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MOT Failure
https://forums.tipec.net/viewtopic.php?f=27&t=15940		 Page 1 of 2
Author:  mikec [ Sat Aug 10, 2013 4:16 pm ]
Post subject:  MOT Failure
Ok I got my car back from the MOT station. It failed on
1) Number plates
2) Indicator bulb
3) Nearside rear Fluid suspension unit interconnecting pipe corroded and seriously weakened
4) Brakes imbalanced across the axle

1&2 no problem. I have spare plates I can put on

3 is nothing to do with the suspension and is I think one of the pipes coming from the PSD unit in the rear passenger wheel arch. So the MOT guy has got this wrong. Should this have been a failure or perhaps an advisory? Is it dangerous? It's to do with the slip diff right

4 I'll give the discs a good clean, check they aren't sticking and check the tyres are equally inflated.

I'll be going round to my garage in a bit to get the car jacked up and find out exactly which part is corroded.
Author:  Lee 944 [ Sat Aug 10, 2013 4:54 pm ]
Post subject:  Re: MOT Failure
It is complicated and not many mechanics understand the Weissach Axle. Probably, Brian Miller is the only man local who know it and can explain it to the mechanic. Failing that, take it to the same place as I took mine in Carluke ( Carluke MOT Centre. The guys in there know 928's, as they've help with a couple of club members cars, and can honestly tell you what you need to do help get you through the MOT.
Author:  mikec [ Sat Aug 10, 2013 5:58 pm ]
Post subject:  Re: MOT Failure
Weissach Axle. That's what I was trying to explain to the guy. Unfortunately I didn't have all of the facts when I went to pick up the car. The question is though should this be part of the MOT check? It's not part of the suspension. Also I'm reading that that a slip diff can cause issues on a brake test and perhaps shouldn't be done on a brake roller. Anyone know anything about that. Unfortunately I need to get this car MOT'd early during the week as I was meant to be heading off camping on Monday. If the lines coming from the PSD aren't dangerous and don't need to be fixed for the MOT then that would be my preferred option and I'll replace them when I get back. If they are dangerous and they do need fixed for the MOT then I'll get on the phone to Porsche on Monday and see when I can get replacements. Failing that I'll be hiring a campervan. There's an MOT station up near Brian Miller, I used them a couple of time on his recommendation, I'll maybe take the car there, they could phone him if there is a problem.
Author:  EL Gordo [ Sat Aug 10, 2013 6:27 pm ]
Post subject:  Re: MOT Failure
Dont understand how they can fail a part when ghey dont know what it is!
Author:  Lee 944 [ Sat Aug 10, 2013 7:06 pm ]
Post subject:  Re: MOT Failure
EL Gordo wrote:
Dont understand how they can fail a part when ghey dont know what it is!

After you picked my auto correct earlier...........all of sudden you've went homophobic?
Author:  EL Gordo [ Sat Aug 10, 2013 8:08 pm ]
Post subject:  Re: MOT Failure
Noooo !!!!!
Author:  Sean Smallman [ Sat Aug 10, 2013 8:28 pm ]
Post subject:  Re: MOT Failure
My 911 has a slip diff and they won't put it on the rollers.
Author:  EL Gordo [ Sat Aug 10, 2013 8:32 pm ]
Post subject:  Re: MOT Failure
Seriously if they cant identify a part how can it be an mot failure
Author:  stratfordshark [ Sat Aug 10, 2013 9:07 pm ]
Post subject:  Re: MOT Failure
I am almost certain the PSD is not tested as part of MOT, so am baffled why yours failed even with a leak (by the way I've never heard of leak in this system before, but the hydraulic pressure is extremely high).

My PSD equipped MY91 has always been brake tested on rollers. It is an issue with 4WD vehicles where the 4WD must be disengaged for brake test.

The brake imbalance could indicate corrosion behind the side plates in one of the calipers, preventing pads from moving freely.
Author:  tr7v8 [ Sat Aug 10, 2013 10:37 pm ]
Post subject:  Re: MOT Failure
stratfordshark wrote:
I am almost certain the PSD is not tested as part of MOT, so am baffled why yours failed even with a leak (by the way I've never heard of leak in this system before, but the hydraulic pressure is extremely high).

My PSD equipped MY91 has always been brake tested on rollers. It is an issue with 4WD vehicles where the 4WD must be disengaged for brake test.

The brake imbalance could indicate corrosion behind the side plates in one of the calipers, preventing pads from moving freely.

If it works as an LSD then it should NOT be tested on a roller brake & should be road tested with a Tapley meter.
Author:  Maybach_man [ Sun Aug 11, 2013 10:44 am ]
Post subject:  Re: MOT Failure
Hi
On three did you explain what it was to the tester?
on four you will also probably need to move the callipers in and out a few times with a retraction tool or a g clamp and some wd 40 as the calliper pistons will probably be stuck.

Geoff
Author:  Brett928S2 [ Sun Aug 11, 2013 1:30 pm ]
Post subject:  Re: MOT Failure
tr7v8 wrote:
stratfordshark wrote:
I am almost certain the PSD is not tested as part of MOT, so am baffled why yours failed even with a leak (by the way I've never heard of leak in this system before, but the hydraulic pressure is extremely high).

My PSD equipped MY91 has always been brake tested on rollers. It is an issue with 4WD vehicles where the 4WD must be disengaged for brake test.

The brake imbalance could indicate corrosion behind the side plates in one of the calipers, preventing pads from moving freely.

If it works as an LSD then it should NOT be tested on a roller brake & should be road tested with a Tapley meter.



Hi Jim :)

Absolutely true.... its how they do mine with an LSD... ROAD TEST....with that meter....

All the best Brett :)
Author:  mikec [ Sun Aug 11, 2013 9:37 pm ]
Post subject:  Re: MOT Failure
I did attempt to explain to the MOT guy but I didn't have all the facts at hand at the time. I did say it wasn't suspension but I'm not so sure he believed me. He's done my car before with the previous owner. He's probably just always assumed it was related to the suspension. I'll print out some evidence and take it down there and show him. They are actually alright they have got my 944 through it's last two MOT's and arranged all the welding work for me at a different body shop, prices were reasonable and work was good. I don't get the impression he's the type to fail cars on trivial stuff, just a genuine mistake. He even said not to bother sticking on the legal plates which he saw I had in the boot. The only reason I'm keeping the illegal ones is because the B gets mistaken for an 8. Saved me a parking ticket.

So I have been around to the garage and I swear this car fricking hates me. First off I jammed my finger nail between the calliper and the ally wheel. Then I stripped a bolt on the rear wheel. The stud doesn't look too bad I'm hoping I can save it with a die. Any idea what size I need?

The front brakes seem in good shape. The pistons compressed pretty easily but there is possibly a little bit of plate lift as the pads took a bit of work to get out. I filed the edges of the pads down a little and gave everything a good clean with brake cleaner and the pads went back in nicely.

I took the rear wheel off (stripping a bolt) and got a few pics.


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Pretty sure it must be the 3rd picture. I can just see a hose there and line looks a bit rusty too so I would replace the whole lot.

Also in the first and second pics there is a loose wire or tube. Not sure what that is. The whole unit seems pretty loose too. It just feels like it is bolted on at the front two bolts that can be seen in the pic
Author:  mikec [ Sun Aug 11, 2013 10:12 pm ]
Post subject:  Re: MOT Failure
I've just checked the catalogue. On page 124 in the automatic transmission section I believe I need 928 315 095 02 and 944 355 081 01. I've been doing a bit of reading and think this may be a safety issue what do you guys think?

Think I may struggle to get this sorted for camping.
Author:  Brett928S2 [ Sun Aug 11, 2013 10:31 pm ]
Post subject:  Re: MOT Failure
Hi :)

On the subject of plate lift on the brakes... if you had to FILE them to get the new pads back in then you HAVE got plate lift....normally a new set will slide in easily....

All the best Brett :)
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