I have a 1991 180e which has about 67000km on the clock. I have noticed that when I start it from cold the oil pressure takes 2-3 seconds to come up to normal, and during this short time there are some valve train rattles. As far as I know the 1.8L engine is exactly the same mechanically as the 2.0L 8v(m102?) engine so it would have hydraulic lifters and presumably the rattling is because the lifters haven't any oil in them for these first few seconds. The car is in very good condition and I have the oil changed every 5000km and ensure that the appropriate weight oil is used.

I have had this happen on another car (not a benz) and I found that when using cheap oil filters, the oil pressure bypass valve in the filter weakens after a while and causes low oil pressure on start and occasionally at idle. I wondered if that might be the cause in this case, since I had a service fairly recently and am not sure if the filter is a genuine part or a cheapie.

I'd be grateful for any advice anyone can offer.

Regards
MLC