Internal engine painting

[JustDave]

In the late 60s I worked for an old man,he was a machinist and an engine builder,after hot tanking an engine he would mask cylinder bores and mainbearing journals and paint the inside of the engine with rustoleumn,is it still a good practice if so what paint are people using now,do we clean it differently,    Thanks dave

[John_Mereness]

It was probably Glyptal if he was into racing or really high quality builds. 

[StillOutThere]

Eastwood was selling Glyptal.   Presume they still do?

 

[jan arnett (2)]

It was Glytal and it was supposed to make the oil flow better.  When I raced I did it but I am not sure it did anything.  One old timer said it kept the engine from rusting.  That sure didn't make sense.

 

[c49er]

You wouldn't want it not to stick to the block...plugged pick up screen.

[Rusty_OToole]

I wouldn't do it for fear of the paint peeling off and plugging up the oil line. The exception would be a cast aluminum block, some of them were painted at the factory to prevent leaks since sand cast aluminum can be porous.

[46 woodie]

As others have stated it was probably Glyptal and not Rustoleum paint. Before you decide to coat the inside of your engine, think about the millions of car engines that don't have it and are running great. I have rebuilt probably a dozen or so engines and all are running well and I have never coated any of them. Coating the interior of a stock engine, won't do anything for improved engine oil flow. If you are thinking about coating the interior of your engine, do not use paint. You are only asking for trouble. If you do use Glyptal, don't cut corners and follow the instructions exactly as instructed.

[edinmass]

Pre war high end engines were painted inside, as well as transmissions and rear ends. It was done to stop the early oil from producing excess sludge, and help prevent porous castings from leaking. We still do it on all our builds. 

[Mike "Hubbie" Stearns]

When I was drag racing, instead of painting the inside, I polished it up and removed any excess casting at holes. It works the same as painting without the fear of plugging up the filter, pickup or plugging oil lines. It just takes time and a lot of work. My engine was polished to 120 grit. It was a sbc from a 70 Impala . Mike

[Hans1]

I have several engines from 27 to 31, all were painted internally.

 

Might also seal block to trap sand from casting process.

[Spinneyhill]

3 hours ago, edinmass said:

It was done to stop the early oil from producing excess sludge

How did it do that? My reading is that sludge formed as the oil broke down in shear?

[Hans1]

Sludge: likely contaminants from combusting dirty air, bad gas and entrapped contaminants in block casting.

[edinmass]

1 hour ago, Spinneyhill said:

How did it do that? My reading is that sludge formed as the oil broke down in shear?

 

Spinny.....my fault, not expressing a correct and clear thought. It prevents it from sticking to the block, it did not prevent it from forming. It held the contaminated particles in suspension. It was certainly temperature related also, running the motors hotter prevented build up. 

[plymouthcranbrook]

Well  you learn something new every day

[Ben Bruce aka First Born]

8 hours ago, plymouthcranbrook said:

Well  you learn something new every day

 

 Or not!

 

  Ben

[bryankazmer]

sludge is more likely from reactions like oxidation.  Breaking of molecules in shear results in lowering the viscosity ( the viscosity modifiers are big molecules).

[Curti]

I had a six cylinder 1934 Auburn engine ( Lycoming ) that actually leaked oil thru the porosity of the cast iron.   

[plymouthcranbrook]

12 hours ago, Ben Bruce aka First Born said:

 

 Or not!

 

  Ben

Donald, is that you?

[Ivan Saxton]

Earliest I have encountered on antique car engine and gearbox that I know have never been "beeped"-around by enthusiasts is my 1911 4 cyl  left hand rotation Type 38 Napier.   It is a bright aluminium paint similar to what Protec in Adelaide used to sell in pressure pack spray cans, that was American manufacture of brand I do not know.   Those Napier aluminium castings also carry multiple fine hammer dots where they seem to have checked for any casting fault that could be detected audibly when the casting was struck with their pin-point hammer