Replacing Risers and Exhaust Manifolds

[bigddaddy]

I'm looking to purchase a 1987 V-20 I/O with a chevy 305 V8 and mercruiser outdrive. The owner has indicated that the risers and exhaust manifolds are in need of replacement. The boat is currently at a marina and they have quoted the work at around $1000. I am a moderate DIY'er and would like to do the work myself if I proceed with the purchase.

How difficult would this job be? How much could I expect to spend on the parts? Any caveats?

TIA for any advice.

[macojoe]

Well having been threw this myself, I would let them do it next time!!
the rust and corrosion make the job a huge pain!! Add to the fact that fitting in that engin compartment is dam near impossible!!

OK If I was to do it again, I would put a motor lift in the boat on Plywood, I would pull the outdrive and service it while you are at it.
Lift the motor up out the hole so you have a clear shot at all!
Heat & PB Blaster are your friends!! Work slow and take your time!! and you should be fine!!

Now that you have it all out check all wires, change the oil and inspect the oil pan for leaks and or rust ( I had to pull the motor 4 monts after the deal to replace the oil pan >:() ck all hoses conetions, ect ect ect.. These are all things you can never see and this is your time to get it all done!

$1000 is good to pay with out having to do your self, but then again if you do like i said, yourself you have the time to fix all the other little things you may find on the way, with out paying the guy who finds it and then you go from 1000 to 2000.

well this is my opion Good Luck

If you do this job, there is this thing called a Camera!! We expect pic of all!!

[bigddaddy]

Thanks for the update Macojoe. If I make the purchase, I think I will try and do the work myself.

Can anyone recommend any places on the web with good prices for these parts? I'd like to start getting some prices.

Thanks

[captbent]

YOU CAN DO IT! ;D

Its not easy. Lots of rusty bolts which will twist off then you have to use easy outs etc with no room to work. I've done two, one in the boat ( a 351 ford) and one with the engine and outdrive out (a 350 chevy) but it was still a lot of knuckle busting work and if you dont have the gaskets just right you have a water leak like I did and get to do it all over . I would never do it again but thats just me.. Frank

[Franco]

Take your time and it's not so bad. A few tips I learned when I did mine and some info to help you prevent bolts from breaking off
1) uses good sockets - 6 point sockets are the best
2) use wrenches that are in good shape -
3) run the engine till it gets warm - after you shut it off liberally spray the bolts with rust penetrating lubricant, try and find non-flamable or keep a fire extinguisher handy
4) let them soak over night
5) Borrow or buy an Impact driver - it has a 3/8" square drive to accept sockets - you put the socket on a frozen bolt and smack the driver with a hammer to loosen frozen fasteners - only use it on frozen nuts and bolts
6) use a long handeled ratchet - apply steady pressure when breaking loose bolts
7) when re-assembling use anti seize lube on all bolts
8) buy new bolt kits, they are cheap, about $15 at West Marine - elsewhere would be cheaper
9) they make plugs for the ends of the manifolds that have a zinc attached to prolong the life of the manifold
10) Remove the spark plugs prior to removing the manifold, when you remove the last bolt, the manifold will drop down and break one or more of the spark plugs, ask me how I know
11) label the sparkplug wires
12) usually it's a dirty greasy job, so put something down on the deck so you dont have but so much clean up when done.
13)buy some hi heat header paint and paint the manifolds again - 3 or 4 light coats keeps them looking good on the outside for a long time
14) It aint as bad as it looks
15)You can do it

I did the job when I re-powered my 5.7 OMC. I thought the job was easy, but that was on a brand new motor. I used Sierra manifolds and risers. The fit and finish were excellent. Sierra paints them with an epoxy finish that is very tough. It has been 1 year and they still look brand new. I also used all new hardware that made installation easy.
I would much rather do the job on my boat than replace a set of V8 exhaust manifolds on a car.

BassOMaticII
On the left coast in search of Whales

also helps to tighten the bolts a little more if you can before loosening them, and tighten some and loosen more if you feel enough resistance to snap them.