Valve stem sealsPosted: October 6, 2012
The original type valve stem seals fitted to post 1967 Citroen D models were made from a white plastic material, possibly PTFE, and they worked very well. The same type of seal (but different size) was also used in other models like 2CV, GS and CX. Lately we’ve noticed that the reproduced versions of these seals, although looking the same, did not fit as easily or as well as they should. In fact, we found they were becoming dislodged in service, so not working at all and causing smoky engines at idle and on overrun.
We conducted some tests and found that when fitted, the seals were a tighter fit on the valve stem than they were on the valve guide, so no wonder they were coming off! They were also so tight on the valve stem that it was making them difficult to fit without damaging them.
We took it up with the supplier and they agreed to speak to the manufacturer, but also said that as the manufacturer was a major European gasket and oil seal manufacturer, they would probably not listen to a small customer who only orders a thousand gasket sets a year.
Upon hearing this, I decided to take matters into my own hands and researched all I could about valve stem seals. It turns out that there is a better, more modern design which happens to be made in the right sizes for D and CX models. The exhaust valve and guide sizes are a bit unusual though, so it is harder to obtain this newer type for the exhaust valves, but we do try to keep them in stock. These are a much tighter fit on the valve guide than on the valve stem, so no danger of it coming adrift and it still seals the valve well too. We now only sell this type of valve stem seal, although if you order a complete gasket set, at the time of writing, it will still come with the old white plastic seals and the better ones will need to be ordered separately.