1978 In-line Merc 115

[jrichardson88]

I have a 115 Merc. that has not been in water in 10 years, I saw the post on what to do. However, my question is that the compression is down on one cylinder. It was checked a few weeks ago. If the cylinder is carbonized will it show low compression? Or sitting in storage for 10 years. Just not sure where to rebuild or not. I am being told today fuel will not run in the old Merc. engines.......?

 

[gator1959]

Re: 1978 In-line Merc 115

i wouldn't panic yet,sounds like the rings are seized,there is alot of magic potions that you can pour into the cylinder,to try and free them up,before you need to tear it down,i would service the l/u w.a new water pump,and let the upper cylinder soak for awhile,and get it ready to run,then go from there.

 

[daveswaves]

Re: 1978 In-line Merc 115

I have a 115 Merc. that has not been in water in 10 years, I saw the post on what to do. However, my question is that the compression is down on one cylinder. It was checked a few weeks ago. If the cylinder is carbonized will it show low compression? Or sitting in storage for 10 years. Just not sure where to rebuild or not. I am being told today fuel will not run in the old Merc. engines.......?

How far down is down?? What cyl. Todays fuel runs just fine, you just have to drop your timing on the engine by 2 degrees, from 23 to 21 degrees.

 

[jrichardson88]

Re: 1978 In-line Merc 115

Not, sure what cyl. I think # 3. All I know is that the Spark Plugs are very dry almost Rusty( possibly not in water for 10 years). I have Marvel mystery oil soaking as I type. It just seems everybody I talked to about repair around my area, They tell me to scrap the motor and start over. Just don't want to see a engine die when it may can be brought back to life!!

 

[Chris1956]

Re: 1978 In-line Merc 115

Pull the transfer covers off and inspect the cylinders for scratches. If the scratching appears on the cylinder with low compression, a rebuild is in order.

just so you know, +3 cylinder is usually the first cylinder to fail on an inline six. #1 is the second to go. This is usually caused by overheating, over advanced timing or lean fuel mixture.

If you do decide to rebuild motor, replace waterpump impeller, clean and rebuild carbs and perform link and synch.

 

[Plainsman]

Re: 1978 In-line Merc 115

DeepCreep is a good product to lube the cylinders up before trying to start it. Use it in all the cylinders.

 

[jrichardson88]

Re: 1978 In-line Merc 115

Pull the transfer covers off and inspect the cylinders for scratches. If the scratching appears on the cylinder with low compression, a rebuild is in order.

just so you know, +3 cylinder is usually the first cylinder to fail on an inline six. #1 is the second to go. This is usually caused by overheating, over advanced timing or lean fuel mixture.

If you do decide to rebuild motor, replace waterpump impeller, clean and rebuild carbs and perform link and synch.

OK, update # 3 Cylinder has zero compression according to placing finger over spark plug hole and turning flywheel. No compression is noted, probably hole in piston i guess. So, Rebuild or used motor, that's the question?