What year Force 70hp do I have

[wishfish]

I've inherited a Force 70hp that will need rebuild because "someone" baked the top cylinder . Compression is 60, 120, 120 as you go down the head. Runs good even tho. But won't idle down properly. And has "warm up" issues. So I'm doing major surgery on her.
I've come across a 93 Force 70 that is a parts motor for $130 with the head blown. But I can't find a plate on my motor anywhere to identify the year. I know Chrysler built these for Mercury '91,'93, '94 and '95 Mercury built them. Does anyone have any idea how I can identify the year of this motor. I know just by comparing the decals on the cowling it isn't a 94 or 95. I'd like to buy this 93 for $130 just for back up (minus the head). But I don't know if the parts will work on my motor. There are too many miles separating these motors to compare side by side. Can anyone help?

 

[roscoe]

Re: What year Force 70hp do I have

Just a little background: Chrysler made the motors until 1983. Then USMarine made them thru 1989.
After that, Mercury made them until 1999 when the ceased production.
The 70 hp was not made by USMarine.

Mercury made the 70 hp from 1991 thru 1995, they were
dark granite in color.

The 91 and some 92 models used an older 2 stage fuel pump, like in the 1st picture below.

The newer motors used the square Mercury fuel pump in the second photo.

Other parts that were different on the 91 and some 92 models were: carburetors, tower shaft, spacer plate, tilt and trim, and some ignition components.

91/92 models had a black switchbox with terminal connects on the switchbox.
Later models had a black switchbox with bullet connectors on all the wire leads.

You can compare parts for the 91-95 70 models here: http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=823089

 

[Frank Acampora]

Re: What year Force 70hp do I have

First: 60 psi is not that low; While it will cause running and idle problems, it does not necessarily indicate major damage. Usually a damaged cylinder and piston will have 20 PSI or less.

So: Before you go tearing the engine apart, this is a case where I would try a gas decarb treatment like Seafoam. If it does no good or only improves compression a very small bit, then pull the head and check the head gasket. Repalcing a damaged head gasket may be all you need to do.

While you have the head off, check the low PSI cylinder for scoring. If it is scored, then it is time for rebuilding, overboring and installing an oversized piston.

ALL Force 70 HP engines used the same size piston and I'll bet the blocks are exactly the same mounting pattern.

 

[wishfish]

Re: What year Force 70hp do I have

Great information Frank. You may have saved me a lot of unpleasant and unnecessary work (and a few choice words). I'm amazed this motor runs despite the cramps it must be experiencing.

 

[wishfish]

Re: What year Force 70hp do I have

Roscoe, thanks for cutting corners for me, I was at wits end and don't want to miss out on a good deal on a spare parts motor. thanks. The local Mercury dealer was a bit short and didn't want to dig any deeper to help me out, but alas, I should have come here first. I will from here on out.

 

[azlakes]

Re: What year Force 70hp do I have

...hiya wishfish,

dont have anything to add about your O/B, but I hear Coeur d'Alene is a beautiful place. are you by lake Coeur d'Alene? how is it these days, good places to camp? we've talked about making a trip up there on vacation and polking about. how is it in May or August.

cheers

 

[element]

Re: What year Force 70hp do I have

Dear friends. Prompt please where it is possible to buy piston kit for Force-70 1994 819690A2 (819690A3) or 834797A5 (834797A6.) there are greater problems. I can not find anywhere. Excuse for my bad English language. Best regarts.

 

[roscoe]

Re: What year Force 70hp do I have

Welcome to iboats, element.


http://www.boats.net/parts/search/Merc/Force/1994/H070412PD/CRANKSHAFT AND PISTON/parts.html

 

[element]

Re: What year Force 70hp do I have

Thanks! I shall try to order. In Russia there are certain problems with spare parts for Forse.

 

[element]

Re: What year Force 70hp do I have

Roscoe thanks for your attention to my request. I have Force-70 1994 in current of 3 seasons. Greater problems was not. What resource of it Force? Whether it Will work 3 more seasons? I am sorry for my English.

 

[Frank Acampora]

Re: What year Force 70hp do I have

The english is nothing to be sorry about--at least you are trying and that is commendable. My company had some Russian visitors recently. Even though we had a translator, I tried to learn a few simple phrases to make them feel comfortable. I may not have pronounced words correctly but at least I tried and they appreciated that.

But let me see if I understand you correctly. Are you saying you have owned the Force 70 for three seasons? Right now you do not have problems or do not have major problems but wish to know if it will last three seasons more? And if it does have problems, are parts available for it?

Is that what you meant?

 

[element]

Re: What year Force 70hp do I have

I had Force-70 three seasons. All was good. In October, 2008 I have found out a fire of the second piston. The reason for me is not known (cooling works well). I wish to put pistons .010. I have doubts in expediency of such repair. Whether I can use Force three more years? The motor old!