Re: [MBZ] Valve adjustment - 617.95. engine - crazy idea?
OK Don wrote: Reduced cam follower wear? Only reason I can think of -- It's been reported (rather frequently) that the use of Mobil synthetics will reduce the need for valve adjustment (but I don't know why that might be). I KNOW it reduces timing chain wear (I've measured that) by about half and I understand why, but I can't figure out why it would reduce the need to adjust valves. Marshall As intake valves wear they get tighter - can't be cam follower wear any way I can imagine! Marshall -- Marshall Booth (who doesn't respond to unsigned questions) "der Dieseling Doktor" [EMAIL PROTECTED] '87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi
Re: [MBZ] Valve adjustment - 617.95. engine - crazy idea?
Three things, really, I would guess -- reduced wear on cam follower and adjuster nut (also reduced wear on the cam lobe, but that won't affect clearance), reduced wear on guides (and hence better seating and reduced wear on seat), and less ash in the combustion chamber since there is less consumption and less zinc stearate in the oil (I think, not sure on the last one). I've not run Mobil 1 in a 61x engine long enough to need to do a valve adjust yet (will be checking my brother's 300D this weekend or next), but on the Volvo, only a couple valves were out of spec after 50,000 miles. Peter
Re: [MBZ] Valve adjustment - 617.95. engine - crazy idea?
Reduced cam follower wear? Only reason I can think of -- > It's been reported (rather frequently) that the use of Mobil synthetics > will reduce the need for valve adjustment (but I don't know why that > might be). I KNOW it reduces timing chain wear (I've measured that) by > about half and I understand why, but I can't figure out why it would > reduce the need to adjust valves. > > Marshall -- OK Don, KD5NRO Norman, OK '90 300D, '87 300SDL, '81 240D, '78 450SLC The FSM created the Diesel Benz http://www.venganza.org/
Re: [MBZ] Valve adjustment - 617.95. engine - crazy idea?
Hans Neureiter wrote: Since the valve adjustment job is fairly easy but a PITA, why not adust the valves a bit looser than specs, i.e. .005"/.015" instead of .003"/.013". This would throw the timing off a hair, open a little later and close a bit sooner. But will it be significant enough to notice? The benefit being longer intervalls between needed adjustments since they always tend to tighten up. A well maintained engine lubricated with good oil that's changed as required, will not need adjustment very often, but they still need to be checked before each cold season to insure flawless cold starting. The process is far from linear and often changes quite suddenly! Once you have become "one with your car," you may be able to tell that the valves need adjustment from the sound, but I was never able to count on that even after 20+ years of trying. Increasing valve clearance will make them noisier, increase wear (at least a little) and the engine won't run as well. Tight valves quiets the engine, but results in slow/no cold starting, poor running when cold and excessive valve wear/damage. Valves can tighten (usually intakes) with wear (and that prevents cold starting) and they can also loosen (usually exhausts) and that makes the engine noisier, but neither of those results are exclusive - so they really must be checked every 15kmi or so and adjusted if they are out of specification. It's been reported (rather frequently) that the use of Mobil synthetics will reduce the need for valve adjustment (but I don't know why that might be). I KNOW it reduces timing chain wear (I've measured that) by about half and I understand why, but I can't figure out why it would reduce the need to adjust valves. Marshall -- Marshall Booth (who doesn't respond to unsigned questions) "der Dieseling Doktor" [EMAIL PROTECTED] '87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi
Re: [MBZ] Valve adjustment - 617.95. engine - crazy idea?
Hans: If you use good oil (synthetic is best) you will find that you don't need to do much adjustment. Set to specs, the difference in performance can be noticeable. Peter
[MBZ] Valve adjustment - 617.95. engine - crazy idea?
Since the valve adjustment job is fairly easy but a PITA, why not adust the valves a bit looser than specs, i.e. .005"/.015" instead of .003"/.013". This would throw the timing off a hair, open a little later and close a bit sooner. But will it be significant enough to notice? The benefit being longer intervalls between needed adjustments since they always tend to tighten up. -- Hans Neureiter, Houston, TX '82 300SD, '95 E300D
