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Old 12-05-2021, 10:22 AM
nUcLeArEnVoY's Avatar
nUcLeArEnVoY nUcLeArEnVoY is offline
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Default 11-Bolt Timing Cover question...

FWIW, I scoured the forum and Google and could not get a direct answer for this.

Has anybody ever truly verified if any of the six 11-Bolt Timing cover fasteners go into the water jacket on a 400? Specifically any mid-late 70's block.

According the '78 Service Manual, if the mounting studs are removed (you know, the two studs with the coarse and fine threading at each end that go in the two middle holes on the timing cover - I've attached a pic and circled the holes in red), you need to use thread sealant when you re-install them. Now, I'm assuming they mean ACTUAL THREAD SEALANT to keep out moisture and not threadlocker. That implies those two holes on the block go right into the water jacket, but I'm not sure.

Can anybody with frequent Pontiac engine building experience, or even someone with a spare block lying around verify this?

The reason I ask is because I happened to replace that passenger side mounting stud and nut on the timing cover, since on the one that was there before, the nut wasn't fastened down all the way and was seized to the fine threading. Problem is, I didn't know I had to use thread sealant and so I didn't put any on it. Ever since I did that and put on the new water pump, I've noticed that on that same side, the uppermost corner of the timing cover-to-block gasket won't dry up and keeps wicking coolant. Not leaking, per-say, but it won't dry up. I'm wondering if it's because coolant is wicking up the threads of that stud that needed sealant and dampening the gasket.

Thanks, everyone.
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1979 Trans Am W72 400/4-Speed WS6 - Starlight Black Hardtop
  #2  
Old 12-05-2021, 02:15 PM
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Gary H Gary H is offline
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None of the 6 bolt holes that hold the timing cover to the block go into a water jacket. I've built well over 100 Pontiac engines and have never used sealant on any of those bolts.

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Old 12-05-2021, 03:07 PM
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No sealant needed.

However a somewhat liberal application of anti-seize would be wise, those two fasteners as well as the two above are notorious for rusting and breaking off when servicing the water pump or timing chain.

You have to make good and sure that the gasket surfaces on both the block and timing cover are clean and flat. Leakage of coolant into the engine internals can happen here, one of the design faults of this particular engine unfortunately. If your timing cover is corroded excessively replace it.

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Old 12-05-2021, 04:24 PM
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nUcLeArEnVoY nUcLeArEnVoY is offline
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Got it, thanks, guys.

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