evinrude 75 hp middle cyl. comp. low

[mcguyvermike]

Looking at buying a pair of 75 hp. evinrudes. A 92 & 93 model years, one running and one not due to running engine with no oil and loosing middle cyl. Second motor is off a set net skiff that was seeming to work fine. top 125 psi, middle 97 psi, and bottom 130. Plugs all seem to look the same. From what I have read it points to several things

 

[mcguyvermike]

Re: evinrude 75 hp middle cyl. compression low

Re: evinrude 75 hp middle cyl. compression low

Sorry, didnt finish...
I don't know if I have a complete list of things to check before I can make a decision. Can someone walk me through this list?
I won't be able to run the engine till middle of may when the ice goes out on the lakes. So all will be done dry or in a drum. Besides the head gasket, carb, compression is there anything else to check, like "reed valves" etc?
I can purchase both engines for $1,300 as is, but could cost a lot more in the long haul.

 

[WillyBWright]

Re: evinrude 75 hp middle cyl. comp. low

The head comes off quite easily and head gaskets are not expensive. I'd want a look inside. That should answer your question. I would also have a look at the gearlube and give the propshafts a spin to look for wobble. Reeds wouldn't cause low compression.

 

[mcguyvermike]

Re: evinrude 75 hp middle cyl. comp. low

WillyBWright,
Thank's for the info on the head. It will be a bit before I can get back to the engine as I live quite a ways from town. That and I have not purchased it yet. Thank you for the advise. Mcguyvermike

 

[jim_in_day]

Re: evinrude 75 hp middle cyl. comp. low

Well, that middle piston compression is below spec. According the the real 3 cyl guru's on this site (i'm not one), the middle cyl fails most often due to lugging the motor. I do know that every single blown 3 cyl we get in the shop it's the middle cyl. I'm rebuilding mine right now, it had a low middle cyl, but also got ran lean and scored all 3 cyls so it's getting a total rebuild. If it were me, I would be leary of buying a motor with a cyl that far out of spec.

 

[mcguyvermike]

Re: evinrude 75 hp middle cyl. comp. low


I know rebuilding is not an easy task, but one would have a good tight motor at this point. I personally know the owner and he is willing to work with me (financially) on these motors. Hesaid if I want to take them and look them over we would work out something depending on the depth of the problem. Still trying to look at all the options. short of an expensive one.

 

[DHPMARINE]

Re: evinrude 75 hp middle cyl. comp. low

Sounds like a lot of money for a 14 year old motor with a possible compression problem.I don't value the motor run without oil as worth much in the deal.While you may need it for spare parts someday,you also may not.

If it turns out to be just a head gasket the deal would look a lot better.Then you might Ebay some of the parts off the bad engine,but except for the lower unit,there isn't much call for the rest.(not much value).

DHP