88 johnson 6 hp tell tail weak, and hotter then it should be

[oldboat1]

I did notice it seems to be only over heating on the upper cylinder with a tempgun.

suggests to me you might be getting temps at the plugs or locations that might normally be hotter than at the top of the the head. Having said that, 190F is hot, and a hot tell tale stream suggests overheating.

guessing, but if the top cylinder is hotter (whatever the temp), maybe you are dropping the bottom cylinder(?) Could do a drop test, and see if it's firing on both.

 

[relics hunter]

A quick refresher. changed the pump impeller, (but it looked good), hosed up from below and water came out all the places it should nicely, changed the exhaust cover gasket on side, tested and then replaced t stat( found no gasket someone used silicone), tested between things no improvement. Head gasket replaced ,found a couple spots that didn't look good. Had the motor about two years, it's been great and it was supposed to have been rebuilt at some point and the main power head looks newly painted and bolts have been easy. I have tried to clean all passages during this. The last test had good tell tail water for 30 seconds then it dropped off and the temps were higher on the top cylinder. So I will pull the power head and replace that gasket and see what I find.

 

[oldboat1]

If haven't pulled the powerhead yet, think I might do a spark test just for grins. Need a tester to do that best -- look for 7/16" spark on both.

 

[relics hunter]

Back at the beginning of the evaluation of the first problem ( not getting up to full throttle heading to dock), I did a spark check with an adjustable tester and got a big bright spark on both. Just have to keep digging deeper.

 

[oldboat1]

Still could be losing spark on one when at temp. and throttled up (CDI component failure at temp). With the 6hp, could test it in a barrel (pulling boots off plugs). I sometimes use a timing gun.

But pulling the powerhead to check further is sure appropriate, and may pinpoint the problem.

 

[relics hunter]

OK so I finally got some time and pulled the pqwerhead and found both the gasket and grommet are pretty gnarly looking so I have those on order and I noticed the Large O ring on the exhaust (Part #79 in the lists) is kinda worn, do you think it would be prudent to replace this?

 

[relics hunter]

Anybody?

 

[Vic.S]

Anybody?

If its not serviceable replace it!

 

[Tim Frank]

OK so I finally got some time and pulled the powerhead and found both the gasket and grommet are pretty gnarly looking so I have those on order and ....

I know you are not supposed to answer a question with a question, but ...

I noticed the Large O ring on the exhaust (Part #79 in the lists) is kinda worn, do you think it would be prudent to replace this?

What do YOU think?
There are probably only 3 or 4 gurus in this forum who have the chops to look at an o-ring like that and correctly judge whether it is truly fit to reuse or as Vic puts it, still serviceable.
Since I am not one of them, I use a slightly more folksy method. I mentally divide the cost of the part (I'd guess that ring is $8- $10 range) by the number of hours that it will take to redo the job.....I couldn't do it in less than 2 hours. Saving $5- an hour is a mug's game. Alternatively, would I sell two hours of my time for $10-? Not just no....he** no!

Replace it!
(Unless you can actually show it to someone like FR, Racerone, or High Trim and they say it is near-pristine. )

 

[oldboat1]

Ah, Tim would know too if he was there to look at it. That o-ring is part of the gasket assembly between the powerhead, inner exhaust tub, and the exhaust housing, or at least that's the way I view it on my 9.9s (o-ring seals off the area around the driveshaft). As appears to be happening with another poster, you could get an exhaust leak which might affect operation (o-ring in that location would leak up under the hood, I think, with exhaust potentially sucked into the carb). I would replace it while under there.

 

[Tim Frank]

Ah, Tim would know too if he was there to look at it. .

Very kind.
Were I actually there, what I would do is hold it up to the light, squint knowingly....maybe squeeze it a few times between thumb and forefinger (as though I knew what an allowable compressibility threshold would be for the part) and then shake my head sadly and pronounce it too far gone for further use.

 

[relics hunter]

I was really surprised that the grommet was so degraded, because when I pushed hose water up from below it came through the tell tail and exhaust port nicely. I know the grommet is a regular suspect but I thought I ruled it out. The gasket was real beat up as well and well you live and learn. When I am done the motor will be ready for many more years on the water. I am trying to find the o ring locally rather then pay $7 to ship a $8 o ring. Anything else I should tear down while I am here? Thanks for all the help.

 

[oldboat1]

Pulling the powerhead a second or third time gets to be a pain (and boring). Like Tim says, better to spend the bucks if there's a chance you will want or need to replace it later. (Good sleuthing on the gasket and grommet.)

Shipping costs are a bugger for things like that. If it's a flat shipping fee, my solution is to increase the order -- buy more stuff!

 

[oldboat1]

Very kind.
Were I actually there, what I would do is hold it up to the light, squint knowingly....maybe squeeze it a few times between thumb and forefinger (as though I knew what an allowable compressibility threshold would be for the part) and then shake my head sadly and pronounce it too far gone for further use.

Think squinting is the convincing part.... (A little pacing or toe tapping is also good.):smug:

 

[relics hunter]

Well I finally got this thing put back together and it runs great and cools like it should ,took it out to the river and had no problems except the fish weren't biting.
Thanks to all for the help on this!

 

[oldboat1]

success story! Thanks for posting back. All good.