227
More on curing heat in an RV8 cockpit - are your heat shields on top!
A thread of V8BB postings in February 2005 returned to the difficulty of finding a cure for excessive heat in an RV8 cockpit. (Mar 05)

Paul Mascall (Nightfire Red 1473) in Australia posted a note saying he "would be grateful if members could add anything to what is already in the RV8NOTES regarding heat from the exhaust system entering the cockpit as it is discouraging my lovely wife from riding in the car. I would really like to resolve the problem which is a particular nuisance during our hot Sydney summer days". Four suggested cures came up - lagging, making sure the heater valve is really turned off, fitting reflective foil to the heat shields on the catalysts, and making sure the cats have not been welded in upside down!

Lagging the manifolds and downpipes as far as the cats to stop heat being absorbed by the chassis rails and the firewall was suggested by David Boniface (Oxford Blue 1589) in Tokyo but Gavin Brown (Woodcote Green 1479) who runs the MG Car Centre in Tasmania commented that he "would not lag the pipes as lagging is known to deteriorate the pipes much faster than they normally would".

Gavin Brown pointed to another cause, the heater tap not closing properly. Gavin suggested anyone wishing to check this should "stick your head in the driver's footwell with a torch or inspection light and look up to the heat vent outlet at the foam seal on the flap. The seal on my car had become unglued in some places so it no longer was sealing the flap when it was closed so was letting hot air into the cockpit. To fix this it is a heater-out job which is not too bad - I just have not got round to it yet!" The heater tap controls the supply of hot water to the heater radiator and indeed, if not closing properly will allow hot water through the heater matrix when the valve appears to be closed. However, the foam seal has nothing to do with this specifically; the flap mentioned controls air flow to the foot vents.

Gavin Brown then pointed to another cause of heat transfer - the shields on the cats - saying
"as a side note, I just fitted a stainless steel heat shield in place of the standard item but found that the cats on that RV8 had been welded in upside down so the heat shielding was on the bottom and not the top! So it might pay to check that - in Australia it will depend who "complied" your car on importation".

John Hornabrook (Woodcote Green 1781) in Queensland Australia, who had provided an earlier RV8NOTE170 on this topic, then added that "fitting reflective foil to the shields and making sure that all the hot water taps are turned off is a start. But the thing that really cooled my car - and the heat was a serious problem as it would burn my right heel! - was fitting a larger radiator which then lowered the under bonnet temperature considerably. The operating temperature is now some 10 degrees below where it was and on a cold night (remember this is Queensland), my heater is now only just good enough but in the hot weather things are fine".

Geoff Harris in the UK then sought details of a supplier of the reflective foil for the cat shields to which David Boniface responded "a good supplier for this and many other useful items is Agriemach at www.agriemach.com in the UK". Shortly after the thread concluded with Geoff reporting he had ordered a 48" x 36" sheet of reflective foil from them.

Paul Mascall reported a week or so later that he was fiddling about with his RV8 over the Easter weekend and thought of the comment about the cats being welded in upside down. So he got down on my hands and knees and, guess what? The heat shields were underneath the cats - obviously to ensure that no undue heating of the road surface takes place! Paul commented "looks like I'm in the market for some reflective foil. Thanks for the tip, Gavin".

Ses also RV8NOTES 126 (Roger Parker), 128 (heater control cable), and 204 (water valve by Gavin Bailey and Brian Moyse).
Copyright reserved by the V8 Register of the MG Car Club, PO Box 251, Abingdon-on-Thames, Oxfordshire OX14 1FF