Bad crankshaft seal or seals on 9.9?

[ba_50]

I am having the same problem with this '92 Johnson J10RENA as before. It won't get a 14' aluminum boat up on plane like it used to.

How can I tell if the CS seals are bad? This motor got used about 3x in10 years and it probably sat in the Florida sun the rest of the time. I put 10-15 hours on it before the trouble started. Here is the dope again...

It has a new fuel pump, fuel lines, new upgraded carb cover (plastic, screws torques at 10# each), carb kit, spark plugs (tried 4), cleaned the carb about 15x.

The linkage was adjusted using an OMC manual. The idle knob on the shift handle was screwed all the way in. The throttle was opened as far as possible, choked, bulb pumped hard, and still wouldn't start.

The motor won't start without pre-mix sprayed into the air shroud. The choke plate opens and closes ok. I checked the float level.
After putting the new fuel pump on it got full power and quit throwing raw gas and oil out the exhaust. After cleaning it again it to see if it would start with the choke it wouldn't power up.

The fuel tank line works with the 35hp motor. Tank vent open.
New home made carb to motor gasket and float bowl gasket.

Compression is 100 & 102#. Motor shouldn't have only 25 hours on it.

7/16" spark jump on each plug.

Thank you.

 

[schematic]

Re: Bad crankshaft seal or seals on 9.9?

-do the carbs spit fuel out when trying to start or at idle?
-have you checked the flywheel wheel key for being sheared?
-any water showing up on the plugs?

 

[ba_50]

Re: Bad crankshaft seal or seals on 9.9?

No, I just checked it at full throttle.
Do I taste or smell it for gas vs water?

Two more possibilities came up. Partially plugged exhaust ports, and reed valve adjustment or they could be sticking.

 

[bktheking]

Re: Bad crankshaft seal or seals on 9.9?

How do the plugs look after running it, if a valve is stuck open or closed you will either see a plug that isn't firing or a fouled plug covered in gas. A water washed plug will look like it came out of the package, clean as a whistle. If you suspect gas, don't taste it, tap it out of the plug onto a surface and put a match to it, you'll know if it's gas cause it will burn, nes pas?

 

[jmendoza]

Re: Bad crankshaft seal or seals on 9.9?

OK, you want to know if one of the two crank seals is bad, and more importantly, if you have good crankcase compression, right? All without doing a teardown, which would be nice to be able to accomplish as part of your trouble shooting, guess what? I have been there , done that, and here is what I did:

Remove both spark plugs, then spin the engine over with the rope starter, or your palm on the flywheel and carefully feel for slight resistance as each piston goes down, and a Thoopa-thoopa-thoopa sound each cylinder will make as it uncovers the transfer ports on the down stroke. Additionally, you should hear each reed wheeze or honk as you rock the flywheel back and forth, thus making the piston go up and down at bottom dead center: it will be opening and closing the transfer ports and causing the reeds to open and close with the changing crankcase pressure, and rocking the flywheel back and forth a few degress by hand should produce the wheeze/honking noises from each cylinders reed valve if they are sealing, and there are no case leaks.
The upper seal is easily changed by removing the flywheel and magneto plate, I ran a deck screw into the seal and then pulled it out using a claw hammer and a short 1x2 piece of wood against the block to protect it. The lower seal is easy to change as it's in the crankcase head, which comes off with three bolts. Bad news is you have to remove the power head to get at it.

With the power head off, you could make up block off plates for the intake manifold, and exhaust, and pump up each case via the plug hole to do a leak down test, but this is complicated to do, and requires some fabrication on your part. The good old reed honk, and case thoopa sound will verify the presence or lack of case pressure, allowing you to make a quick and accurate assesment.
On my engine, it had a leak between the block and crancase cover(manifold) right where the taper pin is located, it had been driven in to hard and turned up a burr in the metal causing the cases to leak. I actually saw a slight oil weep at the case seams with the engine running, and noticed one cylinder was not honking the reeds, or making the thoopa sound of the crankcase pressure passing into the cylinder via the ports when pulling the engine through. It was hard starting as well, taking many pulls and choking. If the case leak is on the cylinder that runs the fuel pump, you will have hard starting problems as well because the pump won't deliver until the engine is reved up due to the leak.

 

[ba_50]

Re: Bad crankshaft seal or seals on 9.9?

Thanks for the procedure details. I will have to wait a few months to try it and have filed in by boat repair file. Bob