What's new
Van's Air Force

The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!

firewall-forward high temperature RTV options

D

dmn056

Well Known Member
Sponsor
There seem to be a lot of different high temperature RTV sealant options. Some one-component types that I have seen include:

Permatex 81160 High-Temp Red RTV​
Permatex 81630 Ultra Red High Temperature Gasket Maker​
Permatex Sensor Safe High-Temp Rtv Silcone Gasket Maker 85G - 81422 - PX81422​
JB Weld Hi Temp Silicone Gasket Maker and Sealant, Red​
Loctite Si 596 - Hi Temp RTV​
BOSTIK RTV 936​
FulaSeal Pro 260 Heat Resistant RTV​
Sanvo Red Super RTV Silicone Gasket Maker​

plus a number of two-component sealants.

Does anyone know any reason to choose any particular one of these for firewall-forward work, or any which should be avoided?
Are there any other options which are preferable?

Thanks for any help.
 
I use either the Permatex hi temp red sealants for 99% of my FWF needs. Only variant would be if a certain sensor specifically called out for a different sealant.
 
dmn056 said:
There seem to be a lot of different high temperature RTV sealant options. Some one-component types that I have seen include:

Permatex 81160 High-Temp Red RTV​
Permatex 81630 Ultra Red High Temperature Gasket Maker​
Permatex Sensor Safe High-Temp Rtv Silcone Gasket Maker 85G - 81422 - PX81422​
JB Weld Hi Temp Silicone Gasket Maker and Sealant, Red​
Loctite Si 596 - Hi Temp RTV​
BOSTIK RTV 936​
FulaSeal Pro 260 Heat Resistant RTV​
Sanvo Red Super RTV Silicone Gasket Maker​

plus a number of two-component sealants.

Does anyone know any reason to choose any particular one of these for firewall-forward work, or any which should be avoided?
Are there any other options which are preferable?

Thanks for any help.
Click to expand...
Dan,
When used in areas where maximum heat rating is needed, Permatex also makes an RTV rated to 700 degrees F.

Permatex 81878 Ultra Copper Maximum HIGH Temperature RTV Silicone Gasket Maker​

Permatex Ultra Copper RTV

This product is available at most auto parts stores.
 
Permatex Ultra Black at the auto parts store, also known as Loctite 598 on the commercial side. Highly adhesive, shrugs off oil and chemicals, and it's a dark charcoal color, so your engine compartment doesn't like a seagull roost.
 
DanH said:
Permatex Ultra Black at the auto parts store, also known as Loctite 598 on the commercial side. Highly adhesive, shrugs off oil and chemicals, and it's a dark charcoal color, so your engine compartment doesn't like a seagull roost.
Click to expand...
Preferable to red or gold? I'm considering the following locations:

Baffle gaps and cyl #3 "zero height" duct
Sealing cowl insulation layer edges
Case and sump parting lines (is this overkill?)
Firewall holes

Follow up question: do you like to spray exhaust gaskets or ports with anything?
 
I don't put anything on ex gaskets, but I do like high temp lubricant for the ex ball sockets. One example is mouse milk but there are other examples
 
skirting_virga said:
Preferable to red or gold? I'm considering the following locations:

Baffle gaps and cyl #3 "zero height" duct
Sealing cowl insulation layer edges
Case and sump parting lines (is this overkill?)
Firewall holes

Follow up question: do you like to spray exhaust gaskets or ports with anything?
Click to expand...
All of the RTVs have operating temps going up to 400* with the hi temps going to 450 or 500. No need for the high temp stuff in our applications. As mentioned by others, the ultra black sticks better and is more oil resistant than the others and therefore the best choice FF on the RVs. While RTV sticks to a lot, it doesn't like oil and the black does better at not letting oil migrate into the adhesion zone.

I would NOT recommend RTV being applied on the sump case sealing line. It will make a mess and all but gauranteed to not seal any leaks there. There are other approaches that have a chance of sealing that.
 
skirting_virga said:
Preferable to red or gold? I'm considering the following locations:

Baffle gaps and cyl #3 "zero height" duct
Sealing cowl insulation layer edges
Case and sump parting lines (is this overkill?)
Firewall holes

Follow up question: do you like to spray exhaust gaskets or ports with anything?
Click to expand...

Yes.
Yes.
Yes, but unnecessary if you'll finish the inside of the cowl with a good two-part paint. Vans self-stick foil adheres very well to a painted surface.
No, but not due to sealant choice. It's just generally useless. Sometimes you can stop a spot leak with proseal. If oil makes you unhappy, replace all the slotted hose clamps on the drainback tubes.
No. Use an intumescent sealant.
 
DanH said:
Yes.
Yes.
Yes, but unnecessary if you'll finish the inside of the cowl with a good two-part paint. Vans self-stick foil adheres very well to a painted surface.
No, but not due to sealant choice. It's just generally useless. Sometimes you can stop a spot leak with proseal. If oil makes you unhappy, replace all the slotted hose clamps on the drainback tubes.
No. Use an intumescent sealant.
Click to expand...
We've used the high temp red for sealing our hose cuffs for years.
 
Some informational drift.

In technical discussions with aerospace grade RTV suppliers when I worked in that industry a million years ago, the stated difference between regular RTV and high temp was pretty basic. The higher temp was the same base as the lower temp rated material. The basic colorant was deleted and powdered iron oxide was added to help diffuse heat through and ultimately transfer out of the polymer. Products and processes could have changed in the years since but probably not much if at all.
 
You must log in or register to reply here.
Back
Top