12a Rebuild: Repainting the Oil Pan
06-29-14, 05:53 PM
#1
12a Rebuild: Repainting the Oil Pan
12a Rebuild continued.....
Almost everything has been cleaned.
When I first pulled the oil pan I found rust on the exterior along with bare metal and some paint.
After cleaning the inside I found some rust, some bare metal, some paint, and some paint flakes on the oil pickup strainer.
I had planed on painting the exterior.
Is it recommended to repaint the inside?
Any suggestion on process?
I've removed all the loose paint inside and out.
Should I sand down to bare metal, or is there an alternate?
Images attached, prior to final cleaning, showing rusted areas.
Thanks as always for your help.
Almost everything has been cleaned.
When I first pulled the oil pan I found rust on the exterior along with bare metal and some paint.
After cleaning the inside I found some rust, some bare metal, some paint, and some paint flakes on the oil pickup strainer.
I had planed on painting the exterior.
Is it recommended to repaint the inside?
Any suggestion on process?
I've removed all the loose paint inside and out.
Should I sand down to bare metal, or is there an alternate?
Images attached, prior to final cleaning, showing rusted areas.
Thanks as always for your help.
06-30-14, 01:09 AM
#6
Do you have any rust problems? If anything, paint your pan silver metallic or white. Why? The white won't absorb any additional heat from your hot socal roads, if that was ever even possible(?) or silver metallic because maybe the metal flake will help transfer heat without allowing rust. What do you think? The added benefit is you'll be able to tell instantly whether you have an oil leak or if it's just dirty. It looks better than rust too.
06-30-14, 10:16 AM
#7
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,832
Received 2,603 Likes
on
1,847 Posts
from the factory the oil pan is just painted black inside and out, obviously with oil in it, it won't rust, so the interior paint isn't very important, might be better to just leave it bare
Trending Topics
06-30-14, 10:55 AM
#9
I used electrolysis on mine to deal with the rust, sprayed it with metal ready from POR-15, then painted the outside black with high temp paint... Wish I had thought of the silver idea before I installed it... 
I didn't chime in on the recent question about using a gasket or not, but I followed the FSM which says to use 4mm bead of sealant on either side of a gasket to seal the oil pan. Obviously there are several schools of thought about using a gasket or not.
I didn't chime in on the recent question about using a gasket or not, but I followed the FSM which says to use 4mm bead of sealant on either side of a gasket to seal the oil pan. Obviously there are several schools of thought about using a gasket or not.
06-30-14, 05:25 PM
#11
Not sure about the thermodynamics of the exterior paint on the oil pan; my car's always run borderline too cold so it's never been something I thought about.
Seems like the pan (when full of hot oil) would be hotter than any road surface nearby, so it's unlikely to pick up any heat from the road; direction of differential heat flow is wrong.
Main question would be which color paint is better at radiating heat (some black coatings actually radiate better than lighter colors; no interlayer reflection of the thermal energy back into the coated surface), and if the insulating quality of the paint & it's binders wouldn't make the color moot.
Sadly, I know just enough physics on the subject to grasp most of the questions, but not enough to work up the answers.
Seems like the pan (when full of hot oil) would be hotter than any road surface nearby, so it's unlikely to pick up any heat from the road; direction of differential heat flow is wrong.
Main question would be which color paint is better at radiating heat (some black coatings actually radiate better than lighter colors; no interlayer reflection of the thermal energy back into the coated surface), and if the insulating quality of the paint & it's binders wouldn't make the color moot.
Sadly, I know just enough physics on the subject to grasp most of the questions, but not enough to work up the answers.
06-30-14, 05:57 PM
#12
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,832
Received 2,603 Likes
on
1,847 Posts
i do have a data point though, when i'm waiting for the race car to come around and take tire temps, i'll usually take track temp too, on a 100f day its usually in the 130f range... so its still colder than the car, and not by enough to really matter. black asphalt is hotter than light concrete.
06-30-14, 11:32 PM
#14
84SE-EGI helpy-helperton
The physics behind this is that black both absorbs and radiates heat faster than any other color; this has to do with the color itself, which is not truly black, but absorbing of all colors in the spectrum EXCEPT black. That's a mind-twister, but true of any color you visually 'see'. Yellow, for example absorbs all wavelengths of the visual light spectrum except yellow - which it reflects, and therefore is what your eye detects.
A quick test of the physics would be to take a white and black car and take laser temp readings after 4 hours of sitting in the sun - the black car would be hotter, since it absorbed more light energy (all visible spectrum wavelengths EXCEPT black) than white. Then, after dark retest the temp readings 4 hours after sunset - and the black car would detect cooler (radiating all visible spectrum wavelengths except black) compared to white. Though this may seem counterintuitive, check it out in a physics text book for confirmation.
So, if you're trying to radiate as much heat energy as possible (not part of the visible spectrum unless you're a snake), paint your oil pan black. If you're trying not to absorb heat from other sources nearby, paint it white - but know that it will retain more heat for a longer duration of time.
A quick test of the physics would be to take a white and black car and take laser temp readings after 4 hours of sitting in the sun - the black car would be hotter, since it absorbed more light energy (all visible spectrum wavelengths EXCEPT black) than white. Then, after dark retest the temp readings 4 hours after sunset - and the black car would detect cooler (radiating all visible spectrum wavelengths except black) compared to white. Though this may seem counterintuitive, check it out in a physics text book for confirmation.
So, if you're trying to radiate as much heat energy as possible (not part of the visible spectrum unless you're a snake), paint your oil pan black. If you're trying not to absorb heat from other sources nearby, paint it white - but know that it will retain more heat for a longer duration of time.
06-30-14, 11:54 PM
#15
The tricky bit is, what we're mainly looking at here is not visible-spectrum light, but heat, which is to say infrared radiation, in the spectrum just below visible red.
Some items (including paint pigments) that are fully absorptive in visible light, and so appear black, are actually highly reflective of infrared light. Others absorb it. Just as some glass readily passes infrared and others reflect it. Infrared security cameras have to use IR-corrected lenses to focus properly at night because the index of refraction of the lens is a functions of the light's wavelength (iow, it's color).
I recently was working with some infrared security cameras, and was amazed to see that some items in the wife's store that are black-pigmented reflect IR so strongly as to appear white. The other weird thing is that the clear-glass thermal doors on the beer cooler look like mirrors in IR, yet in normal light the camera sees right through them.
Some items (including paint pigments) that are fully absorptive in visible light, and so appear black, are actually highly reflective of infrared light. Others absorb it. Just as some glass readily passes infrared and others reflect it. Infrared security cameras have to use IR-corrected lenses to focus properly at night because the index of refraction of the lens is a functions of the light's wavelength (iow, it's color).
I recently was working with some infrared security cameras, and was amazed to see that some items in the wife's store that are black-pigmented reflect IR so strongly as to appear white. The other weird thing is that the clear-glass thermal doors on the beer cooler look like mirrors in IR, yet in normal light the camera sees right through them.
07-01-14, 12:38 AM
#16
Makes sense, LongDuck. I always paint my pans black anyway. Good to know there was a sciencerific reason why.
Divin, you think that's cool, go find an old Sony playstation CD; the black looking ones, or if you have some NyQuil, look through them with your IR camera. It's interesting. Oh and look at a Sharpie. The ink they use is probably IR, because it seems to reflect kind of a dark red in sunlight. And yes some fabrics are IR, not black.
Up next, get yourself an IR glass filter and make up kind of a welding mask and go out walking around on a sunny day. The sky is really dark but any vegetation, including those trees with the purple leaves, is very, very bright. Just don't go driving a car with it because the newer LED tail lights don't show up like the old incandescents do. Don't want to rearend anybody.
Oh yeah, one more thing. Your story reminded me of when I made an IR viewer using an old tube from WWII with high voltage and didn't use a filter over it. Tried to look at a candle. There were two images. The visible one and the IR one. I noticed the IR was at a different wavelength and had to adjust the focus to compensate. Fun stuff.
Divin, you think that's cool, go find an old Sony playstation CD; the black looking ones, or if you have some NyQuil, look through them with your IR camera. It's interesting. Oh and look at a Sharpie. The ink they use is probably IR, because it seems to reflect kind of a dark red in sunlight. And yes some fabrics are IR, not black.
Up next, get yourself an IR glass filter and make up kind of a welding mask and go out walking around on a sunny day. The sky is really dark but any vegetation, including those trees with the purple leaves, is very, very bright. Just don't go driving a car with it because the newer LED tail lights don't show up like the old incandescents do. Don't want to rearend anybody.
Oh yeah, one more thing. Your story reminded me of when I made an IR viewer using an old tube from WWII with high voltage and didn't use a filter over it. Tried to look at a candle. There were two images. The visible one and the IR one. I noticed the IR was at a different wavelength and had to adjust the focus to compensate. Fun stuff.
07-01-14, 08:19 AM
#17
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,832
Received 2,603 Likes
on
1,847 Posts
i recall the light blue car being the hottest actually, but this was like 20 years ago!
we also got out hands on a g tech once, that was FUN, the parts truck ran a 17.8...
07-01-14, 08:21 AM
#18
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,832
Received 2,603 Likes
on
1,847 Posts
oh and the most recent neat test was to photocopy money. take an old style dollar, a new style dollar, and try them individually and then together, its neat.
07-02-14, 10:34 AM
#25
Dupli-Color DE1651 Cast Coat Iron
Dupli-Color® Engine Enamel With Ceramic™ DE1651 - Engine Spray Paint | O'Reilly Auto Parts
https://www.rx7club.com/1st-generati...k-12a-1061516/