W124 Estate brake load sensor? Self levelling suspension

[John Turner]

My W124 250 TD (1989) has just failed its MOT (3.6.F.3) because 'the rear brake load sensing valve linkage is broken'.

I was unaware that there was such a link to the rear brake. Is it possible that the testing station are confusing the link rod (part 41) on the self -levelling suspension?

http://www.detali.ru/cat/oem_mb2.as...852F101441&CT=F&cat=506&SID=32&SGR=345&SGN=06

The only part I can see in the diagram that connects to the brake is part 140, the line described as the height contril valve to right spring loaded brake unit

However, since the part broken was described as a short rod which had snapped, I suspect they are confusing it with the link rod. If so, is this really an MOT failure (since it has nothing to do with brakes and I am not carrying heavy loads)? The ride is not bouncy nor flat - but very normal without loads.

The car was recently serviced, and I was told that I was going to need 2 new hoses (part 71) from accumulator to spring legs, and a new rear axle load valve sensor (which they describe as snapped). Does anyone know which part the latter is? (Apparently it costs £18.60 + £1.05) - is it part 59 in the diagram? I was not rushing to do this, but the MOT result is changing things! The suspension level fluid is low in the reservoir, and I suspect the drivers side pipe part 71 has leaked where it is corroded.

I am aware that MOT testing stations may be unfamiliar with the self levelling layout, and may be giving me a confused picture. The car was off the ramps and others on when I came to collect, and hence I have not been able to see the damage for myself.

Any advice would be gratefully received.

Thanks
John

 

[Number_Cruncher]

>>If so, is this really an MOT failure

Yes, it is a failure, although you're quite correct, the MOT station has incorrectly identified the part.

See section D of this page

http://www.motuk.co.uk/manual_240.htm

I think you're needing part number 41

http://www.detali.ru/cat/oem_mb2.as...852F101441&CT=F&cat=506&SID=32&SGR=195&SGN=04

and doubtlessly some of the other fittings around it will be badly corroded, and will break as you try to undo them. I would buy them all in to be sure of completing the job.

>>I was going to need 2 new hoses (part 71) from accumulator to spring legs

These aren't cheap. If they are leak tight now, clean them up, and grease / waxoyl them.

Leaks anywhere in the SLS pipework are an MOT fail.

 

[John Turner]

Sorry, Parts 41 (link rod) and 59 (height control valve) mentioned above feature in a separate close up drawing: http://www.detali.ru/cat/oem_mb2.as...852F101441&CT=F&cat=506&SID=32&SGR=195&SGN=04
Thanks
John

 

[kth286]

John

Does your car have ABS brakes ?

If so, then you are correct.

 

[John Turner]

Yes, my car does have ABS breaks.

The car is overall in excellent condition with a full MBSH and current mileage of 177,000. I have owned it now for 11 years. The interior is near perfect, the exterior is barely marked, but age is showing underneath with some pipes showing corrosion (such as on the self levelling suspension) and some degraded bushes. To date anything faulty has been replaced, but I have to accept it is now 20 years old and worth little (except to me). I am having to weigh up the cost of biggish labour intensive jobs against the car's value. There are no MB specialists in my area, and while I am happy taking on simple labour intensive tasks myself, I do not have the tools, workshop or time to tackle the trickier tasks. The local MB dealer have been great, and for many years have offered reduced labour charges on older models, and they have some technicians well used to the older models too. I