60hp Water Pump Caused Overheat - How to clean off piston deposits

[jimi]

My out board water pump failed (probably too old... my fault) and clogged the cooling lines. The bottom cylinder didn't fair badly at all but the top piston seemed to melt and smear itself on the cylinder wall above the exhaust port (see pic). I tried to estimate the depth of the damage and found that it seems like aluminum deposit from the piston. What do the experts recommend? scrap first then hone or just rebore?

 

[flyingscott]

That's looks like a re-bore minimum IMHO. A machine shop can tell you how deep those are. Usually after it scores the bore, the piston starts scraping and leaves aluminum behind.

 

[F_R]

Tear it down and hone lightly to remove the aluminum scuffing. Then evaluate it for re-bore (or not) need. It needs a new piston and rings for sure.

 

[jimi]

The piston head looks quite nasty on the exhaust port edge. Looks like the edge got sand blasted with coarse media.

I have a felling that a re-bore might necessary. Is it worth trying to hone first? The undamaged bore is roughly 3.188" or so.

 

[racerone]

Step # 1 is to take the motor apart.----Then determine what caused it.-----Measure and inspect all parts.-----There may be service bulletins out on this motor.

 

[Faztbullet]

Rebuild needed

 

[jimi]

[FONT=&quot]racerone: [/FONT][FONT=&quot]The overheat was caused by a water pump failure. I was going to tear it down but thought I'd start with a picture because the "scoring or gouging" looks and feels like a deposit. Got me curious...[/FONT]

flyingscott: I suspect it will take a re-bore. I was looking for some opinions as to whether it is worth trying to hone it out first.

F_R: that's my plan (now)

All
A friend of mine does it on motor cycles and has offered me the use of his facilities and I have a spare block with nice looking sleeves in it.Does anyone have any experience with changing cylinder sleeves?

 

[racerone]

Take action.-----There may be service bulletins / modifications to be done on this motor to prevent repeat overheat failures.----One is a waterpump kit with different poppit spring / cover as an example for you.---If oil injection is in service you may want to check oil output on that system too.

 

[jimi]

Has anyone tried Muriatic acid to clean off piston deposits before honing or re-boring to reduce the amount of wall to be machined off?
[FONT=&quot]http://www.scootertherapy.com/acidpage.html[/FONT]

 

[flyingscott]

I have used it on chrome bores and it works. Never used it on cast iron sleeves because when they look like yours I tear the motor down. It also doesn't matter if it has aluminum on the bore when it goes in the machine shop will handle that.

 

[jimi]

Thanks FlyingScott for the info.

While have your attention have you ever re-sleeved a block? Heat it up to 350f pull out the old sleeve and put in a new one.

 

[flyingscott]

I have LA Sleeve do my sleeves. For $300 a hole they do everything for me all I have to do is reassemble. I don't want to deal with the hassle of making sure the ports are lined up and the sleeve height is correct. And even after the sleeve is in you still need to do the final bore and hone.

 

[jimi]

Thanks flyingscott. That was exactly what I was looking for.

Any idea where I could find the dimensions and tolerances for the cylinder bores?

 

[racerone]

Is this a 2 or 3 cylinder motor ?---Did the overheat warning buzzer sound ??

 

[Faztbullet]

That cylinder does not need resleeving...you can get pistons from .010-.040 oversize. Tear it down and measure and bore accordingly.

 

[jimi]

Racerone: it is a two cylinder 45 cu.in. block p/n 328100. The boat came with no temp gauge or buzzer. However, there will be a temp gauge next season for sure

Fazbullet: you may well be right. I'd estimate the aluminium build up as about 0.010". I remember my Dad doing exactly what you suggest on an old 5hp Johnson many, many years ago. However, he found a way to scrap some Aluminum off the bore before honing to reduce ovalization during the honing. Hence the muriatic thought line...

The only attraction in swapping sleeves is that I have a parts power head and it has nice looking sleeves in it. If I got the sleeves out, then using muriatic acid it would be easy first step to removing the aluminium. Also, Spending an afternoon with buddy swapping sleeves might be fun because we like the same scotch

I bought this power head used so I don't know whether the pistons are stock or already over sized.

Does anyone have, or know where i could get, the bore specs? diameter +/- tolerance?

 

[Faztbullet]

1st...Putting in a used sleeve may not line up due to top of cylinder being milled. A new sleeve is not a drop in operation as it has to be milled flush with block and then bored out to STD size. 3.187 is STD bore and .003 is wear limit so if cylinder mikes 3.190 after using a RIGID hone not a ball/spring type need to go up as size.

 

[mickyryan]

don't use the muratic acid trick because it will eat everything up and cause hydrogen embrittlement if not cooked out properly and I'm not sure you could cook it out without warping the rest of the motor safely.

 

[ondarvr]

Don't over complicate this, get a manual, take it apart, see if it can be bored (more than likely can be), then make a plan.

The manual will have all the details needed for your exact motor.

 

[jimi]

Fazbullet: Thanks! And I agree on the ridge hone 100%

PS which publication gave you the nominal 3.187 diameter and 0,003" wear limit?

Ondarvr: This is a used 45ss I bought some years ago from my brother (nice guy... zero documentation and he painted over the model/serial number plate :blue. 45ss were a limited series of stock racing engines produced from production parts in the late 80's (I think 80's... maybe 90's)..

There is no 45ss manual that I know of and no active 45ss racers where I hang. I will have to get a 40, 50 and 60 hp manual for a late 80's OMC. Never been that happy with Cylmers. Is there a better source? an OEM manual?

All: I post this way to find information because I have never found a direct manual for this motor. Now that I Knowing that the wear limit is 0.003" over a base dimension of 3.187 eliminates muriatic acid and lots of other crazy ideas.

Thanks again for all your help!