Force 1251X9D Bottom Cylinder Issues

[gregmsr]

History; compression thru all four cylinders has been ok and the motor ran fine. Now, was on the water and engine started missing at low speed and cut off. Took home and ran compression top to bottom 135, 138, 132, 60. Bottom plug looks "cleaner" than other three. Shot oil in low cylinder and re-test compression 135, 138, 132, 126. It came up. Spark is all good. Same plugs, just cleaned them. De-carbed with Seafoam. Engine purrs like a kitten. Was it a stuck ring? Back to water and it ran fine. Still the bottom plug is "cleaner" than other 3 but no sight of water. Now, during my winterization to put it to bed, ran it in a tank at home, pulled plugs to fog cylinders and....crap, a drop of water on the bottom plug. Just as I suspected. Now, this engine block has had a hairline crack on the outside of this cylinder since i owned the boat. It will "bleed" small droplets of water outside as it sits and runs. Hasn't been a problem. Has the crack finally migrated to include the cylinder wall (inside) or just time for a head gasket?
I first intend to check compression, remove head, inspect cylinders and gasket, replace gasket, re-check compression.
Where else can water come from? What else should I check and/or replace while im at it?

Thanks for any help!

 

[pnwboat]

Re: Force 1251X9D Bottom Cylinder Issues

A crack on the outside of the block probably won't migrate to the cylinder as there is a hollow water jacket between the two. Really depends on exactly where the crack is though. A bad exhaust cover gasket or cracked stainless steel exhaust cover baffle plate will also allow water into the cylinder. Head gasket and or exhaust cover gasket need to be checked first.

 

[jerryjerry05]

Re: Force 1251X9D Bottom Cylinder Issues

Remove the head and check the gasket.Don't wait for spring as it will rust up pretty bad and ruin the cylinder.J

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

I was hoping the crack wouldn't make it to the cylinder, and it don't seem to be getting worse. I'll go ahead pull it down and see.

Jerry, I sprayed the heck out of lube in that cylinder with rust in mind but your right, don't wait too long.

I'll post what I find. Thanks.

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

The "exhaust cover gasket", is this what it's called? I didn't see any gasket with that exact wording.

 

[jerryjerry05]

Re: Force 1251X9D Bottom Cylinder Issues

Called an exhaust port cover.
Minor leaking can be fixed with a gasket change.
Just be real careful when trying to remove the screws.
They get weak from age and heat.
The bottom ones usually are the worst.
For the removal of the tough ones??
I use PB Blaster and a small hand held torch and a hammer and drift.
I spray for a couple of days then start with heat and tap on the head of the screw.
Repeat and repeat.
I just disasembled a 15hp Evinrude and it took almost 2 and 1/2 hrs. To remove 2 head bolts.

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

Is there a sequence for head bolt removal?

Should I use lube/oil/anti-seize on head bolts?

Should I buy new bolts?

Should I put the 225 in-pounds torque all at once or half way then all the way?

 

[jerryjerry05]

Re: Force 1251X9D Bottom Cylinder Issues

For removal NO.
I use grease on the bolts.
Anti Sieze turns into perma sieze when you add salt water.
No use the old.
The tourqe is only 20ft#s and no way is 20 gonna affect the bolts.
I set the wrench at 17#, tourqe the bolts and then set at 20 and retourqe.
Then they should be OK from there.

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

I went to change the thermostat but found out it didn't have one. Should I go ahead and put one in (already bought one)?
Is a thermostat really necessary?

Thanks

 

[pnwboat]

Re: Force 1251X9D Bottom Cylinder Issues

Thermostat is necessary for best performance. Motor needs to be at a certain temperature for maximum power and efficiency. Without one, the motor runs too cold. It'll run OK, just not the best it can.

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

Fired it up Sunday and it fired right up after winter nap. Warm compression; 137, 140, 132, 125 (top down). Pulled head (bottom four bolts were a bear). The gasket really looks ok to me (non trained eye) and I couldn't see anything that would cause the minor water intrusion into bottom cylinder but i'll keep looking. The bottom piston has a small "nick" along the top edge and a slight marking on the cylinder wall, can bearly feel it with my finger, so im sure thats not good. But compression was 125 so...
I dont have plans to rebuild so I will clean it up and re-install head with new gasket (btw the new gasket looks different in some ways but all holes align perfect with the old. Anyone know the part # Sierra 1989 head gasket? To make sure I have the right one?) The bolts are VERY rusted so im off to get new ones.
Any tips or suggestions please let me know.I might try and send a few pictures of the "nick"

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

I notice the head had a silicone type sealant applied. I cleaned it all off and now ready to put the head back on. Is a sealant required for re-install head?

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

Advice needed!
Should I go ahead and rebuild/repair with the hairline crack I have in the outer water jacket of the lower cylinder on the block? I was told once that the crack wouyld not effect the cylinder wall. It seeps water droplets out thru the JB Weld (now cracked also).
Thanks

 

[Jiggz]

Re: Force 1251X9D Bottom Cylinder Issues

I have serious doubts about the small nick you mentioned about the bottom piston. Can you post pics of it. Usually, a small nick like this is a sign of a piston ring catching up with the exhaust or intake ports. As for the water intrusion, a picture of the gasket and the head will also help.

 

[jerryjerry05]

Re: Force 1251X9D Bottom Cylinder Issues

If it's cracked it's gonna need welding to fix right.
The JB weld will NEVER stop a leak. The block heats up and expands. Then contracts when cool.
The JB won't hold .
It might have cracked internally.Did any water ever get into the cylinders?
Like Jiggz said the bottom piston is probably bad.
Start looking for a different head. Craigslist or e-bay.
If you have trouble finding one, I might be able to get one.

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

Jiggs/Jerry,
See attached pictures and note nick in piston, JB Weld attempt on right side of cylinder.
Comments?
Looks like I need to start looking for another head.

 

[Frank Acampora]

Re: Force 1251X9D Bottom Cylinder Issues

That "Nick" in the piston is where the top ring broke and got caught in the exhaust port. The liner is steel and the piston is aluminum. Guess which one will give. Note the small "dots" denting the top of the piston where the ring portion was bashed around before it finally blew back out the exhaust. You will see the same damage on the head but it does not affect the head in any way.

These engines seem to break the top ring quite frequently. It is a semi- keystone cross section and seems to be weaker than the rectangular lower ring.

At any rate. while the engine may run nicely and seems to have adequate compression on that cylinder, you do need to replace the piston. Past experience tells me that the engine will run almost as well as with a new piston, (Mine did the same thing) so there is no great rush, but you really need to examine the bore for any deep scratches and sooner than later, replace the piston.

As far as the leaking crack coated with JB weld: The crack is on the outside of the water jacket and will do no harm for compression. IF you can find each end, drill a small hole to stop it from migrating, Vee out the surface of the crack with a Dremel, and then recoat with epoxy. be certain that all paint, grease, and moisture is cleaned before using the glue.

The best repair would be to have a welder go over the crack but if you can live with some weepage into the cowling you can run it as it is.

Understand though that there is no guarantee on the block. It may run forever as is, and then again it may crap out on the first run.

Were it my engine and I cruised a good distance from the ramp, I would repair it ASAP.

The damage you have is repairable without dismounting the powerhead and it will not be too expensive either. So look to replacing the powerhead (if I read you correctly) as a last resort.

 

[gregmsr]

Re: Force 1251X9D Bottom Cylinder Issues

1. There are elp some groves in the cylinder wall not really sctatches but shallow depressions you can see and feel. How bad is bad? Can these be honed out without removing the head? (debris dropping down into engine)
2. The water weeping out of the crack don't bother me but I will look into the epoxy.
3. There IS water getting into the bottom cylinder from somewhere. I replaced head gasket but not help. (actually I lost about 15psi compression on all cylinders with the new gasket. I torqued and re-torqued as required but still the compression changed)
4. I will research piston change threads. Recommended brand?

Thanks to all. Any other suggestions welcome! I will report progress.

 

[Frank Acampora]

Re: Force 1251X9D Bottom Cylinder Issues

How bad is bad? Difficult to say. A machine shop with a bore micrometer can tell you if the cylinder is worn, out of round, or tapered beyond specifications of .002.

On the other hand, you may not need to even hone it.

There are a number of aftermarket pistons sold, including stock from Sierra, Vertex, and Wiseco.

I prefer Wiseco because they are forged, which makes them stronger, and easier to install than stock.

Water in the bottom cylinder (only) can result from a broken or pinched exhaust cover gasket. It usually fails at the lower front "dogleg" where it is thinnest. Sloppy installation can pinch it there too.

Be careful in removing the exhaust chest cover. The bolts are only 1/4 inch and if there is any corrosion, at least one or two may snap off.