#1  
Old 09-19-2021, 05:09 PM
nUcLeArEnVoY's Avatar
nUcLeArEnVoY nUcLeArEnVoY is offline
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Default Timing cover coolant leak...

Car is a 1979 Trans Am w/ 400.

Pulled my old water pump to replace it since it was a crapola stamped impeller A-1 Cardone unit, and the clearance was .200. No wonder I was getting hot in traffic.

Anyway, once I started loosening up the water pump bolts, I could see a very small coolant leak spring suddenly from behind the timing cover where it mates to the block on the passenger side. It's near where the heater hose goes onto the timing cover. I'm guessing it's because I loosened the long 3/8" Bolt that mates the water pump to the timing cover and to the block. Doesn't seem to have happened on the driver side. For what it's worth, I didn't drain as much coolant as I thought I did. Still made a heck of a mess once I took the water pump off.

So what do I do here? Is this a relatively normal thing when those big bolts are loosened, or did the gasket fail?

Should I just install the new water pump, torque everything down and see if that seals it it or should I pull the timing cover and re-gasket?

I have the blessing of having not run the engine yet, and I doubt any water is leaking into the crankcase, it just seems to be doing it on the outer edge of the timing cover but I'm not sure.

Would appreciate advice.

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1979 Trans Am W72 400/4-Speed WS6 - Starlight Black Hardtop

Last edited by nUcLeArEnVoY; 09-19-2021 at 06:09 PM.
  #2  
Old 09-19-2021, 08:48 PM
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Tighten everything back up and see what happens.

  #3  
Old 09-19-2021, 09:01 PM
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nUcLeArEnVoY nUcLeArEnVoY is offline
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Quote:
Originally Posted by PunchT37 View Post
Tighten everything back up and see what happens.
Hmm... okay. I REALLY don't want to have to pull the timing cover. But I also don't want to risk water getting into the crankcase.

I've never seen a single drop from this spot until I removed the water pump, meaning those two long 3/8" bolts...

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  #4  
Old 09-19-2021, 09:59 PM
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Quote:
Originally Posted by nUcLeArEnVoY View Post
Hmm... okay. I REALLY don't want to have to pull the timing cover. But I also don't want to risk water getting into the crankcase.

I've never seen a single drop from this spot until I removed the water pump, meaning those two long 3/8" bolts...
Been pulling wrenches for almost 30 yrs. I might not be 100% perfect all the time, but right most of the time.

  #5  
Old 10-04-2021, 03:08 PM
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Update on this, in case anybody experiences anything similar:

Put on the new water pump (got a bit carried away with the Permatex Blue, admittedly - it ain't pretty lol), cinched everything down to spec (I torqued the 5/16" water pump bolts to 15 lb-ft, and the two long 3/8" bolts that mate the water pump to the timing cover and to the block to 30 lb-ft), filled the engine with coolant and so far no leaks from the timing cover. Shining a light on the gasket around where it leaked between the timing cover and block, a small area of it still looks a little damp where it seals around the water passage, but that could just be residual moisture from when it WAS leaking, since these paper gaskets will wick fluid. I'd imagine a heat soak from the running engine will dry that right up.

Haven't started the car yet since I'm putting on a new alternator and want to do a precautionary oil change just in case some coolant did leak into the timing chain area (oil level hasn't increased, but I'm paranoid about these things), but I just wanted to see if there would be any leaks from behind the timing cover and from the water pump gaskets after the new install, and as said, so far none. Hope it stays that way once I run the car and the system goes under pressure.

Also found a big reason that probably contributed to the leak in the first place (besides the fact that I did not adequately drain the coolant all the way, stupid me); turns out the stud that mates the timing cover to the block using a nut on the passenger side was not tightened down AT ALL, while on the driver side it was fine. I could spin the washer under the nut with my finger. Sadly, I couldn't tighten it down the moment I noticed it, since the nut was completely seized to the fine threading of the stud, but I was at least able to remove the entire stud itself. Had to get a new repro from Inline Tube, so I did, torqued the nut/washer to 30 lb-ft and now I have peace of mind knowing the timing cover is properly fastened. That means the entire time I've owned the car, the top and bottom 3/8" bolts were all that was holding the timing cover to the passenger side of the block - I'm surprised the gasket didn't already leak. My theory is, once I undid the long 3/8" water pump bolt, all that was holding the entire passenger side of the timing cover to the block was the bottom bolt, and it's likely that the pressure from the intake-bypass connection (where you torque the draw bolt to pull the intake and squeeze the donut o-ring) caused the timing cover to unseat on the passenger side just enough to spring the leak, even though I couldn't physically see it move (only takes .003" for water to leak after all). So yeah, that happened.

Timing cover is fastened down properly now, so is the new water pump... so far, no leaks. I hope it stays that way once I start the car. Hopefully it's all worth it and this new Flowkooler circulates coolant far more effectively. Just in case, I also clearanced the divider plate. It's at about .045"-.050" from the impeller WITH the gasket.

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1979 Trans Am W72 400/4-Speed WS6 - Starlight Black Hardtop

Last edited by nUcLeArEnVoY; 10-04-2021 at 03:36 PM.
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