1981 Johnson 90 HP overheating, but not all the time

[ranger335]

I screwed up and only ordered 2 water diverters. Somewhere on here I've read what size fuel hose works as a replacement. Can't seem to find it now that I need to know.

 

[ranger335]

Evinrude Crossflow - Water Diverter Tubes

175HP 1990 My engine has been overheating. I am installing new water diverter tubes as they were swollen completely closed. My question is, is it normally required to have to trim the new tubes? They stick out from the cyliders about 1/4" which will cause them to be tight up against the head...

forums.iboats.com

Found it!

 

[ranger335]

So, I started it up yesterday afternoon. At idle, it backfired, something it had never done before. When I placed my hand on the exhaust cover and it shocked me, I thought the backfiring was because one of the coil wires was almost off the coil. That was some of it, but it still backfired some. I let the motor run on muffs for about 20 minutes. The port side seemed to heat up more than the starboard. Hotter but not hot. When I retorqued the head bolts, every one of them on the port side took a quarter turn or so. What do y'all think? Are the head bolts, the heating up, and the backfiring related? Might be a week or more before I can put it in the water.

 

[ranger335]

I thought I'd give an update. Still haven't got it in the water. The shower kit came in, and I'm remodeling a bathroom. So goes life.

 

[Chris1956]

It looks like you have some rust in the bottom cylinder. That implies a head gasket leak. Compression leaking into the water jacket causes overheat.

Make sure the cylinder head is flat, the block is flat, install the diverters and new head gaskets and torque to specs.

 

[ranger335]

It looks like you have some rust in the bottom cylinder. That implies a head gasket leak. Compression leaking into the water jacket causes overheat.

Make sure the cylinder head is flat, the block is flat, install the diverters and new head gaskets and torque to specs.

That's not rust. It's residue from the Ballistol I used to prevent rust while the cylinders were open. There were no signs of a head gasket leak when i removed the heads.

 

[Chris1956]

OK. Just what I saw.