Looking for Late Model Manifold

[RobH2]

I'm looking for a a Late Model A4 Manifold that's in pretty good shape. Mine is showing some significant external flaking and it's only a matter of time.

Before buying a new one I'd like to try to find a used one.

[ronstory]

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. ;^)

[RobH2]

Excellent advice Ron. I appreciate it. I did find a new one from Barr Marine. I got it with shipping for less than $300.

What I'm worried about is getting the old bolts out. They are rusted to the manifold that has just started to shed metal layers off of the surface. I just noticed this last week and was shocked. One of the nuts is actually growing a split. Yikes...! It might take me 12 hours to do the job.

On an off topic note, I replaced my rear oil seal last fall. I bought the puller from Moyer but could not use it as I didn't have enough clearance behind my engine even as I was on the hard and had pulled the prop shaft back. It took me 13 hours to get the 5 bolts out and 5 to get it all back in. I was lying on the block working one-handed. It was the worst experience in my life...lol... But, I now have no oil leaks.

[ronstory]

Nice find. I would consider adding the stud kit.

The 3 side bolts shouldn't be too bad with a good soak of pb-blaster or the similar.

The bolts on the flange are going to be a "dog of the female gender".

If the flange bolt heads are intact, I would just try and soak them to see if they will loosen with a bit of heat. If that is no-joy, since you are replacing the manifold I might be able to just twist off the heads with a 6 sided socket and breaker bar... or if you have one an electric impact wench.

Then just get a block of wood and hammer and tap off the flange. Check the the condition of the flange, and if it looks sketchy... this is then a perfect time to replace it and the exhaust stack.

[JOHN COOKSON]

When the day comes start the engine and run it until it gets up to temperature. While the engine is running go after the bolts. The heat + vibration will help loosen the bolts. Careful not to burn yourself.

ex TRUE GRIT

[RobH2]

When the day comes start the engine and run it until it gets up to temperature. While the engine is running go after the bolts. The heat + vibration will help loosen the bolts. Careful not to burn yourself.

ex TRUE GRIT

Most excellent suggestion. That's exactly what I'll try first.

[RobH2]

Nice find. I would consider adding the stud kit.

The 3 side bolts shouldn't be too bad with a good soak of pb-blaster or the similar.

The bolts on the flange are going to be a "dog of the female gender".

If the flange bolt heads are intact, I would just try and soak them to see if they will loosen with a bit of heat. If that is no-joy, since you are replacing the manifold I might be able to just twist off the heads with a 6 sided socket and breaker bar... or if you have one an electric impact wench.

Then just get a block of wood and hammer and tap off the flange. Check the the condition of the flange, and if it looks sketchy... this is then a perfect time to replace it and the exhaust stack.

When you say the flange, do you mean the metal part with two bolts that holds the beginning of the exhaust pipe water lift to the right end of the manifold? If so, I redid my exhaust two years ago and it has new bolts those should be no problem. I don't have an electric impact wrench but have been needing and excuse to buy one. Maybe it's time to head to Harbor Freight.

[JOHN COOKSON]

When the day comes start the engine and run it until it gets up to temperature. While the engine is running go after the bolts. The heat + vibration will help loosen the bolts. Careful not to burn yourself.

ex TRUE GRIT

This procedure also helps when loosing a temperature sending unit.

[ronstory]

Yes, the flange is the chunk of metal that the metal exhaust riser screws into. If you got those bolts out in the last few years, you are golden.

I would still recommend the stud kit, it makes installation easier since you can hang the exhaust on the studs and not wrestle with it while trying to get a bolt threaded. But if you already have experience doing the bolt method, that may be easier and no waiting for a stud kit.

So perhaps you just need paint.

[RobH2]

... you can hang the exhaust on the studs and not wrestle with it ...

So perhaps you just need paint.

I already have paint. I'm not sure I understand how the studs work. I looked for a diagram or a 'Tech Tip' and didn't see anything. How do you use those T-bolts?

[ronstory]

The studs are installed semi-permanently into the threads of the exhaust manifold holes. They go in just like the bolts, but with a threaded end versus the head of the bolts you are currently using. You then slide the flange over the studs and tighten down with a nut and lockwasher.

See the pic, it should be pretty clear how they work.

https://moyermarine.com/product/exhaust-flange-studsmanifold-exht_05-2_321/

Not sure why you mentioned t-bolts, I never talked about them and they are a very different animal and purpose.

[RobH2]

Sure, I know that photo. I said "T" well, because they are "T" shaped, not being sure I know the technical name for them.

I'll look at it when I'm down there and it should make sense. I'm just seeing 3 sets of threads on each one and wondering how it all bolts up. Again, I need to put a fresh eye on it when I disassemble mine. Thanks for the input. It's valuable.

[TimBSmith]

Picture is misleading to untrained eye...the studs seem to overlap...

The studs are actually just threaded on both sides. There is an optical illusion in the photo because of the overlapping studs foreground and background. I had the the same thought when I first looked at the photo. How in the heck will a "T" shaped stud work? : )

[RobH2]

The studs are actually just threaded on both sides. There is an optical illusion in the photo because of the overlapping studs foreground and background. I had the the same thought when I first looked at the photo. How in the heck will a "T" shaped stud work? : )

That's hilarious!!! They are straight bolts with two threads, not 'Ts'... Now I see it. How funny. Yes, that photo could have been better thought out for sure.

I get it. Sure, makes complete sense now. Thanks for making me feel unobservant. Now, looking at the photos, it's obvious. It's like seeing Jesus in the potato chip. Once you see it, you can't "unsee" it...lol...

[ronstory]

Yes, those simple things... and pic that show three when you only need two doesn't help.