Paint Inside Powerhead?

[sffar]

I'm rebuilding a 1970 6HP Johnson (and a couple of other OMC's). Much of the inside of the motor was painted with a red primer or paint. I've heard it said priming inside the crank case, etc. is a good idea to promote a clean motor. Is this still true, and what (if any) paint or primer would be a good choice?
Thanks!

 

[tashasdaddy]

Re: Paint Inside Powerhead?

never heard that.

 

[SKEETR]

Re: Paint Inside Powerhead?

All I see is paint gummed up in bearings or plugged up oill feeder holes.

 

[sffar]

Re: Paint Inside Powerhead?

I'm looking for the original source of my information now. One other source was a local mechanic (more a motorcycle guy) who told me it's a good practice. Of course, the insides of the OMC were originally painted, so presumably there was a good reason for it. One post I looked up said new gas eats up paint in the engine, but I'm not quite convinced.

 

[sffar]

Re: Paint Inside Powerhead?

Here's one source. I took this as an explanation for the original OMC application . .
"Some engine builders paint the inside crankcase area of the block. This is recommended as a detergent to carbon or sludge buildup, and also seals the pores of the iron preventing oil from washing deposits, left in the pores after cleaning, into the oil. Painting will help insure the absolute cleanliness necessary for top quality performance and engine life."
I've read Glyptal paint or Rustoleum red moisture resistant primer is the stuff to use.
Thoughts?

 

[Dhadley]

Re: Paint Inside Powerhead?

What OMC used wasn't actually a paint. It was a sealer that would prevent leaking in the water jackets. They added a red color so what was covered was visable. It actually impregnated into the aluminum, that's why it's so hard to get rid of.

 

[sffar]

Re: Paint Inside Powerhead?

What OMC used wasn't actually a paint. It was a sealer that would prevent leaking in the water jackets. They added a red color so what was covered was visable. It actually impregnated into the aluminum, that's why it's so hard to get rid of.

Thanks, Dhadley. Is there a similar product available, I wonder? Is it worth doing or worrying about? It would seem to be a part of an thoroughly complete engine restoration.
Sam

 

[Dhadley]

Re: Paint Inside Powerhead?

We've never worried about it because the sealer portion is already embedded in the aluminum. Some rebuilders use red primer in the water passages which may or may not make a difference in salt water. That's up to you but at the very least it can't hurt anything, at the very most it might help slow corrosion in salt if the motor is never flushed.

Personaly I would never paint the inside of a 2 stroke where gas is present. The fuel we get today may loosen it up and cause all kinds of issues.

 

[kandil]

Re: Paint Inside Powerhead?

Hi I am rebuilding my 25hp Yamaha and I used this zinc chromate primer inside the water jacket I did clean it of where the gasket goes.

 

[F_R]

Re: Paint Inside Powerhead?

Dnadley got it right. It is a sealer intended mostly to prevent corrosion in the water jackets. That's just one of the reasons why OMC held up in salt water so much better than the competition.

 

[Benny1963]

Re: Paint Inside Powerhead?

i use a epoxy base paint in the lifter valleys of the car race motors i build
but its to help oil drain back to pan which two strokes dont need

 

[Randybeall]

Re: Paint Inside Powerhead?

I have painted the inside of a number of engines. It can help with sealing porus castings and make a clean dry engine. Inside the water jacket it will minimize corrosion, though you must consider the loss of heat transfer in a high performance application. In outboard engines this does not seem to be a problem since we have an unlimited supply of cool water to dump heat into. Using it in the crankcase of a two stroke engine is questionable. I would test the paint with fuel, oil and Seafoam and see if any one softened the paint.

 

[1946Zephyr]

Re: Paint Inside Powerhead?

Yep, I've seen lots of that red **** inside of the blocks too. As I understand, it's to keep the corrosion down.

 

[sffar]

Re: Paint Inside Powerhead?

Thanks for all the responses! Now I'm wondering if anyone at OMC would recommend some product similar to the original or let it be known what it consisted of. It's tough stuff!