M42 camshafts / lifters

[TedKarslake]

Afternoon all,

Just wondering if you can help me. I've been building a 1975 BMW 2002 with an M42 engine for the past couple of years and this week was the first time it was finally ready to run. The engine was unknown as it was bought already fitted in the car, but we checked the compression etc. a few months ago before the fuel lines went on and it all seemed fine.

Started the car up this week for the first time (it's running DBILAS ITB's, a custom exhaust, custom race loom and a Haltech 550 ECU) and though the car started up fine it sounded like a diesel.

Fine we thought, it must be the hydraulic lifters - we'll run it a little while and hopefully when the oil gets round the engine (which hasn't been run in 12+ years) the noise should go away.

It didn't.

So we think we're going to need to replace the lifters, and whilst there I may as well upgrade the camshaft to a fast road / race one. I've just got a couple of questions please:

- I'm in discussions with Newman Camshafts about a custom set. They've said that I will need to upgrade the valve springs and seats, can anyone recommend a good aftermarket set?

- Does anyone know of a place in the UK where you can get hold of a new timing chain, tensioners etc. i.e. the whole kit to replace? I would be gutted to do all this then the tensioner broke.

- Who supplies a good hydraulic lifter set? Preferably OEM. I may look at going for solid lifters but after doing some reading it may require further mods, I'm not sure.

- Has anyone gone for solid lifters on this engine and what have been the results?

Thanks,

Ted

[1998ccc]

Diesel sounds are normally from the chain assembly.  Try a new tensioner and see if it quietens down.  If not, I think the early guides are backordered.  Good luck.

[bmwman91]

The diesel noise is almost always the result of valves and pistons contacting. Since it is an interference design, relatively small timing errors lead to piston-valve contact. The M42 is surprisingly tolerant of this, with the hydraulic lifters allowing enough give in many minor cases to prevent damage. Obviously you do NOT want to be running the engine like this any more than is absolutely necessary to check that whatever is causing it gets fixed. More than a decade ago, I also thought that I had collapsed lifters after replacing the timing case, and even drove the thing around the block revving to ~3000RPM to "bleed out the air." Well, it turned out that my timing was off by a whole tooth on the cam sprockets lol...and the engine ran more or less fine for another 6 years.

As mentioned, the chain tensioner can cause diesel sounds if it sticks or is otherwise not properly tensioning the chain.

The tensioner rail or longer left-side guide would really need to be on the way out to cause the diesel noise.

Clogged lifters might cause it if they sat for a really long time and the oil is all varnished-up. You could try running a detergent additive in the oil to try to clear this out, if it is in fact the problem. 12 years of sitting is a long time!

Check that the cam sprockets have not shifted, sometimes they will slip if the 4 bolts holding them to the cam are not sufficiently tight.