LTCMontana

Having a strange situation. I've checked pads on variocam and they are perfect. But, after 20-30 minute drive, the chain rattles pretty bad at idle. As soon as I bring revs up beyond agout 1500, the noise stops.

I've tried running a little thicker oil (20w-50) but issue continues.

Ideas?

thomasmryan

There is a little restictor on the rear of the passenger side head but I believe that is for the lifter galley. 3mm Allen head, if memory serves.


Most things without a crank driven fan seem to like 35mph or so through the radiator to reach an equalibrium of heat created vs heat diapated. Slower and the slack is taken up by the fan circuit. Faster, the work is done by the thermostat.

Since the oil cooler is external, anything slower than 35 isn't taking any heat out of the oil. I would check the oil temps if your seeing anything below two bar. If your hitting 220 or so, you might pull the bumper and clean the fins and checking the duct.

If all else seems ok, it may be rod bearing time to get the oil pressure back up a bit.

LTCMontana

Oil pressure seems fine. Pegged at 4-5 bar at anything over 1200 rpm. Below that, and after a long run, it's around 1.5 - 2

Good cal on the oil cooler. I will check that out. Any recommendation on how to check oil temps?

thomasmryan

A lot of junk finds its way into the oil cooler plastic duct but you might be able to blow it out from the back with the fender liner out of the way.

Most of the home improvement places have the twenty dollar infrared pyrometers. You have to be close to get accurate readings but I would hit the lines at the oil filter. There won't be much of a difference in temps with the car stopped.

I will check the manual when I get home but it specs 2.5 bar is the minimum at hot idle. If it is lower, changing the rod bearings ie recommended. I ignored the part about getting the updated rods but my oil pressure went up 0.5 bar afterwards.

LTCMontana

Reading up on the Oil Pressure Relief Valve. Looks like that might be place to look also.

Jfrahm

I do not think oil pressure at the filter means there is enough oil pressure in the head. If that little pressure regulator described above sticks there will be low pressure at the lifters and variocam.
You might also check the check valve at the S tube on the variocam unit. Maybe it's missing.

thomasmryan

I would see how hot the oil is getting and roll from there. you might see if the relief spring is fatigued by seeing what the dump pressure is when the oil is cool. if you have the time, put a threaded barb fitting in the pressure sender and run a clear tube back to the oil fill. if you see bubbles, it will indicate a pick-up issue.

the picture of the head restrictor is on the previous page in the wsm. that o-ring leads a hard life