Seized motor

[Stoehrdp]

Hi all,

I have a 1980 25 HP Johnson Seahorse J25RCSA. and limited mechanical experience. I store boat and motor uncovered.

I took the boat out about a month ago and had some very bad gas (water) managed to make it a few hundred yards and engine kept conking out.
I put the boat back on the trailer and within a week fixed the problem by mixing new fuel and running the motor for 15 minutes or so in the barrel. Two weeks later I put the boat in and took it out to a dive site about ¾ mile away from ramp. Tell tale was working fine. I brought the boat back, did not look at telltale so do not know if it was working. I heard nothing unusual from motor and shut it down with the stop switch. Trailer the boat and brought it home.

Two weeks later, I tried to take it out again and found the motor frozen. Starter rope would not move more than 6 inches and flywheel not at all. I had problems getting it in and out of gear but finally got the prop to spin freely.

Talked to a few people and they recommended I check the gear lube. I did found it to be almost all water. I checked previously the beginning of the season but not since about June.

Removed the gear case and tried to spin flywheel, motor still frozen. Prop spun fine. I put a few ounces of Marvel Mystery Oil (MMO) in each of the cylinders and left overnight to soak. I also filled the gear case with MMO spinning it a few times.

I managed to use a breaker bar on the flywheel nut and free the pistons. Motor spins freely now. I plan to run a compression test on the cylinders in the next few days. . I plan to rebuild the water pump.

My questions to all of you are the following:

How did the water get into gear case? I see no signs of MMO leaking out.
Why did the engine seize to begin with? Was it the bad gas?
If the compression test comes turns out well, what should I consider doing anything else before trying to start it up again?
Should I rebuild the gear case as far as seals? Any other tests I should run?
Can some one of limited mechanical ability do this or is it best left to a mechanic?

Thanks in Advance
Dave

 

[tiller7104]

Re: Seized motor

Just a thought.....I have seen it happen before, if you had to much water in your fuel or there was to much moisture in your engine you may have just had a rusted cylinder...rare but I have seen it. I would not imagine though that it would have taken a breaker bar to free it though in that short of time? There are so many variables here and things that it could be? Get your self a lower end seal kit, and while you have it apart replace the seals, you can buy the kit right here at iboats. Make sure your prop seal is good.

Just a thought .....did you check your pull start mech? Does it have water in it or is it rusty? You will get some debate here but MMO is so great stuff, I use it to free things but I have been told do not rely on it for lubrication!

 

[mikesea]

Re: Seized motor

Yep.you have at least 2 problems NOT connected.The gearcase is leaking,hopefully there was enough oil to keep things lubed enough til you MMO'd it.thats certainly bette than it being drained with nothing but air.The thing that NEEDS to be done there is,total disassembly,visually check all parts,replace all seals.Reassemble and pressure check.As for the The powerhead.I suggest taking the head off,do a visual,if it look OK.New head gasket,run with a double dose of oil and hope for the best.Unless your real uneasy,have the time,pull the powerhead apart,hone the cylinders,if all looks ok,maybe new rings ,reseal and put back together.I definatly would do the lowerunit thing.I would do the headgasket ,visual,double oil for 1 tank. Good luck

 

[wbeaton]

Re: Seized motor

Exactly what mikesea said. Inspect the head first. If things still look ok then proceed to repair/reseal the lower unit. Do the water pump while you are in there.

If the pistons/cylinders are damaged you will need to rebuild the powerhead. If you are not comfortable rebuilding it yourself then look for a replacement motor since a professional rebuild would be cost prohibitive.

Also, buy the service manual if you intend to do this work yourself.

Good luck.

 

[wbeaton]

Re: Seized motor

Almost forgot...yes you can do this, but not without a good manual and a lot of patience.

Water can get into the lower unit at several different places and for different reasons. The fact that oil is not leaking out does not mean water can't get in. Somewhere in the lower unit you have one or more bad seals.

 

[tashasdaddy]

Re: Seized motor

when you check the lower in june. did you replace he seals(washers) on the screws. they can cause water intrusion. pull the cylinder head and see what it looks like, the pull the power head is it's bad. do you compression test first, before pulling anything, and post results. compression test can be done with the lower still off.

 

[Solittle]

Re: Seized motor

A bit more on tahasdaddy's advice on the gear case - replace the filler & drain plug seals and refill it with fresh oil. Try it before taking it apart and replacing all the seals. Check the gear oil every trip. If it still leaks do a pressure check to determine which seal is leaking before you open it up.

Also do the compression check before you do much else and post theresults back here.

 

[freddyray21]

Re: Seized motor

I agree to replace the fill and drain plug seals first and keep a good eye on it. From June to now it could only be allowing a little water, but over several trips it will fill up. A frozen motor had to have locked up for a reason. Could be water in the pistons. I doublt it came in from the carbs but could have. Could be a blown head gasket letting water in the pistons. All the more reason to pull the head and take a look

 

[Silvertip]

Re: Seized motor

Depending on how much force you used to break the engine free, you may now be dealing broken rings and ring lands. While its too late in this case, never force a seized engine. Break it loose by "gently" rocking it back and forth within the distance the engine will turn. That may be just a degree or two or rotation. Keep adding MMO (or lub of choice) let it soak a few days and then repeat. The engine will likely free up over time but one must use patience -- not force. See whether you have a good engine before spending a great deal of time on the lower unit.

 

[Stoehrdp]

Re: Seized motor

Hi All, Thanks for the responses. I did not replace washers on the lower unit and they do look worn. I will probably do as suggested rebuild water pump and replace washers and gear lube and watch it over a few trips.

The Power Head, Cylinder pressure in both cylinders are about even. After three pulls of the rope they both read between 65 and 75 pounds. I rechecked each cylinder 3 times. I used a rubber tipped compression tester (and am a little leary of the readings) I borrowed from a friend (hence the reason it has been a while before I replied back). They were always pretty much the same reading between the two, ie if cylinder 1 read 70 so did cylinder 2.

I'm wondering if I should buy a screw in type and redo the tests before taking the Cylinder head off to check the condition of each cylinder.

It did not take too much force to break the head free. I was not going to do it with the rope starter. Will try to A. avoid repeats in future and if not possible will use rocking method then.

Questions are should I trust these readings? nWhere do I go from here?

Thanks again for the support
Dave

 

[Solittle]

Re: Seized motor

Beg, borrow or buy a decent compression gage. The readings you are getting now are low but relatively even which is a good sign. Lets see where they are with a decent gage.

 

[F_R]

Re: Seized motor

That powerhead didn't just freeze up for no reason. And it might be related to the conking out you experienced earlier and blamed on bad gas. What I'm saying is it might not have actually been bad gas. You need to find out what is letting water into the powerhead. Could be head gasket leaking, Could be exhaust cover gaskets leaking, to name just a couple of could-be's. Water in the powerhead will convert your motor to a pile of junk in a very short time. Do that before spending money and time on the lower unit.

 

[Stoehrdp]

Re: Seized motor

I bought a new compression gauge tonight (screw in type) I can not warm motor due as the lower unit is still off.

I removed and grounded both plugs and then I pulled the rope 3 times each cylinder. This is the same procedure I did with rubber type gauge.

I got the following readings:

Top cylinder was 120#
Bottom cylinder is 125#

My clymers manual says this is ok.

I plan to remove cylinder head and peak inside next.

Thanks for all the help
Dave

 

[andy6374]

Re: Seized motor

Your powerhead is fine.
With those compression numbers I would just get the L/U back on (maybe with a new impeller), get some new plugs, and pump a 25:1 mix into it. I bet it will fire up.

You'll probably need to clean the carbs too.

 

[F_R]

Re: Seized motor

Your powerhead is fine as regards to compression. However, you have not determined why it froze up and had to be forced with a breaker bar. That is not normal and indicates either that water got into the cylinders or you had it stored in the Great Dismal Swamp. Continued water intrusion into the cylinders will destroy it. The dump is full of them.