push rod tube, to paint or not Options

[jacksun]

Hi,

got my first push rod tube cleaned up and would like to paint it with

hi-temp paint? any problems doing so?

tks

randal

[914Sixer]

Paint holds heat. They were plated gold or clear zinc.

[jacksun]

hmm ..... now I have four painted..............

fresh paint should wire wheel off easily enough. too bad..... they look great

purple..............

tks

randal

[Mike Bellis]

Has anyone really done a study to find out how much heat is held in by paint?

If you google it, the answers are back and forth on both sides. The only argument I found that made any sense was that radiators are painted black because black color radiates heat better.

I have not seen any conclusive information that paint will affect heat soak. In theory, any applied surface on the tubes will have some marginal insulation effect. But paint is not considered an insulator or our homes would only have paint and not insulation.

I think the jury is still out on this urban legend...

[Mike Bellis]

BTW,
Kirchoff's Law of Thermodynamics basically states black (black body) absorbs better AND radiates heat better due to it's infrared properties. If this is the case, we should all paint our engines flat black.

[jacksun]

just kidding about the purple....... they are black hi temp rattle can paint.

so the black will radiate the heat away like a radiator..... good........

they were developing some surface crud so I wire wheeled that off and thought

some paint would protect them for another forty years....


tks again...

r

[Mike Bellis]

just kidding about the purple....... they are black hi temp rattle can paint.

so the black will radiate the heat away like a radiator..... good........

they were developing some surface crud so I wire wheeled that off and thought

some paint would protect them for another forty years....


tks again...

r

I'm sure this debate is not over... But it's hard to argue against Kurchoff's Law. The only person that may have real world testing info on a T4 is Jake Raby. I'm sure he will chime in at some point.

[swooshdave]

Some of you are worried that a little paint on the push rod tubes will cause the engine to overheat? (IMG:style_emoticons/default/huh.gif)

[Mike Bellis]

Some of you are worried that a little paint on the push rod tubes will cause the engine to overheat? (IMG:style_emoticons/default/huh.gif)

The paint debate goes much deeper than just pushrod tubes... (IMG:style_emoticons/default/smile.gif)

[r_towle]

Some of you are worried that a little paint on the push rod tubes will cause the engine to overheat? (IMG:style_emoticons/default/huh.gif)

If I was to add 40 holes in your house about 1 inch in diameter, it would be like leaving a window wide open.

So every little tiny incremental improvement using new chemicals, new knowledge etc can allow us to add more horsepower and reduce heat.

Things like paint versus zinc plating could add a few degrees and keep you from the full potential of the motor.


So yes, we argue about it, but it's so we can all learn.

[swooshdave]

What happens if I paint my jackstands?

(oops, I hope I don't get banned already…) (IMG:style_emoticons/default/biggrin.gif)

[PlantMan]

What happens if I paint my jackstands?

(oops, I hope I don't get banned already…) (IMG:style_emoticons/default/biggrin.gif)

You will then have some cool looking Jackstands........but only if they match your car!
(IMG:style_emoticons/default/idea.gif)

[malcolm2]

I painted mine.....
But masked off the o-ring seats. I wonder if engine paint is hotter or colder? (IMG:style_emoticons/default/piratenanner.gif)



and then installed....

[PanelBilly]

It it looks good then do it. Are you going to race the car professionally or compete in an endurance contest?

[malcolm2]

It it looks good then do it. Are you going to race the car professionally or compete in an endurance contest?

Not a racer, just a daily driver. Fastest I have had my car in these 1st 5000 miles is 75.... maybe. Not positive, cause the speedo is squirrelly.

Painting stuff ended up being one of those, "while your in there" things. makes you take your time during assembly. did not want to scratch the paint. And having a light color on the tins has helped me fined leaks etc...

Any thing that would fit in my wife's oven got painted and baked.

another shot of the engine on the table...

[Keyser Sose]

All the oil that goes to the rocker assemblies, which is a lot, drains back through the push rod tubes. They're out in the cooling airstream, so they cool quite a lot, like eight tiny oil coolers. It's true that radiators are painted, but that's a special heat conducting paint that lets the metal conduct (and shed) even more heat than bare metal. That high-tech engine paint does the opposite, retaining heat. Bottom line there was a good reason VW zinc plated those.

Looks pretty good painted so try it, what the heck. Who knows, you might get away with it, especially if you never thrash the engine so shedding heat doesn't ever become critical. I wouldn't myself, but I'd be curious to hear how it turns out for you.

[jacksun]

http://www.vw-resource.com/cooling_qa.html

"
Miscellaneous Ideas to Improve Cooling


All of us want a cool running engine, one that can take 70 mph into a headwind at 95 degrees all day.

The stock cooling system will handle higher power okay, but do include the thermostat and cooling flaps. (See our discussion of Cooling Vanes and Thermostat. If the thermostat is expanded, the flaps should be open, (as long as the control rod is moving freely).

Another useful trick is to examine the heads carefully, and use a Dremel or small chisel to remove any casting flash between the fins. This improves airflow for better cooling.

Paint the cylinders (not the heads) with a very thin coat of matt black heat resistant paint (brush-on, not spray paint -- according to John Connolly (Aircooled.Net), using the brush-on type is much better than spray-on, maybe it sticks better. Also paint the push rod tubes with the same stuff (that will cool the oil just a little, since it's just come from the hotter heads and is dribbling past the cooler cylinder air).

Don't be tempted to install those shiny "cool" aluminium rocker covers. The black VW ones shed more oil heat according to Bob Hoover. Apparently VW offered an Arctic Kit many years ago which included chrome rocker covers to slow the radiation of heat in cold climates.

If it's really needed you can alter the oil cooler doghouse to fit the wider Type 4 oil cooler.

Dave wrote to "Speedy Jim" asking about these methods to increase cooling. Jim wrote back -

Sorry. My personal feeling is that all of those measures are "lily-gilding". Any improvement is likely to be small and probably insignificant.

Many people install a larger oil sump in an attempt to reduce oil temperature. The Gene Berg catalog says that oils sumps aren't really effective in reducing the oil temperature. You only end up with more hot oil. The deep sumps don't have enough surface area to make much cooling difference. They were originally designed to prevent oil surge in hard cornering (racing), not for oil temperature reasons.""


and the debate continues............

my guess is that the thin coats (2) of paint a rattle can applies is nominal and

wont make much if any diff... just protect the surface from corrosion, hopefully.

[Keyser Sose]

Oil 'dribbles' back? Sure, at idle. Fifteen or twenty years ago I saw a video made by a guy who'd lost a racing engine from oil starvation, so one thing he did to find out what was going on was glue a plexiglass 'window' into a hole he'd cut into a valve cover. At high rpm's there was oil that half filled the rocker chambers, showing where a lot of his oil was going, and staying, at speed. Those pushrod tubes do more than you'd imagine. If you're determined to paint them my suggestion would be a very thin coat or two of flat black radiator or BBQ paint, at the most. But then again this is internet wisdom, so do whatever you want.

[stugray]

BTW,Kirchoff's Law of Thermodynamics basically states black (black body) absorbs better AND radiates heat better due to it's infrared properties. If this is the case, we should all paint our engines flat black.

The old wive's tale of "Black gets hotter" or "Black radiates better" was made even worse by Dr. Iam Malcom in Jurrasic park.
We all know that the black interiors of our cars definitely get hotter in the sun, so why?

Just because the color "looks" black to our eyes does not mean that it is black as far as the Infrared spectrum is concerned.

Black is "Black" in the visible spectrum because it does not reflect light that we can see. It means nothing to the BIG contributor - Infrared.
The term "black body radiator" actually has nothing to do with the color of the radiator.
The term "black body" really means that the radiator has no actual color other than that which is due to the temperature and nothing else.

The real answer is that we dont know if one paint radiates better than another unless we can measure it's emissivity which requires a high tech instrument.
If a material absorbs heat good, it has a low reflectivity.
Flat Black paint might radiate heat better (high emissivity), but if it absorbs better (low reflectivity) than it will get hotter becuase it is absorbing the heat from it's surroundings better.

So to make something good at getting rid of heat you want high emissivity and high reflectivity.
Those two are often conflicting because a good radiator is a rough surface which makes it a bad reflector.

But keep in mind that heat moves away from the pushrod tubes three ways: Radiation (light), convection (moving air), and conduction (it's touching somehting else).

For this application the biggest contributor to cooling is the convection part. SO if you really want to make a difference, put some aluminum cooling fins on the tubes and orient them so air flows downward through them.

/Lecture

[Java2570]

And we all know what happened to Dr. Malcolm in Jurassic Park!!