1 manifold warmer than other side.

I have a 78 898 pre alpha that came with a cracked block.
Replaced with an 85 305 from a car.
Reused the same heads and manifolds as they were not too bad.
But the starboard side now gets much warmer than the port side.
I have only run it for 15 mins total in 3 bursts of 5 mins all on muffs. Enough to get the temp to 140. The t-stat housing and lines to the bottom of the manifolds are cool. But the manifold under the t-stat is warm. Warmer the the port but cooler than the starboard risers.
The port side manifold gets warm quickly but even after 5 mins, I can still keep my hand on it but just barely. The big rubber hose that connects to the y pipe however is too hot to keep my hand on for more than a few seconds.
The other side is lukewarm at best.

So I removed the plug on the top riser and ran it and lots of water comes gushing out.
But it smells of exhaust. Is this normal?

So now I don't understand why this side gets so much warmer than the other.
Maybe its running normal and the other side is running too cool?
This is my first inboard so I am not sure if it should run that warm or not.
I tried to remove the port riser plug as well, but part of the skirt broke off making it almost impossible to remove.

Any ideas, suggestions, opinions or comments would be greatly appreciated!

Re: 1 manifold warmer than other side.

You say "manifolds...not too bad".
Does that mean you had the risers off the manifold to clean and flush the water passages? And there's not a lot of corrosion?

The water gushing out "smells of exhaust...normal"?
No, it shouldn't. At that part of the riser there should be only water present in the jacket. The water & exhaust mix after the riser drops towards the transom. There may be a hole from inner to outer passage, or a failed gasket.

Re: 1 manifold warmer than other side.

You don't have the water hoses hooked up to the risers as they should be. Looks like they are just looped together behind the thermostat housing.
The hoses you have have going to the bottom of the manifolds are hooked up after the thermostat. Which means there is no water to the risers until the Tstat opens.
The missing hoses have water to them even when cold.

Re: 1 manifold warmer than other side.

Better find the hose connection diagram. The picture sure doesn't look right to me either.

Re: 1 manifold warmer than other side.

Hmmm... Thats the way the boat came. Those 2 hoses just loop around and back into that t-stat housing.
There is really no other place for them to go.
I suppose they are for a fresh water system.
The red hose used to feed a heater core in the cuddy but I removed that and just looped that line back.
The lines from the top of the t-stat cover are the ones that go to the bottom of the exhaust manifolds. But no water flows through them I'm assuming until the t-stat gets hot and opens. Is this not right?
There is no provision to connect anything to the risers unless I remove some plugs and attach some fittings.
So I guess that all the water that is gushing out is flowing from inside the engine and through the heads?
Isn't that how it should flow?

I did not remove the risers from the manifold. There was not too much rust, that I could see, just some surface rust. This was a low hour motor and the boat lived on a trailer.

Re: 1 manifold warmer than other side.

Ok I have the Clymer book and I am looking at the diagram and it does not look like what I have.
The manifolds and risers are totally different.
The book shows the risers at the rear of the manifolds but mine are the center riser type.
Also the book shows that there is an inlet and exhaust for coolant in the front and rear of the manifolds but there are none on mine. And no provision to install them either as the are no plugs on the front or back. There are however 3 big plugs along the bottom ( one being used for the t-stat line) along with 2 smaller brass plugs at the front and rear.
The 1st pic is of the port mani showing the front fitting and center plug.
The 2nd shows the starboard mani with the front plugged and a center fitting installed.
The risers have no fittings either.
I guess they would get installed where I pulled the plug?

It is puzzling why it was reconfigured. And it seems to be fine in the port side. Or is it supposed to be that cool?
Would it be harmful to leave this configured the way it is? ( assuming that I can figure out why the difference in temps)