Acceptable temp/heat for pushrods and rockers / Applying engine coatings

I'm trying to find out the max acceptable heat/temp I can expose pushrods and/or rockers to, without damaging them.

It is known that the 4.0L-OHV has poor top end / valve train oiling; often leading to premature wear of pushrod ends and pushrod cups in the rockers. So, I thought I would try using a dry-film lubricant engine coating.

http://www.techlinecoatings.com/hi-performance/bs-internal-engine-coatings.html

I'm looking at the DFL-1 PowerKote:

DFL-1 POWERKOTE (Dry Film Lubricant)
High pressure lubricant.
Reduces friction, galling and scuffing. Increases part life.
Requires no clearance changes to compensate for the coating.
Apply to any part subject to sliding or rotating friction.
Excellent for use on bearings.
Water based no hazardous fumes.
Requires baking. Cures at 300�F minimum. Must be oven cured.

My concern is the 300deg, for 1 hour. Does anybody see any problems with this; such as loss of "temper", unintended hardening/embrittlement, and/or warpage of the parts? As I said, I intend to use it on the pushrods, the inside "bore" and both the pushrod cup as well as the valve end tip of the rockers. I would also probably use it on the rocker shafts, as well as possibly on the inside bore of the rocker shaft springs/spacers. Basically, anything that will slide/rotate, or otherwise make metal-to-metal contact.

The cost of this product is $37.95, for 1oz. It is intended to be sprayed with an airbrush, in a very thin film. So, that 1oz should be more then enough according to the manufacturer I already have a "spare" toaster oven, so with a cheap harbor freight airbrush, I can do this for $100-$150. It supposedly can substantially reduce friction, and therefore heat.

I may also coat the stock exhaust manifolds with the appropriate thermal barrier coatings to retain exhaust heat in the pipe, and reduce under hood temps. Unfortunately, I don't think a manifold would fit in my toaster over. Maybe I can build an "extension" box, so I can still use the toaster ovens heating elements and thermostat?

 

[QueenCitySleeper]

300degreeF is nothing. Depending on material as long as you stay under 1000F your fine. Bake it in your kitchen oven same as you would a casserole. They hold a more constant temp than toaster ovens do, unless you have real nice one that is. -bill

 

[Carguy3J]

300degreeF is nothing. Depending on material as long as you stay under 1000F your fine. Bake it in your kitchen oven same as you would a casserole. They hold a more constant temp than toaster ovens do, unless you have real nice one that is. -bill

Definitely don't want to use a kitchen oven. Anything you use for this can NEVER be used for food again.

Also, steel can definitely lose temper and "sag" well below 1000deg. Anything over 400deg, I know can affect the properties of the metal. I'm just not sure about 300deg.

 

[QueenCitySleeper]

Ok then so your parts have a lower carbon content than 1018? I find that extremely unlikely. And if by some way you did lose temper, who cares. Re-temper it.

 

[Turdle]

400 degrees is a common cure temperature for normal powder coat paint. Some primers go as high as 465 ( part metal temperature)

300 degrees is not going to do anything to the parts. Heck I have burned off coil springs at 650 for 4 hours. Let them cool overnight and they were fine.

I would try to find a used home oven for this though, as the toaster oven will have hot spots.

freecycle.org or craigslist will help you here. You might get lucky and find an oven with non working stove you can score free.

The cure time is started when the part hits 300 degrees. A handheld IR thermometer would be a good idea also. Good luck, I want to see the results please.

 

[Turdle]

Definitely don't want to use a kitchen oven. Anything you use for this can NEVER be used for food again.

Also, steel can definitely lose temper and "sag" well below 1000deg. Anything over 400deg, I know can affect the properties of the metal. I'm just not sure about 300deg.

It is amazing what a self clean cycle will do for an oven--FYI

 

[Carguy3J]

400 degrees is a common cure temperature for normal powder coat paint. Some primers go as high as 465 ( part metal temperature)

300 degrees is not going to do anything to the parts. Heck I have burned off coil springs at 650 for 4 hours. Let them cool overnight and they were fine.
I would try to find a used home oven for this though, as the toaster oven will have hot spots.
freecycle.org or craigslist will help you here. You might get lucky and find an oven with non working stove you can score free.

The cure time is started when the part hits 300 degrees. A handheld IR thermometer would be a good idea also. Good luck, I want to see the results please.

I'm curious if you tested those coil springs before and after? At 650deg, I wonder if they may have lost some of their spring rate?

I agree an oven may be "better", but I don't have access to one. I don't even have a stove/oven for food. I use a toaster oven, hot plate, and microwave for all my cooking. It works fine for one person. The only problem is the toaster oven is just too small to accommodate those big Stouffers frozen lasagna trays, so I haven't had those since I moved. I thought about getting a convection oven. The biggest one at Wal-Mart will fit one of those trays (an exhaust manifold might also fit). On the other hand, I only have a "dorm" sized refrigerator, so storing the big things would also be an issue. Even if I did pick up a free stove/oven, I don't have the electrical (or gas) hookups for it. That's why my 220v shop compressor, 220v welder, and 220v electric dryer have all been sitting unused for the last 4 years.

In any case, the manufacturer of the coating doesn't seem to indicate that precise temperature control is important, as long as the part reaches a MINIMUM of 300deg for at least an hour. So, if I set it to 350deg, for an hour and a half, after pre-heating first, I think it should be ok. In fact, the manufacturer specifically recommends using a toaster oven, for small parts, for "home users" of their product.

What about cool down? Should I do a "step down" process? Say, 250deg for a half hour, 200deg for a half hour, 100deg for a half hour, and then no heat/natural cooling? Or just turn off the heat after the hour or so of heating time, and let the parts immediately begin to cool down to room temp?

For bigger parts, there is a local powdercoater in town. If someone brought you something like this to bake, would you do it, or would it "contaminate" your equipment that you use for the appearance related exterior powder coating?

 

[Turdle]

I talked to a spring manufacturer to ask about re coating a set for my coilover conversion on the Turdle Mountaineer I used to have. I was told by the engineer they burn off mistakes and warranty chipped units in house, before blasting and coating. so, I did that to them.

I then burned off the set of springs in the vitamin d, no spring rate or ride height difference was noted, although I admit I did not have a scientific method to confirm this. You'll just have to take my word.

If anything was going to change from baking it would be an aluminum wheel. Guess what, your factory explorer wheels have been baked well over 350 degrees.

As far as shooting it here, my gun shoots powder. Liquid would ruin it.

 

[Carguy3J]

I talked to a spring manufacturer to ask about re coating a set for my coilover conversion on the Turdle Mountaineer I used to have. I was told by the engineer they burn off mistakes and warranty chipped units in house, before blasting and coating. so, I did that to them.

I then burned off the set of springs in the vitamin d, no spring rate or ride height difference was noted, although I admit I did not have a scientific method to confirm this. You'll just have to take my word.

If anything was going to change from baking it would be an aluminum wheel. Guess what, your factory explorer wheels have been baked well over 350 degrees.

As far as shooting it here, my gun shoots powder. Liquid would ruin it.

I was thinking more about the baking part, not shooting the coating. I guess I could just ask the local guy if he'll do it.

I don't have any plans for before/after dyno runs, but I can report/post some pics of the process, if I do end up doing it.

 

[Turdle]

If you were here we could give it a go. I'm intrigued.

My main concern is part placement - support while curing. Would the pushrod ends be the only coated part? if so they could be wrapped with wire an hung. I wouldn't want them sitting in a tray-there would be a void area where it made contact.

Will you need to mask? You will need high temp tape if you do.

 

[Carguy3J]

If you were here we could give it a go. I'm intrigued.

My main concern is part placement - support while curing. Would the pushrod ends be the only coated part? if so they could be wrapped with wire an hung. I wouldn't want them sitting in a tray-there would be a void area where it made contact.

Will you need to mask? You will need high temp tape if you do.

Yeah, I kinda was thinking about those things myself. Really, there wouldn't be any benefit to coating anything but the tips. Since I don't have guide plates, the pushrod shafts don't touch anything, hence no friction to reduce. On the other hand, since this stuff ends up being so thin, it doesn't really matter if it does get on the other parts. If they are telling you it doesn't affect bearing clearances, then I wouldn't be concerned about a little "over spray". Also, unlike the powder coating you do, there is no harm from a second "firing". So, I could always coat one part, cure, then do a second "stage" to do the areas where it was resting on the first time. The idea behind this stuff is to fill in the microscopic pores of the metal leaving behind a smoother surface, not to leave a visible surface "covering".

My concern about supporting the push rods was more along the lines of the whole "heat causing warpage/sagging" thing. I'm still kinda worried about that. If your coil springs did sag, say an 1/8 of an inch, you'd never know, and perhaps the manufacturer wouldn't be concerned about that. On the other hand,if a pushrod bends/warps even a couple thousandths it could eventually lead to severe engine damage. I would probably try it on a junk one first, just to be sure it stays straight and true. The same concern would apply to the rocker shaft. Any bending/warping there will increase friction, at best. I asked Smith Bros about all this, and they were the ones who told me not to do it, and that it would ruin the heat treatment/temper on the pushrods. On the other hand, this stuff has been the "worst kept secret" in auto racing (including NASCAR) and the high performance world, for DECADES, so maybe the guy at Smith Bros was just talking out his butt.

This coating stuff is pretty incredible in what can be achieved. There are many, many different formulations, for different purposes and different engine parts. In many cases they can even be "layered". For instance, on an intake manifold where the underside is exposed to hot engine oil, you can first apply a heat rejecting coating, followed by an oil shedding coating. This will keep it cool, both from the first layer of heat rejection, as well as preventing hot oil from clinging to the metal and transfer more heat. Bearings might get a dry film lubricant and oil retaining coating. Combustion chambers, piston tops, and valve faces can all receive a heat rejection coating, to keep as much combustion energy as possible working to move the piston down the bore, instead of being wasted as heat absorbed into the parts. It goes on and on. Technically, nearly any mechanical part, from engines, to ring and pinions, could benefit from some type of coating or another. The results are well established, and can be significant, in both increased efficiency, and part durability.