Down under rebuild of 90HP Force

[pnwboat]

Re: Down under rebuild of 90HP Force

Yes I would say that the stator is probably OK. I forgot about that. Old age you know...LOL!

 

[boatmert]

Re: Down under rebuild of 90HP Force

I have a theory on what happened to your upper main (thrust) bearing. If my theory is correct, it would have happened to the old bearing as well.

I'm in the middle of rebuilding my 1989 Force 85HP. Your block looks almost identical to mine. I'm waiting for a new upper main bearing and to have it pressed on this week before attempting my second reassembly.

Very similar thing happened to my engine after the first reassembly with the old upper main. I reused all my crank and lower rod bearings because I couldn't find any wear in anything. My old pistons looked like yours, and I had no compression on #3. Rebuilt using Wiseco pistons .020 oversized, ordered after the machine shop measured my cylinders and told me what to order. I trusted them on piston clearance and I believe they got it right because every ring end gap was right at .012 when I checked the new rings.

I didn't make it to the lake. A minute after starting the first time, the engine bound up and died. Wasn't seized, but very tight. Removed the flywheel and discovered the crank had slipped down in the upper main bearing. Cut a donut out of some 3/4" hardwood and made another spacer out of 3/16" flat steel then used the flywheel and nut on top of those to pull the crank back up. Reinstalled flywheel and ran again for a few minutes and the same thing happened again.

Now waiting for a new upper main bearing. My old one didn't look like yours. However, the flywheel ground down on the bearing cage, and after disassembling again, I found the crank counterbalances had also rubbed on the case shaving off some metal. Now totally disassembled again so I can clean all that metal out of everything.

When I assembled the crank in the block the first time, the bearing wouldn't seat quite right in its case journal. The Clymer manual said to tap it down, and when it seated it didn't make contact with the lower part of the journal. Then I installed the case cover and torqued it, and after that, while tightening the bearing cage, the cage had to push the bearing down into place.

My theory is that the bearing didn't land square in the block, so when the engine ran, it acted like a screw, pushing the crank down out of place. In my case, I think it was extreme enough to cause this at idle. Seems to me in your case, the same thing happened, but less extreme, so it took some higher speed to move the crank.

Second assembly I'll be making certain the bearing seats correctly and will be checking the fit of the bearing cage before torquing the case halves.

When I checked for binding after torquing the case halves, it seemed OK, but I did need a wrench on the flywheel nut to turn it. I'm thinking now that I have learned more, the crank should turn quite freely without compression by hand, and I'll be monitoring for binding much more carefully this time.

I don't think your new bearing was defective. Just seems like an assembly error, like mine, IMHO.

I've also read that a hammer should not be used to press bearings or seals in bearings, as it can damaged the bearings. I'll be having my machine shop press the bearings and upper and lower crank seals for me.

Leave it to us inexperienced engine builders to learn the hard way.

The Clymer manual I have places so much emphasis on the alignment of the crank end rod caps, and none on the placement of that upper main bearing, that I worried too much about the one and overlooked a critical item on the other.

Wish me luck on second reassembly. Looks like yours is working well now.

 

[hundee r1]

Re: Down under rebuild of 90HP Force

wow, thanx for taking the time to read this thread!!! and first up, best of luck with getting yours going again!! The guys on these forums have been a huge help and I couldnt have done it without them

When I assembled the crank in the block the first time, the bearing wouldn't seat quite right in its case journal. The Clymer manual said to tap it down, and when it seated it didn't make contact with the lower part of the journal. Then I installed the case cover and torqued it, and after that, while tightening the bearing cage, the cage had to push the bearing down into place.

My theory is that the bearing didn't land square in the block, so when the engine ran, it acted like a screw, pushing the crank down out of place. In my case, I think it was extreme enough to cause this at idle. Seems to me in your case, the same thing happened, but less extreme, so it took some higher speed to move the crank.

My theory is different as to why mine failed.
I had no missalignment issues during assembly, I was super vigilant in locating all the bearings on their dowels, both the top and bottom bearings seated perfectly in the case, and upon torquing them up, a small amount of gasket maker (Loctite) oozzed out comfirming they where home.

My crank rotated quite freely aswell, and it shouldnt matter too much whether the case is torqued up or not. The bearings are rolling needles and dont rely on crush , so the whole assembly should feel very much the same whether its torqued up or not.

In your case, your 100%, yours seized due to missalignment and I think you didnt have one of the bearings located properly, thus skewing it all. I paid special attentions to this aspect, tripple checked it and made sure I had a small ooze of gasket maker squeeze out on all edges of the case.

I honestly think I made the mistake when installing my new upper bearing.

I used a piece of pipe over the inner race and a big hammer.
I didnt clean the inside of the pipe and noticed a small amount of scale fall out into the bearing during the hitting. I then used WD40 and compressed air to clean the bearing, it spun smooth, but not perfectly.

Upon assembly, I didnt take much notice of lubricating this bearing, may have got a spalsh, but not much, if any oil.

So hitting it on is not ideal, then cleaning all the oil out off it from when its made ( using WD40),nor is letting it run dry upon startup cos I didnt pack it with grease or oil.

I think the last factor broke the camels back. Its at the top of the motor, and would require some considerable running time before getting 2 stroke mix on it, take note of how close the crank counter weights are to it aswell.

Im not saying the design is good, speaking to guys that play with other outboards are astounded that the whole crank "floats" in the case, they say most others have a retaining plate that bolts the upper bearing into the case much nicer iinstead of the Force clam "shell clamp".

I was super lucky, didnt smash anything and the bearing didnt turn in the case.
I feel if the bore of the case is scored or damaged from the seize, it would struggle to hold the bearing properly ever again.

I suggest you press the new bearing on, use loctite on its journal, and pack it with grease from the top before you put the upper cover on.
Then pay super dfarefull attention during assembly to make sure all bearings are located 100%

Im no expert, but this aspect of my build is goin sweet 5hrs into its new life.

keep us posted!!

 

[hundee r1]

Re: Down under rebuild of 90HP Force

So over the last couple months I?ve been taking it pretty easy on the build. Slowly getting into the rebuilt motor a bit more, with longer trips, more revs and all had been going reasonably well.

From day dot the motor had never charged the batteries, not a huge issue cos I always charge them prior to a trip, but not ideal.

Had this thread on here :

http://forums.iboats.com/force-chrysler-outboards/another-battery-charge-thread-613454.html

So with that sorted and having done 8 odd hrs on the motor and figured it was ready for a proper tune up and rev out to see if all my work had been worth it.

So armed with some tools I had a few things to check last time I went fishing. But the weather had different plans so I just came in without having a look at anything under the cowling.
Back home and thinking: even tho I hadn?t tried too hard, I didn?t think the rebuilt motor was quite performing to its full potential yet, especially in regards to its top end, it just didn?t seem to be willing to rev much harder than before.
Id done the tune and sync and hadnt done much difference, so I started these 2 threads :


http://forums.iboats.com/force-chrysler-outboards/bad-stator-cause-so-much-grief-me-627618.html
http://forums.iboats.com/prop-questions-topics/please-help-me-find-my-revs-631514.html
and to help me with the above this one:

http://forums.iboats.com/force-chrysler-outboards/what-my-final-drive-ratio-631674.html

So a quick trip to a local shop had me picking their brain aswell. They confirmed no harm in trying another prop. He promptly dug one out and offered for me to drop by the shop on the way to ramp so his head mechanic could double check that my tacho was indeed reading correct aswell

http://forums.iboats.com/force-chrysler-outboards/20-pole-stator-631605.html

So on the way to the ramp, I dropped in to the shop, they checked it and was indeed reading right and sent me on my way.

Our destination, a section of water in front of a speedboat club on a local river. First WOT run, and as suspected the motor maxed out at 4100 rpm and just under 50km/hr.
I check with the timing light at WOT confirmed that even tho the timing had been set correct on muffs, under load it was 4-5 degrees retarded.
Slowly eased the timing up and the motor started responding well, few tweaks of the carbs along the way and I had the 3 cyl going much better.
We got it to rev cleanly to 4600rpm and max out at 58.6km/hr.
It was at this stage that we had a good baseline to work with so planned to head back to the ramp to try the different prop.
A quick 5mins and 1 bolt latter ,saw us back at the speed boat club for another round of testing, this time with the different prop.

Straight away we could tell the motor was more responsive, willing to rev freely and make the boat lurch from any revs. Quick check of the timing and it was still bang on, so opened her up and got the same top speed of 58km/hr but this time the oldshool 3 cyl was singing at 5100 rpm.
No rocket ship, but probs as good as its going to get with the package as it stands.

Anyway, just thought I string it all together in case someone else finds my saga usefull

Thanx to all that have helped, if ever in australia, drop me a line

 

[hundee r1]

Hey Guys, just thought I?d check in with an update from down under.

Happy to report that 1.5 years on and the 3 cyl Force is still running like clockwork!!
Thought I?d compression test it yesterday, and glad to say all comps are between 142-150psi, pretty much the same as after the 10hr running in time.

Around here, not many have much love for the Chryslers or Force, but I can tell you since rebuilding this motor and doing the couple electrical fixes on it, she hasn?t missed a beat!!

Starts easily every time, common 60-70km round trips with all our fishing gear on board, even in less than ideal conditions the old girl has got me back to the ramp every time. I have extreme confidence in it these days after a rocky start.
Even getting good bags of fish which is a nice bonus!!!

So there you have, once again, many thanks to all that have helped around the way, and I still log in on occasion for a bit of a browse.

 

[pnwboat]

Happy Boating!

 

[jerryjerry05]

Thanks for the update!!!
Glad it's running good.
I take a bunch of different people fishing and they leave my boat with a new appreciation for my Forces.
Both 27yrs old.