Looking for instructions/hints on exhaust manifold replacement

[bds85466]

1982 Merc 898 V8 Port Side Exhaust Manifold

I believe (and hope) the Merc part is 77234.

In my previous post I was speaking of this:

http://forums.iboats.com/showthread.php?t=346262&highlight=cooling+manifold

I'm now looking for any instructions or hints on replacing the manifold before I dive in. Does it need to be drained, are torque wrenches really required, etc.

 

[TowRoper]

Re: Looking for instructions/hints on exhaust manifold replacement

if there is a drain hole drain it just to help keep any water out of the ports and you should use a torque wrench to keep from striping threads and even tightening of the mani be sure to follow that sequence too not just start at one end and go for it lol also get all the old gasket off scotch bright pads work great and if needed for hard spots emery cloth good luck

 

[bds85466]

Re: Looking for instructions/hints on exhaust manifold replacement

I've found a good article on manifold replacements by Don Casey, but there's not a lot of actual replacement strategy.

http://www.boatus.com/boattech/exh.htm

 

[freeone]

Re: Looking for instructions/hints on exhaust manifold replacement

manuals on "Adults only" http://forums.iboats.com/showthread.php?p=1693398#post1693398 posted by Don S are a great help.
Service Manual #3 1978 - 1984 All engines http://www.myotherdrive.com/dyn/pv/318.450722.23072009.53414.6a64fi/cover.pdf

 

[Bt Doctur]

Re: Looking for instructions/hints on exhaust manifold replacement

If you have the room to slide the old one off, then you can try using a short piece of threaded rod installed in a middle bolt hole in the block, slide the new manifold on, install the front and rear bolts just enough to hold the manifold in place, remove the threaded rod, using header gaskets(1 piece) notch the end holes in the gasket to slip over the 2 bolts installed, install the rest of the bolts and tighten manifold.

 

[bds85466]

Re: Looking for instructions/hints on exhaust manifold replacement

That's a nice tip. I suppose these things are heavy. I've not removed my OEM manifold yet so I'm not sure on the thread size. When my new one arrives (hopefully today) I'll have a better idea.

I see that the port side manifold also has a bracket attached which holds the alternator. Any ideas on how to do this part smoothly with the belt and all?

 

[Bondo]

Re: Looking for instructions/hints on exhaust manifold replacement

I've not removed my OEM manifold yet so I'm not sure on the thread size.

Ayuh,... It's 3/8"x16....

I see that the port side manifold also has a bracket attached which holds the alternator. Any ideas on how to do this part smoothly with the belt and all?

Just like everything else,... Take it Apart,+ Reassemble in reverse....

 

[bds85466]

Re: Looking for instructions/hints on exhaust manifold replacement

As usual, you make it sound so simple, bondo. Socket size: 9/16"?

I don't have a large space to store the manual linked below (work CPU hehe) Would anyone know off the top of their head what torque rating these bolts need? Would you torque them, run for a bit, and torque them again?

Obviously the head will need to be cleaned of old gasket remnants. Will I need to do either of the following?:

1.) Clean out the exhaust ports in the new manifold to make sure no casting particulate migrate back down into the engine?

2.) Clean/smooth (scotchbrite, sandpaper?) depaint the new manifold at the gasket contacts?

 

[bds85466]

Re: Looking for instructions/hints on exhaust manifold replacement

Well, I got the new manifold installed. Everything went ok, beers went down smoothly; to tell you the truth, the most time consuming part was scraping the gasket remnants off the riser and end caps. Getting at the thing was a bit tough, and the alternator bracket served as another good challenge.

I did notice a small leak coming from the stud which protrudes into from the riser. I believe it was coming out from the threads (above the nut) and not the gasket. I've heard this is fairly common. I retightened the studs (tough, had to use the two nut trick) and it really reduced it. After I ran the boat for a half hour it seemed to cease all together. I figure if it comes back I'll try a bit of silicone or teflon tape on the stud.