1990 90hp Evinrude (e90tlesb) overheated

[rogerrabbitis]

first time out ran on muffs before I left everything fine...went through about a tank and 1/2 of gas then went for a ride and without warning it stopped and smoke coming from engine. It had overheated right side more the left. (paint was pealing) wanted for next day to cool down started and ran rough though lots of water coming from tell but also from head gaskets. Any ideas where to look first as to a cause?. Why was there no warning? Bought motor last year and ran without issue.

 

[racerone]

Perhaps warning horn was disconnected.----Now it is time to do a compression test.---Post results and we can go from there to see what needs to be done.

 

[SigSaurP229]

Yep start with compression check. If it's ok then obviously change head gasket. Change water pump thermostat and inspect cooling passages for blockages

 

[emdsapmgr]

Lots of reasons for an overheat. You can have a strong impeller and still suffer an overheat if the thermostat sticks shut or there is a problem with the nylon pressure relief valves in the thermostat housing. Also, there an be a misalignment of the 4 rubber water diverters inside the block, by each cyl.-which can close off water to a cyl. You could have sand/weeds clogging the cyl head cover water passages... Looks like you've got some testing to do.. Have you tested the horn by shorting the two cyl head temp switch leads to ground?

 

[rogerrabbitis]

so here I am guessing is my bad news: my Compression test showing (looking at the back of the motor) Left side top piston showing 70psi and bottom one showing 100psi. Right one both top and bottom are showing 120psi. I don't know because of the head gasket leaking might be part of my low compression on one side but it is also the side the did get the most hot. I have never tested the horn and not 100% how to check them but I will be if I can fix this.

 

[emdsapmgr]

If one side overheated, it possible the head gasket lost it's seal. Could be as easy as replacing the head gasket. When you have the head off, check it for flatness. If it got warped during the overheat, you will need to get it planed to flatten it out prior to re-assembly. Are you working from an original factory service manual?

 

[rogerrabbitis]

Well the next day after it had over heated I was able to get it started..and water was coming from the gasket's so I would say there is no seal left. I would like to try to re torque the heads and do the compression test again. I have a manual I found online.....not sure where it's from seems to be missing front page but has all the information? do you know a good one to get.?? thanks for all your help you guys are great. Hopefully I can get her back up and running only my second season with this motor.....and I paid a fair chunk for it last year to be re-done I rather not go though that again.

 

[racerone]

Pull the head off to inspect.----A bad head gasket may allow water to get into the engine.---That is an absolute NO,NO and can result in major rust damage.

 

[racerone]

The cylinder head is very likely warped and can be resurfaced at home with a piece of glass and emery paper.

 

[emdsapmgr]

I'd only want to work from an original factory service manual. Spend the extra $ for it, it's money well spent. Check out this website if you want to purchase a new original for your engine: outboardbooks.com or try ebay

 

[rogerrabbitis]

so maybe some good news.....I have not had much chance to look at the motor lately and a break in the rain today let me go out and on the suggestion of a friend mechanic. I re-torqued the heads and re-tested....and the compression on the left side that was low went up to 110 on the top and 100 on the bottom......I am now moving on to take off the head and inspect and looking in to order new gasket's.....any other areas I should take a part and check I am guessing the passage for the thermostats....still looking in to why this happened...

 

[emdsapmgr]

Good news on the compression. A new head gasket may resolve the compression problem. You still need to find the reason for the overheat. Am sure you will want to replace both stats. When you are in the thermostat housing, you'll want to verify that the nylon pressure relief valves are not heat-distorted. Also, water seeps through to the back of the stats to heat them up so they will open. This hot water flows through a small oval hole in the thermostat's Valve Body. That oval hole feeds both stats, so make sure it is open. When the head is off, also check for proper alignment of the two rubber water diverters-one by each cylinder liner.

 

[rogerrabbitis]

So replaced both head gaskets and stats one was stuck open ( on the side that did not seem to get as hot ) so I ran it and it seems to still be getting really hot could not keep 2 fingers on it for even 1 sec also a little water came out of exhaust port cover on back tightening seem to fix that got a heat gun and temp seem to range between 180f and 250f depending where I placed it . The tell was squirting water but not as strong as I liked I guess I'll be dropping the bottom end next to take a look at the impeller !!

 

[rogerrabbitis]

took a look at the impeller today and did not see a whole log wrong..other then the design. that little white tab did not seem to keep the impeller tight to the tab don't know if it's suppose to be that loose when put back on seem to be tight but not when I first took it off.......not sure if I should just replace it....any way...seem to be tight and fit good in the pump......housing.

 

[emdsapmgr]

You need to quit running the engine and overheating it before something really bad happens. The overheat warning horn comes on at 212 degrees. Shuts off when the engine gets back down to 175-still too hot for normal operation. The stats in that engine open at 143 degrees and normal running temps should be between 143 and 150. When you had the head off, did you check the position of the rubber water diverters by each cylinder?

 

[rogerrabbitis]

I am not purposely trying to run it and overheat it......trying to fix it.. was getting a lot of mixed up readings from my heat gun and did not know what the temp should have been. want to fix it not have to buy another motor. I replace the impeller found a little O-ring that goes on before the impeller missing it says in the instructions its required for proper operation the new one is also a lot stiffer then the old one....hoping to test tomorrow night.....I won't let it run any higher then 150 now that I know. I also did check the position of the rubber water diverters and they were moved but I put them in the correct spot. keep you posted. thanks for your information and help.

 

[rogerrabbitis]

deleted dup post

 

[rogerrabbitis]

So replaced the impeller am dram it again the stream coming out of tell was much stronger and my temp gun was only reaching around 140 or so. So that is much better now got to figure out why I did not a warning but it appears the cause was the impeller !!

 

[wayneo99]

to check the over heat horn, coming off the head is a wire which is glued into the casting and it should go to a black rubber inline connector. Slide the rubber cover off and it will expose a scissor like connector. Take the connector apart and ground out the wire going back to the engine harness and the horn should sound. the key needs to be in the run/on position. do this with each head. if you don't get the horn to sound when grounding out the wire you need to look into the wiring starting with the key switch to the horn which maybe in the control box or under the dash depending on your setup. good luck

 

[rogerrabbitis]

so I found the horn in the control box is fried....any ideas on a part number for this and a price..??