924Board.org

Neil@Bournemouth · Joined: 25 Oct 2005 Posts: 24 Location: Bournemouth, UK

Hi everyone,
My car's recently failed its MOT due to one of the rear brakes being half as good as the other. The MOT guy thought it was probably a leaking brake cylinder and on inspection it looked like it was, so I replaced both sides.

Today I checked it before the re-test and the inside of one drum has a puddle at the bottom. I dont think its coming from the cylinder cos its dry around it (even after pumping the brakes...) so im wondering where its coming from.

So my question is, what could this liquid be and where is it coming from?
Could it be from the bearings due to a poor seal or something?

Thanks,

Neil.
_________________
'84 924 Guards Red
'85 944 White

968rz · Joined: 21 Aug 2006 Posts: 537 Location: S. E. Wisconsin

Was the drum really wet with brake fluid before the repair? It could be that, after sitting the fluid worked it's way down the drums and out of the shoes and puddled.
_________________
Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

Ozzie · Posted: Sat Sep 16, 2006 7:25 pm Post subject: Re: Rear brake question

Jaf · Joined: 08 Jun 2006 Posts: 194 Location: Oria. Spain

If you've got that much brake fluid around I'd reckon you'll need to replace the shoes. They're no good once contaminated, they clean up and look ok but just never work as well.
_________________
1978 924na

Neil@Bournemouth · Joined: 25 Oct 2005 Posts: 24 Location: Bournemouth, UK

Thanks for all your suggestions/advice guys.

I've sorted the problem at last. Ive cleared up the fluid and bled the brakes. It was definitely brake fluid so ive replaced the shoes for the second time in a week.

There's no fluid coming from anywhere now so its weird that it leaked at all. My thoughts are that there might have been fluid under the rubber gaiters on the cylinders when i installed them...
Oh well an unsolved mystery!

Now thats done im on to bigger things... got to replace the oil cooler seals and steering rack on my girlfriends 944.

Wish me luck!

Thanks again,
Neil.
_________________
'84 924 Guards Red
'85 944 White

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

Good luck, Neil.

Presumably you got through the MoT second time?
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

Neil@Bournemouth · Joined: 25 Oct 2005 Posts: 24 Location: Bournemouth, UK

Thanks,

Yep it got through the MOT on the second attempt.
The brakes were the only failure in the first mot, im quite impressed for a 22yr old car.
_________________
'84 924 Guards Red
'85 944 White

Slam · Posted: Sat Sep 23, 2006 11:33 am Post subject:

Good luck, Neil. Have you got the alignment tool for the oil cooler? You'll kick yourself if not...and a misalignment can cause oil pressure to cannon that oil filter right off the boss. Or starve your bearings. Sorry, not trying to come across as doom and gloom, but forewarned is, after all, forearmed.

I know I have forearms... Four arms?

Whatever.
_________________
'88 944 Auto - may or may not resurrect

JB 924 · Joined: 03 Apr 2006 Posts: 606 Location: Hessen, Germany

Neil@Bournemouth · Joined: 25 Oct 2005 Posts: 24 Location: Bournemouth, UK

Hi Slam,

No I haven’t got the oil cooler alignment tool and didn't realise it was that important. I though the pressure relief valve could be used to do the same job?

Does anybody know where I could buy an alignment tool over here in the UK? Failing that is it possible to make one up myself with the dimensions?...
_________________
'84 924 Guards Red
'85 944 White

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

No. you can't use the OPRV as a oil cooler alignment tool. If you do, then there will be the risk of damage to the OPRV, or that it will hang sometime in the future, and then the engine will suffer from complete oil lubrication system failure or at the very least dangerously low oil pressure. Do you expect your GF to pay attention to the warning light, or act like most females on this planet and ignore it?

If you have the car apart already, it should stay that way until you find/buy the correct oil cooler alignment tool (there are two, and the one you need is the more common, easier to purchase one).

You also need to replace the OPRV if the one from the engine is the old three piece design that is prone to failure. Porsche recommended removing and replacing the three piece OPRV with athe newer one piece design probably close to over fifteen years ago. A new OPRV sells for over $300 here in the U.S.

The oil cooler housing needs to be checked to see if it has been replaced yet. In another TSB, Porsche instructed that older style oil cooling housing be replaced with a newer design that is supposed to seal better with a new instructions for assembling the seal stacks and way to determine the proper length for the seal stacks with the new oil cooler housing.

Slam · Posted: Tue Sep 26, 2006 11:59 am Post subject:

gohim's right. What year is your GF's 944? It may have the updated oil cooler housing already. There's a good writeup on this at www.clarks-garage.com and you should have a look at it.

Porsche TSB does stipulate the housing update, but I stuck with my original housing and have had no problems to date. At least no oil cooler OPRV problems... But I keep an eye on everything.

BTW, have fun with your girlfriend's rack...

Steering

Rack.

Jens, time for my medicine.
_________________
'88 944 Auto - may or may not resurrect

Neil@Bournemouth · Joined: 25 Oct 2005 Posts: 24 Location: Bournemouth, UK

Thanks guys,

Ive taken your advice and ordered the tool. Turns out it wasnt too expensive - £15 including postage from the USA.

Im going to go with the original housing and OPRV as the seem in good condition and as long as they are aligned properly im hoping they will work OK.
Thanks to the pointer to Clarks garage, thats a damn good resource which I havnt come across before...
_________________
'84 924 Guards Red
'85 944 White

Slam · Posted: Thu Sep 28, 2006 10:25 am Post subject:

If you're planning to use the original housing, check the way the element sits in the housing and do the clearance check as described on clarks. Also, make sure there aren't any burrs or scratches on the piston itself, or in the bore. I sanded mine gently and cleaned up with acetone. The only other thing I'd be careful of is torquing the housing back onto the engine block. Very easy to strip these. So far I haven't found torque specs on this anywhere, so I'm sorry but I can't help there.

One thing in your favor is that oil pressure is higher than coolant pressure, so after you're done watch your coolant recovery tank like a hawk. Any oil getting past the seals will end up there.

HTH
_________________
'88 944 Auto - may or may not resurrect

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Slam, 924S and 944 owners always have to watch for the rising oil level which signals an oil cooler leak. While the oil pressure is higher when the engine is running, when the engine is shut off, the rising pressure in the cooling system (due to heat soak) will force coolant into the oil lubrication system if the oil cooler seals are weak.

This is a primary reason for the specific seal stack, and the revised oil cooler housing. The bumps at the bottom of the oil cooler housing which used to be where the seal stacks contact the oil cooler housing have been removed making the oil cooler fit down deeper into the oil cooler housing. If you use the current oil cooler seal stack instructions with an old oil cooler housing, the stack is going to be way too high.