Help with 93 johnson 90hp

[Attila Jeney]

" I just got a used boat this

" I just got a used boat this summer(first one, 94 crestliner v170 sportfish, 93 johnson 90hp).

I have had a couple of problems with the motor.

Sometimes it takes a little long to warm up at the launch. I take it out of idle into gear and it quits. have to start/restart a few times.


The first month I had it, while out on the lake the motor suddenly powered down on me. No warning at all. fished for a while. Got it started, rought idle for a few minutes and then okay. 3 weeks ago from this week, was out again, coming back from a spot in the lake the motor just powered down. No warning. Could not get it going. Drifted and fished for a while. Changed out the plugs and spent 10 mins trying to start it. Got it going. Went about 2 miles and then it quit again. Cranked for a bit but only got it running in idle.

Took the rig to 2 shops for compression test. Top 2 cylinders were 110 psi, bottom 2 read 80 and 85 psi each. Both said to rebuild the engine. One quote was 2500 (rebuild powerhead, carbs, new vro pump, checks water pump, puts about 9 hrs on it in his tank, 1 year warranty). forget the other shop. Have one more to take to.

Granted I am new at this, based on the compression is this really needed?

Also, The same shop said he was getting a 98 115 hp johnson oceanrunner in on an upgrade. Used 120 hrs in fresh water. Rough price about 3200 but will give me 600 trade on my motor and I will have to change out the wire harness( another 300 or so) Is the oceanrunner a good engine?

Depend on the price should I just upgrade or get the current rebuilt. My boat is rated to 140hp.

thanks. "

 

[jon]

" Hi,

The compression o

" Hi,

The compression on your Johnson 90 is bad, you really want the cylinders to be within 10 PSI and above 100. It might be ok if all the cylinders were around 95 PSI, but having 2 at 110 and two under 90 is not good; Although, it sounds like in addition to the sloppy compression, there is another problem that is causing the engine to run inconsistently. If you fixed whatever else it is, you could possibly get by for a while (without the rebuild), but you're not going to get anywhere near optimal performance, and it may not even give you satisfactory performance.

I can't break down the specifics of the rebuild cost for you, but the quote you have up there is in the ball park. A one year warranty sounds like a fair deal as well, I've heard of shops giving 60 and 90 day warranties on cheaper rebuilds.

I don't know the specifics on the 98 115, but if the motor is in good condition, with only 120 hours, (you'll want to know the compression on that), 3200 (and the 600 on trade) would be a very fair price, and well worth it if you ask me -an extra $100 (after the trade) and you end up with a like new engine with 25 more HP and 5 less years on it.

If you decide to go that route, 3200 is a big chunk of change to be paying without a warranty, something in that price range should come with some backing by the shop. If you don't own one, you also should probably swing by a local auto parts store and pick up a compression gauge, you'll want the type that screw in, about $25, and well worth it, in my opinion. Hope this helped,

Jon "

 

[joereeves]

"Attila.... In addition to Jon

"Attila.... In addition to Jon's reply, the reasoning for the normal compression on the top cylinders and the poor compression on the bottom cylinders is due to the lower carburetor being somewhat clogged/fouled which results in the two bottom cylinders being run lean (improper lubrication). You might try cleaning and rebuilding the carbs to see if the compression will improve but don't get your hopes up. Usually the only cure is the overhaul route which is normally in the $2000+ area if it's done right.

This would include restoring the powerhead to new condition, rebuilding the carburetors, installing a complete new water pump assy and a new VRO pump, checking all engine operations and all components (coils, stator/charge coil assy, coils, p/packs, etc etc).

A one (1) year warranty is unheard of. If you had the factory rebuild the engine, you would only receive a 90 day warranty, and at most dealerships you'll find that (imprinted on the repair slip) warranty is strictly 30 days regardless of what the repair may be. Be sure to read the fine print and get the warranty in writing.

Not offense intended to anyone but I have never heard of any mechanic or dealership running a customers engine in a tank for 9hrs.

Joe (30+ Years With OMC)"

 

[Attila Jeney]

" Thanks for the reply.

I j

" Thanks for the reply.

I just pulled the cylinder heads off both sides. I also pulled the water cover(bolts to the cylinder head, hope thats the right name) off the right cylinder head before pulling the head.
Wasn't thinking, too much turkey.

Visual results:

Bottom right cylinder-- not good. Worst of the
4.has groves in it plus a grove at the bottom. that groove looks about 3 thousands deep.

Bottom left cylinder-- feels a little rough in a couple of spots. Has a scuff mark about the size of a quarter.

Top 2 cylinders look okay.

Noticed that the right 2 piston heads were dry, brown looking.
The left 2 piston heads appeared wet with fuel.

I have done a couple of car engines in the past.
I know that all 4 cylinders will have to be bored and put in oversize pistons based on what I have seen.

I have 2 options:

1. How difficult would it be for me to rebuild myself? I don't have any of the electronic testers. What is a rough average to get the block bored out and get the oversized pistons? What repair manual would you recommend?

2. get it done by the johnson dealer. The 2500 quote I mentioned is the same shop that has the 115 ocean runner. That guy doesnot have the room to keep my boat, so he has to pull the motor off.
That's were he will breakin the motor in his tank. He gets a remanufactured block(has had trouble with the boring bit).
Have to get with him about the 98 115hp for a final price and what his warranty is.

I may take the boat to 1 more shop to see what they will do. I know they can't run the motor now that I have popped the heads and that one water cover. I will call them before hand.

Thanks for you advice so far. "

 

[joereeves]

"Attila.... The water cover na

"Attila.... The water cover name? You're close, it's called a water jacket cover.

It's not necessary to rebore all four cylinders unless all four are damaged. Installing only two oversize pistons will have no negative effect on the performance of the engine. You do not need to reply on a marine dealership to have the engine rebored.... and if they do not have a reliable machine shop themselves, or use a outside source machine shop... I strongly suggest that you find a highly reliable machine shop and have the reboring done yourself. And always supply the oversize piston with the block to the machine shop so that they can do a proper bore job with no lack of communication.

At most marine dealerships, you can purchase a repair manual published by (possibly misspelled here) "Cylmer".... or check with Andrew at this site for manuals.

You won't need any electronic test equipment if you decide to do this job yourself, however be advised that the slightest mistake would be expensive. Good luck with whatever route you decide to take.

Joe

"