Port Manifold/Riser running hotter than STBD side

[Ocean Escape]

I have a 5.7 L in a 1991 2300 SCR and recently had her at the shop where the leg was rebuilt and new port manifold installed. The mechanics say the manifold and risers were clear yet after 15 mins or so the STBD side runs hotter than the Port. The Port side you can leave your hand there no problem but the STBD side the hand can only stand it for short periods. Compression is all good. I recently purchased the boat in September. Any help would be appreciated

[seapuppy]

OE..welcome to the3 zoo...first off..it's common for the port to be hotter than stbd...stbd is closer to the cooling water..then the port gets cooled...but harbor frieght has a laser thermometer for something like 50 bucks...might wanna get one or borrow one ...and then shoot the two manifolds while they are running...
get a real number on the engine...shoot different parts of the cooling system just to make sure and see what the results are.....
also at idle the water flow is quite a bit slower from one side to the other yet at rpm the water flow will stabilize from one side to the other....

as long as nothing is blocked...then it should be ok..

SP

[Ocean Escape]

Thanks for the help, I will put a gauge on each manifold to monitor the temperature. I was out today and although the STBD stayed Hotter than the Port, it levelled out and did not continue to increase in temperature and was still able to keep the hand on it but it was borderline uncomfortable. The engine maintained at 150 at 3750 rpm. What is the normal running temp for the manifold?

[seapuppy]

depends.....is it fresh water cooled??...raw water cooled....as long as you can keep a hand on it..it's ok....

raw water cooled will obviously run a bit hotter...bout 120 degs.....fwc'd will run about 102-110 degs...

SP

[Ocean Escape]

it is a Raw water cooled engine. Thanks again

[Harley31]

I had the exact same problem. People thought I was crazy, but when I read the temp. with a temp. gun, there was about a 50 or 60 degree difference. Like yours, the starboard side manifold and riser was so hot, I couldn't put my hand on it, but the port side, although hot, was not too hot for me to put my hand on it. I completely dissasembled eveything from the thermostat (replaced that) all the way to the shutters. I cleaned everything out, ran a hose through it then reassembled it. I still had the same problem. My next step was to check the compression, but I had the marina mechanic look at it, finally. He said that is normal. I believe there is something called a reclaimer on the starboard side of the exhaust, which reburns or recirculates the exhaust before it exits, for epa purposes. Anyway, I'm glad to see it seems to be a normal thing for those engines.