thing. It magically disapears when I jack it up to check it. I keep hoping it will get worse but it has not yet.
Here is what I have seen:
1. on the firewall where the AC vents the excess moisture I have seen green coolant. This is more towards the passenger side of the car that the heater hoses.
2. I have seen steam and a stain where it leaks onto the cat.
3. I actually pulled the heater core box apart and tested the heater core and it's ok. It holds pressure and no signs of leaks.
My next step is to pressure test it after I buy a new overflow bottle.
(crossthreaded slightly)
Please let me know what you find. It's not a huge leak but just enough to be annoying.

[white95SL1]

Originally Posted by ssicarman

It is not so much that you are using the heater it is because you have to use the heater. The leak from the intake gasket tends to leak more in cooler weather. You tend to use the heater more in cooler weather.

You don't have to remove the injectors to get the intake off of the engine. The fuel line does need to be disconnected though.

TSB

Subject: Engine Coolant Leak at Intake Manifold Gasket #01-T-15A - (04/16/2003)

Models: 2000-2001 Saturn S-Series vehicles equipped with DOHC (LL0) engines up to and including VIN IZ305500

Condition
Some customers may comment about loss of engine coolant, low coolant level, low coolant telltale illuminated and/or engine overheating.

Cause
This condition may be caused by a coolant leak at the intake manifold gasket. The leak may occur at the cylinder head-to-intake manifold coolant passage located to the rear of the number four cylinder intake port. The seal may experience a compression set allowing an external coolant leak past the seal during cold engine operating conditions.

Correction
Refer to service procedure in this bulletin to replace the intake manifold gasket with the new design 2-piece gasket.

ssicarman, you are awesome. I've been struggling with this problem since it started getting cold this year in my new to me SC2. I got under it and started trying to find where it was coming from, and it fits that description perfectly. I just wasn't sure if there was a coolant passage through the intake manifold.

And to complicate things, I think the last owner or dealer I bought it from decided that it would be a great idea to empty and refill the coolant with regular green coolant. But they apparently didn't do such a hot job of flushing the system. It was nice and green when I got it, but not so much now. I was going to flush it today, but I couldn't get the plug out of the radiator. I've been driving the '93 because of the coolant mix, and it'll be great to get my good car back in proper running order.

[madpogue]

Originally Posted by white95SL1

but I couldn't get the plug out of the radiator.

That plug isn't "threaded"; it's more of a "bayonet" mount. A lot of people try to just unscrew it, and bust it off. You only turn it 1/4 turn, then you pull it backward. But yeah, the "pull it backward" part can require some mondo strength.

That coolant might be one of those "compatible with everything" types, that happens to be green in color. Or it may be Sierra, which is based on propylene glycol. The color may be from one or more ginger tablets.

[white95SL1]

Originally Posted by madpogue

That plug isn't "threaded"; it's more of a "bayonet" mount. A lot of people try to just unscrew it, and bust it off. You only turn it 1/4 turn, then you pull it backward. But yeah, the "pull it backward" part can require some mondo strength.

That coolant might be one of those "compatible with everything" types, that happens to be green in color. Or it may be Sierra, which is based on propylene glycol. The color may be from one or more ginger tablets.

I know how it's supposed to come off, I've done it on my past Saturns. This one won't even turn the 1/4 turn though. It's pretty stuck in there. I'll hit it up again tomorrow when I have more time and I'm not worried as much about trying to figure out where the coolant's leaking from.

Anyway, I suppose it's possible that it's a use with "all compatible" thing, but either way, it's getting the flush if only for my own peace of mind.

Thanks for the help! You guys have no idea how relieved I am to know where my leak is probably coming from. It's been bothering me for the past month or so.

[nightwolf364]

When I had my '00 SL2 i had a coolant loss problem too. It was the intake manifold. Saturn has a recall on '00-'02 S-series cars take it to them and get it fixed for free!

[madpogue]

Originally Posted by nightwolf364

When I had my '00 SL2 i had a coolant loss problem too. It was the intake manifold. Saturn has a recall on '00-'02 S-series cars take it to them and get it fixed for free!

Was this also all about that batch of cars that was assembled with a fold in the intake manifold gasket (also often causing a vacuum leak)?

[ssicarman]

Originally Posted by nightwolf364

When I had my '00 SL2 i had a coolant loss problem too. It was the intake manifold. Saturn has a recall on '00-'02 S-series cars take it to them and get it fixed for free!

You are mistaken. No such campaign (recall). There was a TSB (the one that I posted) for the coolant leak on the DOHC engines but no campaign.