300 sel tappet noise

[Dusty`NZ]

Hi , I just bought a lovely '88 300sel , the next day , after I got it home from the dealer ,when first starting the car, the engine rattled , like some of the tappets were extra loose , until the oil pressure came up.
Definately a top end type of noise , and a smooth runner the rest of the time.
The 300D that my wife owns , with twice the mileage on , does not do this.
Is it likely to be valve adjustment , or cam chain ? or something else .
Anyone had this experience?

 

[Francois]

I have been having the same problem after I did an oil change on the car.

I always thought it was the filter canister making a noise because it might be empty after a long stand.

I am starting to get concerned though and would also like an answer.

 

[Dusty`NZ]

I understand that the oil filter doesn't drain out , as there is a valve in it to prevent that .
Hmmm , , maybe it is the chain tensioner rattling until the oil pressure comes up.
Can someone tell me how to check this please .

 

[Mikesmerc]

Hi all
Im not an expert but I think you may need to to replace your hydraulic tappets. Not 100% about this but when the they wear the oil drains from the suspect tappet leaving a large gap resulting in a rattle until the oil is pumped in again closing the gap and keeping it closed until the cycle starts again.
Regards
Mike

 

[Dusty`NZ]

Thanks for your thoughts Mike , but on my wifes 300D the cam runs directly on the valves with only the adjuster between them.
I was under the impression that the M103 engine has the same setup .
Please some one put me right here .

 

[DavidBlake]

Hi,
On the M103 the valves are actuated via rockers turning on short shafts, six little assemblys for each set of inlet and exhaust valves. The hydraulic tappet is fitted in the rocker, at the valve stem end.
Sounds like you need to replace them, best to do all 12.

 

[Dusty`NZ]

Thanks very much David , that is the definative info I was looking for .

I changed the oil and the startup noise is halved , so I think I can leave the repair till the end of the month.

Thnks for all your input guys .

 

[shirubaby]

Hi,
On the M103 the valves are actuated via rockers turning on short shafts, six little assemblys for each set of inlet and exhaust valves. The hydraulic tappet is fitted in the rocker, at the valve stem end.
Sounds like you need to replace them, best to do all 12.

HI there,

I too have hydraulic tappet noise on startup but it goes away when the engine is warmed up. This I can accept..since the lifters will drain oil over night. BUT what I'm concerned about is...when I've been driving for a while, a few things happen:
1/ the oil pressure drops to 1 bar at idle (even though it shoots up to the top when the accelarator is pressed).
2/ at idle and with a fully warm engine...the tappet noise comes back.

My conclusion is, that since the lifters are working at high oil pressure (i.e. accelarating)... they are fine.
So what's stopping me getting good oil pressure at idle? I use a thin oil in the hopes of it circulating better (but no luck). I used engine oil flush to clean the engine before an oil change...still no luck.

Could this be the oil pump? or a hydraulic lifter issue?

OR something else?
Any advise is greatly appreciated.
Shiru

 

[television]

Once an engine has been over 100k mlies, things do or can start to wear.
the oil is pumped first through the main and big end bearings, wear on any one of these will reduce the oil preasure. the oil preasure releif valve only works at max preasure, so you can forget that. Thicker oil is better than thin. When synthetic oil first came out, it was not recommended for worn engines. Short of slipping in new big end shells and main bearing shells I do not think you will solve the problem.

Malcolm.
Run the engine with the rocker cover off and if no oil coming up at idle,its the sbove.

 

[shirubaby]

Yet again Malcolm,

That sounds like a definitive answer...I may just live with it for now and change to a magnatec semi-synthetic oil...like I've been using on my past bangers. Thanks for setting me straight with the oil pressure relief valve.

Will also test with the rocker cover off.

 

[Stevie A]

It's normal for the oil pressure to be lower on idle.

 

[clive williams]

HI there,

I too have hydraulic tappet noise on startup but it goes away when the engine is warmed up. This I can accept..since the lifters will drain oil over night. BUT what I'm concerned about is...when I've been driving for a while, a few things happen:
1/ the oil pressure drops to 1 bar at idle (even though it shoots up to the top when the accelarator is pressed).
2/ at idle and with a fully warm engine...the tappet noise comes back.

My conclusion is, that since the lifters are working at high oil pressure (i.e. accelarating)... they are fine.
So what's stopping me getting good oil pressure at idle? I use a thin oil in the hopes of it circulating better (but no luck). I used engine oil flush to clean the engine before an oil change...still no luck.

Could this be the oil pump? or a hydraulic lifter issue?

OR something else?
Any advise is greatly appreciated.
Shiru

Hi Shiru,

I would have expected better oil pressure at idle on either engine - you don't say which has the low oil pressure. My 500E has typically 1.5 -1.8 Bar at 500RPM in drive depending what sort of run we have just done. This is on an engine that's just topped 350,000km (~218,000mls). The only time I have seen lower was after a high speed run on a German autobahn in 37degC temp with the A/C on. The water temp on the gauge was over 95 degC at idle in drive with both fans on. You could not stand next to the open bonnet for the heat - 5 litres and W124 engine compartment means huge heat and the pressure gauge still read 1.3 - 1.5 Bar @ 500RPM. I've never had any tappet noise.

If you're getting only 1 Bar under normal conditions and tappet noise at start up then there are only two causes:
1) Worn crank bearings
2) Worn oil pump
A good pump and bearings will overcome a leaky hydaulic lifter and although it may rattle at start up the pressure should be OK at warm idle.

More worrying is that 100K for a Merc engine is only just run-in!

Clive

500E
E320CDIT210

 

[shirubaby]

Thanks clive,

I'm tending to agree with you on your diagnosis...
It is worrying that a 100K w124 has this problem... I might eventually get up the nerve to change the oil pump sometime in the summer when this rattling is at it's worse (I am assuming a bit here). As for crank bearing, I'm not sure on how to change it.
At the moment, I am using a semi-synthetic thin oil (5w-30 i think) in the hopes that oil circulation is improved... the oil pressure as a result drops to 1 bar at idle (after a run)...kinda scary BUT... it seems to have cured the tappet noise.
The oil pressure of 1 bar is obtained by as fully warmed up engine (above 85c) and at idle only. At throttle the oil pressure shoots up to 3 bar.
The theory is far from perfect...but this means oil is now getting to the top of the engine and curing the tappet noise. - thus eliminating the need for me to faff about with the hydraulic lifters. All of this happened after an engine flush.
I said the theory is not perfect... since for a worn engine, i should technically be using a 10w-40 or a 15w-40 grade oil. a thicker vicosity would improve the oil pressure situation, but circulation might degrade..
So after bugging many a member on this forum I have come to a difficult decision. Do I change my oil to a thicker viscosity or keep things as they are..?
The decision may well be:....It's too cold! I'm gonna leave it until the summer. Change the oil pump and describe my nightmares in a fresh new thread.
Meanwhile I've treated the engine to a bottle of "wynn's hydraulic lifter treatment" as suggested by a forum member. Waiting for the results.

I've read somewhere that 1 bar oil pressure is still ok on a merc so long as it's up to the top at throttle. Can anybody confirm this?

 

[shirubaby]

Recent update:
The oil change has improved the situation since having driven it for the past few days.
1. Tappet noise is very obvious at startup and lasts for 5 to 10min with city driving conditions....this improves if it's a clear run.
2. The engine pressure is at 1bar when idling with a warm engine.
3. When warm and with low oil pressure NO TAPPET NOISE, either at idle or at high revs.

My conclusions:
1. hydraulic tappets are ok. the wynns' hydraulic lifter treatment was unnecessary.
2. the thin oil has done some good in getting oil onto the top of the engine.
3. 1bar pressure is down to the thin oil.
4. tappet noise at startup is the a result of oil being too thick and thus not being pumped fast enough.

So ultimately, it's either down to the clogged oil passageways that the engine flush didnt manage to clear and through which thin warm oil can get through.
OR the oil pump.

 

[clive williams]

So ultimately, it's either down to the clogged oil passageways that the engine flush didnt manage to clear and through which thin warm oil can get through.
OR the oil pump.

Could be the flush has dislodged some cack, which is partially blocking the oil way to the tappet or in the tappet itself. You could try another flush although personally I'd change the offending lifter, the cost is not too great (cheaper than an oil change) and it might cure the problem.

Clive

500E
E320CDIT210

 

[shirubaby]

HI,

I would love to do a haydraulic tappet change...the problem is: to quote the haynes manual "...if however component ware becomes excessive, or the valve train becomes noisy...after renewal of the camshaft, rocker arms, valves or any of the valve lifters themselves, it is possible that the operating clearance has now become outside the operating limits of the vavle lifters...it will be necessary to change the spacer washer for one with a different thickness.
To determine the required thickness a Mercedes Benz special dial guage tool and clamp are required, and the work should be entrusted to a dealer..."

Arrr, the DEALER. Oh well, if that's the case why bother.. why does the wretched haynes manual give so much description...only to say it may require a visit to the dealer.

It's like when my gran used to bake a cake and says it's for the visitors she's having that afternoon...knowing full well that they may not eat it... always on a diet..or show up with less people. My bro and I could have done it justice.

Am I being too overly worried about these spacer washers? Who's got experience of changing these little buggers?

Meanwhile, I'm gonna get some cake...this forums made me hungry.

 

[Stevie A]

Oil Pressure

Quote MB Manual for my car "At operating temperature, the operational reliability of the engine is not jeopardized if the oil pressure at idling speeds drops to 0.3 bar gauge pressure. However, the oil pressure must increase immediately upon acceleration".

Your oil pressure is ok. Don't worry about that at all. The engine may have done more than 100K if you haven't owned it since new. Could have been clocked.

 

[shirubaby]

Quote MB Manual for my car "At operating temperature, the operational reliability of the engine is not jeopardized if the oil pressure at idling speeds drops to 0.3 bar gauge pressure. However, the oil pressure must increase immediately upon acceleration".

Your oil pressure is ok. Don't worry about that at all. The engine may have done more than 100K if you haven't owned it since new. Could have been clocked.

Steve A
Thanks for the confirmation...Clocked? Bugger!..I just dont know...The speedo needle wavers under 40mph (sign of it being clocked?)...BUT then again there are other telltale signs that the car has genuine mileage...well either way I've been lucky (in the past) when buying bangers with my limited knowledge....maybe my luck has run out.

On to more pressing things...cake!

 

[clive williams]

HI,

I would love to do a haydraulic tappet change...the problem is: to quote the haynes manual "...if however component ware becomes excessive, or the valve train becomes noisy...after renewal of the camshaft, rocker arms, valves or any of the valve lifters themselves, it is possible that the operating clearance has now become outside the operating limits of the vavle lifters...it will be necessary to change the spacer washer for one with a different thickness.
To determine the required thickness a Mercedes Benz special dial guage tool and clamp are required, and the work should be entrusted to a dealer..."

Shirubaby,

This is why I have lost confidence in the Haynes manuals to provide good solid engineering advice and not a DIYer's handbook, which they now appear to be. Put the Haynes manual to one side and purchase a copy of the WIS manual from e-bay. This is the MB fitters bible and will give the complete instructions for the full job. Its not rocket science as MB fitters do it!
The Haynes manual does have its uses and I use one for the 500E in conjunction with the official manual as unlike MB fitters I don't service/repair several cars every day and Haynes helps in identification if nothing else.

Clive

500E
E320CDIT210

 

[shirubaby]

Shirubaby,

This is why I have lost confidence in the Haynes manuals to provide good solid engineering advice and not a DIYer's handbook, which they now appear to be. Put the Haynes manual to one side and purchase a copy of the WIS manual from e-bay. This is the MB fitters bible and will give the complete instructions for the full job. Its not rocket science as MB fitters do it!
The Haynes manual does have its uses and I use one for the 500E in conjunction with the official manual as unlike MB fitters I don't service/repair several cars every day and Haynes helps in identification if nothing else.

Clive

500E
E320CDIT210

Hi Clive,

So, in your opinion, I dont have to worry about the spacers?

In which case I'm good to go...but it's the silly season and I will most likely be drafted into Christmas Shopping...:Oops: