1982 Johnson 50 Sea Horse - Constant Beep While Accelerating

[Crosbyman]

I would warm it all up with a heat gun no flames !! then try to slide (tap) a thin putty knife blade at a few locations on the rim .... to separate the 2 parts

 

[Elessar_94]

BOOM - got it! A quick and gentle pull of a pry bar against the block did the trick.

Honestly, not as bad as I thought. I definitely think the gasket is deteriorated (if not blown), but what are your thoughts on the cylinders, pistons and cooling channels overall? I don’t see any obvious blockages. I do see some pitting on the cylinder head front face though (where the spark plugs sit):

 

[Mc Tool]

Looks OK to me , once you have cleaned it up a bit and dressed the gasket surfaces .
next place I would look now would be the exhaust cooling cover , could be leaking exhaust gas into the cooling water , and keep your eyes peeled for anything that might be a hole to prevent air locks hasnt been blocked .
If you havnt already done so see if you cant nut out how the water flows thru the motor ..... maybe the water uses the exhaust cover as a sort of pre-heater so as to not feed cold cold water into the cyl / cyl head .
I bought a bunch of digital thermometers with 2m leads and 20mm high displays ( 4 NZ bucks a piece .....with batteries!! . Stick the probe to whatev with a bit of thermapath ( heat conducting paste ) and duct tape and put the display where you can see it while on the move . I used it to suss some oil cooling issues I had on my 900SS and my quad .
Oh yeah , I was talking about my cast/enamel frying pan ...........forgot to put that aye

 

[Elessar_94]

Looks OK to me , once you have cleaned it up a bit and dressed the gasket surfaces .
next place I would look now would be the exhaust cooling cover , could be leaking exhaust gas into the cooling water , and keep your eyes peeled for anything that might be a hole to prevent air locks hasnt been blocked .
If you havnt already done so see if you cant nut out how the water flows thru the motor ..... maybe the water uses the exhaust cover as a sort of pre-heater so as to not feed cold cold water into the cyl / cyl head .
I bought a bunch of digital thermometers with 2m leads and 20mm high displays ( 4 NZ bucks a piece .....with batteries!! . Stick the probe to whatev with a bit of thermapath ( heat conducting paste ) and duct tape and put the display where you can see it while on the move . I used it to suss some oil cooling issues I had on my 900SS and my quad .
Oh yeah , I was talking about my cast/enamel frying pan ...........forgot to put that aye

Lol funny you mention it, I JUST ordered a new gasket for the “water passage” (part# 26 in the diagram below) because that’s another one that I’m thinking could use replacing. Could very well have some blockages in there.

 

[Elessar_94]

Questions for the group:

1. Where specifically should I be scanning the motor with IR gun? Near the spark plugs? I only scanned the top of the engine block near the lift bracket.

2. Is it better to scan temps while motor is idling or completely off? I only scanned while it was off.

3. The head gasket does NOT require sealant, correct?

 

[Grub54891]

Scan while running. After you shut it off the actually get hotter due to no circulation, it's called heat soak. As far as the head gasket, as long as both surfaces are completely flat it doesn't need any sealant. Scan in several places around the powerhead, that will tell you about the different hotspots.

 

[Elessar_94]

Scan while running. After you shut it off the actually get hotter due to no circulation, it's called heat soak. As far as the head gasket, as long as both surfaces are completely flat it doesn't need any sealant. Scan in several places around the powerhead, that will tell you about the different hotspots.

Thank you so much I will see if she’s cooling properly this weekend when I test for overheat again. Both the head gasket and water passage gasket will be replaced and the channels cleaned by then.

 

[Elessar_94]

Well this sucks… no easy way to get this cover off due to the bottom bolts having no room to come out. Plus the cover is stuck on tight. Does the whole powerhead have to come out in order to open this thing??

 

[Elessar_94]

Managed to remove the water passage cover by unbolting the lower cowl guards so that the engine pan was free to wiggle a bit. This provided just enough space to get the bottom bolts out from my last post.

I don’t see any blockages here either. All holes feeding water into the cylinder cooling channels are free and clear. Tiny bits of gunk here and there but no real buildup. I’m going to scrape off the old gasket, clean things up and replace the water passage gasket in addition to the cylinder head gasket, put it all back together and re-test the running temp. Standby for another update soon.

 

[Elessar_94]

All cleaned up and ready for new gaskets

 

[Elessar_94]

UPDATE:

I disconnected the temp sensor and still heard the high-pitch ringing noise. It is REALLY quiet now and sometimes disappears completely. I think it is some type of mechanical whirring. So we can safely conclude it is NOT the overheat alarm that I’m hearing…

I’m going to buy a better temperature scanner because the one I bought jumps all over the place and I feel it isn’t accurate for metals. It will read 150 one moment then 200 the next in the exact same spot. The temperatures do seem a little better after changing the head gasket and the motor is running beautifully overall. While idling in my driveway the highest temp was 120 after a few minutes of idling.

I have a question: should the tell tale water line run up over the top of the powerhead? Ours is too short to run over the top and it sits behind the spark plugs instead. I’m wondering if, from a water-pressure standpoint, this is causing the cooling water to drain out the tell tale before filling up the cylinder channels. Maybe it’s nothing, but thought I’d ask.

As a reminder to all, here is what I’ve done so far to address the overheat condition:
- New thermostat
- New poppit valve grommet (should I go back and also change the spring?)
- New water pump / impeller
- New head gasket, t-stat housing gasket, and water passage gasket

Will be changing the lower unit gear oil this week since I’m assuming it hasn’t been done in a while. Will report back soon.