Screw on oil filler cap

[zak]

One of my many favorite style things about my 250 SL is that magnificent screw on oil filler cap. It's a work of art , so large and heavy weight with those scalloped edging, a precision instrument.
I thought that they were eliminated and changed to the modern style prong, twist on  caps with the 280 SL . But I saw a 1969 280 SL on BAT that has the old style screw on type.
When did MB make that change to these caps ?

jz

[MikeSimon]

As the valve covers are basically interchangeable, you could fit an earlier cover to a later car and thus have a different filler cap.

[neelyrc]

When did MB make that change to these caps ?

Sometime after my car, 007749, January 1969.  I thought this change may have been listed in the Pagoda Notes list of changes published several years ago, but I could not find it there.

[Pinder]

i have a 69 and it has that cap screw on. it is a work of art.
I have a 70 and it is crap. Replaced it and continues to leak.

Some changes are not good.

Overall I think the 69 280SL has the right amount of quality before plastics and  other optimization took it down hill. the 71 plastic overflow tank is an example of pure stupidity.

[Jonny B]

I also checked the listing of the 280 SL changes, and a change for the oil cap is not noted.

I also looked at the M130 engine parts book, and the changes here go by the engine number not the chassis number.

It shows that the screw cap ended at engine 3498 for left/right hand drive manual transmission cars
For automatic cars, the screw cap ended at engine 5620 for left/right hand drive.

Ralph does that square with your data card?

My car is engine number 8153 and it has the later style oil cap.

[stickandrudderman]

I have a 70 and it is crap. Replaced it and continues to leak.

These caps are normally perfectly reliable, if less aesthetically appealing, so you must have an underlying issue.

[MikeSimon]

As the valve cover was used across the model lines, it is not really a W113 issue and could be regarded as a 280SL "degrade"
The plastic overflow tank was used only for a short period and they went back to metal.

[Pawel66]

There is something I noticed on this topic and something I do not know.

1. What i noticed: in several cars, when breather is clogged or disconnected the screw cup starts leaking. These were cars with rebuiklt engines and with very good compressions.

2. What I do not know: there should be no pressure of oil under valve cover. If the pressure is there, means there are blow throughs from cylinder and repair is required. But I thought that perhaps the timing chain just throws oil on the cap. The breathing channel under the the valve cover (the riveted metal sheet one) is preventing that as suction diverts oil thrown by timing chain. I do not know if it make sense.

In any case - rather than chamging caps, I would check the breather - ppipes outside and the channel inside the cover.

[MikeSimon]

Pawel:
There is pressure under the valve cover. The downstroke of the pistons create pressure in the crankcase which goes up through the oil drain passages all the way under the valve cover.

[Benz Dr.]

Completely different animal but it's how I check a diesel engine. Remove the vent hose from the valve cover and plug it off. Most diesel engines will continue to run for a short while and then stall. Good engines will run on for quite a while and may not stop running at all. I've never tried this on one of our engines but it could produce interesting results.

[Pawel66]

Pawel:
There is pressure under the valve cover. The downstroke of the pistons create pressure in the crankcase which goes up through the oil drain passages all the way under the valve cover.

Thank you for explanation!

[neelyrc]

It shows that the screw cap ended at engine 3498 for left/right hand drive manual transmission cars
For automatic cars, the screw cap ended at engine 5620 for left/right hand drive.

Ralph does that square with your data card?

Yes Jon, my engine number is 002901, so there were about 600 manual cars after mine with the screw cap.  My car is a January build.  The change over was likely complete by mid-1969.  Maybe we could zero in on a date if a few other owners could contribute data on their cars.

[Shvegel]

I think the smaller bayonet cap was introduced along with the newer cylinder head etc.  i assume it may have provided an “escape valve” for any built up crankcase pressure.  Probably about the time the US market evaporative emissions system (large tank on right of trunk) connected to the engine crankcase.  I have seen three “genuine” versions of the cap.  The original “OEL” cap, the later universal genie lamp symbol and the later still black plastic version.   They tend to get grabbed with pliers a lot so straight original ones are tough to come by.

[Pawel66]

In the parts list there are several part number changes without engine number description as a change date and there is one that provides the engine number at which the change was made:

Filler cap:

A 111 018 03 02

Replaced with
   
A 000 010 02 85 FILLER CAP (NO TEXT)

Note: As of engine: 980 10/50,20/60 009548 980 12/52,22/62 019394 981 10/50,20/60 000238 981 12/52,22/62 001536 983 10/50,20/60 003499 983 12/52,22/62 005621 984 10/50,20/60 000200 984 12/52,22/62 000092

Replaced with

A 000 010 12 85

Note: As of engine: 980 10/50,20/60 009548 980 12/52,22/62 019394 981 10/50,20/60 000238 981 12/52,22/62 001536 983 10/50,20/60 003499 983 12/52,22/62 005621 984 10/50,20/60 000200 984 12/52,22/62 000092

Replaced with

A 000 010 14 85

Note: As of engine: 980 10/50,20/60 009548 980 12/52,22/62 019394 981 10/50,20/60 000238 981 12/52,22/62 001536 983 10/50,20/60 003499 983 12/52,22/62 005621 984 10/50,20/60 000200 984 12/52,22/62 000092

The engine numbers are the same for all these 3 parts numbers into which the cap was changed (not sure what it means in reality).

The valve cover:


A 127 010 00 30 ROCKER COVER

Up to engine: 980 10/50,20/60 009547 980 12/52,22/62 019393 981 10/50,20/60 000237 981 12/52,22/62 001535 983 10/50,20/60 003498 983 12/52,22/62 005620 984 10/50,20/60 000199 984 12/52,22/62 000091

Replaced with

A 130 010 00 30

Note:

As of engine: 980 10/50,20/60 009548 980 12/52,22/62 019394 981 10/50,20/60 000238 981 12/52,22/62 001536 983 10/50,20/60 003499 983 12/52,22/62 005621 984 10/50,20/60 000200 984 12/52,22/62 000092
Up to engine: 980 10/50,20/60 026729 980 12/52,22/62 061162 984 10/50,20/60 000488 984 12/52,22/62 000237

Replaced with:

A 130 010 03 30

Note: As of engine: 980 10/50,20/60 026730 980 12/52,22/62 061163 984 10/50,20/60 000489 984 12/52,22/62 000238 - so this replacement did not apply to 983 engines.

Maybe the above gives some clue on change of cap and cover.

[ja17]

The screw on caps were used on the Mercedes four cylinder engines of the era also. In fact the same screw on cap was used on earlier MB "ponton body" models on both the valve cover and gas filler cap. With a gas fill application a cork gasket was used instead of the rubber gasket used on the valve covers.