lower unit

[brokenwrist]

ok guys here comes another chrysler question. Before the question let me tell you about what I went through in finding my hidden problem. Last year I bought my boat and got the outboard running mostly going ok. Got it out on the lake last year a couple times, made the engine work a little bit, but performance really wasn't where it should have been, but the first time it was out my dad and I noticed what sounded like a grinding sound, never figured out what it was until today when I pulled my prop bearing cage to replace the two orings and prop shaft seal. I discovered after the cage was out that the bearing had completely failed and come apart, the race in the cage is crooked, where the race seats is bent, the prop shaft is scored to hell. So I now believe what the noise we were hearing was the bearing failing and coming apart. Apparently who ever worked on my outboard years before me, had 0 clue what they were doing and screwed everything up. Some parts are hard to come by. Now back to my question. I found on ebay a complete 1978 75hp lower unit. Will this lower unit work on my 79 70hp, or do I need to find one for a '79 70? Could I put a force one piece 70hp lower on? For these engines what are the interchanges? I've searched a few different areas and couldn't find a clear answer or chart.

 

[jerryjerry05]

Yes it will work, the part #s are the same.

I don't think the one piece unit will fit.

 

[brokenwrist]

Would the 85 horse lower unit work? I have found on Craigs list locally a complete 85 horse Chrysler. Apparently all it needs is a top piston, otherwise apparently it's a good runner. My thought was if the 85 horse lower will fit and work, pick it up use the parts I need and then sell the rest as a parts motor.

 

[Nordin]

I will try to explain...
3-4 cyl. Chrysler had the 2 piece gearcase up until about 1977-78, then they used the 1 piece case.

A 2 piece will not fit to the 1 piece midleg and vice versa. The 3-4 cyl. Chrysler or Force powerheads will fit to midlegs from a 1 or a 2 piece case.

BUT late 70Hp Force was a complete different engine with Mercurystyle gearcase and a different powerhead with one carb feeding the 3 cylinders.
An odd design with some problems with the fuelfeeding.

 

[brokenwrist]

Being a 79 chrysler, I have a 3 stud 2 piece lower/gear case. All of the parts diagrams show the exact same thing. So if I understand correctly any 2 piece 3 or 4 cylinder gear case will bolt right up.

 

[Nordin]

Yes, thats right.

 

[brokenwrist]

Since I've been having trouble tracking down a known good lower or rebuilt one. I've decided since I can locate all of the parts I need, that I am going to rebuild it. FYI for everyone Timken bearing apparently still makes the bearings for our lowers.

 

[jerryjerry05]

I believe Granger is a good place to compare parts, if you can see a part# scribed on the bearings.

​Valley Sales in Prudenville, Mi. has a big salvage yard.