Is rebuild difficult for 86 Johnson GT 150?

[lexkyboater]

I have experience rebuilding a few automotive engines (down to bare block), but not marine. I have a Seloc manual for this motor, and a rebuild doesn't look that hard after reading the powerhead chapter. I took it to a shop a few weeks ago and they said the fuel tank and carbs are clean, the vro2 pump is working, but they said compression is low. They used power tune on it to get rings unstuck (it had been sitting a few years) but said it still smokes a lot they said. I was thinking about selling as is, but might consider a rebuild if it doesn't take a lot of specialty knowledge or experience with marine engines. I'm comfortable with a wrench, but also realize there's a lot I don't have experience with on the marine side yet. Please advise.

Looks like tschamp20 and theoutdoorsman completed rebuilds just fine, but not sure of their experience levels. Allexperts.com and some friends are discouraging attempts a rebuild without marine experience. My friends don't have marine experience either, though. If you guys recommend that I could probably do it, where can I find a reprinted OMC manual? Thanks for any info, Steve

 

[Dhadley]

Re: Is rebuild difficult for 86 Johnson GT 150?

I don't think you'd have any major problem rebuilding it but let's start at the begining. What are the compression numbers? Is "low" compression the sole reason for a rebuild. I know it can't be because it smokes. Most 2 strokes do.............

 

[lexkyboater]

Re: Is rebuild difficult for 86 Johnson GT 150?

Thanks for the response. A couple of the cylinders are below 100 they said, but I was still going to try tilting the engine up and pouring some OMC Engine Tuner into the cylinders and let it sit overnight to see if that helps. Unfortunately, they didn't give me the compression numbers even though I paid $200 for the service they performed to power tune it 3 times and check it out. Not sure if the port or starboard cylinders are within 10 - 15 psi of each other either. I've read that's the main thing that would cause engine failure. I'm just going on what the shop told me, and I assumed smoking a lot meant that it's smoking a lot more than it should.

The rebuild is to address the low compression, as they said it would self-destruct over time, and I didn't want to ruin the engine completely. I can check compression myself, but not sure if you're telling me to just run it as is, because it will be a long time before it fails if the only problem is low compression? Not sure if the compression should be 120/130, or if it's okay if it's in the 90's, as long as there's not a big difference in cylinders on one side?

If a rebuild is in order, since I don't have marine experience, are there some gotchas I need to look out for? I'd hate to sink $1000 in it and then lose it. If I followed the Seloc manual, should that be okay, or is it highly recommended to go to kencook.com and get the omc service manual?

 

[iwombat]

Re: Is rebuild difficult for 86 Johnson GT 150?

There's nothing inherently wrong with low compression as long as the engine performs well. You'll start to see it first with a rough idle. As long as the compression is even, you can run it until the performance forces you into a rebuild. Now, if you just want to tear into the thing and have it all done that's another matter.

Not sure what the shop meant by suggesting it will self-destruct over time. Unless maybe you've got one cylinder out of whack or something and that's what they're talking about. Sure would help if they gave you the compression readings. Do the power tune treatment and take some compression numbers. If they're all close you should be fine.

 

[Solittle]

Re: Is rebuild difficult for 86 Johnson GT 150?

Any reputable shop that does a compression check for you should give you the numbers to support their recommendations. Check it yourself as others have mentioned and post the numbers back here.

 

[Swampmouse]

Re: Is rebuild difficult for 86 Johnson GT 150?

Don't be scared. I am in the middle of a rebuild on a '83 115hp. I have been amazed how easy it has really been. I should start putting it all back together tomorrow - $550 in parts sure beats the heck out of a $2200 rebuild cost at the shop!

Sm

 

[lexkyboater]

Re: Is rebuild difficult for 86 Johnson GT 150?

Thanks for all the help guys. I went out this morning to check compression and pumped the gas bulb and fuel started running down the side of the engine. Lifted the cover, and the fuel line running from the oil/water separator was split, then when I tried to cut it back and put it back on, the fuel line to the separator also split... I haven't started it since it came back from the shop.

So, I'm going to work on replacing the fuel lines tonight. That might explain the excessive smoking, because it was probably sucking air the whole time the shop was looking at it which caused the vro pump to push too much oil (which I read on some other threads here). Thanks for the vote of confidence on the rebuild too, and I read all your thread sm, very good information. Haven't ordered an OMC manual yet, but will if we determine it needs rebuild. It doesn't seem like it'd be bad - the main thing is guidance with a detailed manual since it's a different animal from the automotive world.

 

[Joe Reeves]

Re: Is rebuild difficult for 86 Johnson GT 150?

I'm wondering how that shop managed to run the engine with that split fuel line.

Right around that time, compression was lowered due to the poor quality gasoline we were receiving, and I believe that the 1986 150hp Evinrude/Johnson, when new, had a compression reading of approximately 90 psi on one bank and 95 psi on the other bank. A factory rep told me that the 5 psi difference was due to the crankshaft design. Frankly, I fail to see why the crankshaft would have that effect but apparently that's the nature of the beast as the saying goes.

The VRO..... Either replace it or convert the engine to pre-mix as follows:

(VRO Changeover Judgement Call)
(J. Reeves)

The VROs first came out in 1984 and have been upgraded quite a few times. In my opinion, back around 1988, they had perfected them but I think that they were upgraded even more since then. As long as the warning system is operating as it should, I feel quite at ease with them.

Some boaters have voiced their thoughts such as "What if that overpriced plastic horn should fail while I'm under way for some reason, and the VRO decides to fail five minutes later?" Obviously that would result in a big problem which really brings their fears into view.

The word "ease" is the key word though. If one has the slightest feeling of being ill at ease with that setup, then they should take the route they feel more at ease with. A judgement call each individual would need to make on their own.

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
********************
(VRO Pump Conversion To Straight Fuel Pump)
(J. Reeves)

You can convert the VRO pump into a straight fuel pump, eliminating the oil tank and VRO pump warning system, but retain the overheat warning setup by doing the following:

1 - Cut and plug the oil line at the engine so that the oil side of the VRO pump will not draw air into its system. Trace the wires from the back of the VRO to its rubber plug (electrical plug) and disconnect it.

2 - Trace the two wires from the oil tank to the engine, disconnect those two wires, then remove them and the oil tank.

3 - Mix the 50/1 oil in the proper amount with whatever quanity fuel you have. Disconnect the fuel line at the engine. Pump the fuel primer bulb until fuel exits that hose with the tint of whatever oil you used. Reconnect the fuel hose.

That's it. If you want to test the heat warning system to ease your mind, have the key in the on position, then ground out the tan heat sensor wire that you'll find protruding from the cylinder head. The warning horn should sound off.

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store

I know the VRO is expensive BUT if you intend NOT to convert to pre-mix, replacing it with a new one is cheap insurance.

The carburetors? Rebuild them! Make sure that you manually clean the jets, especially the hgh speed jets (6) that are located in the center bottom area of the float chambers. A slightly fouled jet results in a lean running engine which will damage bearings, pistons, etc. Keep us up to date.

 

[lexkyboater]

Re: Is rebuild difficult for 86 Johnson GT 150?

Got fuel lines fixed and compression ended up being okay. My Dad thought that maybe the rings expanded some more with time after getting it back from the shop. I started it after about a minute and half of trying and ran it for about 5 minutes on a flusher. Without gas primed it tried to start several times, but it kept kicking the starter down, so I had to let off and try again, but didn't have trouble really. I'd say it's been at least 3 weeks since started last. It starts with just a touch of the key once warm. It doesn't smoke that bad, but did seem to burn off some extra fuel/carbon once I got it started. Water pump seems to pee a decent stream, but not like the new 93 Yamaha 115 I bought this past weekend. It probably needs a new impeller. Compression numbers are:
1 - 100
2 - 100
3 - 101
4 - 97
5 - 98
6 - 91

It seemed to run good, but the hull is toast. I don't think I mentioned that earlier, but did in another post. When I bought it, it looked like the transom fiberglass and paint that was missing was superficial, but ended up being in pretty bad shape. Plus to the left of the transom, the decking is pulled away from the end of the boat for about a foot to the left of the transom. You can see it moving when you push and pull on the tilted motor. So I can't use it, and would be afraid it would end up on the bottom of the lake. Should I sell entire boat, motor, extras all together or separate motor, trolling motor, fish finder, prop, dual steering setup, gas tank, trailer? I was thinking to put it on eBay? Thanks for all the help on it so far. --Steve