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I'm losing roughly a quart of coolant a day from the stock 122k mile ls1 in my 1998 TA. It's been doing this for the few months that I've owned the car. I've tried everything I can think of to track down the problem with no luck. So far I've tried pressure testing the cooling system and visually checking for leaks. This lead to finding a tiny seep at one of the heater hoses and I looped the fittings at the pump temporarily to rule it out as the source. No change. I've also tried one of the Lisle combustion leak detector kits to rule out a BHG. The instructions said to idle the engine with the tester in place for 2 minutes and the fluid inside would change color if combustion gasses were present in the coolant. I held it in place for a full 10 minutes of idling with no change. I've replaced the radiator cap and inspected the line to the expansion tank to rule out pulling in air instead of coolant as the engine cools. At this point I'm out of ideas short of shotgunning new parts at it. I would think with the amount of coolant being lost that it would be easy to tell where it's going but I can find no sign of a leak.
Any troubleshooting advice or pointing out things I've missed would be greatly appreciated.
Thanks,
Tony
I remember when this same issue was happening to me I couldn't tell the reason. My car would never overheat, I would just loose coolant on the regular. Just so happen one day when I was looking under my car after driving it I noticed a small steam leak coming from my radiator. It did not leak fluid but was leaking steam. You have to have some kind of steam leak somewhere in the coollng system if you visually never notice a fluid leak. Only thing that kind of has me baffled is that you are losing 1/4 fluid a day... thats a pretty good amount...
In worst case scenario you could have a cracked block... check your oil cap and look at it... if it looks like milk shake then that is bad.. coolant is going into the oil.
Thanks for the reply! I do get a little condensation under the oil cap but then I make a lot of short trips where the oil never gets a chance to fully warm up. What I'm seeing under the cap looks like a few drops of pure water. I even taste tested a drop of it and it wasn't sweet like coolant. The oil itself looks fine, not milky, and the oil level doesn't appear to be increasing. I'll keep an eye out for steam leaks. What really gets me is that the cooling system held 20 psi for an hour on a pressure test. I'd think any significant leak would have shown up then but the only thing I found was the very slight seep in a heater hose that I mentioned. Nothing that would account for that much coolant loss.
So, does anybody have any suggestions as far as what to do next? I'm seriously considering throwing a new set of head gaskets on since everything with the exception of passing the combustion leak detector test seems to point to a small head gasket leak that's pushing air into the cooling system. Has anybody ever seen a blown head gasket act like a 1-way valve where combustion pressure forces its way into the cooling system but the cooling system will still pass a pressure test?
Ok so it isn't in the oil, it's not leaking out visibly, and you've ruled out the head gasket? Can you smell coolant in the cabin? Like from a leaking heater core?
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OMG! Myk's still driving an LS1!
So, does anybody have any suggestions as far as what to do next? I'm seriously considering throwing a new set of head gaskets on since everything with the exception of passing the combustion leak detector test seems to point to a small head gasket leak that's pushing air into the cooling system. Has anybody ever seen a blown head gasket act like a 1-way valve where combustion pressure forces its way into the cooling system but the cooling system will still pass a pressure test?
Thanks,
Tony
Yes.....you could still have a BHG. Sometimes idle is not enough to pass the leak if its too small. But under increased rpm and increased cylinder pressures it will. And a leak can sometimes only take coolant in and out the exhaust and not necessarily push combustion into the cooing system. A quart is allot. Have a friend rev your engine, see if any coolant comes out of the tail pipes.
Also, water pump seals and tiny pinholes can do the same thing. They will only leak after you have shut the engine down and then after about 20 minutes......pressure and temps RISE after an engine is shut down for about 30 minutes because there's no more coolant flow and cooling ram air or fans. Fans that run after an engine shuts down only cools the coolant sitting in the radiator, it does nothing for engine cooling. The coolant may be pissing out of a leak at that time.
So, get the engine up to operating temp.....put the front end up on ramps. Then 15 minutes later get under there with a flashlight and look everywhere for leaks. Little pinhole leaks will hide until those pressures and temps rise.......
Ok so it isn't in the oil, it's not leaking out visibly, and you've ruled out the head gasket? Can you smell coolant in the cabin? Like from a leaking heater core?
No coolant smell inside, no fogging up windshield, no wet carpet. To rule out anything heater hose/core related, I unhooked the heater hoses at the water pump and looped the fittings with a short piece of heater hose. I've driven it around for a few days since unhooking the heater and it seems to have made no change in the amount of coolant it's losing.
Out of curiosity, does the water pump on an LS1 have a weep hole? If so, where is it? Maybe I've got a leaky pump that's only getting bad when the engine is running and I can't see the leak for all the clutter under the hood?
I just want to exhaust every option before throwing new parts at it. I've got a set of long tubes to install though so if I can't find anything, I'm going to go ahead and do head gaskets when I install the headers.
Yes.....you could still have a BHG. Sometimes idle is not enough to pass the leak if its too small. But under increased rpm and increased cylinder pressures it will. And a leak can sometimes only take coolant in and out the exhaust and not necessarily push combustion into the cooing system. A quart is allot. Have a friend rev your engine, see if any coolant comes out of the tail pipes.
Also, water pump seals and tiny pinholes can do the same thing. They will only leak after you have shut the engine down and then after about 20 minutes......pressure and temps RISE after an engine is shut down for about 30 minutes because there's no more coolant flow and cooling ram air or fans. Fans that run after an engine shuts down only cools the coolant sitting in the radiator, it does nothing for engine cooling. The coolant may be pissing out of a leak at that time.
So, get the engine up to operating temp.....put the front end up on ramps. Then 15 minutes later get under there with a flashlight and look everywhere for leaks. Little pinhole leaks will hide until those pressures and temps rise.......
Out of curiosity, does the water pump on an LS1 have a weep hole? If so, where is it?
Yes. Bottom 6'oclock position.....behind the snout. You'll be able to see if its leaking from there when you get under it with a flashlight.
Sometimes they leak allot...sometimes very slowly.
Yes. Bottom 6'oclock position.....behind the snout. You'll be able to see if its leaking from there when you get under it with a flashlight.
Sometimes they leak allot...sometimes very slowly.
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Cool, Thanks!
Gonna put it up on jackstands this afternoon and have a good look around like you suggested. If I still can't find anything, I'll run to the parts store and grab some head gaskets, head bolts, and whatever else I need (intake gaskets?) and get started. I'm out of work right now so I have time to fool with it but I could get called out for a job at any time so I'd like to get it reliable asap.
Cool, Thanks!
Gonna put it up on jackstands this afternoon and have a good look around like you suggested. If I still can't find anything, I'll run to the parts store and grab some head gaskets, head bolts, and whatever else I need (intake gaskets?) and get started. I'm out of work right now so I have time to fool with it but I could get called out for a job at any time so I'd like to get it reliable asap.
Thanks again!
Tony
You could do a leakdown check too, before doing the head gaskets. To be sure.
Intake gaskets are cheap, might as well change them too.
A little update on this. Turns out it is a BHG on the pass. side bank. I evidently didn't have the combustion leak tester sealed to the radiator filler neck good enough and it was pulling enough fresh air to cause a false negative. Tested both banks separately by unplugging the coils and allowing a couple minutes of running for the CO2 to leave the cooling system. when it was running on the driver side bank the fluid in the tester didn't change color but did when it was running on the pass. side.
The engine is coming apart now. Just lack valvetrain, ps pump, and pass. side exhaust manifold to be ready to pull the heads.
A little update on this. Turns out it is a BHG on the pass. side bank. I evidently didn't have the combustion leak tester sealed to the radiator filler neck good enough and it was pulling enough fresh air to cause a false negative. Tested both banks separately by unplugging the coils and allowing a couple minutes of running for the CO2 to leave the cooling system. when it was running on the driver side bank the fluid in the tester didn't change color but did when it was running on the pass. side.
The engine is coming apart now. Just lack valvetrain, ps pump, and pass. side exhaust manifold to be ready to pull the heads.
Well, at least you got it. Sometimes those leaks are small......and don't really give the typical clear-as-a-bell symptoms of a BHG......
Well, at least you got it. Sometimes those leaks are small......and don't really give the typical clear-as-a-bell symptoms of a BHG......
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I'm not so sure now that it's apart. I couldn't find any clear evidence of damage between a water jacket and a fire ring. I wasn't expecting much with that small a leak but was hoping for something definite. Now it's got me worried about a cracked head or even worse a crack in the deck surface of the block. There was also evidence that the heads have been off before which leads me to believe that I may have inherited somebody else's problem that they couldn't fix by throwing gaskets at it.
At the very least I think I'm going to have a machine shop check and resurface the heads before it goes back together.
So, after pricing machine work (check & resurface the heads), I did a little poking around on ebay. I ended up buying a "brand new" "never bolted on" pair of assembled 806 castings for about $50 more (including shipping) than the machine work would cost. I'm not sure if that's a testament to the high cost of machine work or the low cost of replacement parts for our engines but either way I was pleasantly surprised.
So, after getting back from vacation I jumped straight into putting the TA back together. While prepping the deck surface for the new head gaskets I found what appears to be a small crack extending from a water jacket towards the #8 cylinder. It looks like it stops at or just short of the sleeve. In my head it seems like if there is a good seal between the fire ring and the sleeve the crack shouldn't be an issue but maybe that's just wishful thinking... Any suggestions on getting it to seal up? A new short block is way above budget right now and since this is my DD, I need it back on the road asap (the engine in the old jeep I've been driving is on it's last leg). One way or the other it's got to go back together for now and I'll just have to keep dumping coolant in it if I can't get it to seal. On the bright side there's no evidence it was drawing coolant into the cylinder, just pushing combustion gasses back into the cooling system so there shouldn't be any issue of contaminating the oil. I guess at this point I'm just going to throw it back together and hope for the best unless anybody has any suggestions on something to try to improve the chances of sealing it up.
You might try to fill the crack with JB Weld or engine block filler. If it's an extremely narrow hairline, it might be tough to force anything to penetrate into it, though.
__________________ 00 Formula Bright Silver A4 Bolt-ons, SS3600 stall, 3.42s; PB:12.37/109.62/1.69 02 Formula SOM M6 lid/catback 09 G8 GT Black/Onyx 19's, sport pkg - stock - wife's car 69 GTO Judge 400 4 spd.
69 GTO 428 TH400
You might try to fill the crack with JB Weld or engine block filler. If it's an extremely narrow hairline, it might be tough to force anything to penetrate into it, though.
It is a narrow hairline. Enough so that if I hadn't had the light shining across it just right I never would have noticed it. I racked my brain trying to think of a way to fix it. Even considered drilling and tapping for lock 'n stitch pins and then using a file and straight edge to work the pins level with the deck surface. I finally just decided to throw it together and drive it while I save up for a new short block. Being that this is WV and 90% of the population drives a truck, I should be able to find a nice low mile 6.0 out of a wreck if nothing else.
To bring this thread to a close, the new heads and gaskets seem to have sealed it up somehow.
I've put a few hundred miles on it since reassembly and the coolant has been full to the bottom of the cap every time I've checked. I can only speculate that the crack I found was superficial and the real cause of the problem was fixed with the new heads/gaskets. I can't help but feel like I dodged a bullet on this one. Anyhow, thanks for the help and suggestions everybody!
Disappearing antifreeze. Need suggestions. 
Cracked Block 
I would still save for this 6.0 though.
