Repair old motor or buy newer?

[Josedcr]

My old evinrude 140hp outboard from the middle 1970s broke. It overheated once and I changed the water pump. I took it out for the first time after the overheat a couple of days ago and it would shut off before I got the chance to move the throttle. then it started to make a grinding sound and would not start anymore. I later dicovered that one of the spark plugs is smashed an you can see the piston right against the plug hole. I figured it snaped a piston rod and I might need to change the rod, piston and some other parts. I can do most of the work, but I'm trying to figure out if I should just scrap it and buy a newer one. Money is an issue... I'm trying to go for the cheaper...

 

[RogersJetboat454]

Re: Repair old motor or buy newer?

Hard to say until you dive in to the engine and tally up the damage. At this point you may have (a) scored cylinder wall(s), which means the block will need attention, and new pistons are in order. Then there is the possibility of damage to the crank and the blocks crank case. Also keep in mind it being a 30+ year old engine, your probably going to find things that may not be damaged, but close to worn out.

If it were me, I would take it apart to see exactly whats going on before I made a decision.

 

[oldcatamount]

Re: Repair old motor or buy newer?

Re-build it! You can re-build your motor for less than you can replace it (if you do the majority of the work yourself). Plus, if you were to buy a used motor, how would you really know what you're getting? Take advantage of the quality advice here at Iboats and do it your self. There are guys on this forum that can re-build that motor in there sleep, so, don't be afraid of asking for there help. My advice to you is to get the service manual for your motor and also get the parts book too.

 

[tashasdaddy]

Re: Repair old motor or buy newer?

if you do it your self, it is cheaper, but no warranty. others do it here, and it will be around $1,800 up for a rebuild. i would lean toward looking for another powerplant.

 

[trendsetter240]

Re: Repair old motor or buy newer?

70's is a little old for me. I'd be shopping craigslist for a newer running condition outboard. There are lots of them available.

Earlier this year I opted to rebuild my 1995 outboard rather than buying new. It worked out great and runs like a charm. Cost a little under 3 grand and I did the work myself. In my case I needed a new crank shaft as well as pistons/rings and the lot.

For the cost of rebuilding that motor you could find a nice late 80's to mid nineties looper.

 

[emdsapmgr]

Re: Repair old motor or buy newer?

The 140's started in 1977. Pull the engine down an inspect it. Rebuilding will depend on the condition of the damaged cylinder wall and the head. If the damage includes cracks on the cast iron cylinder liner (specifically the bridges) by the intake/exhaust ports-it's scrap. It may be hard to find a replacement head if it is also damaged.

 

[JWhit]

Re: Repair old motor or buy newer?

For what it's worth I have most of those parts on a 77 johnson 140 i'm giving up on and parting out. sold some parts already but most of the powerhead still around and not sure there's much market for it. my lower bearing went out and seized up, replaced it with an 89 before i took it all apart

 

[Josedcr]

Re: Repair old motor or buy newer?

Thank you all for the replies! I finally cracked the powerhead open and found:
1. the lower left piston bearing (rod to piston) locked and caused the friction to snap one of the piston rings.
2. the ring bounced around and dinged the head, piston and spark plug
3. the cylinder got scored lightly on on side

I also noticed that the two lower pistons, rods and bottom half of crankshaft were dry when compared the the top half which was well lubricated.

I think the engine ran with the top carburator working while the lower carb did not provide gas/lubrication causing the dry condition and locking the bearing. Is this a correct idea?

I dont know what work has been done before so im not sure if the pistons are oversize already. What can I do to make sure I get the right piston up size after i get the cylinder worked on?

 

[yorab]

Re: Repair old motor or buy newer?

From somebody who will soon complete his first rebuild, I say rebuild! Of course that depends on how bad the damage is. You can find good deals on eBay and you can also scour the web for boat shop clearance lists. Be careful though, as some people on eBay sell parts at list price and you will also be responsible for shipping. If you have a local boat shop, you might as well get parts from them and avoid shipping. I got lucky and found a set of four .040 oversized pistons with pins for $40 shipped to my door. Takes a bit of time to do some web searching but it's worth it.

You'll need to find out what OS pistons are available for your motor. That information is usually listed in the factory service manual. Others on the forum can probably tell you that as well. Tell your machine shop guy what those sizes are. He can then bore the cylinders to the correct size based on the available options and the amount of damage that exists within the cylinder walls.