1987+ Merc 70/80/90hp variances?

[100333624]

Re: 1987+ Merc 70/80/90hp variances?

TD: Yes thankfully I have a mechanic whose knows these old motors very well! There was an old supermarket we used to go to that I remember from when I was like 4 or 5 years old. Beside them was this outboard shop. He has been there ever since and his father used to have it before him. Its their family business and he now has his sons working there who will be taking over eventually. Great service and help there! Their prices could be a bit better but you gotta do what you gotta do when you have such a big facility to run on a seasonal basis...

You think 50:1 will be good even though its rebuilt? I thought the first tank would need around 25:1 mixture? My existing controls aren't going on this as I picked up an awesome set of quicksilver binnacle controls with built-in trim button since my boat is a center console. I picked it up yesterday and was supposed to pay $180 for them shipped as a COD, but the post office didn't charge me anything! lol so I think I got free controls for now....

 

[100333624]

Re: 1987+ Merc 70/80/90hp variances?

So I found out today why the 75hp merc was rebuilt again. This is what he told me!

"The original crankshaft was broken. It broke in a way that did no damage at all to the block or I wouldn't put any money into it. I bought another parts motor for the crank. Measured the journals and cast number to make sure. I think the crank broke from the last rebuild the guy must not have used the right tools to press on the new bearing and fractured the crank. I put new bearings again honed and new piston rings seals etc."

Now as a buyer, how can I be sure that the crank broke from not being installed properly rather than something else being the culprit? How do I know that it won't break again due to something that was not found? Any advice?

 

[TD_Maker]

Re: 1987+ Merc 70/80/90hp variances?

Man, thats a loaded question....and it may be way beyond my qualifications to answer. A broken crank is no joke, and I am not sure how a person can check to see if there was any interior damage or not....without disassembly. Maybe someone else will jump in this thread.

My point on the 50:1 mixture is this: Go with mixing your own fuel instead of the oil injection system. During the initial break-in, you may want to mix a little heavier....again, someone else will need to give their advice for this. I know this much. When I purchased my 1988 90 BRAND NEW, Mercury suggested a 50:1 mixture along with the Oil Injection for the first several hours of use...during break-in. It certainly can't hurt, may fould the plugs a little, but it can't hurt to err on the side of caution. Just use good oil TCW3 rated.

 

[100333624]

Re: 1987+ Merc 70/80/90hp variances?

TD I appreciate your honesty and your comments! I found a guide for the break in off here so I will be using that as my guide for about the first 10 hours.

Ya I don't know what to think of the crank breaking, very odd and definitely no joking matter.... I do think the guy is being honest when he says it didn't cause any damage though I don't know how that's possible.... I mean as we have talked quite a bit and he does seem like a legit person. I don't think someone whose got about 20+ motors at his HOUSE for sale, some rebuilt and some tuned, would lie about something like this at this price because the way I see him he definitely wouldn't be able to sleep at night if he knew he was scamming someone out of $1800... I mean who would?

Now the question is this, since he got a parts motor, why didn't he just use the block from that one instead of the one the crank broke in? Unless it was a different motor altogether but same crank, which could be the case considering he said he measured the journals and cast number to make sure.. Then the other question is if it DID cause damage to the internals, which obviously won't be worth rebuilding, then why would he invest $1500 in parts into it and almost 50 hours of work into it to sell it for $1800 to profit $300? Where is the sense in that....?

Can anyone give their take on this please?

Thanks!

 

[100333624]

Re: 1987+ Merc 70/80/90hp variances?

Ok so I found out some more news today! Turns out the guy keeps a log for all his motors and how they came in vs how they go out. This 75hp came in with a spun rod bearing... The parts motor he got had the broken crank in it not this one!!! So thankfully nothing to worry about there! He used the parts motor fo ther switchbox and some other parts that this one needed. I'll be going up to take another look at it possibly on wednesday and start it for the first time since the rebuilt carbs so I'm excited!

Now thats out of the way, is there any way I can mount one of those trim switches on the motor itself for when I'm pulling out and trailering the boat that I don't have to jump in and out to trim it to the trailer/transom saver? Like the newer 4 strokes got that switch directly on the motor, is it possible to put one on these older ones? I think there is just a little bit of space on the inside of the bottom cowling from what I remember when I took mine apart to put it on. Anyone done anything like this?

 

[TD_Maker]

Re: 1987+ Merc 70/80/90hp variances?

If you got the room, then you can mount the switch anywhere you wish. There is nothing wrong with a parts motor; in fact, I am parting out my 87 Mercury right now. You may be worried about nothing. If it passes a compression test, and sounds and runs good, then thats is about all you can do. Good Luck with this. PS Make sure the T&T is working. Can be expesive to fix.

 

[100333624]

Re: 1987+ Merc 70/80/90hp variances?

So I am now the almost new owner of this 1986 75hp Merc!!!!! (pending pickup next week)

Ran it and fired it up from a cold start and she started right up first turn of the key! Checked everything to make sure and this thing sounds awesome! Wiring is new all around, no water in the lower unit, nice stream out of the tattle tale... Let me tell you I was VERY impressed and didn't expect the inside to be as nice as I saw it!

Can't wait to break her in!!!!

Thanks for ALL your help guys!!!!!