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Old 03-18-2021, 05:08 PM
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ronstory ronstory is offline
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Be careful on used manifolds

One thing to be careful of regarding a used manifold is checking the threads for the exhaust flange. I has been my experience (2 used manifold) that the threads were sketchy. If they have been repaired via helicoil(s), I would pass and just buy a new one or a used one with very threaded exhaust holes.

Be aware with the threaded hole if someone installs a helicoil but messes-up drilling/tapping on the top hole it could penetrate the water passage. I had one of those, and replaced the beat-up helicoil with a fresh one, used the MMI stud kit and high temp exhaust sealant. Ken told me to just replace it, but I thought I could make it work.

Well, it still leaked. I tighten it, it still leaked, etc. Now it was a small weeping, but this if a fresh rebuilt... so any leaks are too many and I didn't catch on the run-in.

The solution was going through the pain of replacing it with a new MMI manifold in a very tight engine compartment. I should have listened to Ken-the-Wise and just bought the new one. 20/20 hindsight. Wait, is it too soon to reference 2020?

Now the MMI manifold had its own issues. I did check the threads and they were tight and opted to purchase to two sets of studs... trying to learn from my early penny foolish moment. It was lucky I did.

What I discovered that the threads in the brand new MMI manifold were not tapped deep enough to bottom out studs so the nuts were not able to tighten down on the exhaust flange. Unfortunately, I discovered this at the boat during the re-install. Of course, I had a set of bottom taps at home, but could only find taper taps in-town at the marina on the Saturday.

Ultimately, I just modified and sacrificed one set of studs and brute forced them to work as taps. Even then, I barely got the stud deep enough to mount the flange. It's working now, but it took over 6 hours to get it back together.

That reminds me I need to give Ken that feedback. He owes me a set of studs. ;^)
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Ron
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Last edited by ronstory; 03-19-2021 at 04:21 PM. Reason: typo, always typos
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