1986 V4 90HP port side overheating

[FyshHunter]

Hi guys, first post but not first time browsing the forums.
I have a 1986 90HP Johnno where the port bank is over heating.
I have replaced the thermostats and that gives marginal improvement. With the thermal gun I get up to 200 and chicken out and turn it off. Starboard side works like a dream at 140

So I'm thinking I need to remove either water jacket, head or both and check for blockage.

I'm stumped as to where should I start ? Most issues I have read refer to starboard bank, not many with port side.

If I go down the remove the head route I have a problem in that the left bottom bolt doesn't want to budge.. The others were easy peasy. If I snap it does it mean taking the engine off to remove whats left of the bolt. Not sure how else you.d get to it other than making hole in cowling and maybe that is the way to go. Engine is not worth a lot and Id prefer it running with cosmetic blemishes than having to buy new motor. If I go the head route I can check the deflector tubes, maybe they're perished/squashed but dont no how much water they pass iand how important are they.. Only got the boat week ago and hasn't been used for quite a few years.

I havent replaced the impeller but seems to be good stream out the telltale and I got a good stream of water out the pipe connection to the starboard thermostat cover coz I forgot to clamp it.. Would the impeller make a a big difference between port and starboard bank temps ?

Many thanks
Cheer
Tony

 

[racerone]

Facts----The water that comes out the tell tale does NOT go through the motor.-----The water does NOT go through the deflector tubes.-----Those tubes guide the water around the block for proper cooling.----Head gasket must be installed the correct way for proper flow.

 

[FyshHunter]

Thanks for the reply racerone
ok on the tell tale, but didn't know about the deflector tubes, hence their name eh ?
Makes heaps more sense now, thanks.
Going by what I found when I removed the thermostat cover makes me wonder if the original gasket was put on correctly. I'll soon find out. Thanks for the heads up

 

[Fed]

You could disconnect the Port side hose where it enters the thermostat housing & check for water flow compered to the Starboard side.
If it still gets hot with the hose disconnected it would indicate a problem before the thermostats.

I have replaced the thermostats and that gives marginal improvement.

Did you check the little holes in the thermostat base plate, if one is blocked you won't get water flow to open the thermostat.

 

[F_R]

Hasn't been used in quite a few years!! The impeller needs to be changed, no matter what. Do that before looking for something more exotic.

Beyond that, where are you running that thing? On a boat, on the lake? On muffs in the driveway? In a bucket? It was designed and engineered to run on a boat on the lake.

 

[FyshHunter]

Thanks for feedback
Running on the muffs
Thermostats replace, pin hole was totally blocked, not any more
Pulled the head, water jacket will come off when I get the gasket set, and this is what I found. No wonder it was over heating.

 

[racerone]

See post #2----The head gasket was NOT INSTALLED PROPERLY on the port side !

 

[FyshHunter]

I have replaced the thermostats and that gives marginal improvement.

Did you check the little holes in the thermostat base plate, if one is blocked you won't get water flow to open the thermostat.[/QUOTE]

"holes" ??? Bummer, I only found one hole in centre of small oblong cutout. Did I miss one ?

 

[FyshHunter]

See post #2----The head gasket was NOT INSTALLED PROPERLY on the port side !

Wouldnt surprise me at all How can you tell ?
I have gaskets on order and before I fit I'll get your advice if I could please.

 

[racerone]

Factory gaskets are clearly , very clearly marked with an arrow that points to the exhaust.-----OH, I just looked at a cylinder head to confirm it is wrong on yours.----And I have seen this blunder made before too.

 

[FyshHunter]

Thanks racerone.
I'll ensure I don't make that mistake.

 

[FyshHunter]

Ive cleared the crud out of the water ways as best I can with bamboo skewer,
What is the recommended procedure ?
Dont want to squirt water in there in case gets into the cylinder block. Maybe just run it on fresh water for a while.

So is there a trick to removing the deflector tubes ?

 

[racerone]

Pair of pliers and pull them out.----Replace with solid rubber material / 3/8" diameter hose / or $ factory ones.

 

[Faztbullet]

Hope your going to do starboard side also....likely looks like the port but not acting up yet. Salt-away and a trashcan are your new buddies..

 

[FyshHunter]

Hope your going to do starboard side also....likely looks like the port but not acting up yet. Salt-away and a trashcan are your new buddies..

Yep, will do. Just want to get it running to see if worth investing more money in it or I just trade it in.
Have bigger problem with steering rod frozen in tilt tube. Probably easiest to replace tilt tube and steering rod in one piece, but that's another story.
Seen saltaway suggested elsewhere, looks like the go. Trashcan I assume to dunk the leg rather than muffs.

 

[Fed]

"holes" ??? Bummer, I only found one hole in centre of small oblong cutout. Did I miss one ?

Sorry Fysh, you are correct only 1 hole.

 

[FyshHunter]

Sorry Fysh, you are correct only 1 hole.

phew, thanks. really didn't want to wrestle with the thermostat cover and springs again
I should be getting workshop service manual in post very soon, that will sort out a lot of my questions.
Thought Id get the ball rolling while waiting and tackle some of the simpler jobs.
I'm off to get a bolt removed from water jacket. Head came off and rest of it doesnt want to budge.