Some recent discussions have mentioned heat entering the passenger compartment and (seriously) affecting ambient cabinet temps. I am about to pull the engine/tranny and stripping my Jag to bare metal
From my foxhole, there appears to be three approaches to containing / preventing / shielding heat from entering the passenger cabin (what did I miss?):
Factory Applied Seals, Plugs, and Grommets. These can be negatively affected by age and (ironically) heat. I have no idea how many there are but they are found on the firewall, transmission tunnel and who-knows where else.
Factory Applied Heat (asbestos appearing?) Shields. On the Series III there are 6: LH + RH vertical shields on the join of the firewall and tranny tunnel, LH + RH Forward Heat Shields (betw tranny and mufflers), a single Muffler Heat Shield (betw mufflers and floor pan) and what I call the IRS Heat Shield (fits inside the IRS cradle). There may be more or less on the earlier series.
After-market Heat Insulation. The most oft mentioned is DynaMat but there are several options. They come in various thicknesses and materials.
IMHO the seals, plugs, and grommets are a no-brainer. Leaving them out or not renewing them allows hot air to be literally blasted into the passenger cabin.
My question is: given the technological advancements in the after-market peal and stick (peal and seal?) items, is there utility to applying / installing (some or all) of the Factory Applied heat shields?
Let’s eliminate the concours-correct argument from the get-go-- I am seeking the best combination and technique(s) to keep the passenger cabin as cool and comfortable as a 45-55 year old sports car can be.
Put Eastwood’s Xmat, a Dynamat like product, on the floors, transmission hump, firewall, and drive shaft hump. I also applied it to the transmission side of the transmission tunnel cover.
I applied a self sticking insulation, silver face and insulation backing, to the transmission side of the tunnel.
I made sure all the plugs and grommets were doing what they were suppose to do.
Small gaps make a big difference. I thought I had the hole where the AC hoses come through the bulkhead pretty well sealed. The first highway drive of the summer convinced me otherwise. At 70 mph the air coming through there felt like a hair drier set on hot and medium fan speed. I stuffed some foam rubber in there from the cockpit side and eliminated that air source.
The interior is livable on the highway after 2 hours in the sun on a 95 F degree day. The flipper windows were open and the dash vents were set to dump air into the foot wells. The latter would work better if the air didn’t have to make it’s way through a steel tunnel in the engine compartment containing 500 lbs. of hot iron and aluminum.
This leads me to questioning if there would be an advantage to insulating the heater air intake channel in the engine compartment as it runs right by the exhaust manifolds. I suspect at highway speeds enough air moves through that it does not matter much but in city driving it might help a lot.
Can you expand on why you choose Eastwood over DynaMat?
I read a review on Eastwood’s Xmat: “Only downside is on a hot day, the thick adhesive side will melt into black tar and flow like water wherever there’s an opening.” Have you experienced such oozing?
How long ago did you put Xmat in your Jag.
In hindsight, what would you have done differently?
When I had mine torn down… well MORE torn down, I got the expensive silicone thermal mat stuff, can’t remember the name now but it lined every inch of the floorboard and tunnel in the cabin. Then did the reflective Home Depot stuff the entire length of the tunnel from inside the tunnel.
DON’T FORGET THE PILLOW FOAM OVER THE TRANS !!!
Drove a rally in Austin TX with temps in the high 90’s with no problem other than sunburn on one arm.
I did not insulate that duct but rather blocked it. Seems that even with the heater valve off the core gets hot and air gets past the flap - so I cut the rim off a plastic lid to fit over the screen:
My TR6 would get so hot in the passenger footwell my wife did not want to ride very long.
I decided to wrap the exhaust pipes from manifold to behind the cockpit. I used HeatShield Products 175111 available from Summit Racing. Not cheap stuff, but worked wonders. I can actually put my hand on top of carpet and not feel a thing anymore.
Cut to fit and secure with available straps or stainless wires using kraft paper to make patterns. The company provides great how to.
Did not want to use Dynamat or other such tar based insulation. It is very difficult to remove if required.
I’ve experienced no oozing or melting tar. The black goo is butyl rubber, not tar. Eastwood claims it withstands temperatures up to 350F. Dynamat says it’s stuff is butyl based and withstands 300F.
Differently? Looking through the retrospectoscope I guess I should have added some kind of insulation over the drive shaft hump. Under the console area between the white arrows in the below picture.
I had a local shop coat the entire exhaust system from the manifolds on back to the tail pipes with Jet Hot type ceramic. Then I scrapped the factory heat shields for a full width aluminum honeycomb belly pan above the exhaust system. A high temp foam is sandwiched between the belly pan and the floor. These items are in addition to the previously mentioned improvements. So, heat control on the outside of the cab, sound control on the inside.
I’d be curious to know how one gets insulation inside the drive shaft tunnel. Heated air in the engine compartment in, in part, funneled back through the transmission tunnel, alongside the bell housing and transmission and makes it’s way down that tunnel along side the drive shaft. The only way to insulate that area is to apply something to the cabin side of the driveshaft tunnel.
Hi Craig,
Here’s my 0.02$ worth, proceed with steps 1 & 2 and forget step 3. I think that the S3 has much better heat and noise insulation than the earlier cars that your going to be wasting your money and time.
If you decide to chase that rabbit consider Koolmat, for heat insulation I believe it is far superior to the peal and seal products.
