4.3 yamaha exhaust manifold

[malone748]

I have a busted exhaust manifold and need a replacement will any other manifolds work because I am having a hard time finding another Yamaha manifold

 

[Bondo]

Re: 4.3 yamaha exhaust manifold

Ayuh,.... Welcome Aboard,.... You could re-engineer Merc or Volvo manifolds, 'n risers to fit,...

Donno exactly what any differences are though,....

I just caution you Not to go with 1 piece manifolds,...
Go with Manifolds, 'n Risers,...

 

[Capt Ken]

Re: 4.3 yamaha exhaust manifold

You will need to change over to Mercruiser style manifolds. If you want to keep your current thermostat housing then you will need some creative plumbing skills.

 

[malone748]

Re: 4.3 yamaha exhaust manifold

Thanks for the information. Looks like I have a little custom work to start on.

 

[Bondo]

Re: 4.3 yamaha exhaust manifold

Thanks for the information. Looks like I have a little custom work to start on.

Ayuh,.... Feel free to photo document the process,...

The knowledge base is lackin' in Yamaha stuff,...

I'm thinkin' there's gonna be dimensional differences, 'n diameters of outlets, etc....
It'd be Great if you could point out what ya find,...

I once found that some OMC risers were 1/2" different diameter at the outlets when marryin' to Mercruiser stuff,....
OMC, 3, 1/2",... Merc, 3" or 4"....

 

[triman]

Re: 4.3 yamaha exhaust manifold

Many moons ago, somewhere in a boating forum, I posted photos of my 350 Yamaha with Mercruiser manifolds and a "different" thermostat housing setup.
I'll see if I can track these down. Not that relevant to a 4.3 but it is possible to fit Merc gear to a Yammie.

 

[Capt Ken]

Re: 4.3 yamaha exhaust manifold

Actually you can use the Yamaha thermostat housing but you have to use a block off plate under the riser. You then install a 90 degree nipple in the top of the manifold just ahead of the riser. The water exits the manifold there to return to the thermostat housing. Then the water exits the thermostat housing to the riser. Same as the Yamaha manifold setup.
The exhaust hoses are all the same sizes and will match up. Only modifying is going to be bolting the brackets to the risers but it can be done.

 

[malone748]

Re: 4.3 yamaha exhaust manifold

I was lucky enough to find a Yamaha manifold used that is in good condition thanks for the information