1990 johnson 115 vro no compression

[BEKO1212]

i just picked up a boat that was sitting for 6 years.the guy i bought it from said it was running but said the
motor was weak. he found that 2 of the cylinders had low compression.so when i brought it home i put a
compression gauge on motor and got 0 compression on all cylinders.when looking at the the motor the head on the right side looked like there was a milky substance around it.when motor was turning over it was making a
squeaking sound.all spark plugs were out when i did the compression test.im not sure if the motor is worth tryin to fix or just install my johnson 155 and not waste time trying to get this motor running.

 

[archcycle]

Re: 1990 johnson 115 vro no compression

Yes good call. Let's escape where we all went with this last time. Don't say the E word on here

But still, pull both of the heads and post lots of pictures. Show us all of the pistons, into all of the combustion chambers (you'll need to turn the flywheel clockwise to get some of them out of the way), and the piston side of both heads.

The damage to these components is going to be what determines how low the compression is (or whether it is there or not) and whether it is worth proceeding with a rebuild. The pics are step 1.

 

[emdsapmgr]

Re: 1990 johnson 115 vro no compression

If the prior owner had severely overheated the engine before it went into storage, that could explain the low compression. You may find the head gasket seal rings leaking. Pull the heads and check them. You will get a chance visually check out the pistons and top ringsets.

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

well i took took one of the heads apart and took some photos.when i was taking the other head off i snapped the last bolt i had to take off.ill get that off tonight.anyway here are some pics i took.

 

[archcycle]

Re: 1990 johnson 115 vro no compression

On that head bolt- do you mean you snapped one of this bank's bolts off and the head came off, or you snapped one of the other bank's bolts off and the head won't come off? If the head with the snapped bolt is already off you'd be best leaving it for the machine shop that does the rest of the work. They can remove it and re-thread it if necessary with very little of the risk of doing it yourself. If it were me and I was going to have it in the shop anyway, i'd just let the professional handle the broken bolt. If you snap off an ez-out in there then god help you. I recently got turned down by several machine shops looking for one to get one of those out.

Now which two had the low compression?

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

no the head wont come off.well no cylinders had any compression.i put my finger over the spark plug hole and felt very little compression.not enough to push my finger off the hole.

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

my guess is it has a head gasket leak as u can see in the pistons there is moisture and oil mixed with water.looks light brown. let me know on your opinion.im not sure what else to look for.should i change head gaskets only or do anything else while the heads are off?

 

[archcycle]

Re: 1990 johnson 115 vro no compression

Try the obvious and cheap route first. Why don't you clean it all up in there, get the water out, run a Light bead of silicone around each cylinder hole on each side of the head gasket (you can't re-use head gaskets but we can seal it for a moment here), bolt the heads back on, and take a compression reading. Let it dry for the night.

If it's still low put about 1 teaspoon of 2 cycle oil in each cylinder and check the compression again. The idea is that first you're going to test if there was just a head gasket issue since there's water in there, then you're going to test whether you're losing a significant amount of compression out around the pistons because when you wet and oily (fills gaps) them you can temporarily raise the compression a little.

If at that point you still don't have good compression then it'll be time to either tear it down for a rebuild or put the other motor on it. IMO if you did rebuild it with 4 new pistons and got it running smooth you'd be able to turn the motor over for a good profit. Otherwise part it out and put that other motor on it.

By the way what is the boat?

 

[Cofe]

Re: 1990 johnson 115 vro no compression

It would help to clean the water passages in the block and heads. Replace those water deflectors in the block,..... they look old and swelled.

Once you get it all back together, a good decarb could free the rings up enough to get some compression......

 

[Solittle]

Re: 1990 johnson 115 vro no compression

Precisely how did you check compression? The only way you could get 0 compression is with the heads off.

 

[emdsapmgr]

Re: 1990 johnson 115 vro no compression

A lot of water in there! I'd be concerned about whether the crank and all bearings on the rotating assembly are all rusted and pitted. If so, that will condemn this powerhead-considering the cost of everything. The good news is that it's likely the rings are ok on the side with the head off-since there are no dents on the piston crowns or head face. I'd also suggest a temporary test before just scrapping the powerhead. Scrape the current head gasket off the head and put the flat heat against the powerhead. See if the head lies flat against the powerhead, or if it will rock somewhat-indicating the head is warped. You may be able to have someone plane it flat if it is warped. Rub some light oil on the cyl walls by hand. No need to add much oil to the cyl, as excessive oil justs gives an inaccurate/high compression reading for a 30 seconds or so, till the oil dissapates. Put one one new head gasket on then the head- then torque it to spec. Crank the powerhead and take a compression reading. If you get decent compression readings, do the other head. You might be lucky. You will eventually have to pull the exhaust manifold covers off and install new gaskets. I see the rubber water deflectors appear to be a problem. One actually looks like it is closing off the water passage in the block. Before you finally reassemble, you will want to replace all 4 in the block and insure they are properly positioned for good/correct circulating water flow. These diverters could have been a reason for any prior severe overheat.

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

all of the plugs were off when i tested the compression. i made sure that the battery was fully charged.like i said in an earlier post i was putting my finger on the spark plug hole when cranking and it didnt push my finger off the hole.maybe the compression tester is bad but just by putting my finger there and not getting pushed out tells me there is weak compression.

 

[Borgey401]

Re: 1990 johnson 115 vro no compression

all of the plugs were off when i tested the compression. i made sure that the battery was fully charged.like i said in an earlier post i was putting my finger on the spark plug hole when cranking and it didnt push my finger off the hole.maybe the compression tester is bad but just by putting my finger there and not getting pushed out tells me there is weak compression.

Do you have another motor you could use the gauge on to see if it's faulty or not?

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

Yes i do.i will do that and see what happens.

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

Yup 0 conpression on good engine!! Ill buy a new one in the morning and check it.

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

Well i got a new gauge and sealed the head with permatex and on 3 of the cylinders i got 86- 88 lbs but the top right cylinder barely gets up to 10. I put some 2 cycle oil in each cylinder and none of the readings changed. Where do i go from here? Should i just change the head gaskets or? Maybe on that cylinder with low compression reading the permatex didnt seal right?

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

Well i got a new gauge and sealed the head with permatex and on 3 of the cylinders i got 86- 88 lbs but the top right cylinder barely gets up to 10. I put some 2 cycle oil in each cylinder and none of the readings changed. Where do i go from here? Should i just change the head gaskets or? Maybe on that cylinder with low compression reading the permatex didnt seal right?

 

[apollothesun]

Re: 1990 johnson 115 vro no compression

im not to familiar about your motor but im gonna throw out this suggestion. have you tried
torqueing down the exhaust manifold for the piston with the low compression? there might be a leak there also.
i would difinitely dry out the motor removing anything that has a gasket and air dry the
inside of the motor. im sure iboats have the gaskets for your motor. i would spray fogging oil on the pistons and the cylinder walls while the engine is drying.
also, those stripped head bolts in the threads are gonna be a biiatch to get out though

 

[iwombat]

Re: 1990 johnson 115 vro no compression

Torquing down the exhaust manifold isn't going to change the compression any. The exhaust ports are closed off at tdc. You can remove the exhaust manifold entirely and still get a good compression reading.

Permatex isn't going to make much of a head gasket. You probably need to sand your heads flat and use fresh head gaskets to get anything resembling a usable reading.

 

[BEKO1212]

Re: 1990 johnson 115 vro no compression

well im going to send the heads to a machine shop and change the head gaskets and check compression after that.hopefully the rings are good.wish me luck!!