1979 Wellcraft I am having an issues with the left (starborad)side exhaust manifold over heating at Y pipe, I had a hand held laser temp gun, the temp from. The riser down to Y pipe the temp was well over 275 degrees, it was so hot it melted the rubber boot. I replaced the boot with a new one and took the boat out today and again smelled the rubber burning again I shut the motor off cool down and play with it for and hour or so and out of the blue the temp was 278 and for some reason it fell down to 87 degrees and ran about an hour and a half running about 1800 rpms and was perfect it went as low 57 degrees. So I thought it was cleared out and problem was solved, but after sitting for an hour enjoying Pittsburgh waterways I started to head back to the locks, the same problem happened again, the temp rose to 252 at the rubber boot and 275 at the pipe right past the boot, when I replace the riser gasket I didn't notice any major rust I cleaned the carbon build up with in the riser, I am lost any ideas what I can do fix the problem would be great! The water pump in out drive is brand new the motor never got up past 130 degrees, mainly ran in low hundreds. Exhaust manifold never got over 130 to 150. It's is a merc 305 I/O, thanks in advance for any and all thoughts
Derek
Derek
