89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

[mike 1985]

I bought an 89 maxum with a force 85. This is the history i got. The boat was run and got hot and started sounding funny. He shut it off and towed it back. the Marina checked the comp, and said 60-100-100. took the head off and seen a scored cylinder ( top one). The guy i bought a new boat and reassembled this one ( using same head gasket). He informed me about all this before i bought it. I checked the comp and all 3 cyl were 120. I installed a new water pump impeller. The boat has been running fine.

well tonight the boat started running terrible, i brought it home, and found 60-100-100 on comp test. i pulled the head and found the head gasket blown ( cylinder ring) between the top 2 cylinders. The top cylinder is scored at the 6 oclock position pretty good. I'm thinking i could have the head machined to trueness (flat) and install a NEW head gasket to get me by through this year? What do you guys think ?

Also why did it have equall pressure (120PSI) on all 3 cylinders with the top cylinder being so scored and the bottom cylinder having the cross hatches still in it ?

thanks guys

Mike

 

[Frank Acampora]

Re: 89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

Sometimes if the scored cylinder is not too bad, it will deliver adequate compression with enough oil to seal it. 100 is a little low: that engine should have 145 approx. but sometimes different gauges give different readings. The important thing is equality between cylinders.

Now for the blown head gasket: You need to check not only the head sealing surfaces but the block sealing surfaces as well. Because of its design, water can collect behind the head gasket and corrode spots in the head. there is no longer support at these spots and the head gasket blows out. The factory recommends milling no more than .010 off the head, but in reality, you can take off .060 and still have clearance for the piston baffle. If this won't clean up corrosion damage, you need to buy another used head.
You also need to check the block. Sometimes the aluminum around the cylinder liner will lose a chip, This aluminum does support part of the steel ring in the head gasket and with a missing chip, the gasket will blow out. If you find that, it needs to be repaired by welding in metal. JB weld (epoxy) will not hold against combustion pressures

Now, with these areas checked, if they are good, A new head gasket through Merc will cost 46 bucks Through WISECO pistons--26 plus shipping. Realize that with a new gasket it may run ok but the only sure cure is to rebuild with an oversize piston. You may be just gambling away the 46 bucks.

Be sure to torque the head bolts to 220-230 inch pounds for 5/16 bolts and 265-275 inch pounds for 3/8 bolts Depending on which your head has. Run engine to heat it up then cool and re-torque head bolts. Use a pattern of starting with the two center bolts and spiral out to the end bolts. This keeps you from warping the head. also, start at 1/2 torque, go to 3/4 torque then tighten to final torque.

Finally, that scored cylinder may indicate a lean condition. When you do get it together, start with all three carbs at 1 1/4 turn open from lightly closed and adjust mixture for idle. In no case go leaner than 3/4 turn, and I prefer 7/8 turn no matter that the idle is rough. Buy a Clymers manual for the full adjusting directions.

As I understand it, You bought an engine with a known problem. Hope you got a really good deal. Although, with only 1 piston to replace and one cylinder to rebore, if you do the work yourself (Except reboring) you can get away for less than 300 bucks.

 

[mike 1985]

Re: 89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

thanks for replying Frank.

I've built many a car motors, some even spraying 400HP of nitrous through them, but never did boat stuff before.

The block and the head look great, as in no missing parts and no corrosion at all. Before it popped the head gasket all 3 cylinders were at 120 on comp.,even though the top has a moderate gouge in it. The boat was running really good before the damage last night.

This motor has that cross fuel induction system and I have found no adjustment screws on the carbs anywhere ? where would they be ? My local marine has a used Force 85 that they want $800 for, but i'm worried I might just be buying the same problem and I think the boat needs a Force 120 because we usually have it loaded down with people.

And lastly does it hurt to run this thing at 1500-1800 rpm for extended periods of time ?
I only paid $900 for the boat and trailer with a new bimi top and fish finder.

thanks for you time Frank

Mike

 

[Frank Acampora]

Re: 89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

At 900, you didn't get hurt.
"Cross flow fuel induction" and "Swirl Charged" are Force gobbledygook for old fashioned technology. It is a plain cross flow 2 cycle engine with a deflector baffle molded in the piston head. The basic block was designed in the late 50s to early 60s and has not been changed much since. Its really like a Chrysler 318: It runs, sometimes forever, doesn't produce a lot of horsepower, and really can't be hot-rodded. There's just nothing there to build. If you have rebuilt auto engines, you will find this easier--very much. Force is probably the simplest outboard that was made.
The three cylinder engines are really rather small--72 cubic inches.
The carbs usually have the low speed adjusting screw in the front, at the top. There are three rubber plugs in the air silencer (sometimes they are there). You remove the plugs and reach in through the holes with a fairly long, thin, flat bladed screwdriver. Some carbs do have a needle in the back where the carbs bolt to the manifold, up top at an angle--but they are obvious. you would have seen them.

These engines are meant to run at about 4500-5500 RPM. Extensive running at low rpm causes plug fouling and carbon deposits on the pistons and in the ring grooves. Running at low RPM at wide open throttle (by overloading the engine, over-propping etc) Is even more harmful. If you intend to do a lot of trolling, buy a small kicker engine for that purpose.

Unless you really want to use the boat immediately or you want to start playing with Force/ Chrysler outboards, don't bother with the used Force for 800. If you really want it, The price is not too bad, but let the dealer start it in a tank and run a compression test in front of you. At least that way you know its functional when you take it. Its really a crapshoot: a lot of outboards (all brands) have problems but a lot of them just run forever.

I myself buy a lot of Chrysler/Force engines ( I have about 15 in various sizes) but I stay away from anything over 200. I figure at that price the engine is automatically trash and anything I can salvage, I save. Sometimes I will rebuild a good block and make a functional engine with salvaged other parts. But, that's my hobby.

 

[mike 1985]

Re: 89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

Thanks for the info Frank.

I'll just have the head milled flat on this one and install anew head gasket and run it for the rest of the summer and go from there.

 

[mike 1985]

Re: 89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

Ok, I had the head milled .022 to clean it up. i was low right where the gasket blew. I'm just waiting on the head gasket to arrive. While the engine was apart i did find the carb adjustment screws. The top cyl ( the one scored up) was 1 turn out, the middle was 1-3/4 out and the bottom 1-7/8 turn out. I put them all at 1-1/4 to start with. I'm assuming the more turns out the richer ? Is this true? When this motor was giving me comp readings of 120 I could turn the motor over pretty easily with my hand on the flywheel?


I went to look at the other Force 85HP. It's a early 90's out of a bass boat. The motor is spotless and when I tried turning it over by hand it felt like what a motor should, goog compression..waay different ( better ) than my old motor. It included almost brand new prop,with ALL the cabeling, I mean every wire, even the ign. switch and key. The previous owner bought a pontoon with a 4cyl and liked it so much he brought his bass boat in for a 115 4 cyl motor and a shore station. (nice to have lots of money)...anyway he gave me the entire motor and accesories for $400. It's going on the boat right now. I'll let you know how everything comes out.

One last thing, now that I own 2 Force 85's, where do I get a manual for them ?

thanks
Mike

 

[Frank Acampora]

Re: 89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

Now you're about to start having fun. It always starts with 2 Forces or Chryslers, and they grow like rabbits on you.

From what you describe, 400 was a great deal. Hell, the lower unit is worth 250-300 alone. And if in the future you need to replace the coils, stator, or cd boxes?

And of course, (2) 85s on jackplates on your transom?

Look on ebay for a Clymers manual. Or go to your library and try to borrow an Intertech manual.

And BTW: Someone told me that (I think) Holley makes a nitrous kit for outboards. Sounds like a good way to lunch one easily.

 

[mike 1985]

Re: 89 FORCE BLEW HEAD GASKET TONIGHT..NOW i HAVE QUESTIONS.

well Frank I hope to stay at 2. One on the boat and one to spare. I have played with alot of nitrous stuff before and had some pretty nice explosions too, but never had to paddle back. So no nitrous for me on this one.

thanks for the info on the manuals.