unusual and messy instrument failure

[s class]

Well, when I bought my 280SE back in 1997, it was aparent that there was some 'sweating' visible around the oil pressure indicator needle in the combination gauge. At that time I was ignorant about the 'live' pressure gauge behind there, and didn't think anything of it. Over the next few years, I removed the cluster a couple of times for various reasons (such as a failed ignition switch contactor barrel).

On those occasions, I could see the progress of the developing fault - clearly the pressure gauge was leaking - the gauge itself, and not the connection at its rear. Anyhow it got to the point that oil stains were visible behind the high beam, handbrake etc warning lights, and there was a general oiliness soaking the cabling, ducting etc behind the binnacle. Really not nice. But its been like that for 10 years, so I just lived with it - until about 2 months ago - its suddenly got worse to the point that oil was coming out the ducting that leads to the driver's door internal ventilation - and there was a small swiming pool of oil behind the plexiglass of the combination guage. The final straw was when the oil started dripping onto the steering column, and running down, through the firewall and dripping out onto the floor by the steering box.

This weekend I removed the cluster, and stripped it completely. I degreased every component, and rebuilt it using a combination gauge saved from a parts car 280S. What a pleasure not to have oil coming out everywhere. the RHS of the dash is still a mess underneath, but it will live that way until I remove it for replacement during the upcoming respray.

 

[oscar]

I can't imagine you leaving something like that for so long. Rather it's something I'd procrastinate on. But so many things pass under the radar these days whilst more important issues pop up.

Any idea why it leaked or have you chucked it out? Not a common problem I wonder if it was a manufacturing problem or rough handling many years ago.

 

[s class]

No idea why it leaked. Its been leaking very slowly until recently when it got much worse. Yep I know, shocking I left it so long, I hope I can still retain my stripes, so to speak.

 

[Styria]

Hi S-Class and Ossie - every once in a while, you get a job that just doesn't seem important enough to fix - it's a case of "yeah, I must get onto this", yet it doesn't get done.

I had a similar situation with the oil pressure gauge in "Gleaming Beauty" - it was inoperative from the day I bought her some thirteen or fourteen years ago and what sane person would buy a car with an inoperative gauge ? Well, me of course. I have a suspicion that the non-operative gauge was the reason why the dealer knocked $4k. off the purchase price without blinking an eye lid - I think he was terrified of the car and what warranty issues that may have come with it.

Anyway, even when I had the dash removed, and having bought a new oil pressure line, I still did not fit it. Sure, it's a bit awkward, but really that was the time when it should have been replaced. Yet, I didn't. Perhaps, I was 'scared' as to what I might find if the gauge was working !

This time, with the valve grind and de-coke, I decided to bite the bullet and fit the jolly thing. It was with great relief that I can convey that the engine is holding oil pressure beautifully - probably better than ANY 6.9 I've had anything to do with. I now have peace of mind.....and satisfaction at eventually having done a job that had annoyed me for all of those years. Regards Styria

 

[s class]

I can report that across a range of driving and temperature conditions, the replacement gauge gives essentially the same readings as the old one did. THe temp gauge now consistenly reads about 5 degrees lower than the old one did - now which one is correct?. The fuel level gauge reads higher than the old one, and I don't think this is correct - it still showed 1/4 full when the reserve light came on - and it took 88 litres to full, so it really was empty.

But at least I don't have oil squeezing out everywhere. Its a new driving experience!

 

[CraigS]

The fuel level gauge reads higher than the old one, and I don't think this is correct - it still showed 1/4 full when the reserve light came on - and it took 88 litres to full, so it really was empty.

The fuel gauges are a pain in the ........... ! I know on the 6.9's that the end of the sender unit gets blocked up. There is a very small hole at the end of the tube and if this gets blocked, which they do, it sends a wrong signal - exactly as you mention - 1/4 full, but the reserve light comes on. I always tend to trust the reserve light more than the gauge.
I have pulled several of these for cleaning and they seem to work for a while, but then resume their old ways. Next time I pull one out, I am going to enlarge the hole and see if that makes any difference. It is only there to relieve the pressure of the inner sleeve as it goes up/down. so I don't think enlarging the hole will cause any major problem, and it will hopefully prevent any small particles blocking it.

 

[WGB]

Over many generations of cars M-B or not in my experience the reserve light is always the one to trust.

If only you could make a gauge as accurate and as reliable as the reserve light.

I understand that US legislation requires the reserve light to come on when the car will only travel a certain distance ?50 miles.

Bill

 

[s class]

I know about the sender issues - I've had this one out and its as clean as can be hoped for. I used to have beautiful linear indication before with the old gauge.

PS - how does one remove the needles from the gauges without breaking anything - so that the individual gauges can be separated from the face plate?