Evinrude 8 Overheated, Can I save it?

[JDusza]

I am in the company of a 1992 Evinrude 8 hp that has over heated. The impeller failed and she cooked. In fact, the throttle linkage arm, the water outlet indicator elbow and the thermostat housing all melted.

I have her back together and she will run well but she doesn't want to start. I am blistering my fingers. I have gone through her, carb to ignition.

The carb is totally clean. If the carburetor is the cause, I am totally stumped. She started and ran very well before the overheat. I don't know what I would ask about the carburetor. I've been completely through it.

I measure the compression at 80 psi in both cylinders. I am not used to seeing this low a number. The other Evinrudes I have worked on are in the 95 to 110 range. Is 80 too low for cold ignition? Maybe she really got hurt. Is this compression too low for a good crisp pop? She runs great when you can get her to start. What is the likelyhood the overheat creamed compression ratio?
I was hoping to keep her running without opening the case. I was really hoping the rings and crank would take it...

Thank you for any advice you can provide.
Jim

 

[BonairII]

Re: Evinrude 8 Overheated, Can I save it?

You can always pull the head to see if there's any visible damage. 80psi should run fine.

How in the heck did it cook that bad? Were there no warning signs that it was running hot?

 

[JDusza]

Re: Evinrude 8 Overheated, Can I save it?

I wasn't on board. Friend's engine. He did say it started to smoke.

Melted the throttle lever around the square boss, so it held fast. When I got the unit the throttle grip wouldn't move. lol
I was gassed about the high-temp, glass-filled plastic, thermostat housing meltdown. It takes a lot of Farenheits to melt that!
Guess I go back to the carburetor and look for fuel starvation. Bummed, but, glad the 80 should be OK.

Thank you.
Jim

 

[Haffiman]

Re: Evinrude 8 Overheated, Can I save it?

If run that hot, both head and exhaust cover gaskets should be changed.

 

[JDusza]

Re: Evinrude 8 Overheated, Can I save it?

Thank you.
I am stumped. I cannot get this thing to fire up.
I disconnected the fuel line from the carb and watched if the fuel pump would push fuel when I pulled the starter. It did not. I took off the fuel pump and opened it up, looking for damage. Didn't find any. Put the fuel pump back on and now it pumps fuel when I pull the starter, but, the engine still will not fire up. I must have freed something in the pump when I opened it.
I do periodically get a sneeze out of her. What is this from? Is it burning fuel from a flooded situation or is it starving when it sneezes?
Any advice is appreciated as I am totally stumped.
Thanks,
J

 

[JDusza]

1992 Evinrude 8 Overheated

1992 Evinrude 8 Overheated

Working on another overheated Evinrude. Water pump impeller split. Replaced impeller and a couple melted parts; throttle linkage, water outlet, thermostat housing. Thermostat also replaced for fear of heat treat. Compression at 80 psi.

Got it back together but it doesn't want to start easily. Takes 40 to 50 pulls. Once it starts, it runs well; just doesn't have that one-pull anymore.

I can't really tell if is starving for fuel or if it is flooding. The plugs are damp but not soaked. The fuel pump will pump when recoil starter is pulled.

It will sneeze after several pulls, but will not fire up. Any ideas?

Thank you,
J

 

[nwcove]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

i would be concerned about melted crank seals.

 

[boobie]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

Squirt some premix fuel in the carb throat once and see what happens. Also check your spark with an open air gap spark tester.

 

[raczekp1]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

80 psi is low i think.
if motor was overheated change head gasketand do the head flatening at auto repair shop

 

[Haffiman]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

And ignition?
Overheat may kill the powerpack!
Pull out the plugs and ground them or even better attach a spark tester.
Pull and notice the spark. It must jump 1-2-1-2-... and not at any time both firing at the same time.

 

[raczekp1]

Re: Evinrude 8 Overheated, Can I save it?

this is 15 hp 79' overheated.
new head gasket, removed 0.4 mm from head,

 

[daselbee]

Re: Evinrude 8 Overheated, Can I save it?

Possible that the timing has changed somehow? Plugs not firing at the right time due to an overheated component?
How would one go about indexing the flywheel of a pull start motor? Tough job I bet.

 

[iwombat]

Re: Evinrude 8 Overheated, Can I save it?

If it heated that badly, it's almost a sure thing that the head is warped. Take it off, plane it down with a piece of sandpaper and a sheet of glass (or other flat surface), and install w/a new head gasket.

 

[boobie]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

You'll never get an accurate spark test by grounding out the plugs. You have to use an open air gap tester set at the proper gap. I've seen those small mtrs run real good with 80 psi providing your compression tester is accurate.

 

[Haffiman]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

You'll never get an accurate spark test by grounding out the plugs. You have to use an open air gap tester set at the proper gap. I've seen those small mtrs run real good with 80 psi providing your compression tester is accurate.

'or even better attach a spark tester.'

Grounding plugs are better than not testing, but a spark tester is BETTER.

 

[boobie]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

A spark tester is the only way to go. If you tell somebody to ground out the spark plugs he may miss the spark gap tester test and create more probs for himself as they are usually in a hurry to get the mtr running.

 

[JDusza]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

Thank you for all the information.
Here's where I am at.
Spark by grounding plugs against block is good. Looks nice and strong. I will look for 1-2-1-2.
Squirting premix into the carb does nothing. No cough. I'll try premix directly into cylinder.
Compression is 80 in both cylinders; perhaps low, but uniform. I shall look at the head gasket and other gaskets around the block. Perhaps compression is leaking somewhere else. The engine runs well if it does start; smooth and quiet, good midrange, good idle, etc....
Compression tester was matched against another; within 7% of each other. I think the 80 psi is a good reading. What psi may be considered "dead"?
What's the concern for melted seals when dealing with not starting?
Thank you,
J

 

[JDusza]

Re: Evinrude 8 Overheated, Can I save it?

Thank you. I will check the head flatness.

 

[Haffiman]

Re: 1992 Evinrude 8 Overheated

Re: 1992 Evinrude 8 Overheated

A loss of compression, if any, normally means a loss of crank case compression which is needed for sucking in the fuel/air mix from the carburetor. However cylinder compression might be on top, but defective crank shaft seals may result in loss of crank case compression. The upper seal may be tested by removing the fly-wheel and spark plugs. Spray some soap water in center at the seal. Put a nut on top of the crank and turn the crank by using a power or battery drill. Bubbles coming up or the soap water being sucked in is a bad sign. For the lower seal, the power head has to be removed and turned up-side down. Leakage in center bearing (between halves) may be tested by removing the leaf plate, pour some STP or other thick oil to 'seal', put the leaf plate back and try to start.
However these are tests for us nerds that wants to know WHY, it might just be quicker to tear down and change seals and center bearing.