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MG MGA - Heat buildup in cabin

I bought an MGA recently and have found that it gets incredibly hot in the cabin whilst driving. It appears to come up through the firewall, the floor and the gear box. If I have the top on the heat becomes very oppressive. Is this normal as I havent heard any other owners complain about this. Thanks for any assistance.
PJ Batman

I've heard it mentioned with MGBs, particularly North American spec with catalyser, albeit on the LHS (assume yours is RHD?) Inside the cabin the tunnel was covered by silvered matting, and later MGBs came with a heat shield in that area (see attached). I've also seen after-market under-floor heatshields advertised at ridiculous cost, can't be that difficult to fabricate something out of thin alloy spaced slightly away from the floor. Also be as well to check timing and mixture, and use higher octanes where available, all of which will help reduce the amount of waste heat that gets into the exhaust.
PaulH Solihull

Yes we have found it too hot in the cabin when in a queue on a warm day - best to keep moving!!
A lot of heat comes up from the wooden floor and around the tunnel. However a lot of heat also comes back through holes in the bulkhead, blanking these of with duct tape, especially around the bonnet hinges has helped a lot.
D G Clark

Search the archive on this site for more on the MGA 'exhaust heat shield' and on 'cockpit temperature' for fuller discussion of how to seal and insulate the space. It's not an uncommon problem even in roadsters, and much considered in this forum. Barney Gaylord offers some useful thoughts on the matter on his site; see http://mgaguru.com/mgtech/interior/int100.htm . Good luck!
Ken Korey

I lined the footwells and transmission tunnel with pro-dex insulation, similar to Hush-mat or the stuff that is sold on JCW or by Moss. I also lined the area above the exhaust pipe with a sheet of aluminum. I plan to double up on the insulation on the tranny tunnel near the outside of my right calf - only area it still is noticeable.

JIM in NH
AJ Mail

Drain the gearbox of the Hypoid oil that it probably has in it and refill with engine oil - it will run much cooler
dominic clancy

PJ - I complain every hot day I'm a passenger in one ...! There ya go, it must be awful in Australia so do warn your passengers that they will be a tad warm - on the other hand, it's lovely in the cold!!!
rachmacb

PJ..I have an MgA..had it since 1989...and keep it on the South Coast of NSW, Narooma. It was as hot as hell in summer and I undertook a number of mods to make it cool. Fitted insulation to engine side of bulkhead and on heater shelf( see pic..this also blocked off a multitude of holes) ), fitted insulation under carpet over tunnel and floor, plus shield above exhaust. As a clincher I also bought and fitted a fan assist heater unit with all airducts ( did not bother with the hw supply). Result is a cool ride even when temp are up to Oz max.

Neil Ferguson

PJ I have a Coupe and lined the entire floor, firewall, trans tunnel, battery cover, door skins, and roof with Dynamat Extreme and installed additional heat material over the trans tunnel. I also made an exhaust shield out of 6"x1/8" sheet aluminium which is shown on Barney's site.

The results are wonderful. There is virtually no heat from engine or exhaust in the car. I tend to drive with the windows rolled up to keep warm until it's around 70+ outside.

Andy 60 Coupe

Andrew Preston

PJ here's the photo of the exhaust shields. There is a front one and back one. I bent the sides down 45* to add strength and stop them vibrating.

Andrew Preston

Andrew,
I love the underside of your car - obviously you don't have dirt roads in California!
Mike
Mike Ellsmore

Domenic,
When I drain the Hypoid oil out of the tranny what type,weight of motor oil do you suggest I add.
Gordon Harrison

Gordon,

Gearbox oil should be the same weight as the engine oil - that is what should be in there anyway, but it seems a lot of people don't read the book and put hypoid in, which makes it run a LOT hptter
dominic clancy

......and messes up the synchro Gordon. Get it out of there as soon as possible, fill with engine oil run a couple of hundred miles then drain and re-fill. Your gearbox will work a lot better!
Lindsay Sampford

Consider it done!
Gordon Harrison

A few guys in our club have installed marine bilge blowers in the air intake hose. They claim it's a great improvement in air-flow.
David Werblow

I have owned MGA's for over 40 years and cannot say that cabin heat has ever bothered me. However mechanical noise on my 1600 coupe (referred to in the road tests of new MGA coupes) has definitely been an issue. A friend (who is a sound-transmission engineer and studied/worked in the UK) explained that one small hole in the bulkhead will transmit more noise than can ever be dampened/eliminated by insulation, etc. I therefore put a lead light (at night time) in the engine compartment of my car and crawled into the cabin to see the myriad of "stars" which I then blocked with black silicone sealant (ie where existing grommets or cable size did not properly blank the holes). The difference was amazing and my coupe is much more "liveable". I also covered the bulkhead with double foam with thin sheet lead between (then available and may still be, also at my friend's suggestion). The factory, obviously aware of the possible problem, glued ordinary plastic foam on the cabin side bulkhead (very ineffective as a sound barrier but perhaps the only product then available?) so my "mod" looks similar but is far more effective. Cabin noise in fixed head sports cars has long been a problem (early Datsun 240Z's?) and I once read that during the road test of a prewar Alfa "hardtop" normal conversation was impossible!
Barry Bahnisch

Looking for the bilge on my MGA......
Neil Ferguson

Has anyone tried insulating paint such as lizard skin to stop heat transfer in coupes? Lizard skin t is horrendously expensive in Oz and I have been tempted to try the insulating house paint with ceramic beads as an alternative. Is this worth considering? If you've tried it, did it work?

Mark
M Wellard

Sounds like a great paint for the outside of a 1964 buick electra.....I had one in Qatar in 1970 and it was in metallic salmon pink..but lizard skin..wow!!
Neil Ferguson


Looking back through archives I see several owners have insulated with Dynamat.As I want to do the same, how much did you have to buy(sq ft)for the floor, tunnel, doors and boot. Did you also find it necessary to fit underfelt between the Dynamat and carpet? I thought I would fit all the insulation and carpet before the body goes on.The dash, wiring and plumbing have already been fitted,so not long now!

Best wishes to everyone for the Festive Season and safe driving.
Regards,
Steve A.
S Ash

Drive an MGA coupe for a day. After that, you'll never complain about cabin heat in a roadster again. But really, these are not modern cars. Don't expect modern comfort. Yes there are some things that can limit the amount of heat, but most of the time, most of the heat felt is sealing and heat shrouds. The exotic materials are not really required IMHO.
Chuck Schaefer

Some beautiful pictures of some great work here. In my lifetime our heater in our coupe has been inop and the heat from the tunnel keeps it comfortable. Because the coupe has the great air diverter windows, during the summer you just roll the windows down and point those things at you and life is good! Roll up windows were why my grandmother purchased the car. Still seems to be a great idea nearly 50 years later!
J DeRienzo

This thread was discussed between 11/01/2011 and 18/12/2011

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