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90 evin 1990 overheated need x-pert advice

timguy

timguy

Silver Medal Contributor
Need a good tech for this one:
Working on a 1990 90 Evinrude which was rebuilt by a local shop after VRO failure. Tech had installed .030 pistons and circumvented VRO, recommending Amsoil premix 100:1. Guy that bought the rebuilt motor from the shop had it installed by the tech on his boat.....but later had it back several times because of poor running and bad idle. Guy says that he was never satisfied with the way it ran. Note: I see all new electronics from CDI. Guy.......we will call him Joe "boat owner", and Jeff the "tech" finally parted ways. So now Joe finds me 3 years later..........Joe never ran boat much at all........and has me fix the problem. Electronics checked out brilliantly so I checked fuel and filter.....all spotless. Noticed melting at base of power pack........obvious overheating.......even coil bases melted......wow!.......No overheat cut out or buzzer? Apparently not. Joe says always saw water stream. So next I check compression.......50, 90, 85, 90.......yuck! I suspect head gasket because motor had pretty loose head bolts with no dressing on threads or bolt head shoulders. Sure enough, cyl 1 blown into water jacket.......long time running that way with water pitting on top of #1 piston. NO scoring, all cylinder finishes flawless. Top of cylinders slightly blued and straw colored from heat. Very excessive piston clearance........can put a .022 feeler gauge between top of pistons and cylinder walls.
Here is my take: Jeff set up with too much clearance to begin with and then improperly torqued heads. Head gasket began leaking compression into water jacket and disrupted flow of fresh cooling water, "not salt water". As leak got worse, engine began overheating but still showed water out the indicator port. The excessive piston clearance and Amsoil protected engine from major meltdown..........
Okay, questions, whose fault is it and what can we do to fix the motor? At that clearance with overheated rings and 90 psi will this be a serviceable engine? Joe has $3,000 invested in this engine and wonders if he wants me to rebuild it for another $1,000........or try some head gaskets for $200. No comment yet from Jeff. This doesn't include hooking up the overheat protection / warning........Okay, Thanks for your help in advance, Timguy
 
P.S. Guys at I-boats forum provided little valuable imput. Hope Mr. Reeves is still out there and can read this, there may be none better........, he has probably "forgotten" more than I know. Thanks
 
I read your post on iboats.
You are asking for quite a bit of neck stretching speculation......

If you measured correctly regarding the cyl to wall clearance....usually done down at the skirt.
The pistons taper a bit from bottom to top.

But, if the clearance is as you say, cyls are way out of spec. Period. It may run, but the cylinders will probably not have good crankcase compression either.
It will be a drag on the motor, never producing HP.

They guy is toast regarding his 3000 bucks. Rebuild it, but be looking at a sleeve job also in the cost.
 
Okay thanks, I know that at 90 psi the motor is below specs, but one of my key concerns is: Who is responsible for the problem? The boat owner "Joe" or "Jeff". Jeff did the overhaul and install on the boat, did not properly hook up the temp warning buzzer, set up the clearance in excess, and messed up the head gaskets. When I install head bolts, I lightly coat the threads and surface where the bolt will torque against the head with anti seize. Motors that I have rebuilt over the last 40 years are still in service so I have been very attentive to detail. We are professionals and need to stand behind our work.........the customer has to be properly schooled when you sell them your services. Joe had brought the boat back to Jeff 2 or 3 times for repair. Joe said that the motor never ran correctly and reliably from the beginning. This time Joe found me on the internet and wanted a fresh diagnosis. I've known Jeff for 20 years and he is considered a very good tech in the Duluth area. Perhaps his machinist messed up the clearances. I go just about 4 to 5 thousandths skirt to wall clearance on this size bore, depending on operating demands......slightly more clearance for racing applications. I am also a machinist and build dirt track race engines. Proper clearance is essential and our engines run 8,000 rpm in dusty, filthy, hot conditions.
So, I see no indication that the boat owner made any mistakes.......other than buying this motor from Jeff. Jeff did a beautiful job on engine assembly that I see, other than the head gaskets. The gaskets are high quality and proper compounds were used to seal the case and other gaskets. Bolts and washers were all in their correct places. I think the head gasket blew right away and you can see compression has been leaking across a long time. The piston surface shows that it was laid up off season with moisture in the cyl as it has oxidation and light pitting. Then run again next season with carbon deposits over the pitting. Joe is careful and said he always uses non-oxy premium fuel and 100:1 Amsoil pre mix @ 50:1 ratio.
Who is responsible here?
 
Most of problem will lay toward Jeff if machine work is incorrect as he should have checked/measured work when he received it. You cannot tell if clearance is excessive with feeler gauges, run piston down and measure with inside mike and if correct size no foul to Jeff. The rest goes to the owner for not staying on Jeff's arse till A) it was fixed or B) he got a lot of his money back.
 
On an outboard measuring piston clearance with feeler gauges is totally incorrect.------The clearance is measured at the skirt !!!!
 
Of course I know that, I build race engines, I am a machinist. I'm only estimating, I don't want to dismantle this machine any more than I have to at this point, the guy is already in over his head. These pistons wiggle around enough to change holes, brother.
 
Right! Nobody knows all, but I don't expect to catch hell from you guys because I have not made thousands of posts. Seems some of you rate the forum users by their # of posts rather than by the sincerity and honesty of what they say.
 
Piston clearance will seem excessive but run the piston down and measure cylinder with a inside mike. I use WSM silicon impregnated head gaskets.
 
Bore size 3.5 so @.030 over and add proper clearance another.005 we want 3.535, brother. I will open it up again and check next week, the guy is in big trouble with his wife, she was against the boat idea from the start. Jeff told him to "kiss off" its been 3 years. Joe wants me to put the new gaskets in and get it running as best as possible. Complete set is $140 my cost. Other gaskets leaking water too, have to fix them so got the full set. Feel bad for Joe.
 
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