Sudden tappet noise

[nmacc]

Hi folks,

My 1993 220 TE has changed it's "oil behaviour". When I got her in January the oil pressure maximum readig seemed to be stuck at just over 2 Bar. No matter how cold she was or how high the revs were, 2.2 was my limit. However this didn't really drop off much when idling hot either.

About 3 weeks ago I noticed that suddenly the oil pressure gauge was more responsive; 3 Bar on start-up and on running, but dropping to just under 2 when hot and idling under load.

So far, so good. Unfortunately the change in behaviour of the gauge has been accompanied by serious tappet noise for 2-3 secs when starting.

Changed the oil and filter, but no improvement.

Any thought? Thanks.

Niall

 

[jibcl500]

tappets, hydraulic lifters are starting to drain and then refill once the engine starts, nothing to worry about they all do it, lifters are good for 100k and then need changing. Thicker oil sometimes does the trick.

jib

 

[nmacc]

Thanks Jib, I know what the noise is; indeed I'm all too familiar with it as this is my fifth old Mercedes and I have the grease of a further 23 other old cars under my nails.

What concerns me is the manner in which it appeared. 3 weeks ago there was no noise from the tappets and I had apparently low oil pressure. Suddenly I have apparently high oil pressure and noisy tappets.

The tappets did not become progressively noisier as time passed; one day they were quiet, the next, noisy. It's only on start-up from cold. I never entirely believed the original low oil pressure reading as the gauge just didn't move correctly. I suspected a faulty sensor.

I have no idea of the oilways in this engine and I was hoping that somewhere among the majority of posters who know so much more about these machines than I do, there might be someone who could explain this phenomenon.

N

 

[dougjoy]

Hi Niall, I wondered if you have managed to clear all the gunk out of the oilways in the engine. if you are doing longish journeys and getting the oil nice and hot where the previous owner was a short journey driver the difference may be explained.

Your oil pressures are what you would expect rather than the previous readings with no real changes.

Just a thought.

 

[nmacc]

Hi Doug,

I am concerned about gunk in the oilways. Just to emphasise: what bothers me here is not the pressure displayed, or the tappet noise per se; it's the sudden and coincidental changes. Too sudden and too coincidental.

I'm concerned that some gunk may have moved up the oilways and is reducing the oil flow to the tappets. If the dirt is after the oil pressure sensor, or indeed has actually come from the sensor port, then that would explain the higher pressure reading, either because the sensor is reading correctly now, or because the blockage is putting back-pressure on the sensor.

Just wondering if anyone has come across this before?

Thanks,

N

 

[dougjoy]

I would tend to think the other way, that the new oil and filter has opened the oilways especially to the tappets. The new fresh oil is cleaning out the gunk from the hydraulic tappets and putting fresh oil into them. But it will take time to get all the gunk out in the mean time the rattle.
I used to have the tappets clicking every morning for a couple of minutes until the engine warmed up a little. I tried various oils, all mobile 1 but different types semi synthetic and full synthetic 10-40, 5-30 ect. I cured it by using Mobil 1 fully synthetic 0-40 protection formula oil. No rattles at all, it seems to quieten the engine down everywhere. With other oils the tappet noise used to come back once the oil had done about 5000 miles. With this oil I'm at 8000 and still all is quiet.

If I were you I would run the oil you have for 5000 miles or so to let this oil clean everything up and then change to the Mobile 1 protection ( not cheap) and see if it fixes it. In the mean time I would not worry about the rattle or the oil pressure guage, just enjoy the car

 

[nmacc]

I like the theory Doug, unfortunately the calender is against us on this:

The problem showed up just over two weeks ago and I changed the oil one week ago without affecting the problem. I asked some mechanics about it, but the only answer I got was: "Oh that's normal, they do that kind of thing". I'm sure they do, after all, mine did! Unfortunately that doesn't get me any further down the road.

As I say, I'd hate to be doing damage if there is something stuck in an oilway. I'm well used to the morning rattle as my last MB was a 190 with 210,000 on the clock, but this motor ran like a watch until less than 3 weeks ago.

N