1989 evinrude 140hp low compression

[PhatCrewy]

Happy new year all! So i am back at it with my 1989 140hp Evinrude ( i believe it to be a big bore?). Long story short i have been chasing a misfire on this engine. I have rebuilt the carbs with new kits, made a new wiring loom, replaced all the spark plugs, checked for spark jumping the 7/16 gap, checked intake gaskets and reed valves for leaks, check the fuel system for air leaks, done a decarb, and replaced the whole recirculate system, conducted link and sync as per the manual. Basically i have done everything! but she still idles rough and has a noticable miss at around 1000-1200 rpm. I conducted a compression check today and all cyc were mid to high 90 psi. I then conducted a wet test and the cyc went to 120 - 130 psi. Like automotive does this sugguest she is tired and needs a rebuild ? I have done plenty of automotive and heavy diesel but not much on outboards. My next thought to is to pull the heads and inspect the cyclinders to see if she can be machined. Chasing a recommendation from someone who knows these motors if i am missing something simple or if they believe im on the right track. cheers

 

[racerone]

Look for possible issues with the 6 metal seal rings found on the crankshaft.

 

[PhatCrewy]

Look for possible issues with the 6 metal seal rings found on the crankshaft.

Yes the crankshaft seals are a thought. I guess all things point to a tear down.

 

[PhatCrewy]

So i went and took the heads off. Looks like she has never had a rebuild. still running STD pistons. quite a bit of corrosion which was to be expected as the owner before me had her in the salt constantly. Looks like the two head gaskets were separated and the bores on 2, 3 and 4 have some grooves i can feel and see. so looks like i am going to have to bore and get new pistons and rings as a minimum. How much of an issue is corrosion of the alloy block holding in the sleeves?

 

[racerone]

The motor would be happy with 4 O/S pistons and rings.

 

[Faztbullet]

When you see that "beer bottle brown" glaze in cylinder , cylinder rings have lost their tension, also that a bridged port exhaust so modify bridge after rebore. You will see stock piston has pinholes drilled in the side to add lube on bridge and replacement pistons will not. Yearly water pump on these blocks needed.

 

[PhatCrewy]

When you see that "beer bottle brown" glaze in cylinder , cylinder rings have lost their tension, also that a bridged port exhaust so modify bridge after rebore. You will see stock piston has pinholes drilled in the side to add lube on bridge and replacement pistons will not. Yearly water pump on these blocks needed.

Could you expand on what needs to be modified?

 

[PhatCrewy]

I'm not sure if the photos show all of the corrosion around the cylinders but at spots it is quite bad. taking the block into the engine shop the guy said she is dead and that it most likely caused the head gaskets to fail. The pistons were pretty scuffed up but he thinks that the bores will clean up with .030" bore. So now i ask if anyone has used defcon or the likes to rebuild the cast aluminum around the bores? otherwise i will need to sort a new block or power head which is not easy in Australia. Thoughts?

 

[Faztbullet]

How about some pics???

 

[PhatCrewy]

Yea sorry that might help. I have decided to scout outboard wreckers here for a secondhand powerhead as it will be cheaper than machining and rebuilding this one. See what happens I guess? But I am still interested in if this can be repaired.

 

[Faztbullet]

Yes it can be repaired...would require grinding out bad areas and fill in with welding,then block decked ..$$ ishigh so finding other block maybe best option. The 120 and 140 are the same block..

 

[racerone]

Perhaps your local machine shop can machine away the corroded material for say 1/2 " ( 12 mm ) and then shrink on an aluminum ring.----I would do that if I was stuck for a block to use.----Have a bunch here but you are too far away , across oceans.

 

[PhatCrewy]

Thanks FaztBullet and racerone. That confirms my thoughts of too much dollars to repair. Apparently one of the wreckers may have one with good compression to sell for $550. I asked them to send the actual compression numbers and pictures before i lock it down. Anything else i should be examining for a secondhand powerhead? also i believe that good compression for these power-heads should be around 120 - 130 psi and within 10 psi of each other that sound about right ? Dont want to get another boat anchor if i can help it

 

[guycooper]

Happy new year all! So i am back at it with my 1989 140hp Evinrude ( i believe it to be a big bore?). Long story short i have been chasing a misfire on this engine. I have rebuilt the carbs with new kits, made a new wiring loom, replaced all the spark plugs, checked for spark jumping the 7/16 gap, checked intake gaskets and reed valves for leaks, check the fuel system for air leaks, done a decarb, and replaced the whole recirculate system, conducted link and sync as per the manual. Basically i have done everything! but she still idles rough and has a noticable miss at around 1000-1200 rpm. I conducted a compression check today and all cyc were mid to high 90 psi. I then conducted a wet test and the cyc went to 120 - 130 psi. Like automotive does this sugguest she is tired and needs a rebuild ? I have done plenty of automotive and heavy diesel but not much on outboards. My next thought to is to pull the heads and inspect the cyclinders to see if she can be machined. Chasing a recommendation from someone who knows these motors if i am missing something simple or if they believe im on the right track. cheers

I don't have my books with me, I believe that's a low comp engine runs at 90psi

 

[phillnjack2]

When you see that "beer bottle brown" glaze in cylinder , cylinder rings have lost their tension, also that a bridged port exhaust so modify bridge after rebore. You will see stock piston has pinholes drilled in the side to add lube on bridge and replacement pistons will not. Yearly water pump on these blocks needed.

factory pistons will not have bridge oil holes at all. that was not done at factory.....

 

[PhatCrewy]

Thanks guys so here's an update. Guy Cooper she is definitely not a low comp model unfortunately. So I ended up getting a secondhand 120hp powerhead 115psi each pot. Took of the heads and checked the bores and new head gaskets.Swapped out the reed valves, and intake manifold from my 140hp before bolting all my fuel and elec systems. But the miss is still there! So I have gone back to it must be electrical. Now the only electrical item that has not been replaced is the timer base. According to the workshop manual one side to port white wire and check all starboard and should be around 45ohms on all but I have an open on blue. So it would seem it could be my issue. Now this confuses me. According to the manual the v4 has 8 sensors. One for each cylinder and another 4 for quick start (guess). So I'm guessing that the quick start coils which is always active for the first 5 seconds are good. But one of the non-quick start coils are no good. Hence why no miss on start and spark testing good. Does this sound pausable?

 

[ct1762@gmail.com]

So i went and took the heads off. Looks like she has never had a rebuild. still running STD pistons. quite a bit of corrosion which was to be expected as the owner before me had her in the salt constantly. Looks like the two head gaskets were separated and the bores on 2, 3 and 4 have some grooves i can feel and see. so looks like i am going to have to bore and get new pistons and rings as a minimum. How much of an issue is corrosion of the alloy block holding in the sleeves?

corrosion should never be INSIDE the motor! make sure you find out why it failed. check to be sure all linkages and cam roller is intact. if it's missing, can give it too much spark and not enough fuel at idle to midrange= hard on the pistons.

 

[PhatCrewy]

corrosion should never be INSIDE the motor! make sure you find out why it failed. check to be sure all linkages and cam roller is intact. if it's missing, can give it too much spark and not enough fuel at idle to midrange= hard on the pistons.

It was not inside the pots just the water jackets. So i got a second hand timer base off of ebay but when i tested it failed the spec output voltage and resistance on starboard green. So now i must wait for a replacement. Hopefully by Tuesday next week ill have her sorted!

 

[PhatCrewy]

Ok update. So I replaced the timer base and still missing. So back to the fuel system. I noticed that one of the throttle bodies from the secondhand motor only had three idle ports instead of 4 that the originals had so swapped that out. Now waiting on a new fuel manifold as I broke mine. Will update once that is repaired.

 

[ct1762@gmail.com]

hmm. all 4 coils voltage tested with power pack primary leads attached? i would think that this point you are looking at a stator replacement. make sure the center timing magnet hasn't shifted under the flywheel, but that usually effects all RPM. disconnected rectifier and retested?