Gas tank reflective heat coating

L

lw8000

Member
Jul 30, 2012
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Side topic to the other threads going about vapor lock feedback. I've read here before about positive results on coating the fuel tanks with a heat
reflective material, to help the tanks from absorbing road/engine heat. I believe that we have experienced fuel boil in the tanks last year in 93+
degree temps on the Interstate highways. On the hottest days, the gas cap was making a noise and upon opening the cap, fuel actually gushed out.

I figured it certainly can't hurt anything by doing this and I can see a number of benefits. To me, having the tanks under that much pressure sounds
dangerous. Has anybody had positive results and what did you use?

Thanks as always.
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
 
I used the correct gas cap. Read the service manual re: pressure in the
fuel tanks and vented vs semi vented caps.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

Side topic to the other threads going about vapor lock feedback. I've read
here before about positive results on coating the fuel tanks with a heat
reflective material, to help the tanks from absorbing road/engine heat. I
believe that we have experienced fuel boil in the tanks last year in 93+
degree temps on the Interstate highways. On the hottest days, the gas cap
was making a noise and upon opening the cap, fuel actually gushed out.

I figured it certainly can't hurt anything by doing this and I can see a
number of benefits. To me, having the tanks under that much pressure sounds
dangerous. Has anybody had positive results and what did you use?

Thanks as always.
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan

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Also - if there is pressure at the gas cap doesn’t that suggest that the vent system is inop?

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, CA
Howell EFI + EBL + Electronic Distributor

>
> I used the correct gas cap. Read the service manual re: pressure in the
> fuel tanks and vented vs semi vented caps.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>

>
> Side topic to the other threads going about vapor lock feedback. I've read
> here before about positive results on coating the fuel tanks with a heat
> reflective material, to help the tanks from absorbing road/engine heat. I
> believe that we have experienced fuel boil in the tanks last year in 93+
> degree temps on the Interstate highways. On the hottest days, the gas cap
> was making a noise and upon opening the cap, fuel actually gushed out.
>
> I figured it certainly can't hurt anything by doing this and I can see a
> number of benefits. To me, having the tanks under that much pressure sounds
> dangerous. Has anybody had positive results and what did you use?
>
> Thanks as always.
> --
> Chris S. -
> 77 Kingsley, 3.70 FD, mostly OEM -
> S.E. Michigan
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> _______________________________________________
> GMCnet mailing list
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You think?
Jim Hupy

> Also - if there is pressure at the gas cap doesn’t that suggest that the
> vent system is inop?
>
>
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, CA
> Howell EFI + EBL + Electronic Distributor
>

> >
> > I used the correct gas cap. Read the service manual re: pressure in the
> > fuel tanks and vented vs semi vented caps.
> > Jim Hupy
> > Salem, Or
> > 78 GMC ROYALE 403
> >

> >
> > Side topic to the other threads going about vapor lock feedback. I've
> read
> > here before about positive results on coating the fuel tanks with a heat
> > reflective material, to help the tanks from absorbing road/engine heat.
> I
> > believe that we have experienced fuel boil in the tanks last year in 93+
> > degree temps on the Interstate highways. On the hottest days, the gas
> cap
> > was making a noise and upon opening the cap, fuel actually gushed out.
> >
> > I figured it certainly can't hurt anything by doing this and I can see a
> > number of benefits. To me, having the tanks under that much pressure
> sounds
> > dangerous. Has anybody had positive results and what did you use?
> >
> > Thanks as always.
> > --
> > Chris S. -
> > 77 Kingsley, 3.70 FD, mostly OEM -
> > S.E. Michigan
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> Also - if there is pressure at the gas cap doesn't that suggest that the vent system is inop?
>
>
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, CA
> Howell EFI + EBL + Electronic Distributor
>

> >
> > I used the correct gas cap. Read the service manual re: pressure in the
> > fuel tanks and vented vs semi vented caps.
> > Jim Hupy
> > Salem, Or
> > 78 GMC ROYALE 403
> >

On that same trip, we stopped at the Co-Op and they checked over the fuel system including the venting ... all checked out OK.

Noted on the gas cap, I will check.

That said, based on some of the data collected with the temps of those tanks (due to a combination of multiple things), it sounds like the temps there
can be lowered with some basic shielding. To me having the temps of the tanks reaching 140+ is only escalating the vapor lock issues.
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
 
Below is the site that shows the paint I used on our tanks. Our Caddy motor has a fuel pump that has a return line. This is suppose to keep the fuel
always moving to eliminate hot spots on the fuel line (vapor lock) We also have an electric fuel pump connected to the aux tank if we would need it.

http://www.gmcmhphotos.com/photos/heat-shield-paint-for-gas-tanks-and-lines/p22343-paint-at-mcmaster-carr-p-2fn-7873t4-it-claims-to-reflect-more-then-90-25-of-h.html

Jim Wagner
Brook Park, oh
76 GMC500
71 Vega355
69 Corvette383
 
I painted mine white on the bottom. It is not any kind of 'insulating' coating, and I can't say that it makes any more than a marginal difference.

I think actually insulating the tanks, like Our fellow member, Armand Minnie did will make much more of a difference:

http://minniebiz.com/gmcmotorhome/2017/02/25/insulating-the-fuel-tanks/
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
One thing mentioned struck me from the article..
Quote:
> The opening in the fuel/vapor separator is about 1/16″.... There are approximately 20 square feet of fuel in those tanks and that much boiling
> fuel cannot be adequately vented through a 1/16″ opening

Are there any easy-ish solutions that will prevent the pressure build up in the tanks and not leave the Coach smelling like gas, or on fire?

I also run into all of the symptoms mentioned in that article. On a hot day I get a huge swoosh when I take the cap off and then can hear the tanks
boiling. Once recently I removed it, got a big swoosh then a few seconds pause before about a pint of gas shot about 5 feet up out of the fill neck.
The pressure definitely seems a bit excessive.

Once the tanks heat up the coach seems to get starved for fuel around 60-65MPH. I'm guessing this is the fuel vaporizing because the pressure in
carb bowl is the lowest it has seen in quite a while.

My fixes to date..
the electric pump wired on the Aux fuel tank switch..
I added the fuel pump with the return line .. (prior to this the coach would just die when the tanks got too hot)
I believe I have the proper vented cap (it came from JimK).
Had the vapor separator changed out at Sirum's (saw quite a bit of improvement after this)
I don't run into any problems when i'm fortunate enough to hit an ethanol free gas station.

Tank insulation seems like a possible solution but I do worry that this would also prevent ambient air from cooling the tanks. Is there more that can
be done that involves the ethanol safely boiling off and venting away before it gets to the fuel pump?

--tim

--
Tim Taylor
Austin TX
76 Birchaven (SB)
76 Triumph TR6
 
Chris,

This may create some debate....

When the temperature of the radiant source is less than ~1000 F, color does not make any difference with respect to the amount of that will be
absorbed by the receiving surface. Since the road surface does not (hopefully!) reach this high of a temperature, all colors of gas tank will absorb
heat via radiation equally. The only difference maker is if the receiving surface has an aluminum finish. A clean aluminum finish will have an
absorption of ~0.1, aluminum paint will be 0.3 to 0.6 and all colors are ~0.94.

My experience in heat transfer is that adding color (even white) will not decrease the temperature rise of the gas tanks due to radiant heat from the
road surface.

If need be, I will post on the photo site a graph from a DuPont white paper that shows this data.

Blocking the exhaust crossover and utilizing an electric fuel pump have solved (so far) my vapor issues.

--
Joe Ricke - KE0CPM
Arden Hills, MN
'77 Transmode
 
That may be true for absorption but for reflectance lighter colors will reflect more heat.

Emery Stora
77 Kingsley
Frederick, CO

>
> Chris,
>
> This may create some debate....
>
> When the temperature of the radiant source is less than ~1000 F, color does not make any difference with respect to the amount of that will be
> absorbed by the receiving surface. Since the road surface does not (hopefully!) reach this high of a temperature, all colors of gas tank will absorb
> heat via radiation equally. The only difference maker is if the receiving surface has an aluminum finish. A clean aluminum finish will have an
> absorption of ~0.1, aluminum paint will be 0.3 to 0.6 and all colors are ~0.94.
>
> My experience in heat transfer is that adding color (even white) will not decrease the temperature rise of the gas tanks due to radiant heat from the
> road surface.
>
> If need be, I will post on the photo site a graph from a DuPont white paper that shows this data.
>
> Blocking the exhaust crossover and utilizing an electric fuel pump have solved (so far) my vapor issues.
>
> --
> Joe Ricke - KE0CPM
> Arden Hills, MN
> '77 Transmode
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Shields will give the best protection, as long as there is an air space between shield and tank. It only needs to be 1/4 to 1/2 inch of space.
However, they will be very hard to fasten secure enough so that they do not flap in the breeze. If they are made with a third dimension, they will be
much stiffer and flap-resistant.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
I was thinking about using something like dynamat on the bottom of my tanks. Lowes sells stuff called peelnseal its not as thick as the good sound
barriers like dynamat but it will still reflect heat and insulate.
--
1976 Palm Beach 26'
 
Joe,
I recall in or freshman Physics lab the Black Body Principal .
As I recall the color mad a difference in the way the object dissipated
heat, also it absorbed heat better.
I realize radiant heat is different, but there must be some reflective
light that bounces off the ground and heats the tank, so a light color
should help.

> I was thinking about using something like dynamat on the bottom of my
> tanks. Lowes sells stuff called peelnseal its not as thick as the good sound
> barriers like dynamat but it will still reflect heat and insulate.
> --
> 1976 Palm Beach 26'
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Emery and Jim K,

Agree that any solar radiation reflected from the road surface would be absorbed less by a white or a lighter color object.

In this application, I don't see much reflection from the road to the tanks happening. The road surface is generally darker in nature and thus
absorbs a large amount of solar the radiation striking it (that is why it gets so dang hot). The tanks are mostly exposed to shaded road by the GMC
above, greatly decreasing the amount of reflected radiation that can reach them.

Jim - I can barely remember any of this from Physics..... But have spent the last 30 years advising customers on design of electrical enclosure
systems. For outdoor applications, temperature rise due to solar radiation is a major consideration.

--
Joe Ricke - KE0CPM
Arden Hills, MN
'77 Transmode
 
I disagree completely.

Well sort of, Yes no solar radiation will be adsorbed, I mean theres not much light under the coach!

BUT, there _is_ a high amount of infrared radiation coming off that black asphalt, have you ever walked barefoot on an asphalt road in the summer? Did you do it twice? I bet not, it's 150 degrees or more. The road is like a huge heat lamp pointed right at the tanks so the tanks need to be insulated, and IR reflective to slow the adsorption rate. concrete will emit less heat since it's both cooler and less emissive. Black surfaces bot adsorb and emit better than white, but they will still add heat to the underbelly of the vehicle.

There's also the engine heat keeping the air wash from cooling the tanks and the exhaust pipe running next to both tanks, plenty of ways to cook the fuel.

________________________________
From: Gmclist on behalf of Joe Ricke
Sent: Friday, June 9, 2017 10:43:38 AM
To: gmclist
Subject: Re: [GMCnet] Gas tank reflective heat coating

Emery and Jim K,

Agree that any solar radiation reflected from the road surface would be absorbed less by a white or a lighter color object.

In this application, I don't see much reflection from the road to the tanks happening. The road surface is generally darker in nature and thus
absorbs a large amount of solar the radiation striking it (that is why it gets so dang hot). The tanks are mostly exposed to shaded road by the GMC
above, greatly decreasing the amount of reflected radiation that can reach them.

Jim - I can barely remember any of this from Physics..... But have spent the last 30 years advising customers on design of electrical enclosure
systems. For outdoor applications, temperature rise due to solar radiation is a major consideration.

--
Joe Ricke - KE0CPM
Arden Hills, MN
'77 Transmode

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Keith,

The issue is that at source temperatures of less than ~1300 F, the absorption of a white painted surface is the same as black or any other color.

I know it sounds wrong. This is because we are used to dealing with the sun as a radiator. Yes, an asphalt road is hot (+150F) but the heat you feel
on your bare foot is from conduction not radiation. The engine heat you mention is forced convective transfer to the tanks and definitely a
consideration.

Unless the road temperature is greater than 1300 F the radiation emitting from it is absorb equally no matter what color the tank surface.

Even when sitting in front of a fireplace, the radiation will be absorbed equally whether you are wearing a white or black shirt. Go outside into
sunshine with the higher temperature, solar source and heat will be absorbed more than 10 times greater with a black shirt compared to a white one.

I am travelling (in GMC!) this weekend. When I return, I will add graphs and explanation from a DuPont white paper to photo site.

Have a great weekend
--
Joe Ricke - KE0CPM
Arden Hills, MN
'77 Transmode
 
Thank you for the explanations... all good to know. I've been tossing around the idea of either painting the tanks (which sounds like it only has a
minimal benefit) vs. installing aluminum shielding. I too have had excellent luck with other aluminum based shielding in different applications. The
problem here is finding something that will fit under the tanks, not collect moisture or debris, yet keep the heat away from the tanks from the road
bed, engine, exhaust, etc.). Another idea I thought about is putting a diverter to reflect the hot air down and away from the tanks but that probably
won't help much.

Lots of good thoughts and info, thank you!!
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
 
I'll tell you a story and admit I know little about what is or was used. My next door neighbor here in Indiana moved to Phoenix and built a new home
there. I visited shortly after he moved in and his daughter had her feet bandaged due to bad burns on both. She had walked on the couple of months
old concrete in her bare feet in July. He told me that there was something that they usually paint on the new concrete around there that prevents
excessive heat build up. He had not done that. He showed me the difference in heat build up between his and the neighbors concrete. I have no idea
what that product is or was. This was 25 or 30 years ago.

Could something like this be used on our tanks?
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Ken,

Here you go:

https://www.environmentalcoatings.com.au/eca_products/insultec-heat-reflecti
ve-paint/

Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Ken Burton

I'll tell you a story and admit I know little about what is or was used. My
next door neighbor here in Indiana moved to Phoenix and built a new home
there. I visited shortly after he moved in and his daughter had her feet
bandaged due to bad burns on both. She had walked on the couple of months
old concrete in her bare feet in July. He told me that there was something
that they usually paint on the new concrete around there that prevents
excessive heat build up. He had not done that. He showed me the difference
in heat build up between his and the neighbors concrete. I have no idea
what that product is or was. This was 25 or 30 years ago.

Could something like this be used on our tanks?
--
Ken
 
Joe,
Thank you for explaining it .
I thought that I was very familier with airflow till I encountered some
phenomena that I was not aware of in clean room.

> Thank you for the explanations... all good to know. I've been tossing
> around the idea of either painting the tanks (which sounds like it only has
> a
> minimal benefit) vs. installing aluminum shielding. I too have had
> excellent luck with other aluminum based shielding in different
> applications. The
> problem here is finding something that will fit under the tanks, not
> collect moisture or debris, yet keep the heat away from the tanks from the
> road
> bed, engine, exhaust, etc.). Another idea I thought about is putting a
> diverter to reflect the hot air down and away from the tanks but that
> probably
> won't help much.
>
> Lots of good thoughts and info, thank you!!
> --
> Chris S. -
> 77 Kingsley, 3.70 FD, mostly OEM -
> S.E. Michigan
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
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