collapsed hydraulic lifter - PeachParts Mercedes-Benz Forum

jsmith · #1 07-20-2003, 03:55 PM

when i leave my car for several days i have found that upon initial starting, a cylinder will not fire then catch on after a few seconds. in the meantime a lifter tapping away like crazy then gradually fading to nothing. this started this past winter on a very cold day. it did not recur again until i left it for a week and happened again when i went away this past week.

my mechanic said that the lifter is collapsing, with the oil running out and the lifter losing pressure after a few days. he says that it should be ok for now since the pressure builds up and stays up as long as i drive the car regularly. i'd like to know is first, if the diagnosis is plausible and second, what it would cost to replace the lifter? what is the prognosis of such a problem - will it deteriorate rapidly? i came across a post somewhere about the cost of a lifter being replaced but i can't seem to find it...

psfred · #2 07-20-2003, 05:56 PM

It's a collapsed lifer all right.

Don't know about the cost, if they are like those in the M103 they aren't too bad to replace.

What kind of oil are you using, and how often is it changed? More frequent oil changes or using synthetic oil may help, may not, depending on engine condition and crud buildup.

Peter

jsmith · #3 07-20-2003, 07:55 PM

i change religiously at 3k or less. i was trying 15w-40 delvac 1300 over the winter hoping to help clean the engine when it happened. i'm wondering if that had anything to do with it. i even gave it a dose of auto-rx (there's a thread somewhere on the forum). i switched to 10w-40 castrol again. will a thicker oil help? the lifter is ok once i have gotten it going and the problem does not start again unless i leave it for several days.

psfred · #4 07-20-2003, 08:45 PM

The lifters aren't too hard to change, if they are like the ones on the M103 engine (I think you have the M104, dual cam right?).

It's probably worn out, they are known for relatively early failure (in comparison to the rest of the engine). You can either live with it until it clacks all the time or change it. Probably different oil won't help.

Since you've been changing the oil frequently, I woudn't think sludge buildup would be a problem. However, if you have a large amount of visible varnish (golden brown to black coating) visible through the oil filler cap, it might be causing some of the trouble. Using and "engine cleaner" could certainly dislodge hard sludge and cause some havoc, but I don't see how that would damage the oil holding capacity of a lifter. I'd expect it to stay down rather than pump back up!

Peter

jsmith · #5 07-20-2003, 11:54 PM

yup it's the m104 in the smaller bore 2.8L. i'm not the original owner so can't tell how the car was cared for in its first half century (of k miles). i do have that golden brown varnish which is what i was trying to get rid of with the auto-rx " engine cleaner". it's still there as far as i can tell. i guess i'll just have to play this one by ear...

psfred · #6 07-21-2003, 06:51 PM

Synthetic oil will clean all that varnish off pronto, but you will need to change the filter a couple times on the first crankcase of synthetic oil -- it will fill up with crud pretty fast.

I'd say you have no more than a 50/50 chance the tappet will quit rattling if you use synthetic, it's very likely worn out.

Peter

jsmith · #7 07-21-2003, 07:14 PM

i am deathly afraid of leaks from the synthetic oil. i'm almost sure she's never had a taste of the stuff. i'm willing to try as i've seen how synthetic gear oil cleaned out a differential so that the metal showed on the inner surfaces of the casing.

i'm curious as to the wear process for the lifters. is there some kind of seal that keeps it pumped up? would it be worn out with just 70k miles on the odometer?

psfred · #8 07-21-2003, 07:57 PM

Yes, there is a seal -- really a plunger fitting is a sleeve with oil pumped into a hole. When the plunger is pushed down past the hole, it seals off the oil in the lifter, and there is a small check valve (on top, I think) that allows low pressure oil flow, but not high pressure -- the higher flow causes it to close.

If the seat of the small valve or the bore or the plunger is worn, oil leaks out and doesn't refill fast enough.

Hard sludge from infrequent oil changes will do this, and believe it or not, there are lease cars that have NEVER had the oil changed during the lease -- just gas, nothing else. Why bother, if it isn't blowing oil smoke on return, who cares?

Peter