View Full Version : TR2/3/3A Heat in the TR3A cockpit

08-31-2008, 06:07 PM
I am getting more heat than you can stand after 30-40 minutes of driving. It is coming from the tunnel and under the dash. I have put header wrap on the exhaust that runs through the tunnel and heat resistant padding under the tunnel carpeting. The heater blower is off and the doors are shut. The rubber gearshift boot and gearshift get almost too hot to touch. I also have the HVDA 5 speed Toyota transmission.

Does anyone have any ideas?


08-31-2008, 06:23 PM

Go purchase a cheap infrared gun (Home Despot) and scan
your cockpit for hot spots. Isolate those areas and
insulate them. Check your firewall as well.


08-31-2008, 07:43 PM
Under the dash heat is most likely caused by absent or disconnected defroster hoses. There's no way to turn off the flow to the defrosters (no doors to close)other than turning off the water pipe to the heater, and opening the vent for fresh air.

I have tunnel insulation, HVDA, s.s. exhaust, no header or wrap and don't have the problem. Heat yes but, not too much. I also covered my floor panels and the firewall with heat shield insulation from HomeDepot. Joints are all sealed with aluminum tape.

You might want to double-check the Toyota fluid level just to be safe. It could be getting hot. I used Mobil1 Synthetic in mine (recommended by the Toy dealer parts man.)

08-31-2008, 07:48 PM
First step IMO is to search for and fix any air leaks. Put a trouble light into the footwell, and look for any place you can see light under the car or under the hood. Repeat for the other side, then with the light under the hood, etc.

Be sure the heater tap is turned off and not leaking; as the heater puts out quite a bit even with the blower off. Especially if you open the vent (which should be open).

I used water heater insulation instead of padding, helped a lot.

Also check that the seals inside the front fenders are in place, and in good shape. If not, they allow air to blow into the cockpit (although it's mostly cooler air off the road, so maybe not your problem).

You might also want to check exhaust temps (using that heat gun) ... Dad's TR3 used to get the exhaust manifold literally red hot, which also made the passenger compartment get hot. Problem turned out to be worn jets in the carbs.

08-31-2008, 08:05 PM
Thanks for the quick reply. It looks like I have some work to do to fix this problem.


Don Elliott
08-31-2008, 08:16 PM
Years ago, I had lots of problems with my clutch and transmission so I didn't screw down the tunnel over the gearbox so it would be quicker to take out. The areodynamics would cause the tunnel to rise when I was driving and thye tunnel would rattle up and down on rough roads. The heat that came into the car was similar to what you describe. For the last 100,000 miles the tunnel is bolted in tightly and it's not hot like it was back then.

Maybe you have some loose bolts or flanges broken off which would let the heat come in.

But I never use my top or sidecurtains and this keeps me cooler as well.

08-31-2008, 08:28 PM
That reminds me, I also used a tunnel seal kit from a TR4 on my TR3. As Don said if it leaks, it puts out a lot of heat.

08-31-2008, 08:52 PM
Assuming you've verified the heater is isolated/off, I'd check the transmission/clutch.

I run an unwrapped s/s manifold and exhaust, and I don't have heat-reflective padding on the tunnel or the firewall. I do have the heater water cut off at the head-tap, and everything is bolted down and sealed. I've never had heat in excess of +20 degrees over ambient, and definitely nothing that wouldn't disappear as soon as I opened the scuttle vent.

09-01-2008, 12:00 AM
If you don't happen to have the TR4 seal kit handy, silicone adhesive/caulk from HD works well too. Get the more expensive, oil and weather resistant kind.

09-01-2008, 05:57 AM
Murray - I was amazed at the heat around the tunnel when I first got my 59 TR3 last year.

Steps I took:

1. trouble light ahead of the firewall to see "light leaks" - plug 'em.

2. replaced the missing fasteners holding down the tunnel cover, and sealed 'em.

3. added HomeDepot "insulation" (shiny surfaces over "bubble wrap") under carpets throughout.

4. realized HD insulation wasn't enough, so added old wool carpet *under* regular carpet.

5. made *sure* there was plenty of insulation over the tunnel, and included a "loose" piece of insulation which actually moves with the gear shift stem.

6. replaced the heater valve in the engine bay; the old one wouldn't fully shut off, and I felt warmth in the two rubber hoses going through the cockpit heater even when the valve was "off".

When I first got the car, there was only a remnant of the original jute insulation under the inexpensive replacement carpeting. In other words, thin carpet over bare (rusty) metal. With 20-20 retrospect, I'd have chosen good wool carpeting over thick jute insulation.

Also note that it can be relatively easy to purchase "insulation" which is actually for sound deadening, and not for heat transfer. You can find some posts here on the forum which discuss this.

So after a month of trying "this and that", the steps I took (above) have really cut down the heat. Even in high summer (New England - 90 fahrenheit), the only relatively uncomfortable spot now is right between the tunnel and the rear of the passenger seat. Not that I stick my hand there often, of course.