1989, 85HP Force, 90lbs compression all 3 cylinders

[Jlesinski]

Hello,

I have a Spectrum boat with a 50hp Force motor on it, and it can have up to a 90hp on it. I have the opportunity to buy a 1989 Force 85hp that has 90lbs compression on all cylinders and not starting. I am wondering if it is worth picking up the 85hp cheap and rebuilding it? I am thinking 90lbs is low, but there is likely something else keeping it from starting.

Thanks,
Jim

 

[jerryjerry05]

If all 3 have 90# ??
I'd guess the test was done wrong or the gauge is faulty??
You remove all the plugs? needs to be done to do the test right.
Hot battery?

The good thing is all 3 are even
That shows there probably isn't any serious problems inside.

 

[Jiggz]

It sounds like the motor hasn't ran for a long time. So first order to do the compression test after removing all plugs is to oil the cylinders with fuel oil mix. If it still read 90 psi across, it's most likely the gauge is not up to par in calibration. If you can rent or borrow another gauge, it will be great to make a comparison.

Personally, if the compression goes to at least 110 PSI, it'll be fair to surmise the cylinders, rings and pistons are in good working order. Another thing you can do is to use a mini-USB endoscope (approx $20) to inspect the inside.

 

[jerryjerry05]

I think Auto Zone or any of the other stores have a loaner tester you can borrow.

 

[Jlesinski]

Thanks Everyone! I didn't actually test it myself. I was looking to buy the motor as an upgrade to my Force 50HP to put on my 1989 Spectrum 17 foot. It looks like the controls are the same at first glance. I am hoping to get this running and then swap it out.

I ended up buying it for $200 and building a stand that I can move around with my tractor forks. I should be able to start going through it and testing things on it this week.

Is there a good source for service manuals for this motor?

 

[Jlesinski]

I found a manual. Thanks anyway!

 

[jerryjerry05]

Manuals: the factory is best.
Clymer or Seloc is better than nothing.
They don't have enough specific info.
One book covers all the Forces when the service manual covers just the one in question.

 

[Jlesinski]

Thanks Jerry. The one I found is for Chrysler, so maybe it is the wrong one? https://www.manualslib.com/manual/1000030/Chrysler-75-H-P.html#product-85 H.P.

If I can find a factory service manual specific to this motor that would be great. I can't seem to find one on Ebay. Does iboats sell them?

 

[Jlesinski]

I picked up this "1966 - 1999 Chrysler-Force Outboard Repair Manuals CD" disk also: https://www.ebay.com/itm/253735468073

 

[jerryjerry05]

That should help.