The heater pipes are made of mild steel and rust, the rubber seals harden with age. Hard rubber doesn't seal well against blistering rust.
I fitted the stainless steel heater pipes and was lucky to buy a pair of rubber seals whilst still in stock. An all in one matrix and heater pipe assembly is now available. I wish I'd fitted this version.
Adam
TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, S/S Single Pipe Exh, 3.08 Rear, 200lb Spax & PolyBushes all round, Anti- Dive, Strut-Top Roller Bearings, Capri Vented Discs & Calipers, Braided Hoses, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 14" 5 Spokes or Maestro Turbo 15" Alloys, Cruise Lights, S/S Heater Pipes, Replacement Fuel Tank. No Door Stickers. Mine since July 1986, V8 from 1991 courtesy of S&S V8 conversion and big brake kits.