1988 Force 50HP Rebuild Powerhead??

[buckwheat34]

I disassembled the powerhead of my 1988 Force 50HP after finding pieces of the piston rings in the lower unit. I had pulled the gearcase for inspection and pressure test because I was getting frothey oil/water mix from one of the gearcase mounting bolts. The pieces came through the exhaust from what I see and settled in the top of the gearcase. The entire mid section of the motor was full of a tan frothey oil when I pulled the lower unit. One piston is broken/fractured where the ring came through the top/side of the piston. Cylinder walls look ok / no grooves or severe scratches. You can actually see some honing marks on the upper part of the cylinder walls. I see wear on the bearing cages that I removed from the one connecting rod. There are some marks by the ports at the bottom of the cylinders and there is alot of heavy carbon in the lower areas of the powerhead.

Question??? Is it worth repairing a motor of this age if cylinder measurements and crank measurements are ok (have not checked them yet)? How much can I expect to pay for 2new pistons & rings, all new bearings 100%, all new gaskets ( several are bad and all need replace after total disassembly). What else should be replaced since I'm 100 disassembled now? I had a mechanic friend look at it and he said he would not put the money into it because it is a Force. Your thoughts? Concerns?

Thanks,
Buckwheat34

 

[Frank Acampora]

Re: 1988 Force 50HP Rebuild Powerhead??

That's what most people will tell you, however, parts are relatively cheap, you already have the engine disassembled, and the hard work is done. Pistons run about 70-125 depending upon brand while a gasket set will cost somewhere around 50-75. Bearings are a tad expensive but if the rods are OK, then yeah, worth it. Don't buy new rods if yours are trashed: The same rods were used in almost ALL Chrysler and Force engines and usually even in a junker engine they are serviceable. Just stay away from Force 75 and possibly 90 engines--they had different length rods. Boring will cost around 100-130.

So, for around 400-500 you can have essentially a new engine. Now, impeller and seals for the lower unit will cost around another 100.

So, while I say rebuild, the money and final decision is yours.

 

[jerryjerry05]

Re: 1988 Force 50HP Rebuild Powerhead??

Lot's of those motors on e-bay or craigslist.Get a second and use that for parts or use it for parts.
Try to figure out why it went bad.J

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Pulled the #2 cylinder today and got a good look at the cylinder walls, connecting rods and exhaust ports. The cylinder walls look real good and I can still see some honing marks in them. I thought they looked a little rough around the exhaust ports on the bad cylinder (broken ring), but the lighting was not good and I do not see a problem under proper lighting (no nicks or grooves). I'll take some measurements when I go to a friends shop this week to clean-up the parts. The connecting rods and bearing surfaces look ok and I believe the cylinders, rods and crank will measure ok. There is heavy carbon build-up in all exhaust areas of the motor.

With that said, here is what I think may have happened. From my previous post - Compression was 63psi and 75psi when I first got the motor. I did the decarb process posted here on iboats. I then noticed the oily mix comming from the front right mounting bolt of the lower unit. Pulled lower unit and found pieces of piston ring. Found water/oil mixed throughout the motor leg. Presure checked the lower unit and it went over an hour at 10psi. So we figured the oil was comming from the powerhead based on the broken ring pieces and the poor compression numbers. Rechecked the compression and we had 105psi and 125 psi. Stuck camera in the spark plug hole and saw some damage on the piston, pulled head and the rest of the story is above. My theory = I believe the motor was severely carboned up and the ring was probably broken prior to me getting the motor or it broke after the decarb I did. None the less, root cause is lack of maintenance causing the carbon build-up which cause the rings to stick.

I was amazed at the compression improvement after decarb in both cylinders. It has made me a believer in doing this as a regular PM on my motor. Everyone I talked to about decarbing kind of looks at me funny. No wonder there are so many motors needing repair. Question, do you know the gasket set number for my Force 50 - Model #507y8d - serial #1247. Additionally, I have not found the bearings either on iboats. Do you know where I can get them and the part numbers? Connecting rods are gages with individual rollers. I also want to replace the main bearings on the crank.

I'll keep the posting updated with my progress and results,
Buckwheat34

 

[puddle jumper]

Re: 1988 Force 50HP Rebuild Powerhead??

As Frank said its up to you. My only concern is trying to find parts. I have noticed with my 98 50 horse a lot of parts are discontinued. But then on the other hand some parts have also made a come back.

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Now that everything is torn down I have a topshelf Mechanic reviewing the cylinder block, crankshaft, rods, pistons and bearings to give a recomendation on moving forward with the repair process. Everything looks ok to me, but I'm just a quality guy who can read the requirements in the manual. The main problem I see is availability of bearings. I have yet to find a source for connecting rod bearings and crank bearings. Everything else seams to be readily available here on i-boats or other sources. I may try Detroit Ball Bearing when I run downstate this week, but it's a longshot. Oterwis, I'm looking to see what the Mechanics opinion is and see what machine shops will charge to bore it out.

I know I could just replace the bad piston, reuse the one piston and replace the rings, hone the cylinder walls and take my chances, but I think that is a flawed strategy. If your going to teardown a 20 year old motor and not replace the bearings in the repair process, you must have better rowing skills and a lot more luck than me. I don't understand why you can get pistons, rods, gasket sets, etc, but no bearings. I understand that some parts are universal to other models, but no bearings? I don't get it.

Good luck,
Buckwheat34

 

[jerryjerry05]

Re: 1988 Force 50HP Rebuild Powerhead??

Boats.net Can sell you most of the parts you need.Any Mercury dealer should be able to get what you need.
The bearings are expensive.So try to re-use them.Over a #100 each.Upper bearing is about $35 Lower is $85.
Don't use a magnet on anything in the motor.Get assembly grease to hold the bearings in place.It disolves quick.J

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Good news from two mechanics I had look at the parts today. Bearings all look ok and they would not relpace them. They both agreed that the cylinders look really good, exspecially since a ring broke and exited the motor through the exhaust ports. Both told me to measure the bore to determine if they are in spec and determine if I'll need to hone or rebore. Their opinion was that it's likely a hone job, one piston - replace, new rings for both pistons, replace gaskets and some elbow greace from me should get er done. I should be able to do this for a little more than $200 if the measurement is good. Headed to a friends tomorrow to take the measurements.

SUGGESTION FOR OTHER "NEW /FIRST TIME BOAT OWNERS" out there. First, get a manual for whatever rig you buy. This will allow you to become a quick study in the subject / problems you are dealing with. Moreover, this will allow you to do a lot of work yourself and save lots of $$$$$. It also allows you to "patronize" people who will really help you to better understand the issue. This $20 to $35 keeps i-boats or you local mechanic in business. "Patronize", buy products and services from these sources also. I purchased some gear lube and 2cycle oil from my local marina and got a lot of questions answered when I walked in with a problem. I could have saved a couple of bucks on the oil from another source, but it didn't come with the relationship I developed with a simple purchase. Walked in a month later with a block, crank and set of pistons in a box and got a lot of advice on what a professional saw in the parts.

I'll report back on the progress after the measurements are taken,
Buckwheat34

 

[jerryjerry05]

Re: 1988 Force 50HP Rebuild Powerhead??

You can get used pistons on e-bay very reasonable.Just make sure the end cap is the right one.They are broken and each break is different and will only fit one way.
Fill out the profile you might be close to someone who can help.I help a lot of people in my area for free or VERY cheap.J

 

[jason32038]

Re: 1988 Force 50HP Rebuild Powerhead??

One word of advice...don't buy a used powerhead without inspecting it. I bought one for 200 which included the stator and trigger AND flywheel which in itself was worth more than 200 but the powerhead was shot. It was already bored .020 and was in worse condition than the original. Lots of scoring and it looks like it was submerged. Had some sand in the block and the reeds are shot. Lower bearing is seized from corrosion and sand. Top bearing is dry but OK i think and middles are dirty but seem ok just need to be cleaned. I'm just saying if you need to get a used powerhead if your block is unmachinable do a compression test on the block you're looking at. Take it all apart clean it and get a gasket kit.

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Found a boat shop in Detroit who is boring the powerhead for $65 per cylinder, new pistons with pin and bearing $95 each, rings $15 each piston. I'm going to go with it for the peace of mind. He'll match everthing up and I'll asemble, Additionally, I also found new upper and lower bearings for $35 bucks at a place called Motion Inductries. The upper is an exact match, but the lower is no longer made with the hole in the race. Does anyone know if this is actually functional for lubrication on this model? I'm going through the manual later today to see if it says anything. I can always use the old one if needed. Price for both was less than the $39 for the NLA upper I've seen on-line, if you could find one. They say they can also get the center - crank split bearing if I take it off and get a part number for it, or give it to them to measure. These guys have every bearing imaginable at good pricing. They could not match up the rod bearing for the 16 rollers and cages. Problem is the width is not available. If I had a part number from the bearing manufacture, they might be able to get it. I see them on-line for $115 - $117 and they appear to be available. I may just pony up and pay the cash. I'm not going to put a 22 year old used bearing in a rebuild because that just don't seam right to me. Many good mechanics have said it's ok, but I'm not willing to take the risk. We'll keep you posted as we progress with the repair. Should get the power head back 9/27/2010.
Good luck, Buckwheat34

 

[Nordin]

Re: 1988 Force 50HP Rebuild Powerhead??

Contact Franz at FranzMarine@aol.com he might have everything you need to rebuild. He have pistons for your motor factorymade or aftermarket. I know because I have just rebuild my Force 50 1990. He is very fast and servcieminded. Maybee he have bearings and rollers too. All the gaskets you need you can get from him. I live in Sweden in Europe and there is no problem with shipping. Have bought spareparts from him many times to Chrysler and Force outboards. No problem at all.

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Thanks Nordin, I'll check him out and see what he has.
Good luck, Buckwheat34

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Ordered the caged roller bearings for $28 yesterday from FranzMarine, best price I could find. Still looking for the lower crank bearing. Best price so far is around $80 +/-. I have one coming without the hole in the race and I may try to modify it. I only gave $7 for it , but I'm not optimistic I can disassemble and drill the hole without damage to the bearing. If I can't, I'll pony up the $80.

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Got the bearings and they have slight differences, but they look like they could work. BUT, I've decided to pony up the $80 for the OEM part just because I don't want to find out I'm wrong. I'll have to use the ones I got for paperweights or sinkers-($35 waste, should have bought the OEM's first).

Spent 12+ hourd cleaning parts this week and they all look like new. Lots of solvent, toothbrush, wire brush and wheel work required. Mechanics said 10+ hours to clean and they were not kidding. A large part of a Mechanics rebuild time is for cleaning and I've saved a good $500 to $700 doing this task myself. I've been following the requirements as spelled out in my Clymer manual for inspection and cleaning. I also spent a couple hours on a Bridgeport today making the 295/310 spacer tool for piston assembly. Not really certain this is truly required, but I had the time and a friend with a mill I could use. Should get head back from machining next week and hope to start assembly later in the week. I'll keep you posted on progress and cost. Looks like about $550 total at this point - all new OEM bearings, pistons, rings, bore job and gasket set.

Good luck, Buckwheat34

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Does anyone know what tool to use to chamfer port holes after the cylinder is bored? I need to do this per the the instructions I got with the Wiseco pistons and rings I procured for this rebuild.

Side note; these pistons were really easy to assemble because of the "full floating wrist pin design with clips. I used a 1/2" short socket in the rod ends to assemble the needle bearings and I also could hang one of the spacers on the socket. I then slid the pin through the piston, added the spacer, put the rod with the socket and spacer next, and just pushed the pin through. Clips slide in easier if you put the radius side away from the split into the groove opposite the clearance hole.

I'll keep you posted as I progress on the project, buckwheat34

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

The engine is rebuilt and everything is back together and the motor will run at idle no problem, but it will not run proper in forward - misses and stalls. Seams to be ok in reverse. Not certain if I should start another post, so I'll post the issue here. Seams that the wiring to the CDI and Coils / colors do not match what is shown in the Clamers manual I bought on iboats when I started this project. I believe that this is the problem because when hooked up originally after the rebuild I had no fire from the coils. After some wire/circuit moves that made sense I now have fire and can idle, but won't run long in forward, misses, and stalls. Go back to nutrel and it starts back up no problem. Any suggestions on where I could get a proper wire diagram? Another way to figure out the right way to hook up the wiring from CDI, Coils, Ignition junction block.

 

[buckwheat34]

Re: 1988 Force 50HP Rebuild Powerhead??

Pulled another wire diagram from another post and it list most colors that I have with the exception of a blue wire from the stator that was lengthened with a orange/yellow wire. Now we're back to no fire at either cylinder. Rechecked nuetral switch and it works. If we wire it again the way we had it, it will run at idle and rev pretty good in reverse, but spits, sputters and dies in forward. Help Supreme Mariner Guys!