Sump plug question

[Des]

Today I decided to have a crack at changing the oil on one of our cars myself. I've always noticed when you get your car serviced at a workshop they change the sump plug "o ring" I always assumed this to be a rubber or some other gasket type o ring. But they are metal, just like a metal washer.

Why do they change these every 6 months when you have the oil changed?
Is it a case of simply getting some more money out of you or is there a genuine reason for replacing this?

Sorry if this seems like a trivial or obvious question, just haven't seen it talked about.


thanks

Kind Regards
Des

 

[BenzBoy]

Better a new washer every time you change the sump plug than a leak - or worse, a plug that works its way loose....
The washer is usually metal and it performs the twin tasks of keeping the plug tight and keeping it in there - usually a good thing...
Regards,
BenzBoy

 

[Des]

Good points yes,

thanks

Kind Regards
Des

 

[CraigS]

They are generally a compression copper washer, and hence the need to replace them each time.

 

[Des]

They are generally a compression copper washer, and hence the need to replace them each time.

Craig, do you mean that they are really only a use once item?

thanks

Des

 

[WGB]

Some are copper, some are aluminium and some are fibre.

They are all designed to be compressed once and generally don't cost more than about a dollar.

I know I serviced my Son's Subaru Impreza 18 months ago and changed all fluids - engine, 3 diffs, gearbox. The parts guy at the Subaru agency had difficulty finding all the correct part numbers. I assumed and he agreed that they don't change all of them when they do a complete fluid change - if it ever gets done at all.

Bill

 

[Des]

Ok thanks Bill, wasn't really a cost concern, although I didn't think to buy one until I had the oil out of the car.

As the plug needs to be changed anyway, will be doing it again in a few months.


Des

 

[WGB]

Ok thanks Bill, wasn't really a cost concern, although I didn't think to buy one until I had the oil out of the car.

As the plug needs to be changed anyway, will be doing it again in a few months.


Des

These days I use a vacuum extractor to remove the oil and then if it is a special car drain the last few mls out from the sump plug but there is usually surprisingly little comes out.
M-B in the past supplied a washer with the filter when you purchased the original filter but for the last few years they have been using a vacuum extractor as well and the filter is found on the top of the engine so you just tuck in your tie and don't even have to remove your suit jacket

But seriously - the sump plug washers can usually last two or three changes before they get past it. You just end up tightening the plug a little more than should be needed with the result that it is a little harder to remove next time and a little easier to damage something.

Bill

 

[BenzBoy]

Bill - can you tell us a little more about your vacuum extractor, please?
Regards,
BenzBoy

 

[WGB]

It is a plastic cylinder about 1 metre high with a pump on the top.

It has three plastic tubes about 0.5 metre long each of different diameters which are designed to connect to each other end on end.

The smallest diameter goes down the dipstick tube and is pushed into it until it bottoms in the sump. Pump up some vacuum and go and do something else for 10 to 15 minutes or until it is full (with these new Benzes with 8 litres in the sump).

There is also a metal version that looks smaller and more expensive.

I'll post a photo when I get a chance to take one in the next few days.

Bill

 

[Des]

Bill do you then use a flush or is the pump enough to clear out all the gunk and contaminants?

 

[s class]

I agree that on the sump plug one can get away with reusing the copper washer a couple of times - because there is no pressure in the sump.

Des, copper and aluminium washers are used all over in the steering system, fuel system and 6.9 hydraulics. These are pressurised systems, and I virtually guarantee you that if you try to reuse a crush washer when changing fuel pumps for instance, or suspension spheres, you will never get it to seal without leaks.

 

[WGB]

Bill do you then use a flush or is the pump enough to clear out all the gunk and contaminants?

I am talking about engines that are run on Mobil1 and the oil is changed when it is hardly dark so there are not a lot of contaminents and I am sure 50 to 100 ml or so will not make a lot of difference.

For a real dirty engine draining and flushing initially would be useful.

I also agree with S-class that while sump plug washers are potentially re-usable these sealing washers should never be re-used wherever there is any pressure - ever.

Bill

 

[Mercules]

Sump plug washers are usually made from a metal much softer than the plug and the sump itself - When the sump plug is tensioned, the washer will conform the the irregularities in shape or crush - when you try to reuse the 2nd hand washer on an oil change, it sometimes does conform to shape again becasue it has already been squashed and if it doesn't seal correctly... drip...drip...drip! Rather than risk a comback, it is easier to fit a new washer and charge you 1,000,000% markup - the mechanic wins on both counts!

HAving replaced thousands of the little bastards, that is my take on the situation!

Cam

 

[Michel]

For the cost of the washer....

 

[WGB]

The cost is not usually the issue.

The problem is not having the correct size available (even though the correct replacement was supposedly purchased) on a Sunday when nobody open has that size.

On a high pressure joint this is critical and the car would be off the road until the correct washer was found - but a sump plug is not that critical.

There is another reason for using a vacuum extractor. On my wife's previous 163 ML270CDI Diesel the Mobil1 oil change interval was 28,000km which I thought was too long so I changed the oil and filter myself at 14,000 km between services.

On this model all the encapsulation has to be removed from undeneath to get at the sump plug which invariably damages a few of the plastic rivets which then need replacement and even then the plug sits exactly over the steering rack and left hand rack gaiter. Even using a funnel to catch and divert the flow leaves a significant mess to clean up.

While M-B has left the ability to perform a manual oil change in the specification they obviously intend the job to be carried out by vacuum extraction not by time honoured methods.

I mighty add the service intervals have been dramatically shortened and the computer now calls all the 07/08 Oz models back to base at 15,000 km. Petrol and Diesel whereas previously my 2003 W211 E320 Petrol was called back at 20,000 km and the 2002 ML270 Diesel at 28,000.

Bill

 

[Styria]

Hi WGB, these are interesting comments regarding the service intervals. On 6.9's, the recommended oil and filter replacement is listed at 15,000 kilometres, but I have only followed that recommendation once.

At that time, I was using Mobil 1 and I decided , on account of the cost factor, to leave the oil for the recommended period. When eventually the time came to change the oil, the brown syrup posing as lubricant was something else to behold. After that, a change every six months became the preferable option !

On 6.9's, the copper washer is very thin and just about non-crushable and not that easily obtainable unless you buy from MB direct. What I have found useful is to use a thread sealant when refitting the sump plug and that has always worked satisfactorily. Regards Styria