77 Johnson 35hp steaming

[67Heaven]

I have read several threads on here pertaining to this subject but not quite a match. I have my motor in a barrel tuning it up when I notice quick spurts of steam exiting from the exhaust relief. I have installed a new water pump kit, pulled water cover & replaced thermostat just as a part of routine maintenance. So here is the way it acts. After a normal warm up period I put an inf red thermometer to it. The two warmest spots are on the port side of the block almost horizontal with the spark plugs. I watch the temp slowly climb to the upper 160's to low 170's when the steam starts shooting out the relief exhaust lowering the temp to the upper 140's to low 150's, over & over. All the while the pee stream is strong & varies cool & warm. Its almost like this coincides with the thermostat opening. The head is cool in the 120's & the rest of engine is cooler yet while all this is going on. IS THIS NORMAL & IF NOT WHAT ACTION SHOULD I TAKE? Is this a result of being in a 55 gal barrel & not real-time situation on a lake? Btw rpm's during this testing was anywhere from 1000 to 2000 under my control. Any input from the pros would be a huge help! Thank you.

 

[67Heaven]

Re: 77 Johnson 35hp steaming

ANYONE? Please?

 

[Haffiman]

Re: 77 Johnson 35hp steaming

Yes, it is partly normal. Your exhaust cover will heat up when thermostat is closed, as well as the pee stream. The only cooling it gets is from the water going to the pee. As thermostat opens, water flow increases and exhaust cover temp drops. However if engine is 'steaming', it might be a sign that the exhaust cover gaskets are due for a change. it might be exhaust and not steam going out??

 

[67Heaven]

Re: 77 Johnson 35hp steaming

Thank you Haffiman for your reply. Engine doesnt steam at all until temp reaches that "thermostat opening period". the exhaust relief is putting out both exhaust & spitting water as normal. Im just concerned with the steam that shoots out when it does open up. You are correct on the waterflow increasing because it does spurt out at a pretty good clip, keep in mind this may only last about 5 seconds or so. Help me out here, what are you talking about as far as the "exhaust cover gaskets" go? do you mean water cover gaskets? My model # is 35EL77C on marine engine.com.

 

[67Heaven]

Re: 77 Johnson 35hp steaming

Its almost like cool water hitting hot metal when this occurs. You can hear it when it happens like its "blowing off steam". lol

 

[Haffiman]

Re: 77 Johnson 35hp steaming

If you look at the parts diagram and your engine:
http://www.marineengine.com/parts/j...urer=Johnson&section=Cylinder+&+Crankcase

The pee outlet is a bit down on the exhaust cover #23, on the later models it is moved to the top just where water enters the cylinders.. This means that only the lower part is cooled off by the pee stream, and steam may build up in the upper part as it is no circulation. Over the years this may cause the gaskets to fail. 35 years for some gaskets under those conditions????

 

[67Heaven]

Re: 77 Johnson 35hp steaming

Ok I gotcha, that makes perfect sense. So i should have no worries of overheating? I will pull the cover off & check & replace needed gaskets & look for any kind of blockages too. I did however make a typo, i said port side where i was getting my temp measurements from, instead i meant starboard side(right side as standing behind motor) in front of the coils, latteral with the spark plugs. (my mind was saying one thing but yet i typed the other) Basically right on the cylinder walls of the block.

 

[boobie]

Re: 77 Johnson 35hp steaming

If it was my mtr, I'd take it out on the water, run it and then check it.

 

[67Heaven]

Re: 77 Johnson 35hp steaming

Thank you boobie for your input. Haffiman got me curious so i went ahead this eve & pulled the exhaust cover. Sure enough the inner exhaust plate was badly warped. The gaskets didn't look bad, but I'm gonna replace all. While I'm in there I'm gonna blow back through all the jacket holes. Thanks to you too haffiman.

 

[67Heaven]

Re: 77 Johnson 35hp steaming

Update! Replaced inner exhaust cover & both gaskets & wow, I have a nice normal operating temperature motor. Same method of measuring temp was used & now Apr 153? was as warm as it got. Excellent advice guys! Thank you very much!

 

[jasper60103]

Re: 77 Johnson 35hp steaming

Update! Replaced inner exhaust cover & both gaskets & wow, I have a nice normal operating temperature motor. Same method of measuring temp was used & now Apr 153? was as warm as it got. Excellent advice guys! Thank you very much!

Awesome. Thanks for the update.

 

[Haffiman]

Re: 77 Johnson 35hp steaming

Update! Replaced inner exhaust cover & both gaskets & wow, I have a nice normal operating temperature motor. Same method of measuring temp was used & now Apr 153? was as warm as it got. Excellent advice guys! Thank you very much!

Always good to hear that problem has be solved.