Can someone please help understand what those sleeves are for? Found them over all my intake valves.
I cannot find them in the workshop manual and apparently one of them already started disintegrating.
Many thanks in advance!
Max
Can someone please help understand what those sleeves are for? Found them over all my intake valves.
I cannot find them in the workshop manual and apparently one of them already started disintegrating.
Many thanks in advance!
Max
these are valve stem seals, to prevent oil to go down to the chamber when the valve guides are worn out causing smoke.
There are two main approaches for these oil leaks
I’m an advocate of the first approach.
Thanks for the quick and useful response.
I will also go with the first approach.
Max
Lotus never fitted them, hence they’re not found in the workshop manual. Fitting them is not
uncommon during a rebuild of the head.
No seals, versus seals has a lot to do with the materials used for the valves and the valve guides. In the early days valves were steel and guides were often cast iron. They needed some oil for lubrication. Bronze alloys didn’t stand up to the high temperatures and wear, and seal materials which can live at these temperatures were not yet developed. Now we use 214N stainless steel valves running in guides made from fancy bronze alloys, which wear better, dissipate heat better, and we know how to make seals which usually live in these conditions, so the modern valvestem/guide interface doesn’t require as much lubrication. We can add seals which improve performance, and emissions, so we do, as long as the physical space is available at full cam lift. If your engine is already set up for them, then they are definitely worth keeping. Your engine will burn better and run cleaner.
Some interesting stuff about valve stem material versus valve guide material here.
calverst.com/technical-info/val … and-usage/
I’ve pulled down crossflow engines in the past fitted with valves having oversize stainless steel stems running in the original cast iron guide and the results certainly weren’t pretty.
I’ve got fancy bronze guides and stem seals. Not a puff off oil smoke now. It used to be like James Bond escaping from the baddy of the week before I had it all fixed up