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43 exhaust manifold 1990

T

typicalfish

New member
"I am new to the board (it

"I am new to the board (it is a great resource) and have searched on this topic with some but little luck. I have a 1990 CC with twin 4.3's with the one piece exhaust risers; I was told by my mechanic that one of the manifolds is leaking water internally and allowing one side of the motor to foul. I have seen the aftermarket $1000.00+ manifold sets, I am wondering if there is any kind of other replacement option, up to and including piecing together other manifolds/bellows (I am not a purist). Any help and/or commentary would be greatly appreciated.

Thanks in advance."
 
"I just picked up a new set of

"I just picked up a new set of 2008 Mercruiser(not aftermarket) two piece 4.3 manifolds, risers (and Y pipe- which would be of no use for OMC) for $695 off eBay. They were new take offs...so if you look around you should be able to find something.

HGE still shows these as "under development" - I don't know if anyone makes 1 pc anymore.
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I think the OSCO setup could be had for less than $1000... but not much less.
There are aftermarket Merc setups on eBay for around $400, but not sure how well the risers would line up with your Y pipe...you'd likely have to get fancy with exhaust hose"
 
Your problem is not the exhaus

Your problem is not the exhaust mani or the riser elbow but rather the connection to the y-pipe. There is a really nice solution using a Volvo ~90° down pipe. I will check my garage for the pipe part numbers. I would stay away from the 1 piece aftermarket mani. The reason being is its a very difficult peice to cast and is very prone to defects. They have lost the recipe on casting it! You can get the 3 piece set up for about $250 /per side (2xGLM parts+ +90pipe)
 
I think the part # your are re

I think the part # your are referring to is 3854874. It was used on 1996 OMC Cobra 4.3L engines and also on some Volvo engines. I bought a set of these on Ebay for my 1990 4.3 when I changed to the newer two peice manifolds. They fit nicely.
 
"Yes, yes. There are several

"Yes, yes. There are several part numbers that will all work
3853384 should do it as well and are easier to find."
 
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