Hi, I have an early Series 1 XJ. I've got an issue where I'm getting quite a fair of heat coming through the firewall into the cabin. Usually after about 30mins of driving, I get a fair amount of heat coming up in the foot well and under the dashboard.

So I'm guessing it's the engine/exhaust heat getting into to the cabin?
I've disconnected the heater core, so I don't think it's heater related.

Has anyone else experienced this issue? Is it a common problem with XJs or is it an issue with my car?

Any advice/help greatly appreciated
Cheers
Michael

 

I get the same thing, first thing I did was bypass the heater core at the vacuum tap. Made no difference.
I just put it down old car with little insulation. It is what it is and I open the windows for now until JF member "paulyling" checks out my air con for me.

Must reconnect that heater tap one day(not needed in Qld)

 

is it heat-transmission from the engine compartment to the interior, or is it actual hot air coming in the cabin from the engine compartment?

if heat is being transmitted, then it is lack of insulation.

if hot air is coming in, then there is obviously an open passage; air is like water, it will find any cavity to come in.

at the front of the transmission tunnel, on either side of the tunnel, towards the side of the accelerator pedal, there is a removable panel, you have to raise the carpet and any insulation under the carpet to see them on both sides. They are held by about 12 screws.

these panels were caulked at the factory and then screwed into place. If the caulking has deteriorated, air and water will come through. In some cases a mildew odor is a dead giveaway.

worth checking. If you remove them, use silicone caulking/sealant when you reinstall them.

 

To add to what Jose said, you could try using a heat insulating product like dynamat aound the transmission tunnel if its not hvac related
Dynamat.com | Dynaliner for Automotive Use

 

Thanks guys. I don't think it's any hot air coming into the car. That was my first line of thinking. There is definitely heat around the transmission area in the cabin and floor of the car. I also noticed, that when I had the radio out of my car, the cavitiy where the radio sat, the was alot of heat in there too. So I might look into some insulation.

So I would be better off investing in insulation around the transmission tunnel, the engine firewall? Or both?

 

yes, the entire front area of the cabin, flloor, tunnel and interior side of firewall. A big job.

the tunnel of the Series 3 XJ was triple-insulated: a stick-on material like Dynamat, then a layer of Yute, then the carpeting layer.

 

And, that awful rubber like pad that just sat on the transmission. No way was I going to put that back in when the LT1 and 4L60E that were nice and clean going back. It got tossed. No harmful effects, so far.


Now, my car has insulating pads on the bulkhead on the engine side. Sound, but a tad dreary, I freshened them with a spray of silver while the bay was vacant!!


Carl

 

Easy to use stuff that sticks on... just use a roller to press it tightly to the curves...


Makes a great difference in heat and noise...

 

I thought BQuiet was for sound insulation rather than heat?

 

It helps with all of the above. Like adding clothing in layers....