om602 loud ticking around valve cover

[xweezyx]

Hello. I have a 1986 190D with about 180K on it. Ever since I moved to a more dense area, I have been driving very little. I changed the oil and fired the car up after about 2 months of sitting and have noticed my engine is very loud. This doesn't sound like injector nailing to me, but valve noise. If I was working on a car with adjustable valves, this would be the first thing I would check. It's very loud, and very consistent only changing with engine speed. It doesn't change much or at all once the car is warmed up. I'm mostly sure its not the vacuum pump (thankfully). Is it possible my lack of driving has caused some lifters to collapse? I have no problem swapping them all out, I'm just looking for a starting point. I have cracked all of the fuel lines individually with no affect. The are no other symptoms. idle is smooth and there is no smoke or lack of power. Thank you for any suggestions. I'll try to post a video or sound clip.

[Diseasel300]

The 60x engines have hydraulic tappets. If the car sat for a long time, they can drain out and be noisy. Usually they'll pump back up in 10-20 miles of driving, but sometimes they don't if there's a bunch of varnish or sludge in them. They can be taken apart and cleaned (I've had good success doing this on 3 different engines) or replaced with new (parts aren't that expensive). Try a 5W-40 oil and drive it on the highway for 30+ minutes and see if it shuts them up.

[xweezyx]

Originally Posted by Diseasel300

The 60x engines have hydraulic tappets. If the car sat for a long time, they can drain out and be noisy. Usually they'll pump back up in 10-20 miles of driving, but sometimes they don't if there's a bunch of varnish or sludge in them. They can be taken apart and cleaned (I've had good success doing this on 3 different engines) or replaced with new (parts aren't that expensive). Try a 5W-40 oil and drive it on the highway for 30+ minutes and see if it shuts them up.

Thank you for the reply. Yes I'm aware that they use hydraulic tappets. Ive been using 5-40 liquimoly synthetic. Ill probably give it a little time and then order new ones. It looks like less than $150 in parts.

[pawoSD]

My OM601 did the same thing....it never got better. Ended up pulling the camshaft and replaced all the hydraulic lifters. Sounded smooth as a sewing machine afterwards. Well worth it!

[xweezyx]

Originally Posted by pawoSD

My OM601 did the same thing....it never got better. Ended up pulling the camshaft and replaced all the hydraulic lifters. Sounded smooth as a sewing machine afterwards. Well worth it!

Mine has actually gotten quieter and the noise is almost non existent. perhaps one day ill swap the lifters but for now im happy that my engine isn't exploding.

[R.Diesel]

Just replace them. They are inexpensive and not difficult to do.