Refresh merc 165

[spegtoast]

I currently have the motor out to replace the transom. It's a motor from 78' likely never rebuilt. Is there a maint refresh parts list/ or kit I can buy? I heard the piston rings are likely broken from a gearhead here at work. And he also said to buy T6 lump ports for the head. Anyone familiar with these?

 

[Bondo]

Re: Refresh merc 165

I currently have the motor out to replace the transom. It's a motor from 78' likely never rebuilt. Is there a maint refresh parts list/ or kit I can buy? I heard the piston rings are likely broken from a gearhead here at work. And he also said to buy T6 lump ports for the head. Anyone familiar with these?

Ayuh,... There were 2 165hp motors by Merc, the I6, Chevy, 'n the I4, aka: 470,....

So which 1 ya got,..??

Btw,.... Ya oughta ignore yer local motorhead,....

 

[Scott Danforth]

Re: Refresh merc 165

Bondo, if he is talking lump port conversions, he is talking the I6

while a lump port conversion makes a bit of hp for street driven I6's, your not going to justify the work or cost since you will never spin the motor fast enough to take advantage. there is some head porting you can do, however again, the amount of work vs the gains makes it hard to justify

lots of coverage on those at inlinners.org

your 165 is a sister to the street driven 250 cubic inch motors. the difference is the front mounting flange for the motor mount, and of course, the marine motors get specific marine cams, marine head gasket (stainless core) and brass core plugs. take your motor to a local machine shop and get a quote.

If you are quite handy, and can handle the tear down and assembly, you will save yourself a bit of money. However talk to your local machine shop for pricing. for many people, the extra few $ is worth it knowing that the motor is ready to drop in.

 

[Fishermark]

Re: Refresh merc 165

I heard the piston rings are likely broken from a gearhead here at work.

And he based that on what? He could be right of course... but I am curious what he based that conclusion on? On your description of how the engine sounds? On a leak down compression test? Before you worry about a list of parts to buy, it would be good to know what's broken, if anything, for sure. Since the engine is out of the boat, a complete tear down will tell the tale. Then you can replace / fix what is needed.

 

[998cc]

Re: Refresh merc 165

And he based that on what? He could be right of course... but I am curious what he based that conclusion on?

Got my curiosity up as well. I have torn two inline 6 250's down in the past few months and found no broken rings whatsoever.

 

[spegtoast]

Re: Refresh merc 165

I didn't realize there were two different 165's. I will attach a pic. In the meantime I will do some research. The guy says he guarantees at least two of the piston rings are broken based on, as he says "it's common for this motor". I don't have the experience one way or another and value opinions here because I have seen your guys verifiable work. Aw inspiring. So.. the motor ran fine and started right up on drydock. Since I have had the boat it's never been in the water. I just thought while it was out I would like to put a worry free assembly back in it. Really tho.. It wouldn't be much work to pull the motor again if I actually had a problem with it in the future. I just assumed being a marine motor a motor "refresh" was just considered general maintenance. Your thought's are appreciated on that. if I can get out fishing on the cheap. I'll be happy to just throw the motor back in till I have a problem with it. EDIT: It's a 250. And I sprayed a little fogging oil down the cylinders because it's been sitting for about a year. Did a compression test. From front to back I have 133, 135, 145, 130, 139, 140.

and no... that little tree isn't what it's hanging from lol. There is a much bigger tree I was lucky enough to use as the gantry.

 

[wrench 3]

Re: Refresh merc 165

You are lucky! I've got a hole yard full of trees and not one of them that I can swing an engine from. I had to use a John Deer tractor for the last one, a back hoe for the one before that. But the one before that fit into the work shop, so swung it from the ceiling joists.
With the compression you have, I'd take a chance on it. You won't know how the oil control rings are until you run it. But with a tree like that, if it uses oil you can pull it out again next year.

 

[Scott Danforth]

Re: Refresh merc 165

your numbers are a little low across the board, however there is nothing to indicate broken rings. however you did mention it has been sitting for over a year.

at best the rings are probably stuck

i would put a few ounces of ATF or SeaFoam or other down each cylinder, rotate over without the plugs a few times and let sit. that should loosen the rings. then get the motor running (you can run it out of the boat with proper precaution). let it run at idle for about 5 minutes, then retake the comression numbers.

if at that point you have a cylinder that is low, then pull the head and look.

your "gear head" at work is most likely blowing smoke up your arse.

 

[Fishermark]

Re: Refresh merc 165

The guy says he guarantees at least two of the piston rings are broken based on, as he says "it's common for this motor".

Here's a saying more common (and accurate) than that: "If it ain't broke, don't fix it." Do a basic tune up and reinstall the engine and go boating when you get the transom fixed.

While the engine is out and transom work is done, it is a good time to be sure that the bilge pump is in good order, etc. But the engine? That I wouldn't worry about.

 

[998cc]

Re: Refresh merc 165

The guy says he guarantees at least two of the piston rings are broken based on, as he says "it's common for this motor".

Perhaps the gearhead buddy is confusing the ring issue with the automotive GM/Chevy version of the inline 6's of the late 70's where cracked heads were common in the "Integral Head" design. These heads had the intake and exhaust manifolds cast as part of the head assembly and were prone to cracking.

 

[oldsub86]

Re: Refresh merc 165

I had a 1967 Chevy shortbox, stepside, pickup truck in about 1973. It had about 135K miles on it when I bought it. The engine was quite noisy though and we knew when we bought it that the motor was going to be torn apart. It had broken rings, so, it might, but it might not be an issue for you too. I suspect the truck had not been serviced often enough. Mind you, back in those days, a 100K was a lot of miles on a vehicle. They make them better today.
I have an old Lund with the 165 that I will hopefully get running next summer so I have similar issues to you. It has not been run in many years and I have been working on parts of it. Cleaned up the distributor, rebuilt the carb etc. Have to make a new fuel line from the pump to the carb and then I should be able to fire it up. I hope I don't have any real issues either. Good luck and keep us posted on what happens when you get it running.

Randy

 

[wrench 3]

Re: Refresh merc 165

I was working for GM dealers late '60s to early '80s and the only common problems we had with those engines were leaking rocker covers and rough idle. But Mercruiser solved both problems with the cast rocker cover and the two barrel carb.