Poor timing!

[Sandspider]

Hi all Made it there and back again, thanks for the assistance. Thanks EDH for the garage suggestions, but I was already in Paignton, and didn't have a second spare (full on best man mode!) and in any case the car is actually pretty driveable with a little bit of extra care. In fact, the heat and buffeting in the cabin from having to have the windows open was probably the worst thing about the trip. :s Wedding was great though Speech seemed to go down well, and everything happened when it was supposed to but I'm still relieved it's over! (I hear tell it's harder being best man than being the groom - never tried the latter, so can't compare yet!)

 

[Frenchy]

Bet it is the one way vacuum valve adjacent the bulkhead little black/blue valve jobbie, couple of quids from OPC. It is a 928 part number.

 

[924nutter]

ORIGINAL: zcacogp That's a fairly extreme point of view John; once upon a time there were no such things as power-assisted brakes, and people managed cars just fine back then. Indeed, London busses in the 1960's had brakes which were so heavy you would typically have to put both feet on the pedal and lever yourself against the seat to get any reasonable degree of retardation. Giles has a car with perfectly adequate brakes, but no power assistance. Oli.

Yes they did Oli but it is not an exteme point at all; I am not right all the time, as my nonsense about taking the calipers off a 944 to change the pads shows, but in the main, being 62 and having had my head under a bonnet from age about 9 I have amassed a wealth of useful knowledge. Non servoed cars had softer pad material often asbestos based and stopped fantastically; however having broken down in my beetle and being loaned a mk 2 cortina gt ( I think) in about 1973,which had servo brakes , (but with the servo disconnected) I know what I am talking about. You can't believe the difference in pedal pressure. Try this. Go to the top of a shallow hill, turn your engine off. Pump your brake pedal a few times to empty the vac reservoir and let it roll up to about ten miles an hour, then try to stop it with the engine off. You will understand the issue better once you have carried ot this little experiment. It is in the same league as trying to drive a 928 without the power steering. Once I got an old set of asbestos pads for my 924 and the difference in stopping was noticable.

 

[924nutter]

Addiional; I have no idea whether this lack of servo would affect abs abilities but I don't wan't find out the hard way. Run out of petrol and your car will stop. run out of brakes and it wont. Also if you have a crash your insurance company wont be impressed.

 

[zcacogp]

John, You're right - a car that is designed to work with a servo on the brakes will be harder to stop when the servo stops working. And the difference can be significant - more than enough to take someone by surprise if it stops working unexpectedly. And yes, cars with braking servos are designed with the assumption that the servo usually works, cars without a servo have different geometry in pedal leverage, different pad material and so on. However the only difference is the amount of force you need to put on the brake pedal to achieve the same degree of retardation; the brakes still work. Indeed, the who system is designed to be fail-safe; it is designed to continue to work when the servo packs up to ensure it remains safe. To suggest the car suddenly becomes unsafe when the servo is disconnected isn't true; you need to take the difference into account when out on the road, but driving around the conditions presented to is part of being a good driver. Driving with a duff brake servo is similar in many ways to driving on snow and ice; it isn't dangerous if you are aware of what you are doing, although some people will find it too different for them to be comfortable with. Yes, I have driven cars some distances with broken brake servos. (A couple of old Capri's, a somewhat dilapidated Mk1 Passat and a few Golfs. Not the 944, but I assume that is much the same.) No, it's not great. Yes, the brakes are always very very heavy. Yes you need to think about what you are doing. But I don't agree that it is dangerous per se. Oli.

 

[924nutter]

deuce

 

[Sandspider]

For what it's worth - driving without brake assistance was scary when it happened unexpectedly. (I was stopping behind a car at a junction and suddenly the brakes weren't doing their usual job - lucky I wasn't too close). But once I knew about it, it wasn't a problem as such. I drove a bit slower, left bigger gaps between me and the car in front etc. The car decelerates as normal (e.g. from 70mph to 50mph) but to actually come to a complete stop from say 50mph requires more force than normal. (Not both feet on the pedal, but bracing myself against the steering wheel a bit so I could really push the brake pedal firmly). So it could be dangerous if you had to suddenly stop completely from motorway speeds say, or if someone pulled out right in front of you, but with cautious driving it wasn't a major problem. Frenchy - thanks, I'll look at that. Assuming this diagram is accurate, I think I know where the big circular thing that the blue valve you mention (part 8, Porsche part number 928 537 361 02) connects to is, so I should be able to trace the various vacuum pipes from there.

Cheers.

 

[Frenchy]

That's the one Giles, half black/half blue, check the valve itself and the pipework to and from it.

 

[ChasR]

I shall sit on the fence with the no power assistance arguement. Two cars I have driven with rebuilt brakes and no servos (Triumph Spitfire and a Mini City E) were actually quite pleasant to use. OK, they are not quite the same as servo brakes but they still do the job very well. Driving a car with a servo that does not assist is quite scary. Especially with muppets on the road ever more willing to cut you up.

 

[924nutter]

In an entirely unrelated search for the DME relay on a 1982 944, I was sent a link to an online 944 owners manual. Imagine my surprise when the phrase" ....without the servo stopping wil require MUCH more pedal pressure" caught my eye, which was my original point. Get you home, fine but then to begin another journey?

 

[os951]

Usually hot-air-syndrom is caused by a broken plastic clip. It can be found in your case on passanger side of the hvac unit. Remove the plastic cover and you can easily see what is broken. New clip is cheap to buy. When you install it, unplug the electric connector. Have a long electric cord and put 12V + to pin number 4 and - to pin number 5. This drives motor to max cool position (changed polarity will drive motor to max hot position) Then pull from flap shaft as far as it goes (your's is full open/hot now) to put it max cool position. Then just snap shaft to new plastic clip. This problem takes about five minutes to fix. If you do not adjust flap to the correct position you can easily break new clip. If clip is OK, then check outside air temp sensor. It is located on right side of the hvac unit in engine room. Just lift a bit that black thin cover. New sensors are with 964 part number, which are improved ones over original 944-part number sensors. If there are also brake related problems, check out that small blue/black valve. Also check out that small vacuum container (# 3 in that picture) it's quite usual to have containers small tube broken, when it stops giving vacuum to hvac unit.

 

[944 man]

ORIGINAL: os951 Usually hot-air-syndrom is caused by a broken plastic clip. .

This was my first thought too, but with everyone talking about vacuum lines I didnt comment.

 

[Sandspider]

Cheers chaps. I thought it was the little clip at first too (and even mentioned it in my first post). But when I thought about it, the timing seemed strangely coincidental - that that clip should break at the exact same time as the brake assist stopped working from a vacuum fault...? Seems unlikely. If it makes a difference, before that, my heater would only blow fully hot air or fully cold air, it had no middle ground! The problem I find with the 944 is that often lots of different causes could produce a symptom, and it can be a slow process to identify the correct cause... Looks like I'll have lots to look at this weekend. At least there're no bloody weddings for a while...! John - I'm not driving it any more. But, in truth, it's more because it gets so hot inside than because the brakes worry me! They really are not too bad, once you know what to expect. If I'd been worried by their performance, I would have stopped and been recovered down and back. Finally, how do I check that whether the blue / black valve is working or not? Take if off and try and blow through it?! The valve is now £15.84 - inflation I suppose! [&:]

 

[Frenchy]

Giles it is a one way valve to prevent vacuum from leaking when the car is stopped, it will pass air one way but obviously not the other, take it off and blow through it, mine had cracked on one of the inlet tubes.

 

[Sandspider]

Frenchy, you were closest! Not actually the blue and black valve, but the bit from the plastic connector on the big metal disc that the elbow joins the blue and black valve to. (Hard to explain, but it's the little plastic tube with the red arrow pointing to it - it's snapped off and is stuck inside the elbow). See handy diagram:

The question is, can I replace the bit that it's snapped off of? I can't see it mentioned on any parts diagram or anything. I gave it a poke, and it's not part of the big disc (plastic where the disc is metal) but I couldn't see a way to get it off. Does anyone have any ideas on whether the plastic connector thing attached to the big metal disc can be replaced on its own, and what it's part number is if so?

 

[Frenchy]

I would have thought you can still get one if not,secondhand/ carefully applied Araldite !

 

[os951]

I suppose you have a Girling made booster? That part is totally different with Ate made units. Ate made units have just a big hole there, to where you can put a valve. My son installed a Boxster valve to his 951 project, Boxster part was used since original was broken and replacement unit was available from a wrecked Boxster. I suppose you can easily modify your Booster to accept newer style valve.

 

[Sandspider]

Hi all Quick update - I spoke to OPC Exeter who initially said I needed a new brake booster (at £450 +), but eventually I managed to explain that it was part of the check valve that had snapped, not part of the booster itself. They promptly sent me a new one and gasket for the princely sum of £36 odd inc postage, and I fitted it on Saturday. Bit of a fiddly job (and sweaty), especially getting the new check valve through the rubber gasket and into the brake booster, but now all is working again - I have wonderful brakes, and a heating system that reliably blows very hot or fairly cold. Exeter OPC even sent me a second package with the clips for the heater valve behind the glove compartment with no additional postage fees. I'll see if that fixes the blowers only fully hot or fully cold problem... Thanks all for the suggestions, and thumbs up for Exeter OPC. Glad I didn't have to spend hours chasing all the vacuum lines through the engine bay in the 34C heat! Result.

 

[Sandspider]

ORIGINAL: os951 I suppose you have a Girling made booster? That part is totally different with Ate made units. Ate made units have just a big hole there, to where you can put a valve. My son installed a Boxster valve to his 951 project, Boxster part was used since original was broken and replacement unit was available from a wrecked Boxster. I suppose you can easily modify your Booster to accept newer style valve.

Just seen this Oli - seems that I have an Ate brake booster, or at least, when the valve and gasket was removed, there was just a hole left in the booster. And I was happy to replace the valve with like-for-like (which presumably lasted 25 years and 100,000 miles!) rather than try and upgrade and possibly make trouble for myself. (I don't have your facilities, or level of technical competence!) Cheers.