1988 Evinrude 25hp. Hard to pull start and running really rough

[BTL]

Model E25RCCA
Serial R732740

First some background: Last weekend I was running back in to the ramp when my motor started vibrating harder than normal. A minute later it jerks and dies. Tilted it up and saw that the exhaust housing/midsection of my motor was cracked. Closer inspection revealed that 3 of the bolts that connect the exhaust housing to the lower unit were gone, only the stud in front and one bolt were left.

I think those 3 bolts had worked their way out and the excess vibration caused the housing to crack. Fortunately the drive shaft and shift rod were undamaged. Anyway, I ordered a new housing and installed it a few days later.

After performing the repair, the first time I tried to start it up in the driveway, the pull start jammed. That was concerning, but I tried again and it pulled easier and started. Motor sounded a little louder than normal but it was running and pissing water, so I was ready to go.

Got out on the water and again it jammed on the first pull. Started up on the second pull, but when I put the motor in gear I could immediately tell something wasn't right. I was moving, but much slower than I should have been, and the motor was running really rough and jerky.

I brought it back home to check compression and thankfully that's still good (when I can actually pull the rope). After checking compression I pulled both plugs and the rope was easy to pull...When I put them back in it jams again.

So that's where I am. Worried something was damaged internally when the housing cracked but hoping I just put something back together wrong.

Any ideas what could be going on?

 

[flyingscott]

Pull the lower unit off and see if it turns easier. That kind of break can damage the gears.

 

[BTL]

Thanks I will try that. I did change the lower unit oil and didn't notice any metal in it and the prop spins easily by hand.

 

[BTL]

Oh and something else I noticed.The top plug is on the right and the bottom plug is on the left. Looks like top is dry and bottom is wet.



It's seeming like this has something to do with the cylinders/plugs/pistons, though I don't know why any of that would have been affected by a broken midsection.

 

[racerone]

Check the fuel pump diaphragm.----Check spark also.

 

[Chinewalker]

I'm going to guess that there's a good chance you buggered up the lower main seal when the driveshaft was out of alignment. It sits in a small housing at the base of the powerhead and if that housing got cracked, the seal could have moved or been damaged.

 

[BTL]

I'm going to guess that there's a good chance you buggered up the lower main seal when the driveshaft was out of alignment. It sits in a small housing at the base of the powerhead and if that housing got cracked, the seal could have moved or been damaged.

Is this the part you're talking about?

 

[BTL]

I did a little more investigating this afternoon. Fuel pump is in good shape (just rebuilt last winter). The lower unit feels fine, though I haven't disassembled it. Everything moves smooth and freely with the plugs out. I can put it in gear and easily turn the prop and flywheel with one hand.

I took the cylinder head off to check out the inside. The only thing that stood out was the seal on the thermostat was a little messed up.



There is some carbon on the pistons but the cylinders are smooth and clean. I'm going to replace all the gaskets while I've got it apart. If it comes down to it I'll pull the powerhead to check the seals and such, but right now it really seems like it might be some kind of exhaust blockage that's not allowing the pistons to move with the plugs in.

 

[BTL]

I pulled the powerhead tonight to check out the lower crankshaft seals and bearings. The o-ring (part # 0326649) was trashed. Not sure if that would cause any of the symptoms I experienced but it will certainly be replaced along with all of the gaskets.




I haven't pulled the bearing yet but at a glance it looks to be in great shape.

 

[BTL]

Gonna put everything back together with new gaskets this weekend. Don't know if I've actually fixed anything but I will update with what I find out.

 

[BTL]

Put new gaskets on the head and water jacket. Decided to go ahead and replace the lower crankshaft seal since I can't find anything else noticeably wrong.

 

[BTL]

I'm going to guess that there's a good chance you buggered up the lower main seal when the driveshaft was out of alignment. It sits in a small housing at the base of the powerhead and if that housing got cracked, the seal could have moved or been damaged.

Well, you nailed it!

Got my new seal last week and installed it yesterday. Put everything back together, crossed my fingers, and fired it up. Pull start was back to normal and the motor sounds like its old self. I guess air was being pulled through the damaged seal, and restricting the movement of the pistons?

I still need to to give it a true test on the water with a wide open throttle, but I'm pleased for now.

 

[racerone]

How can air restrict the movement of the pistons.--------Air is pulled into the crankcase through the carburetor in normal conditions !!

 

[BTL]

I won't pretend to know the exact explanation, all I know is the pistons didn't want to move whenever the plugs were in, and after I replaced that seal, everything worked as normal.

 

[racerone]

The lower seal is there to seal the crankcase.-----Prevents air / fuel mixture from leaking out when piston is traveling down in the bottom cylinder.----Makes sure that air comes into the bottom crankcase via the carburetor instead of from the exhaust housing when piston goes up into the cylinder.----Prevents cooling water from being sucked into the bottom cylinder.----That seal itself would not cause the issue you had unless it was WATER rusting / jamming the bottom bearings !

 

[BTL]

Well then I guess the motor fixed itself while I was busy replacing the seal. Fine with me :thumb:

 

[Chinewalker]

It's possible a piec of seal or o-ring got jammed between the tip of the driveshaft and the inside of the crankshaft spline hole. This would result in the driveshaft and crankshaft being pushed apart, crank upwards, and driveshaft downwards, which may have caused something to bind. Said chunk may have subsequently fallen out during disassembly, resulting in it fixing itself.