Damaged 1991 2.5 carb 200 mercury outboard parts / tips needed ! (0D0 29244)

First post.

I have had my Mercury for 20 years, and two overhauls by a Los Angeles shop, the second overhaul because they did not determine cause of death on first failure (stuck thermostat)... so this time I am doing labor myself.

I had it out on the Lake fathers day for the first time in 10 years..... and the clear oil line from the oil injection pump to the fuel inlet broke.... engine seized lightly and made a bad sound... back on the trailer untill this week

I tore it down and found scuffing on the port cyls, the port pistons need replacement, the top one is already .030 and has the worst damage of the 3 port cyls.

I am going to use my old motorcycle racing trick of washing the aluminum off the cylinder walls with pool acid (the merc manual says use tidy bowl) and then have it measured by a machine shop to see what it needs.

The questions:

who makes .030 pistons for this engine? (has 636 8118 rods) I only see std and .015 on the mercury parts site.

who can reccomend a good machine shop to do the boring / honing / sleeving as required ?

Thanks a million!

Bruce

1991 Barefoot Sanger
200 hp 2.5L carb merc

Pro Marine for parts, Google there web site. I'm sure Wiseco makes pistons larger than .030 over for that block. Q & E machine in Anahiem does all sorts of 2 stroke stuff, and has done my engines with good accurate results.

I could not find a L.A. / O.C. machine shop on the internet... except the merc dealer in east L.A. that missed the thermostat!

I will head down to Q & E when I have the block cleaned out !

i hope you have better luck with removing the aluminum and reusing that hole then i have:nonod::nonod::nonod: its never worked for me i have them bored over size .

I've done it a few times. Depending how bad it is you have to re-apply the acid 8 or 10 times to get the worst of it off. Of course if the bore is damaged it doesn't matter if you get the aluminum off, you still have to overbore it.

bottom guided rods i buy all my consumables from pro-marine i like their pistons ProV and Vertec be sure to get your block work finished before you buy the guts even if hole cleans up it could be over .003 wear or badly egg shaped

I spent some time with Muriatic acid, no luck. The damage in #2 and #4 is too deep. #6 may be O.K. with a hone and new piston... it will be measured after a light hone.

I dropped the block off at Q&E machine in Anaheim for a bore on at least 2 cylinders.

The damaged #2 is already .030 over, Vance will see if it will clean up for a Wiseco .044 oversize.

The 3 starboard cyls look perfect, and the pistons are clean too.

keeping my fingers crossed......

The .044 Wiseco will make it 60 to 80 hrs and then spit a locating pin. Have the cylinder sleeved or the piston top pinned.

Six

I am not familar with what a "locating pin" is, or what "top pinning" is... any pics to explain?

thanks!