There's an important process to go through after you've just fitted a new cam shaft in your engine before driving with it. Apparently it's a "Little known" procedure and few people I know have ever heard of this - even those who've been maintaining their cars all their life and even rebuilt engines to one extent or another.
When I mention this to people (eg to the professional mechanic who just fitted my Golf head with a new cam in it), I get responses like "I've never heard of that" and "No, no, just drive it".
I know what it is but I'm wondering how many people have this knowledge in the front of their minds?
It's obviously something to do with running in as I'm talking about a "newly fitted cam shaft".
2007-12-08 22:59:34 · 7 answers · asked by iRant 3 in Cars & Transportation ➔ Maintenance & Repairs
Thanks for all answer so far :)
A performance workshop fitted the cam but a local mechanic refitted the head - head gasket blew near home so had to get it to a local place. Was a good time to get the (Wrecked) cam replaced (With a slightly bigger one!)
The cam fitter did use lube - an absolute must IMO Esp as it's an older Golf engine. Mk1 Gti EV (Probably a Mk2 block/head I'd expect). Doesn't have any oil holes on the lobes - I've never seen that myself but I've not worked on anything newer than CVH's and Red Tops.
Pedro S has hit the nail on the head - the 20 minutes at 2-2500 rpm thing was what I was looking for. Apparently this reduces initial pressure on tips of lobes and is effectively "Burnishing" of new lobes to new followers (Or shims in this case). Sounds good to me.
Check here for indepth explanation of what I was on about:
http://www.pumaracing.co.uk/cam1.htm
I agree it *might* not be necessary these days, but probably is on all engines I'll be working on :)
2007-12-09 04:26:32 · update #1
BTW - daddyjohndeer - Drive it like you stole it - Nice :)
2007-12-09 04:28:43 · update #2
in old days you needed to bring rpms up to 2000 for 15/20 min,,,or thr cam lobes would b wiped out...todays cams[roller] dont need any "break in" just drive easy
2007-12-08 23:23:37 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Years ago when things were not made to such high precision and polished surfaces, there was a running in period after which you checked valve lash and changed oil and filters.
Today there is little need for this, oils are tailor made for the new high precision, high speed engines,, bearings are toughter and better fitted, and mating surfaces have much better matching because of machine tolerances being reduced and the use of harder allors prevents undue and excessive wear.
The need for this "Little Known" procedure is lost int he engines of today. It is a whole diferent machine than in the last few decades.
there is one thing about a new cam, however, change the lifters. Maybe that is the answer you are looking for. The old lifters have a specific wear pattern eventhough they spin when the engine is running and SHOULD wear evenly on the cam mating surfaces. They are deliberately offset - the center of the lifter is not on the center of the cam lobe to make the lifter spin and change the contact (Wear) point changing as the cam rotates.
Worn lifters will have a cupping effect on the bottom. this can be measured by a dial indicator.
2007-12-09 07:11:27 · answer #2 · answered by organbuilder272 5 · 2⤊ 0⤋
Prelubing the cam on overhead cams is not so important. The cam has an oil gallery through the middle of it and a hole on each lobe. Oil is there almost the same time the oil pressure is up. One thing I did on a rebuild was to fill the oil filter before fitting so oil was up at the cam as soon as possible. I however, used a prelube on engines where the cam was splash fed as is done on overhead valve engines.
Running in is not necessary.
2007-12-09 07:35:59 · answer #3 · answered by pat j 5 · 0⤊ 0⤋
If the mechanic that installed your cam did it right, you shouldnt have to worry about anything. If he didnt do it right, you would know it already. if your engine is running the way it should be, just drive it. Keep it serviced like you did prior to the replacement. I hope he put a coat of moly lube on it prior to instalation so it wouldnt be running dry at its first startup.
2007-12-09 07:06:10 · answer #4 · answered by bobby 6 · 1⤊ 0⤋
Lube all parts during assembly. You can disconnect coil and crank to get oil to the tappets and cam bearings. then reconnect, start/warm and i would keep the revs low to allow bearings to bed back in - build revs up over about 200 miles.
2007-12-09 07:17:38 · answer #5 · answered by Anonymous · 0⤊ 0⤋
There isn't much you can do after its installed. As long as you used "pre lube" when you installed it ,it will be just fine. Let it warm up for 10 min and drive it like you stole it.
2007-12-09 07:03:45 · answer #6 · answered by daddyjohndeer 5 · 0⤊ 0⤋
what you talking about ther's nothing just drive it
2007-12-09 07:05:49 · answer #7 · answered by Snot Me 6 · 0⤊ 0⤋