Thermostat to riser and manifold plumbing ?
 

Whats the best way to plumb the water hoses from the thermostat to the exhaust manifold and risers. The factory seems to have had the cold water going to the riser and heated water going to the manifold. I tried this and the tailpipes got cold (on start up) and the manifold got hot almost to hot before the thermostat opened, I then reversed the hoses, cold water to the manifold and hot water to the riser. Will the tailpipe get to hot this way? I havent ran it in the water yet. I am thinking for putting it back the way it was and trying it in the water, I dont want to ruin the manifolds or tailpipes , yet!<p> http://members.aol.com/untmaintco/engine The hoses on the t-stat housing are shown reversed in the photo. The engine is (was) a 502 mag, gil manifolds,

Re: Thermostat to riser and manifold plumbing ?
 

If you want to change it, I would run water from both to the manifold. You'll have to change the location of the T. I agree, I can't figure out why Merc lets the manifilds get so hot before the tstat opens.

Re: Thermostat to riser and manifold plumbing ?
 

the water from the thermostat housing is supposed to be going to the bottom of the manifolds. the way it's routed now the manifolds do not have a positive flow of water through them. the water is just passing directly through the risers after filling the manifolds.

Re: Thermostat to riser and manifold plumbing ?
 

Plus, you don't want the manifolds getting stone-cold water. The temperature gradient is not good for the metal. And, a hotter manifold will scavange more from the cylinders.

A hot exhaust is a good thing. We have to remember that the only reason we have water cooled exhausts in boats is so we don't burn 'em to the waterline.