1992 Force 70 HP lower crank seal replacement question how to

[bluestreakj720]

Searched forums but did not find any information on if the crankcase has to be busted open or can I get the bottom seal out and replaced without having to open the crankcase. Not sure if it's leaking but since I have the power head on the bench and after 25 years of age, thought I should do it now regardless. Any info is appreciated as I would rather not open the crankcase.

 

[jerryjerry05]

Should be able to pull it out without breaking the cases.
​If it's removed from the spacer plate.

Just be careful to not score the soft aluminum.

 

[bluestreakj720]

Sweet. It looked like I might be able to try to get it out but wanted to get the second opinion first before trying it. Appreciate it.

 

[tommarvin]

Is there anything else you should doing for preventive maintance, when you have the power head on the bench?
Just a thought.

 

[bluestreakj720]

Ton's on my 25 year old motor. I'm replacing all of the reed valves with carbon fiber reeds, Rebuilt the fuel pump, Replaced the timing trigger coil, Plugs, replacing scavenging circuit reeds, transfer port gaskets, fuel lines and any gaskets I have to replace due to the work I'm performing. Pretty much a complete rebuild outside of the internal crankcase components. Most of the parts I listed were blown or in disrepair after 25 years of service. Original owner by the way..

 

[jerryjerry05]

The reeds were bad?
​The newer ones, carbon fiber won't show any improvement in performance.
After it's back together keep me informed how long they last? I heard they don't last that long?
You taking the exhaust chest off? Be careful with the screws, they twist off real easy.
The recirc system has small screens, don't put them back in.

 

[bluestreakj720]

Reeds were not broken but could see daylight around them. I hope I get good use out of the new ones but I kept the old reeds just in case. I did remove the exhaust tube (assuming that is what you are referring to as the exhaust chest) because the gasket underneath it was blown out. Regarding the recirc system, I had it apart once before but don't recall seeing screens in there. I have to open it back up to replace the reeds in it anyway so will look then. Whats the reason to not put them back in?
Any suggestions on what tool to use to remove the lower crank seal without having to split the case open?

 

[bluestreakj720]

So does anyone have a particular seal puller they would recommend small enough to get in there. I tried making one when I had no luck finding one small enough, but didn't get the steel hardened enough I guess as it broke on me. 2 hours wasted or could chalk it up to lesson learned i suppose. .

 

[tommarvin]

Just in case jerry doesn't reply I think he means the exhaust port plate chest on the exhaust side of the motor on the port side,lots of 1/4 20 bolts to snap off.
We put a hose clamp around our exhaust tube that was leaking, the the exhaust plate is different.
The recirc system looks like a dogbone shape, theres a very small screen at the top and bottom on the inside of each dogbone,he says take them out.
Don't have a clue about removing the lower crank seal.

 

[Nordin]

I use two sheet metal screws. Firts drill two holes in the seal horisontal to each other (ex. 9 o?clock and 3 o?clock) screw in the sheet metal screws a bit and the use them to try to pull out the seal. Can be a bit tricky but it will work.
If the steel outer part of the seal not will come out when prying/pulling, then use an awl and splitt the steel part at the edge of it at the casting/seat at the block.

Hope you understand what I mean.

 

[bluestreakj720]

tommarvin, thanks for the clarification on jerry's post. after reading a bunch more yesterday I understood what he was referring to. Luckily there's no reason for me to remove the plate on the exhaust chest.At least not at this time.
Nordin, appreciate the info but at this time I really don't want to take a chance on scarring the aluminum block or getting metal shavings into the lower bearing. If I can't locate a puller, looks like I will be splitting the block to get to it after all.

 

[pnwboat]

Splitting the case seems a but much to pull the seal out. If you split the case, that creates a whole bunch of more work before reassembly. Getting the crankcase seals on the crankshaft lined up and assembled without breaking them, you break the seal on the two crankcase halves, which means you have to either replace the spaghetti crankcase seal or re-seal with RTV, depending which method was used from the factory just to name a few.

Unless that lower seal is totally shot and causing a problem, I'm not sure I would bother with it. I've never heard of anyone replacing the lower seal. It's a very low failure item, since it's always got a good supply of oil, the oil has a tendency to run down due to gravity. The top crankshaft seal is more likely to be go bad before the lower one.

If you were going to re-build the motor, then that would be a good time to replace the lower seal (and all the other seals). Ultimately the decision is yous, and if you need additional help, there are plenty of folks here that can help you out. Good luck with your project!

 

[bluestreakj720]

Thanks for the input pnwboat. I'm with you, I don't want to split the case even though I believe it uses anaerobic gasket maker for the seal.

Plus this is my 1st time getting this deep into an outboard, but when it started back firing and only running a bit off idle after it ran great for 25 years, and I've gone through the basics. Spark, Carb, Fuel pump which was bad but appeared to be putting out plenty of fuel at the time etc,etc. I thought since I had it off this far I would take care of what I had read could also be an issue, if not now down the road.

Plus the deeper I got the more bad gaskets I found were blown out.I did see oil creeping out from the bottom seal after I removed the powerhead.

Anyway, I've jacked with the seal enough now, I'm pretty sure it's bad now so I'll keep on trying to get it pulled with a homemade puller since I'm not able to anything under $200 that looks like it would work. I'll get it one way or another, but thought it wouldn't be this rough. .

 

[bluestreakj720]

No Title

Hot Dog! It's finally out with the homemade puller.

Broke the puller 3 times and had to re-do it, but it's done. Found out not to harden the puller arms (get them red hot and drop in oil or water) as the pulling tips just snap off. Just heat until red hot, bend as needed and let cool. Grind as needed....

Happy camper once again as I can continue on and get it back on the water and get some fish back in the freezer.

Appreciate all the input from everyone, it really helped me out, and kept me going on this "project".

One last comment since I'm back in a good mood. Whoever said "the happiest day of a boat owners life...(you know the rest) " must have not taken care of their boat. I've owned mine new since 1991 and still love it. (1991 Starcraft 17' fish and ski with this 70 hp Force on it)

Thanks again!

 

[jerryjerry05]

Nice puller!!!
​Necessity , the mother of invention.