1989 Johnson 88 running rich at idle

[RoGun_Mako171]

Have had the boat for 2 seasons and there has been no water in the lower unit so far. No metal flakes on the magnets either, so I think it is good, but your advice to inspect and reseal it before spending the money on the power head is excellent, thank you for the suggestion.

Not a lot of hours. We only use the boat for fishing and in Vermont, the boating season is from ice-out (sometime in late April or May) through October. And we only use it on the weekends and some evenings, and don't run it hard.

So, use my $1000 for a down payment for a new Honda 4 stroke and go into debt and part this out and sell on eBay or go for the rebuild? I have some thinking to do...

 

[racerone]

Makes no sense to spend $12,000 to save $300 per year on fuel with a new computer controlled 4 stroke motor.-------I would fix that motor to go for many more seasons.

 

[oldboat1]

I’m not a rebuilder, so that colors opinion. Just doing a couple can qualify you, I’m sure. An option would be to find a ‘90s freshwater motor for use while you tear the current one apart — or get a good running sister motor to your current one, and keep the current one for parts.

And if it happens you are about to do some house remodeling, add a heated garage big enough for boat storage, and get a new(er) boat. Lots of options.

 

[RoGun_Mako171]

Great advice! I will tear it apart and see how bad it is...after I buy some tools. Any suggestions on inexpensive micrometers to measure the cylinder, pistons, etc?

 

[oldboat1]

Harbor Freight if you aren’t going to do many rebuilds, otherwise Snap-on (but then can’t afford the garage….) Maybe Craftsman for a middle ground?

 

[RoGun_Mako171]

Taking the flywheel off was a bear with the power head off! Wish I had done that with the power head still attached to the rest of the engine. The key barely protruded from the drive shaft, like less than .25mm. I ordered a new key and will compare the sizes to know for sure if it was sheared.

I found a 3-4" outside caliper for measuring the piston on eBay for $25 and some telescoping inside measuring tools on ebay for $15. The pistons measurements checked out and I'm going to reuse them. The inside measuring tools kinda suck to use because it's difficult to see if they are perpendicular against both sides simultaneously, but I think things look good. Ordered new rings and a hone for the cylinders. Soaked the pieces of the crank case in diesel and am in the process of cleaning everything up prior to reassembly while waiting for parts.

While I have it apart, I figure I might as well paint it and am wondering if I try and paint the pieces or paint once reassembled. I will create a separate post for that question. Thanks for all of the advice, I'm hopeful that this engine will have a second lifetime and not spew fuel and smoke all over the place.

 

[racerone]

The key is just there for correct position / timing.-----The flywheel is driven by the locking tapers.-----Note that the same key is used from 9.9 to 300 HP motors.-----Installing new rings in worn grooves may well be a mistake !!

 

[RoGun_Mako171]

There are no worn grooves in the cylinder walls, they look nice and smooth. The piston grooves cleaned up well. I used an old ring to clean them up and make sure the spacing was adequate. Was hoping to avoid dropping $400+ on new pistons, but would you suggest to buy new ones?

 

[racerone]

I rewrite.------Installing new rings in worn piston ring grooves may well be a mistake.------I have inspected ring grooves with a microscope in the past.-----No need to explain any further.

 

[RoGun_Mako171]

Sounds interesting, I would like to hear more about that experience. Well, crap! I might as well do it right and get new pistons. Maybe I'll get a quote from a machine shop to bore out the cylinders and go oversized. From your experience, how much does a machine shop charge to bore out 4 cylinders?

 

[racerone]

I don't know.----Believe it or not I know how to set-up a machine to bore them out.----And I know how to hone them for proper fit of new pistons.

 

[RoGun_Mako171]

I believe you. Do you have any suggestions for proper honing to fit new pistons?

 

[RoGun_Mako171]

I think I get it now, worn piston grooves would be measured as the distance between the square piston ring and the piston groove. According to the service manual, replace the piston when the tolerance is greater than .004". When doing this measurement with an old piston ring I get at least .005" for the first piston I measure, but I don't know if the ring is worn or if the piston is worn. I have searched around, but have not found the thickness of the stock piston ring. Before I drop the $ on new pistons, I need to know if I need to. Does anyone know what the thickness of a new 2nd ring is on a Johnson 88?

 

[racerone]

Actually it is the top ring groove that suffers the most.

 

[RoGun_Mako171]

Is there a way to measure the top piston groove wear?

 

[RoGun_Mako171]

Rebuild is complete with new pistons, was a much longer project than anticipated... but painting it sure did not help expedite the process. Compression on all cylinders is now around 118 psi. Set the timing with the Joe Reeves method and confirmed spark exists on all 4 cylinders. During my first test run on muffs, I had water leaking from the cylinder heads, so I tightened up past the recommended torque and the water leakage stopped. When I quit for the day, I had the black ooze dripping out from the exhaust on the lower unit, so my problem still exists. Going to look deeper into the ignition system next, ordered new coils and plug wires to start, will do some testing on the stator and power pack if the problem persists after the new coils and wires.

 

[RoGun_Mako171]

Replaced the spark plug wires, coils and the power pack. It fires up great and seems to smoke a lot less, but still has the oil leaking down the Lower Unit after running on muffs. Taking it to the lake tomorrow to begin the break in procedure after rebuilding the engine. I've reached the end of my spending and patience with this engine. After break-in, this boat is going up for sale... done with it! I bought a boat with a 1998 90hp Honda and bow mounted trolling motor for $2500 a month ago and love it... am amazed how quiet the Honda is compared with the Johnson. Sure, the 4 stroke may not be as fast and furious as the 2 stroke, but when just fishing that is not a concern.