First post and question 418-8

[Rick3478 428]

I've been told that paint seals porous castings, retards rust, and immobilizes residual dirt and shavings.

[stevasaurus 22,711]

I have never see manual transmissions painted inside.  Hydraulics , yes, but that is a different animal.  I would never paint the inside of an engine block.  I'm not sure how you would even do that...the oil is embedded in the metal...why would you take the chance that it does not stick...did you prime the metal first??

 

[Snoopy11 5,714]

13 minutes ago, stevasaurus said:

I have never see manual transmissions painted inside.  Hydraulics , yes, but that is a different animal.  I would never paint the inside of an engine block.  I'm not sure how you would even do that... the oil is embedded in the metal...why would you take the chance that it does not stick...did you prime the metal first??

 

 

I don't do much cooking... I do a lot of eating though... and I am told that cast iron sucks in oil like a sponge... thus you get a seasoned cast iron skillet.

 

Having said that... I can't imagine trying to paint over that... I would be fearful of disaster...

 

Don

[Jeff-C175 7,199]

7 minutes ago, Snoopy11 said:

cast iron sucks in oil like a sponge

 

OK... perhaps... but how come it doesn't eventually come through the other side then?

 

[Snoopy11 5,714]

2 hours ago, sjoemie himself said:

@Snoopy11 or other.. why is it that all manufacturing machines like drillpresses, cnc-lathes and mills are painted on the inside? Especially in the gearboxes.

Well, from my understanding, right after casting, the old time machinery maker had no good way to ensure grit didn't shed from the casting into lube systems so they walled the bad stuff in with paint. From my research, the traditional stuff used for this purpose was glyptal.

 

As for RE-painting when it comes to machine tools... the concern is that the paint would not adhere properly... and obviously, you don't want paint flakes running rampant through the gears and bearings. The only way to repaint such a machine tool correctly is to heat the casing above 400 degrees to boil off the otha' stuff...

 

Most people argue that all of the above on machine tools is unnecessary.

 

It is certainly unnecessary on engines and transmissions... and can cause serious damage to engines if the paint flakes off.

 

Don

[Snoopy11 5,714]

6 minutes ago, Jeff-C175 said:

 

OK... perhaps... but how come it doesn't eventually come through the other side then?

 

 

Be honest which'ya... I hadda google 'dat...

 

Here is what Google tells me...

Cast iron, properly manufactured isn’t really porous, but it’s not that simple. If it’s porous to the extent that it leaks, then there’s something badly wrong.

The structure of most cast irons, grey irons, contains flake graphite. in a machined surface, the flakes at the surface are damaged by the cutting tool and this results in very small microscopic voids which intersect the surface. These voids generally fill with oil if exposed. That is where the myth of porous cast iron comes from.

 

So... it doesn't suck up oil...  that to me would be another reason that painting it is 'tupid...

Don

[kpinnc 11,922]

Never seen a manual transmission painted inside.

 

But every hydro I've seen most definitely is painted inside with brick red material of some kind. It may be Glyptol.

 

But Glyptol is not paint. It is a resin, and there are several different kinds (names) in use, depending on application. The primary use supposedly is to "slick" the interior of any sump to enhance fluid return to the sump. I feel pretty sure it also prevents flash rusting of cast iron, which greatly extends the life of any hydraulic system. 

 

The fact that our old hydros can sit for 40 years and still work can probably be attributed to how the coating works. I've seen Kohler engines stored under a shed for decades that the top end rusts solid from condensation. Cast iron does not absorb oil.

 

That's my opinion at least...

Edited November 16, 2022 by kpinnc

[Howie 886]

The Glypol was used to coat the inside of racing engines at one time. I

think the idea was to promote better oil drain back. I forget what some 

of the other uses were for it. If the block was cleaned well I believe it

was very hard to remove. Disclaimer, I have never tried it! 

 

[Southern_Secret 463]

14 hours ago, Snoopy11 said:

I can't imagine trying to paint over that... I would be fearful of disaster...

Powder coating is the main choice when painting high heat or high wear parts. As @stevasaurus said, we use to rebuild hydraulic cylinders and always had them powder coated. Don't bury me that's just my 

[Jeff-C175 7,199]

20 minutes ago, Southern_Secret said:

rebuild hydraulic cylinders and always had them powder coated.

 

On the INSIDE? That's what this is about, painting the inside of engines and/or transmissions.

 

 

[Southern_Secret 463]

28 minutes ago, Jeff-C175 said:

On the INSIDE? That's what this is about

"slowly puts bag on head"

guess that's what I get for reading to fast 

[stevasaurus 22,711]

Another disclaimer???  I have never powder coated anything, nor have I ever had it done.    I have rebuilt an HY-2 and I painted the outside of the cylinder and canaster and the bracket with Restoration Red spray cans from TSC.  I've rebuilt two K-181's and I think I painted the outside of one of them with Rusto-lium Regal Red spray cans.  

  I'd like to see where @Southern_Secret saw that statement.   No problem, but that just doesn't sound like something I would say.

Edited November 16, 2022 by stevasaurus

[Jeff-C175 7,199]

14 hours ago, kpinnc said:

Glyptol is not paint. It is a resin,

 

Glyptal - gosh, that stuff is spendy! $$$

 

Website (and cans) say Alkyd Enamel,

 

 

Several colors available.

 

but they also have varnishes (clear only) , epoxies, lacquers, and yes, a silicone resin product in 'aluminum' color.

 

http://glyptal.com/glyptal_products.html

 

 

 

[Snoopy11 5,714]

24 minutes ago, Jeff-C175 said:

Glyptal - gosh, that stuff is spendy! $$$

Indeed. And 1 area of oil that you miss in prep... and it's flaking off just like any other paint and stops up the oil passages! One guys on one of the online forums said, "Doing it on an old casting, even if the part is is thoroughly cleaned, increases the risk of adhesion problems."

 

I thought another comment on one of the forums about painting with Glyptal was funny, "Dont do it ,but tell everybody you did and you will be golden."

 

Have another, "If getting a few spoonfuls of oil back in the crankcase faster will make any difference, you have problems paint won't solve."

 

"Are ya going to paint the rods, cams, valve covers, rockers and rocker galley and crank and pistons too? Those things have oil all over them. Engines have been running for over 100 years without paint on the inside."

 

The best comment of all, "Some have claimed it won't peel and end up in the pan, some have said it will. I say "why risk it?"

 

Precisely. It is not worth the risk for no reward.

 

Don

[kpinnc 11,922]

9 hours ago, Snoopy11 said:

Have another, "If getting a few spoonfuls of oil back in the crankcase faster will make any difference, you have problems paint won't solve."

 

My thoughts too. 

 

I think WH used it just so there wasn't any rust in the hydros. We've all seen 8-speeds with rusty top ends. I'd imagine that would be rough in a hydro.

[RED-Z06 2,220]

When i rebuilt a K181S when i was 15 i spray bombed the block, i masked the deck and bearing plate surface but i got paint all inside the block to the point that it started to look nice inside.  Only cleaning id done was a hot tub of soapy water and simple green.  About 3 or 4 years later i pulled it back off due to having severely overheated and overworked it and wanted to check rod cap torque...and the paint appeared to be intact, it was Red high temp paint..i never had and color in the oil...i don't feel like it hurt anything.  Tough little engine, never have pushed a little engine as hard as i dis that one that day and never hurt it.