Under-Hood Insulation

[Another Ahab]

From recent posting of a new member, regarding his 5-ton, but likely applies across the board for all MV's (with a hood that is, armor naturally excluded):

You might look into sheet Kflex insulation/sound deadener for under the hood. While not required by any means it will quiet the truck some.

Any good reason NOT to install insulation like Kflex (i.e.trapping engine heat in the summer months, etc)?

I recognize it's a judgement call, but wondering if any strong opinion (war stories/experience), one way or the other ("insulate" hood' or "don't insulate").

 

[Jeepsinker]

I saw a 5 ton recently that caught fire and burned down because some of the hood insulation rotted and fell onto the turbo. I would put any and all insulation inside the cab after seeing that. That was a real eye opener. Have another 5 ton in the yard right now that has some melted insulation on the turbo....

 

[stampy]

Well I agree the above post was about replacing rotten insulation with new and the Kflex stuff is good stuff IMO but it may be just as easy not to replace it. I had planned to do my 5 ton and deuces with it to quiet them down so I have some of this stuff an it works well in dampening noise. I plan on putting a heat shield material in front of it to keep heat out of the cab too.

 

[Jeepsinker]

If you can keep it from falling on the engine even if the adhesive breaks down or it rots go for it. But I would be sure to carry a couple of good fire extinguishers with you. I carry four purple k extinguishers and one halon extinguisher in my truck. I'm really fire paranoid.

 

[Another Ahab]

I wouldn't say that you're fire paranoid, as much as fire aware.

My brother is a fire captain in North Carolina, and talks with him over the years have made me more -let's say- alert about fire. Because when it goes wrong, it can go real wrong, REAL fast. So I hear you.

 

[Clay James]

Put a heat shield on the turbo!

 

[Another Ahab]

Well, true, that's one solution; a lot of ways to skin a cat...

Closing the loop on this thread; it seems like a toss-up FOR and AGAINST installing under-hood insulation:

- Arguments AGAINST point to problems from insulation braking up and falling into the engine compartment

- Arguments FOR point to reduction in heat and noise.

So, there's no real consensus here on this issue. And on that note, consider this thread closed. Aloha.

 

[Jeepsinker]

Well what is the end goal of applying the insulation to your truck? You trying to cut down in cab noise, or all around noise?

 

[Another Ahab]

Good question, thank you:

- cutting down on the cab noise.

- already insulated at the firewall, to keep out noise AND heat (in Summer), and maybe that's good enough.

 

[Jeepsinker]

I assume you used a product similar to dynamat to do the firewall, I used some rubberized spray coating to do the engine bay side of my firewall ( flexseal) and put it on thick. Works pretty well and looks good, cleans up of oil easily. No reason you couldn't do the inside of the whole engine bay with a similar product, and there are better options of product to use for that. J.C Whitney has a good selection. And then there is nothing to fall on hot parts and burn or rot away.

 

[Another Ahab]

Thanks for the feedback, Jeepsinker. And yes, it was DynaLiner I installed at the firewall.

And I believe that I am overthinking the whole issue, and that I'll leave it all be as is for now.

Easy enough to come back later and add DynaLiner to the inboard side of the hood, or spray your recommended FlexSeal at the engine compartment, if needed.

I fall into going overboard on the details sometimes, and need to remind myself (like I'm doing now) to throttle back. I mean it's a Deuce, right?! It's just a Deuce.

 

[Jeepsinker]

Well yeah it's just a deuce, but that doesn't mean you can't polish up the ol' turd. And just to be clear, I used flex seal and it works ok. If I were to do it again I would use a product made for the specific application. Purpose built products will work a ton better and they aren't that expensive. Take a look at J.C. Whitney

 

[Dracoheart]

Once i get my deuce i will be adding a fair amount of Dynaliner in the engine bay. I have many friends with diesels and rotarys that battle heat on a daily basis. I know RX7s always deal with massive amounts of heat and some even go as far as insulating the ENTIRE engine bay and wrapping any and everything they can to bring down underhood temps since most run between 9,000-13,000 RPM.

I would cover the turbo on the deuce and wrap the down pipe all the way to the J-tube. I would also cover the underside of the hood, inspection panels, and firewall.

 

[Another Ahab]

even go as far as insulating the ENTIRE engine bay and wrapping any and everything they can to bring down underhood temps since most run between 9,000-13,000 RPM.

But isn't that insulation now TRAPPING the heat inside the engine compartment?

"Cover the turbo", sure to contain the heat generated there. But then any heat under the hood is best allowed to bleed off, right (i.e., NO insulation along the engine compartment sidewalls and under the hood)?

 

[Clay James]

There is the vents on the inner fenders and the open areas on the back of them that should allow the heat to blow out from the fan and driving.

 

[wb9btz]

All M35A3s have fully insulated hoods and side panels as built from AM General. The insulation is riveted on with long rivets through large washers for support. So it can be done if properly supported so as not to fall on anything hot.

 

[Dracoheart]

But isn't that insulation now TRAPPING the heat inside the engine compartment?

"Cover the turbo", sure to contain the heat generated there. But then any heat under the hood is best allowed to bleed off, right (i.e., NO insulation along the engine compartment sidewalls and under the hood)?

Like Clay said, that is where proper ventilation comes into play. There is a reason you see those cars with deep hood vents and cut outs at the rear of the hood all to let heat out while driving.