[oz3litre]

My Potenziata V6 is currently having the rack rebuilt by the specialists here in Adelaide and when I spoke to the mechanic who was re-installing it he said that the seals had all deteriorated and that it will eventually happen again because the exhaust system runs very close to the rack and would heat it up. The guy has over 40 years experience. Now the thing is that this is the first time I have heard of that theory. The rack in my car was supposedly reconditioned by someone in Melbourne about 15,000 km before I bought the car and it was leaking then. I have the receipt from that job as I did for the engine and that was a shonky job, so the rack probably was as well. It seems to me that normally these racks last quite a long time before they start leaking. Our other 75 V6 has done 160,000 km and the rack is fine at present. I don't know if it has ever been re-conditioned. What do you guys think of the exhaust theory? If it is a potential problem do you think the exhaust could be wrapped as an extra precaution?

 

[Duk]

It sounds to me like the rack was rebuilt using improper seal materials. Viton seals will survive heat much better than more conventional seal materials. Whether Viton seals are what Alfa Romeo used originally I couldn't say, but as you have said, it lasted less than 15,000km and another rack is still going strong at 160,000km, so either it was rebuilt poorly or with the wrong spec seals.

If you want to keep heat inside manifolds and pipes, look at having them ceramic coated. High temperature insulation works but tends to add significant bulk to the component. Fibreglass insulation can also absorb oil unless you give it liberal coatings of high temperature paint to help seal the fibres and if the insulation moves it will expose unsealed areas that can still absorb oil.

 

[oz3litre]

I just got the car back today and it feels a whole lot better now. The mechanic didn't enjoy pulling the rack out and putting it back in because the engine mounts have to be unbolted, the engine raised and the right hand exhaust manifold has to come off. He said he felt like resigning for a while there. Alfa weren't thinking of the mechanics when they designed the setup. They could have designed it to slide out sideways and avoid the agro according to the mechanic. He said you can't wrap anything around the exhaust because it would be too close to the coupling. It must have just been a dodgy job previously because the rebuilding of the rack was straight forward and the shaft was fine. The seal kit is a ZF one and is listed as for Alfa 75 and 90 so I assume it is per Alfa specs. It will be nice not to have a puddle of ATF on the driveway all the time for a change.