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1992 Dodge Stealth R/T Twin Turbo
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Discussion Starter #1
I've been pulling my hair out trying to find a pretty significant coolant leak for about a month. I've replaced the thermostat, coolant temp sensors, and radiator cap recently as they were all cheap and aging parts. I've learned that I only lose coolant if I put the car under moderate to heavy load. It doesn't have to be WOT, but any time I go for a more sporty drive over 20 miles I lose nearly a half gallon of coolant. If I baby the car and keep the RPM below 3000 I do not lose any, or only lose very little coolant. There are no apparent leaks anywhere on the car and no puddles form. The car also does not lose coolant when it is not running. I can usually go for about 20 miles before my temp gauge starts jumping up and down from air being in the system / loss of coolant. The top radiator hose feels super tight and is almost ballooning when this happens. I think I'm going to come to the conclusion of a head gasket issue, but I have no coolant in my oil, no smoke from my exhaust, and the car only has 42,000 miles. You'd think a head gasket would last for at least a good 100,000 before it gives out. This almost seems like the symptoms that some have had with head lift, but my car is completely stock and not pushing high boost. Before I blow even more money, is there anything else this could be before I buy a combustion leak test and pressure tester?
 

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You can rent/deposit those two tests from an auto parts store.

I have a similar issue that I caused myself from extended overheating. No outward signs of HG leak/warped head such as water in the oil or puddles but I definitely loose coolant if driven for while or during mild boost.
I borrowed the combustion tester from an auto parts store and it showed nothing, I even pressurized the system with another auto parts borrowed pressure tester and it held past 13lbs with no issue when cold. Warm might be different but didnt think to try at the time.
It only seems to leak when hot possibly out of a cylinder I guess since there's no other evidence.

Its the back up car and so far I'm to lazy to tear it down myself to prove the HG is bad but not much else it could be that I can find through searching the board.

Good luck with yours
 

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1992 Dodge Stealth R/T Twin Turbo
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Discussion Starter #3
You can rent/deposit those two tests from an auto parts store.

I have a similar issue that I caused myself from extended overheating. No outward signs of HG leak/warped head such as water in the oil or puddles but I definitely loose coolant if driven for while or during mild boost.
I borrowed the combustion tester from an auto parts store and it showed nothing, I even pressurized the system with another auto parts borrowed pressure tester and it held past 13lbs with no issue when cold. Warm might be different but didnt think to try at the time.
It only seems to leak when hot possibly out of a cylinder I guess since there's no other evidence.

Its the back up car and so far I'm to lazy to tear it down myself to prove the HG is bad but not much else it could be that I can find through searching the board.

Good luck with yours
Thanks, I've only had the car a couple months so I don't know if the previous owner caused this issue by letting the car overheat. I always get the car to a stopping point before the needle hits red. I don't know if I'm up for a head gasket change myself, and it's my second car so I'm taking my time.
 

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sounds like the head gasket the coolant is being evaporated in the exhasut that is why you are not seeing the leak
 

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My car is a money pit
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I had this exact same issue on mine... except I believe I lifted the heads (causes same symptoms/issues as bad HG). I drove from Indianapolis to Lex. KY (nearly 4 hours) with zero issue. Zero. I got into boost 1 time (when I was close to home) and it immediately started overheating.

Replace headgaskets and head bolts to be safe.
 

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Discussion Starter #6
I had this exact same issue on mine... except I believe I lifted the heads (causes same symptoms/issues as bad HG). I drove from Indianapolis to Lex. KY (nearly 4 hours) with zero issue. Zero. I got into boost 1 time (when I was close to home) and it immediately started overheating.

Replace headgaskets and head bolts to be safe.
I don't know if I'm up for a head gasket replacement on my own, but I can't find a shop around here that I would trust to work on this engine. What all must be removed in order to get to the head gasket? Will the timing belt have to come off?
 

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Most probably a head gasket. Mine showed same symptons. It will be a very small passage between cylinders. If it is showing mist ou the tail pipe. Does it foam out the overflow after a long drive at high speed? One that I had was very hard to spot happened after a water pump failure. Replaced water pump. Then Could drive about 50 miles at 65 70mph before it would start to overheat. Gave no problems driving around town low speeds. Finally took it apart and it had very small damage to gasket between cylinders. Make sure to replace left and right while you have it apart. also tried combustion tester to no avail as it was going out the exhaust. You might try a cylinder leak tester. to pinpoint it. You say tthe car is stock has the water pump been replaced? or maybe a hose?
 

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Removing the heads is a big job on a dohc engine, even more work if it's turbo charged. Yes the timing belt has to come off. So you can start understanding the work involved by reading posts about timing belt removal/installation, and check out videos on YouTube then of course the exhaust has to come off.
When tearing down an original engine that far I'd do a valve job as well.
 

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Discussion Starter #9
Most probably a head gasket. Mine showed same symptons. It will be a very small passage between cylinders. If it is showing mist ou the tail pipe. Does it foam out the overflow after a long drive at high speed? One that I had was very hard to spot happened after a water pump failure. Replaced water pump. Then Could drive about 50 miles at 65 70mph before it would start to overheat. Gave no problems driving around town low speeds. Finally took it apart and it had very small damage to gasket between cylinders. Make sure to replace left and right while you have it apart. also tried combustion tester to no avail as it was going out the exhaust. You might try a cylinder leak tester. to pinpoint it. You say tthe car is stock has the water pump been replaced? or maybe a hose?
Doesn't foam out the overflow. The overflow level has remained constant for the most part, with the exception being the first time I noticed the car trying to over heat when I caught the coolant boiling in the overflow. The water pump was replaced during the 60k service which was done at 40,000 miles by the previous owner.
 

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Discussion Starter #10 (Edited)
Removing the heads is a big job on a dohc engine, even more work if it's turbo charged. Yes the timing belt has to come off. So you can start understanding the work involved by reading posts about timing belt removal/installation, and check out videos on YouTube then of course the exhaust has to come off.
When tearing down an original engine that far I'd do a valve job as well.
Oh boy, looks like I'm in for a treat. Maybe I'll learn a few things in the process. Think I should go for new head bolts while I'm at it? I'm going to get a combustion tester to use this weekend and if it shows exhaust in my coolant I'll be tearing the engine down.
 

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well, i replaced my head bolts with new ones because I thought the originals had stretched, but when i measured the old head bolts and measured the new head bolts, the seemed identical to me. I went with the new anyway, and opinions were mixed about re-using the old bolts.
it's a ton of work, i know I can have the heads off now in a weekend because I've done it before, but I took my time the first time around trying to be careful.
it actually takes longer to put the heads back on because everything has to be assembled in order, and nearly every bolt has a specific torque spec that you have to find scattered on pages in the service manual. I meant to photo copy the specific pages in the service manual with torque specs and the assembly order, but I got busy and never did do that.
 

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Discussion Starter #12
well, i replaced my head bolts with new ones because I thought the originals had stretched, but when i measured the old head bolts and measured the new head bolts, the seemed identical to me. I went with the new anyway, and opinions were mixed about re-using the old bolts.
it's a ton of work, i know I can have the heads off now in a weekend because I've done it before, but I took my time the first time around trying to be careful.
Gotcha, will probably go with new then. Wouldn't want to have to tear everything down again over that...
 

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Discussion Starter #13
Combustion leak test has confirmed a nasty head gasket leak. Looks like I'm in for a fun time.
 
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