| Author |  Topic  |
EdinburghJoe
V4 Fan
United Kingdom
162 Posts |  Posted - 20 Jan 2019 : 18:08:09  
| Hi all,
Last winter I noticed I was losing brake fluid - at one point most of the reservoir seemed to have disappeared in a month or so. I was surprised, because I hardly use the car in winter, but I found drops of brake fluid hanging off one of the front calipers so I changed the seals on both.
All through this summer the brakes have been fine: it continued to lose a bit of fluid, but not as much as before I changed the seals, so I just lived with it, maybe topping it twice in about 6 months.
This winter the car is pretty much unused again (maybe 10 miles in the past 6 weeks), and I've noticed that it has lost about a third of the fluid in the rear section of the reservoir. I looked at the front calipers and they are completely clear, and there's no sign of fluid on the bottoms of the rear drums. There is also no sign of fluid dribbling down the inside of any of the wheels and tyres, front or rear.
Could the master cyclinder be a likely culprit? Since it seems that the leak happens even when the car isn't being used I'd be surprised if the fluid could leak out at the wheels in such quantity at low pressure, without losing a lot of fluid when driving. For a start, the brake pipes run up above the level of the reservoir as soon as they leave it, so it would have to flow uphill (though I guess there could be a siphon action).
Does this sound like it could be a problem with the master cylinder? Should renewing the seals fix it? I have a kit...
Do these problems get worse in winter? Can low temperatures cause seals to shrink and leak?
Thanks for any advice,
Joe |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 20 Jan 2019 : 20:19:52
| If the master would leak, it would do so either on the couplings (easy to spot), or into the brake servo. Also easy enough to check, first by having a look in the vacuum hose for signs of brake fluid. However, I would start by having a look inside the rear brake drums, even if you don't directly see fluid dripping out of them. The rear cylinders are notorious for leaks, especially cheap pattern parts. There should be no need to ever top up the fluid.
www.saabv4.com |  |
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pchristy
V4 Guru
United Kingdom
1790 Posts | Posted - 22 Jan 2019 : 10:03:38
| I'm with Melle on this one. A couple of years back, I had a rear cylinder fail around MOT time. There was no sign of fluid externally, but when I removed the drum, it was soaking inside!
When my master cylinder went - some years ago now - the brakes felt quite spongy and the warning light came on. John-saab got it sleeved for me, and its been as good as gold ever since.
--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!" | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 22 Jan 2019 : 12:15:50
| Thanks for the replies. Last night I started the engine, pressed the brake a few times, stopped it. Then disconnected the vacuum hose from the servo, had a good look inside and there was no sign of any liquid at all. Also, the brakes on this car have (so far) always been sharp and firm, so bearing in mind what you've said it looks like rear hubs are the next thing to look at.
I've never taken the hubs off before. I have a 5-point hub puller and the process looks clear enough, but are there any helpful tips that aren't in Haynes? Also, is there anything else worth doing while I have the hubs off? I'd thought of replacing the grease between the bearings but that's about it. It looks like there's an oil seal in there - assuming it looks OK can I just re-use this? Of course if there are leaky brake cylinders or worn shoes I'll be replacing them...
Joe
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 22 Jan 2019 : 12:35:46
| You normally don't need a puller to remove the hubs; wind out the adjusters and the hub should come right off by hand. If it doesn't, a few gentle taps with a mallet (I use a copper one) should suffice.
If you want to regrease the bearings, which I think is a good idea, just leave the seals in place. If you disturb them, you'll need new ones and good ones (i.e. rated for relatively high rpm automotive applications) have become hard to come by.
Do not blow out the brake dust with compressed air, as asbestos brake shoes may have been fitted in the past. Use brake cleaner instead to wash down the parts; wearing an appropriate particle mask wouldn't harm anyway.
Make sure you put back the brake shoe springs correctly, I think there's a diagram in the Haynes manual (or download the Saab factory manual from my website if you don't have it: http://www.saabv4.com/index.php/saab-factory-manuals/saab-v4-factory-workshop-manual-english/ )
It's also a good idea to check the condition of the brake lines and hoses now you're at it.
www.saabv4.com |
Edited by - melle on 22 Jan 2019 12:36:38 | |
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UK_Sub
V4 Guru
United Kingdom
2558 Posts | Posted - 22 Jan 2019 : 14:40:49
| I've used a spare wheel (without a tyre) as puller in the past, just bolt it on backwards (ie: outward face of the wheel to the outer face of the hub) and give that a good pull.
Make sure the car is solidly mounted though, it's a good way of rocking it off a car jack! | |
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pchristy
V4 Guru
United Kingdom
1790 Posts | Posted - 23 Jan 2019 : 10:41:45
| I would recommend cleaning and free-ing off the brake adjusters, as these always seem to get very sticky.
--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!" | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 26 Jan 2019 : 20:29:54
| After readng all the above, here's what I did:
- visually followed the pipes as much as possible (from the master cycliner to the junction, from the junction to the front brakes, then pushed my hand up behind the board and insulation above where the front passenger's knees would be - I couldn't see, but I could definitely feel where the pipes joined the junction in the engine bay and it was all dry. Then lifted the rear seat, followed the pipes there - no sign of leakage anywhere.
- put the car on stands and got both hubs off. They looked in pretty good condition internally, and no sign of any obvious leakage around the slave cylinders. Couldn't rule out possible 'seepage' on one of them - the brake dust attached to it did seem oily and very sooty, but this could have just been moisture I guess. Since they seemed in order I didn't do anything else to them.
- checked the rear lines from the car body to the slaves - all fine.
So I'm a bit baffled by this- it seems like I've eliminated everything, or am I back round to suspecting the master cylinder? I'm also wandering whether if the leak is hard to find then it's maybe not that serious and not worth going after unless it gets worse, though I'll need to keep a close eye on the fluid level every week.
I also did what Pete suggested and freed off the brake adjusters. Well, one of them - the other is stuck. I read somewhere on this site that the adjuster is a quarter inch square, so I thought I'd use a reversed quarter inch socket, but it was slightly too small. The closest tool I had was an 8mm open spanner, which was a little too big, but I stopped for fear of rounding the edges (they were already a bit round, but not too bad). Does anyone know the right tool?
Thanks again,
Joe | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 26 Jan 2019 : 20:57:11
| | I've had a google and my guess is I need a 1/4" and 5/16" spanner - they seem to be a common combination on the same spanner - is this right? | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 26 Jan 2019 : 21:52:46
| Yes, that's what you need. Try and get one of the swivel head socket type, they're the easiest to work with. Squirt some penetrating oil on the adjuster for a few days in a row. You may need heat as well, they can get stuck quite badly.
quote:
Originally posted by EdinburghJoe
I'm also wandering whether if the leak is hard to find then it's maybe not that serious and not worth going after unless it gets worse, though I'll need to keep a close eye on the fluid level every week.
In my book even the smallest leak in the brake hydraulics is serious, I wouldn't drive the car until I'd found out what's going on.
I would first investigate the suspect rear wheel cylinder. Thouroughly clean its surroundings and then have a helper step on the brake pedal whilst you look for leaks. If you're alone and you have an Eezibleed or similar, you can use that to pressurise the system. Even if you don't see it leaking, it never harms to take it apart and check the condition of its guts. Take the rubber seals off and pinch them between your fingers, good chance they're cracked. Next, I would remove the master cylinder and have a look inside the servo.
www.saabv4.com | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 27 Jan 2019 : 21:15:54
| Swivel brake spanner ordered and WD40 applied!
I don't think that what I saw on one of the rear brake cyclinders could be the culprit- with the volume of fluid that has leaked recently I'd have expected something like Pete mentioned above, where he said 'There was no sign of fluid externally, but when I removed the drum, it was soaking inside'. I'm not even sure what I saw WAS leakage - it was more sooty than wet.
That does bring me back to the master cylinder. I've been thinking about this and have some questions:
1) I pulled the vacuum hose and saw no fluid. Is this one of those tests that are good in the positive ie if there's fluid there's likely a leak, but just because there's no fluid doesn't mean there isn't a leak?
2) Can I check for fluid in the servo by disconnecting the master from the servo, and the push rod from the brake pedal, and just withdraw the master slightly WITHOUT disconnecting the brake pipes? If there's leakage I'd have thought I'd see some sign of it this way, though I guess I'd not be able to check inside the servo directly.
3) If I do need to disconnect the brake lines, will they just screw back on afterwards and still make a good seal? Would plumbers PTFE tape help?
4) Is there a gasket between the master and the servo that will need replacing?
5) I've seen in Haynes that you should replace the seals in the master every 3 years. I've never heard of that before on any car I've had. I expect the seals on my car have been done some point in the last decade (previous owner) but can't be sure. Should I be doing them anyway?
6) The screws that hold the master to the servo look tricky to get to. The open end of a 13mm stubby spanner seems best (I was sizing them up!) Any other suggestions? I've applied WD40 and will do it every couple of days for a while until I get to this job.
Thanks Melle for all your help with this. I know there are a lot of question but I try to think of everything in advance!
Joe | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 27 Jan 2019 : 21:52:21
| quote:
Originally posted by EdinburghJoe
1) I pulled the vacuum hose and saw no fluid. Is this one of those tests that are good in the positive ie if there's fluid there's likely a leak, but just because there's no fluid doesn't mean there isn't a leak?
I suppose so.
quote:
Originally posted by EdinburghJoe
2) Can I check for fluid in the servo by disconnecting the master from the servo, and the push rod from the brake pedal, and just withdraw the master slightly WITHOUT disconnecting the brake pipes?
Easiest to disconnect them. Not sure why you'd need to disconnect the servo from the brake pedal if you leave it in situ.
quote:
Originally posted by EdinburghJoe
3) If I do need to disconnect the brake lines, will they just screw back on afterwards and still make a good seal? Would plumbers PTFE tape help?
No need for PTFE, the connections don't seal on the threads but on the flange; they should make a leak-free seal again.
quote:
Originally posted by EdinburghJoe
4) Is there a gasket between the master and the servo that will need replacing?
Not that I remember (it's been a while!); there is a gasket between the servo and the bulkhead iirc.
quote:
Originally posted by EdinburghJoe
5) I've seen in Haynes that you should replace the seals in the master every 3 years. I've never heard of that before on any car I've had. I expect the seals on my car have been done some point in the last decade (previous owner) but can't be sure. Should I be doing them anyway?
Never harms to inspect the internals of the cylinder and replace the seals (John Saab sells them), but quality seals should last much longer than three years. I do replace the brake fluid every other year though.
quote:
Originally posted by EdinburghJoe
6) The screws that hold the master to the servo look tricky to get to. The open end of a 13mm stubby spanner seems best (I was sizing them up!) Any other suggestions? I've applied WD40 and will do it every couple of days for a while until I get to this job.
You need a 1/2" AF spanner; every nut and bolt on the 96 is imperial (UNF/ UNC), apart from those in the engine.
quote:
Originally posted by EdinburghJoe
I know there are a lot of question but I try to think of everything in advance!
That's what this forum is for!
www.saabv4.com |
Edited by - melle on 27 Jan 2019 22:24:10 | |
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Derek
V4 Guru
United Kingdom
2192 Posts | Posted - 28 Jan 2019 : 10:47:10
| | WD-40 isn't much good as a penetrant. Use Plus-Gas or a similar penetrating oil. Keep the WD for spraying down your electrics to get rid of any moisture. | |
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pchristy
V4 Guru
United Kingdom
1790 Posts | Posted - 28 Jan 2019 : 15:06:54
| If there's no obvious signs of leakage from the rear wheel cylinders, then the next most likely candidate is the master cylinder. The front calipers tend to seize rather than leak. When my master cylinder went, the pedal felt quite spongy, and pressing hard on the pedal would bring the warning light on. However, there was no obvious signs of fluid leak inside the car - unlike a TR7 I once had that filled my left sock up with fluid when the master cylinder let go....!!!
There is a correct sequence for bleeding the brakes after changing the master cylinder. I've forgotten what it is at the moment, but I'm sure someone here will know! I had mine fitted with a stainless steel sleeve, courtesy of John-saab. But be careful when re-assembling it! There is a pin between the front and rear sections, and if fitted incorrectly, one of the brake circuits won't work!
--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!" | |
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green96v4
V4 Mad
Canada
738 Posts | Posted - 30 Jan 2019 : 11:15:26
| | Joe what year is your car? | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 04 Feb 2019 : 21:35:08
| I got the master cylinder (MC) off no problem, it was wet with brake fluid and a bit corroded where it joins the servo, so I think I have found the leak (good news!) For reference, it's the MC with the small cap (the car is 1973)
I have started stripping it down, but have (more) problems:
1) The cross head screws to remove the reservoir are solid and I've messed up the heads trying to get them off. I've read here that drilling them out or hitting them from the side with a screwdriver or chisel are options. John Wyatt suggested I try a manual impact driver, so I've ordered one. I'm thinking the MC is solid enough to withstand the indirect hammer blow? Any other ideas for getting it off?
2) The inside bore of the MC has a small scuff near the open end - it looks like the primary piston has probably been rubbing against it. It's far enough in to be part of the seal travel, so I think I need to deal with it. I've read on this site of some sort of lining process that fixes this sort of thing - what's it called, and what sort of place might be able to do it for me? Any idea of likely cost? I guess it might happen again in another 45 years but I'm OK with that!
3) I have been trying to match up the seals in the kit that I bought from John Saab with what I have got on the primary piston (the secondary is still in the MC until I can get the reservoir off!). I've definitely got the right kit (according to the listing) but the seal that is closest to the open end of the MC is too narrow for the full width of the slot it inhabits - the photos below show what I mean - I've put the original seal alongside for comparison. The seal is the right internal and external diameters, and it is sitting in a shallow groove so it won't slide back easily, but it looks unsafe to me - I'd have thought under braking pressure it could jump out of it shallow groove. Has anyone come across this problem before? There's nothing obvious in my kit that would fill the gap.
This is how I've got the seal - my 'best guess'
This is how I originally had the seal - it's up against the flat plate, which is good, burt that section of the piston is too wide for the seal and it's a bit distorted - I really don't think it's right.
And here's what's left in my kit. The seal in question is number 5
Thanks for any help with this one. I see there are other kits (from Malbrad amongst others) - I could see if they have something that fits better.
Joe
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| Topic | |
Brake Fluid Leak - master cyclinder?
