86 Johnson 9.9 running hot?

[jrs_diesel]

My 86 9.9 seems to be running hot. Earlier this year I replaced the thermostat, thermostat spring, and put a new water pump in it. Seems to be working fine.

Yesterday I took it out fishing, at idle and low speeds (not planing) the tell tale has water flowing out of it. On plane however, the tell tale is intermittant. When I come off of plane and back to low speed, the motor has what looks like a lot of steam vapor coming out of the exhaust relief hole. Water also drains out of the tell tale at shut down, I assume this is water just draining out of the blockl.

The engine runs good and strong, no unusual noises. I'm just worried that it might be running hot. This engine was a salt water motor before I got it.

Any ideas on where I should start looking first?

 

[omcnut]

Re: 86 Johnson 9.9 running hot?

ive had a similar problem with one of my older 9.9s it was a leaking head gasket causing an air lock at high rpm but did not show at idle as it was very small id be doin a compression check

 

[kbait]

Re: 86 Johnson 9.9 running hot?

I've got an' 85 that wasn't cooling or 'pissing' well at all. I found that by shoving a hanger wire up the water tube and drilling around a bit, I could get it to flow, but not enough for high speed (it'd still pump, but not enough, slow down and steam). I'm convinced that it's the upper water tube grommet folded over, obstructed or whatever. I need to pull powerhead to replace, and haven't got to it yet. Maybe you have a similar issue??

Don't have experience w/salty motors, but I know inadequate flushing can leave clogging deposits, and that may well be your issue..

Good luck!

 

[jrs_diesel]

Re: 86 Johnson 9.9 running hot?

Looks like I'll have to pull the head and/or the block in order to inspect everything.

Is there anything simple I could try prior taking my motor out of service?

 

[Daviet]

Re: 86 Johnson 9.9 running hot?

I would take some weed wacker line and inset it in the tell-tale all the way to the block while the engine is running and see if there might be some type of restriction in the tube.

 

[jrs_diesel]

Re: 86 Johnson 9.9 running hot?

UPDATE

I ran it last night in the barrel and found out that it is overheating. I measured over 200? with my infared thermometer on the back of the cylinder head/thermostat cover. While it was doing that the tell tale had decent flow, but would get intermittant at higher RPMs like before.

I pulled off the thermostat cover and pulled out the spring and thermostat. I re-started the engine with the cover off and only had a little bit of water come out of the thermostat housing, the water was only trickling out. If I put my finger over the tell tale hole, the I would get a little more flow out of the thermostat housing but not much.

I think I have a blockage somewhere. I would just like some pointers on where to look next. Should I pull the cylinder head off, or should I pull the whole power head and check the inlet and outlet grommits?

 

[Jim311]

Re: 86 Johnson 9.9 running hot?

Drop the lower unit and look up into the copper water intake tube. Run a coat hanger up there and see if any debris drop out of the tube. Pull the exhaust bypass plate and make sure there is no crap in the passageways of that. Completely remove the thermostat and see if it still runs hot. Use the fitting to hook up a garden hose directly to the copper water tube to help flush debris. If all of that fails, pulling the powerhead is not as hard as it sounds, at least according to a friend of mine that did it last week. The grommets are prone to failure in salty conditions.