1998 90HP Evinrude Problems!

Cooks

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So this is a broader thread due to my lack of knowledge with Outboards, my stubbornness with not taking this to a shop, and the plethora of issues I am trying to resolve.

I grew up with boats but never owned one myself. I am pretty familiar with the mechanics of cars, but boat life is new to me. I bought a 98 Sunbird 170 about a month with this 90HP on it. It runs but has rough idle and stalls randomly. Have been tearing it apart and have found many issues that I am slowly fixing but always seem to find a new culprit to the problems.

Issues:
Cracked primer valve (replaced)
- used the repair/rebuild kits for the primer valve and the fuel pump while I was at it.
Sticky kill switch (replaced)
Broken corroded spark plug wire (all replaced)
- Spark on all plugs
Thinking carbs and timing have to be adjusted (nothing done yet)
Bad/low compression? (Reading 62/30/64/60 cold)


so obviously what I am troubleshooting now is the compression. Some info below:
- lowest compression is the same cylinder that had the corroded spark plug wire.
- the same spark plug hole is a little beat up, maybe had been cross threaded at some time (but didn’t see any bubbles when using soapy water around the tester)

Questions:
What should I check next?
Is ~60psi good for this engine cold?
Read some things about testing WOT, is this just checking compression with the throttle in the forward most position?

Thanks in advance.
 

racerone

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This sounds expensive.-----Next step is to remove cylinder heads.----Inspect cylinder walls.
 

Cooks

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Is this a looper or a cross flow motor? Either way 60 psi is not good at all.
I have heard these terms, but not sure on the actually meanings, it is a E90TSLECM, if that explains anything. And I figured 60 is not good, but also this is being tested with a Amazon gauge. I’m going to check it with my air compressor tomorrow to see if it is accurate
 

Cooks

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This sounds expensive.-----Next step is to remove cylinder heads.----Inspect cylinder walls.
This is what I was afraid of. But would the motor still run and drive in this condition if it was totally fubar’d. Also, what does a replacement 90-115 run? Is it more financially wise to just get a new motor?
 

racerone

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Remove cylinder heads and inspect.----It is always cheaper to repair if you can do the work yourself.----Finding a dealer that will rebuild is not easy.-----At $100 it adds up quickly.------These crossflow motors are famous for broken piston rings.
 

webbd

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Jul 20, 2011
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I have heard these terms, but not sure on the actually meanings, it is a E90TSLECM, if that explains anything. And I figured 60 is not good, but also this is being tested with a Amazon gauge. I’m going to check it with my air compressor tomorrow to see if it is accurate
Loopers have mostly flat-topped pistons and rely on a looping flow in the intake air stream that's produced by the shape of the intake port. Cross-flows have pistons with a cupped top and rely on the piston shape to direct the intake air stream away from the exhaust port.

I thought a 1998 would be a looper until I read racerone's post. He knows these motors and like you, I know them a lot less.

--DW
 

webbd

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This is what I was afraid of. But would the motor still run and drive in this condition if it was totally fubar’d. Also, what does a replacement 90-115 run? Is it more financially wise to just get a new motor?
I did some research on this earlier this week. It probably matters where you are also. A 90HP that's been rebuilt and certified by a repair shop on the west coast of Florida is likely to cost you in the $4K area. My local shop has a 3-cyl 90HP ETEC that he's getting ready to rebuild sometime this winter and sell in a few months. He likes the inlines more than the V engines.

- DW
 

racerone

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In 1998 there were crossflows and loopers.----The TSL models are crossflows.-----1998 was the last year for crossflow.-----I have a 115 HP crossflow 25 " model myself.
 

flyingscott

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Get a different gauge and retest the motor. Make sure the starter is turning fast enough. 98 was the last yr of the cross flow motor get a manual and maybe rebuild it yourself.
 

Cooks

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Remove cylinder heads and inspect.----It is always cheaper to repair if you can do the work yourself.----Finding a dealer that will rebuild is not easy.-----At $100 it adds up quickly.------These crossflow motors are famous for broken piston rings.
I was going to try and get my hands on an inspection scope first, but I may be looking at just pulling this thing apart either way.
 

Cooks

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I really appreciate the fast responses, thanks guys. I will post with any new findings.
 

Cooks

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Get a different gauge and retest the motor. Make sure the starter is turning fast enough. 98 was the last yr of the cross flow motor get a manual and maybe rebuild it yourself.
Is there PDF versions of the manuals floating around anywhere?
 

Cooks

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So just tested out my compression gauge, it is not calibrated. My compressor set to 135 is reading 75 on the gauge. So in assumption the motors compression should be a lot higher than the indicated 60-64 range, but that still means the one cylinder is reading about half the others
 

racerone

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Perhaps tomorrow you will realize that removing the one cylinder head needs to be done.----Easy to do.----In the big picture head gaskets are cheap.
 

Cooks

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Pulled it apart and was not happy...
 

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racerone

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Told you these are nearly ---" world famous " ----For broken piston rings.----All of the crossflows end up on the overhaul bench !!
 

Cooks

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Told you these are nearly ---" world famous " ----For broken piston rings.----All of the crossflows end up on the overhaul bench !!
So obviously the rings are shot, but with that piston and head so ate up and gouged, aside from a new piston and head, should I have to take it to a machine shop and get that cylinder bored? There is some wear markings in the cylinder but no gouges.
 

Cooks

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Told you these are nearly ---" world famous " ----For broken piston rings.----All of the crossflows end up on the overhaul bench !!
So is this something that just happens over time? What caused the piston and head to get so beat up? Could this have been due to the lack of spark (due to broken spark plug wire) to this cylinder?
 

racerone

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Lack of spark has nothing to do with it !!!----It is poor design of the TOP piston ring that is the problem.
 
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