What advantages are there to painting the inside of the block?

[Texas Red]

No such thing as a dumb question if you really want to know the answer to it ..........and I wanna know ...........What advantages are there to painting the inside of the block? besides faster oil return?????????? Would it not make the block retain more heat internally as paint is a insulator so what big advantage is there???????? On a drag race only engine the faster oil return to the sump ----I see advantages ...... What type of paint does one use inside the block that will adhere to the metal?????? Block prep would be a major job protecting lifter bores etc.....
I have toyed with the idea of painting the inside of the block on my 70 model 340 which is still in the machine shop and is not yet finished.................. the lack of heat dissipation would keep me from it for a street engine....... Please advise old wise one..........Texas Red... Gary

 

[Super-Cuda]

No such thing as a dumb question if you really want to know the answer to it ..........and I wanna know ...........What advantages are there to painting the inside of the block? besides faster oil return?????????? Would it not make the block retain more heat internally as paint is a insulator so what big advantage is there???????? On a drag race only engine the faster oil return to the sump ----I see advantages ...... What type of paint does one use inside the block that will adhere to the metal?????? Block prep would be a major job protecting lifter bores etc.....
I have toyed with the idea of painting the inside of the block on my 70 model 340 which is still in the machine shop and is not yet finished.................. the lack of heat dissipation would keep me from it for a street engine....... Please advise old wise one..........Texas Red... Gary

Back in the eighties when we rebuilt engines, we hot tanked them and painted the lifter galley with Electric transformer paint. It was a grey color. It supposedly aided return flow of oil and prevented sludge build up. Not really sure if it worked as intended.

https://www.jalopyjournal.com/forum/threads/is-glyptal-engine-paint-worth-the-bother.644312/

 

[MopaR&D]

The "faster oil return" is questionable. Once the surface is fully wetted with oil any excess flows over it at the same speed so really all it's doing is increasing the amount of oil that stays in the sump while the engine is running by the amount that would normally be "soaked" into the as-cast surface which would be what, 0.5 ounces, if that? I could mayyybe see it reducing the tendency for sludge attaching and building up but anybody who knows enough about engines to be building them isn't stupid enough to extend their oil changes long enough to let their oil turn to sludge in the first place. One of those mods that seems like it would work but with no proven results to show that it does anything measureable. Sure looks nice when you're putting the engine together though.

Edit: the insulation aspect is a good point but in my mind all that's really doing is insulating the oil from latent heat from the block but then the oil is getting way more heat into it from the parts of the engine it's actually lubricating anyway.

 

[RedFish]

Back in the eighties when we rebuilt engines, we hot tanked them and painted the lifter galley with Electric transformer paint. It was a grey color. It supposedly aided return flow of oil and prevented sludge build up. Not really sure if it worked as intended.

https://www.jalopyjournal.com/forum/threads/is-glyptal-engine-paint-worth-the-bother.644312/

I just love the comment,"Don't do it but tell everyone you did".

 

[Oldmanmopar]

Glyptal coating. when the block is clean and dry. Helps the block from retaining oil and any break in particles from sticking. Oil flows to the sump faster. Steve has customers that request it at the machine shop. Usually done before machine work . Block must be spotless and dry

 

[mopowers]

Has any engine failed because the inside of the block wasn't painted?

 

[LO23M8B]

Has any engine failed because the inside of the block wasn't painted?

Too many failures out there to tell.

 

[crackedback]

Has any engine failed because the inside of the block wasn't painted?

Seen the paint lift on poorly prepped blocks.

Engines have survived for years without it. JMO, want to paint, go for it. Don't, then leave it be.

Only real harm is if it lifts.

 

[LO23M8B]

It keeps everything smooth and clean. Lots of metal particles can hang up on rough surfaces during assembly. I personally like it but as said block must be absolute spotless as you don't want pieces of paint blocking your pickup screen. It costs extra to do or have done so if your budget can't handle it just skip it.

 

[6PKRTSE]

I will never paint the inside of my engines. I know the Pros. I know the cons. It's not worth anything to me.

 

[LO23M8B]

So what's the cons.

 

[6PKRTSE]

So what's the cons.

Most can't/don't clean the block or heads well enough before painting them. Clogs pick up screens, makes a mess in the pan. We have had dozens of race engines come in over the years with the paint flaking off. Once it starts it seems to never stop coming off.

 

[LO23M8B]

I agree with that. Most people don't realize what clean is. Like you are painting the outside of your car.

 

[Syleng1]

I’m not going to do it, but for those that do… it looks wicked cool. The only thing I ever paint is the underside of an aluminum intake. It was supposed to prevent oil from leaching thru… although I’ve never seen that actually happen.

 

[Oldmanmopar]

See a lot of painted blocks that are rattled canned inside what looks like red oxide. Some are hemi orange. That **** don't stick on the outside how would it stick on the inside.

We do what the customer wants . Never seen an issue on race engines that come back for refreshing between seasons. But its like anything you coat. Some assholes just don't understand the definition of clean or proper prep.

 

[Oldmanmopar]

double post

 

[jos51700]

Whatever you do, do NOT powdercoat engine interior parts. I had a coworker powdercoat all his Harley engine parts (Engine was a VRSC VRod) and they powdercoated the interior sides, too. They told him it was good to run. It was not good to run. A locked up oil pump resulted.

 

[TheGrateRonzini]

I took a very labor intensive method and ground the lifter valley smooth

 

[fishmens67]

So what's the cons.

Can't see how pretty it is from the outside.

 

[MoparLeo]

The paint type is Alkyd or Glyptal.

Seals the pores of the block.prevents any loose casting material from coming loose in the block and smooths oil return.

 

[NC Engine Builder]

I use 2 different products, I use glyptal as allready mentioned above, and I sometimes use a product from cerakote called "microslick" both accomplish simular results, sealing the pores of the iron, and providing a slicker surface for oil return. HOWEVER, the main reason I use them, is because most of these engines are "hobby" engines that spend lots of time sitting, and I like the corrosion resistance aspect of them. As noted previously, the blocks must be clean. I will only do it after running the blocks through my ampro cleaning system, which bakes the blocks at high temp, followed by shot blasting with stainless steel shot. No other method of cleaning is good enough to coat the inside of the block.

 

[Matts440]

I did it on my engine build for my 67, for the help with oil return, course it was easy since it was a fresh aftermarket block and did it after the machine work was all done. Intake I did more for the heat insulation but also added some DEI insulation tape to the galley and under the runner's.

 

[Mopar69gts]

I tried Glyptal paint once in the lifter valley
It never hardened after a week I called the company
They said I must have put it on too thick?
Idk if that was really the problem or not
So I spent a ton of time getting if off and then sanded / polished the valley.
Just my experience

 

[furrystump]

I could see it if you run alcohol and the motor sits.

 

[Rad8tor]

No such thing as a dumb question if you really want to know the answer to it ..........and I wanna know ...........What advantages are there to painting the inside of the block? besides faster oil return?????????? Would it not make the block retain more heat internally as paint is a insulator so what big advantage is there???????? On a drag race only engine the faster oil return to the sump ----I see advantages ...... What type of paint does one use inside the block that will adhere to the metal?????? Block prep would be a major job protecting lifter bores etc.....
I have toyed with the idea of painting the inside of the block on my 70 model 340 which is still in the machine shop and is not yet finished.................. the lack of heat dissipation would keep me from it for a street engine....... Please advise old wise one..........Texas Red... Gary

If paint ever emulsifies with detergent oil you could have issues from bearing wear to clogged oil passages. IMO no way is it worth doing. But WDIK?