Thread: Changing the Camshaft p38

More probably piston slap, which can be heard more easily on an alloy engine.

Tappets will rattle not knock.

having said that at 197Kk a new cam could be necessary. my RRC has 194 now and very quiet tappets so I see no need as yet to change..
Regards Philip A

I keep reading about piston slap whist searching on engine knocks on warm up. I understand the theory but cannot clarify if its acceptable or needs to be addressed.
Still would like to know how hard to remove the cam in situe

Im no expert on this, but Piston slap i thought would not have gone away as the oil pressure rose (engine became warm).

I would maybe replace the Oil filter and check the oil pump.
If there is a problem with a partially blocked filter or oil pump issue,
that could cause a noise until pressure has risen enough for the oil to flow.

Hard to say without hearing, i could be way off.

The 1st thing I did was flush the engine, change oil and filter ( old oil and filter 4000ks 4 months old), add lifter cleaner additive. Since I have added Lucas oil treatment.
Still wanting to know if the cam comes out easily.

If I recall correctly, I was able to change the cam in situ without disconnecting any aircon stuff. It was 8 years ago.

Pull the grille, radiator and, I think, oil cooler to give clearance for the cam to come out.

Originally Posted by wayneg

I keep reading about piston slap whist searching on engine knocks on warm up. I understand the theory but cannot clarify if its acceptable or needs to be addressed.
Still would like to know how hard to remove the cam in situe

Search google on "GM LS1 piston slap" ...there are several recordings which demonstrate it quite clearly... ...don't ask but according to the "experts" piston slap is no big deal... guess it depends on who is paying said experts...

Wayne, my 3.9 developed a knock on start up and the oil pressure light took about 10 seconds to go out, at this stage there was 240k on the dial so I thought big ends, lifters anything that could affect or be affected by lack of oil pressure. The cause, the oil pressure relief valve would not close properly, don't always assume the most expensive fault especially with knocking engines.
Piston slap is normally associated with worn rings, pistons and/or bore, if the engine is not smoking I would look elsewhere for the source.
I sold my Disco 1 with 275k on the oil, it did not smoke, rattle or knock and at the time I had the oil pressure relief valve changed at 240k oil pressure was still at factory specs. Change your oil and filter every 5k with quality products and your engine will live forever, $60 every 3 months versus a rebuild, no contest.

Cheers

Rushy