70 HP Force Rebuild

jerryjerry05

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May 7, 2008
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The crank and block look good!!!
​The wristpin needs to be pushed out.
I use a press with the appropriate socket to push the pin out.
​The factory used a special tool to hold the piston for assembly and disassembly.
I made a cradle from a couple pieces of wood and drilled a hole so the pin can be pushed out.
​The new piston and NEW wristpin can be assembled by hand.
 

gm280

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Jun 26, 2011
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Your crank looks very good. You did a great job cleaning that up. If you can't get the wrist pins moving, you could try heat and/or penetrating oils. Maybe a nice hydraulic press would be a better idea. Do you have access to such or any of your acquaintances? Or maybe even the machine shop? :noidea:
 

brianq

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Thanks guys!

I was able to separate two pistons from the wrist pins with a ton of force from me and some heat. The third didnt go so well... It broke my vice. I am going to try and find a machine shop that will hopefully do it then and there.

Working on cleaning up the head for reassembly. I cleaned with acetone, break cleaner and a scotch brite pad and brake cleaner. I started using 400 grit sandpaper with brake cleaner as a lubricant. I read conflicting reports online so I stopped until I could ask you guys. It seems to me I could do a lot more damage scraping then with a little sand paper. I have attached pictures of the heads surfaces as they are now.

The spot on the head where the crank shaft sits looks like it could use a little sand paper like the crank shaft. In damage risk there?
 

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jerryjerry05

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The sand paper shouldn't hurt anything as long as the block is washed and dried before assembly.
​​I use a small air powered die grinder with a small wire brush. Use safety glasses.
Just don't apply too much pressure on the grinder as it will eat the soft aluminum
 

brianq

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Happy Thanksgiving to all! Killed it on striped bass on Thanksgiving morning caught 7 from 23-30"

Ok this week in issues!

I got the block all cleaned up using wet sand paper and along the exhaust side the surface edges feel slightly rounded. I tried to take a picture. Not sure if this will affect as the gaskets seem to lay in the middle but I am a rookie.

I also found a few casting imperfections and one which is concerning its near a bolt it is on cylinder 2 which is where the head gasket was broken. It could be a 32nd in depth? Hard to photograph but I tried.

Do i want to take this head back to the machine shop and have him cut down all the surfaces? Maybe put it together and test to save what sounds to be expensive machine work?

Thanks guys
 

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jerryjerry05

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The small nick is nothing to worry about.
​The seal isn't really in that area.

You could get it shaved?? but just use RTV or silicone when installing the gaskets.
​These screws that hold it in place are torqued (70in.#)and the silicone shouldn't let it leak.

The place that seems to leak the worst(for me) on re-assembly is the powerhead mounting gasket.
Use LOT'S of silicone there and make sure there are no defects in that area.
If it does leak the air /exhaust will kill the engine as it fills up the cowl.

​The mating surface needs to be cleaner(sorry)
The grinder with a wire wheel does a great job.$12 at HF.
That is if you have a compressor?
 

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brianq

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After work I stopped at HF and bought the grinder and wire wheel. I only had my pancake compressor which made a slow go and I may never hear again. I cleaned conservatively as there are some pitted areas which i would really have to grind at to clean. I can always do more tomorrow should it not pass inspection! :)

The crank shaft side of the head looks polished smooth so I didnt want to mess with it. Do I need to do anything with the crank shaft cradle spots as they also appear polished, they are smooth with a slight imperfection where I am pointing.

Thanks!
 

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jerryjerry05

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Much better.
The last pic is pretty bad.
It might be a problem with it sealing.
Use lots of RTV in that area.
 

brianq

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Tonight started out great I got all three pistons in with the rings on. The can tool I bought was terrible ended up pinching them around with a small screw driver, they are VERY tight.

Had some trouble lining up the crank shaft on the studs while keeping the crank shaft seal rings in. Squeezing them in while lining up on the studs caused one to snap! When i took out the crank shaft it turns out the other one had snapped. It was very difficult to line up all three like something was holding them up. The rings snapping did a number on morale! lol I was pretty pumped to spend the weekend assembling.

Not sure if I was too rough with them or they were brittle from age or over heating when the piston melted will have to look up their material for this answer. Will work on ordering new ones in the morning, there goes this weekend.

I bought Anaerobic gasket maker at auto zone, SELOC says to use RTV silicone sealer which I have not seen an Anaerobic version of. If I am going heavy with it I am concerned it will end up in the motor and do damage. I also cant find a manufacturer spec for the assembly of this engine, is that available to the public? As an engineer I would love a spec to follow since everyone seems to be using different products.

Side note: I bought a torque wrench from HD since the one I bought at HF I believe over torqued a few bolts in the cylinder head cover which I will need to repair. Immediately noticed the difference when I opened the package there was a a testing log with a name date and torques it was tested to. You get what you pay for, lesson learned; the drilling and tapping will drive that point home.
 

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jerryjerry05

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I believe the factory used black RTV for assy.
That's what I've used on all my rebuilds.
The rings when you find them buy an extra.
On e-bay 112029060385 not cheao but some people are thieves.
 

Nordin

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Jun 12, 2010
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I use Permatex Form A Gasket 3 when I rebuild or maintain.
The package I prefer is the metal can with a pencil in the cap.
Easy to use and apply.
 

jerryjerry05

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I misspoke on the e-bay prices for the rings.
I read the price on something that wasn't available.
​The e-bay site is about the same as others.
Still not cheap :(
 

brianq

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I lucked out today and a local shop which is a former force dealer had the rings! Only two left none the less. I got the crank shaft in and the crank shaft case together. I forgot to take a picture of how much RTV I used but I took a picture of how much squeezed out. I could not find anything online showing how much to use. I would say I used a 1/4" bead and filled all the bolt holes. I followed the RTV manufacturer instructions and made it hand tight then waited an hour and gave everything another half turn. Tomorrow I will tighten everything to spec. I was able to install the head gasket and cover. I realized I never separated the two parts of the cover so I left them together and reinstalled. I will have to drill and tap screw number nine and fourteen as they would not reach spec.

A few questions:

Seloc does not seem to provide a torque spec number for the various bolts on the crankcase cover. Do they all go to the 225 in-lb as the head gasket cover? This question would also apply to the fuel pump and the other covers.

I was unable to separate one of the screws from inside the crankcase from the bit i used to remove it. I used heat, a vice, a hammer, nothing worked. Any idea how I replace this bolt? Its an Allen wrench bolt from behind the reeds. I have attached a picture.

I cleaned the exhaust cover and exhaust gasket plate and will install tomorrow. Jerry you suggested going heavy on the RTV since the matting surface is not in great shape. Seloc does not show where to place the RTV, does it go on the casting under the first gasket?

Seloc says to put loctite 271 on the bearing below the taper. Is this supposed to prevent the bearing from turning? If so it did not work. Can anyone explain what the loctitie is for? A lot of it leaked out since loctitie is surprisingly viscous.

Observations:

Interestingly the crankshaft case cover had been missing 4 bolts when the motor was in working order. Two i found in the engine housing and two I will need to purchase.

The base plate is a mess! The gaskets are hardened on and its covered in grease. I have it soaking in my kitchen sink with warm water and dawn soap to help loosen the gaskets so I can scape them off.


It was great to make some progress! As always everyones hand holding is appreciated!
 

jerryjerry05

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Torque specs? Google : Force outboard Torque specs.
It will open to a bunch of sites. The first is Maxrules and it covers the old and the new.

No pic of the bolt?
I might have one?
There were 2 different sizes used???

You can use the Loctite or just put silicone there.
Once the top cover goes on it should lock it in place.
The Locktite seems to dry after the motor gets hot.

Seal the exhaust gasket on both sides.
If there is corrosion it could leak from all sides.
The factory didn't use a sealer on the gaskets.
You'll need to put it on as they will leak at the weak spots.

Missing bots? That could be why the motor went bad?
Sucking air??

A 1/4 in. bead of silicone is good.
It didn't need to go in the screw holes.
Just around them.
The Loctite should hold them in place.
 

brianq

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Not sure why my pictures didnt post last time, I have posted a picture of the bolt first.

You were correct top bearing cover no longer moving.

I have been using anti-seize on all bolts, should I have been using loctite?

Replaced the missing crank shaft bolts at HD tonight, used stainless steel. Guy at HD thought there might be an issue using stainless on an aluminum block in true internet fashion I found people on both sides of the fence. Coated with anti-seize and installed.

Still had trouble finding torque specs for the crank case, used the bolt dimensions to find torque using maxrules, used 270 in lbs for alen key bolts inside case and 70 inlbs for outside bolts. Did not find a torque pattern, I used a torque pattern based on one I found in the Selco book although not the same engine. Same went for the exhaust manifold cover used 70 in lbs from Maxrules and found a similar pattern in the selco book they had a pattern for a 75hp 98-99 pretty much identical bolt pattern.

Installed 2/3 of the covers above and below the fuel pump. Seems the rebuild kit I purchased may have shorted me one gasket as I only have 2. The other may turn up.

I cleaned up the cover to the right of the fuel pump its a linear cover with two gaskets. I posted a picture of the one of the screens which I removed as it kept coming out when I cleaned the covers, didnt want it to end up the in engine. Are these replaceable? Am I ok without one? I plan to install an inline fuel filter.

Installed the bottom bracket which looks like I need another gasket below it, it was not in the kit. Any idea what the name of that would be?

Any advice on how much I can reassemble before re-mounting to motor outside? Its getting heavy but certainly manageable. Obviously the more I can do inside the better! Its getting pretty cold around here!

Is there a point at which I can do some compression testing without completing reassembly?
 

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jerryjerry05

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I would have used Loctite
​Seems as soon as you put anti-seize in salt water it turns into permanent seize.

​Not real good for marine applications (MY OPINION)

The tiny screens have caused piston failure.
​When I rebuild I leave them out.
​Their there to catch tiny bits of carbon from the system.

What bottom bracket and gasket?
​If it's the base or spacer plate,mounting gasket?? it just gets silicone.

As soon as the head goes on and you can fit the flywheel you can do a compression test.
Just make sure the grounds and wiring are tight.

​I have a lift and a big tree so I assemble almost everything before I install
Some cases the carbs get in the way.

Looks like it's time for a coat of paint??
 

brianq

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Update:

I was able to get the damaged crank case bolt and gasket I was shorted from the same local shop. He took a look at the block and thought I should not have any problems. I tapped the damaged head gasket cover holes one went great the other not sure. I later read I should have used a punch to remove part of the insert. It seemed to take more then the specified torque to get the cover flush with the block because of the insert.

It looks like one of the gaskets above the fuel pump broke when I installed it. I havent replaced since I used plenty of silicone if I need to later I can replace. Picture attached, if anyone thinks I should replace now, I will.

This weekend I painted the block and installed a lot of the electrical / shifting parts. I am missing one slotted screw from the reed plates to the reed spacer plate which is annoying! I will pick that screw up today. I need to order two new plastic parts of the shifters they are both cracked, pictures attached.

A quick update I was correct I was shorted one gasket which is spacer plate to motor case? I attached a picture of the gasket when I took apart the motor. In the picture you can see the gasket which came with the motor, I will try and find one to order.
 

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jerryjerry05

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The gasket should be ok.
​The factory installed them without silicone.

THe screw for the reeds is a 1/4-20 X5/8"
Look on e-bay, there's 1 listed.
​Use loktite.

​The missing gasket(820475A 1) might be hard to find??
 

brianq

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Quick update

HD does not carry 5/8" 1/4-20s. My buddy who works there suggested I cut one down with a bolt on it to clean up the threads. I will check one small hardware store tomorrow and then try that, seems like a viable option.

I have installed everything I can for now and I have a few pieces of hardware left... Cant seem to find where they go. I have attached a picture of them. One bent washer (wave washer?), one lock washer, a C clip and a toothed lock washer. I know its a long shot but cant see find where they go.

The local shop has microfiche ( holy dated) of the entire motor schematic, ever see that online? As dated as it is they can always identify every little part.

You were right about the bottom gasket, I found it from marineengines for $53 delivered super steep but the only place that has it so far. Local shop only has it in a kit for $189 but would give me a deal on the kit... and wont be placing an order for awhile? Didn't feel like arguing but how many people are lining up for that kit? Tomorrow I will reach out to a few people selling kits on ebay see what I can find. Oddly enough I checked my ebay and my amazon accounts cant seem to track down where my kit came from... Weird.

I attached a picture of one of the fuel hoses, one end has an odd attachment cant seem to find where it connects?

i also attached a picture of a left over gasket, not sure where it goes, if anywhere.

Pretty awesome to have such a small box of parts still to be installed!
 

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jerryjerry05

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The hose looks like it could be the pee tube?
The gasket is the thermo housing gasket.
​The washer/ clip ????
 
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