Sunday, 30 October 2011

Fleet Report;- Rover 825Si; Clutching At Straws

So, everything has been splendid for a long while, and I've got lovely spangly floor mats and everything. But as of last Sunday I hadn't actually been able to drive it anywhere. The clutch pedal always did have a lot of travel in it, but about a fortnight ago it got to a point where the pedal had to go right to the limit of its travel in order to let me change gear. On my last journey from work to home, the pedal itself would skulk down by the bulkhead and I'd have to hook it back up with the tip of a size 13. Not ideal.

It also meant that I couldn't do the whole "competitive Grandad" thing away from the lights, 'cos I couldn't change deftly from first to second. So, of course, something hd to be done. Into the workshop we went; a good chance to try out the new ramps my Dad bought only to find that his 540 won't go up them.


Anyway. My totally unqualified diagnosis was a lack of hydraulic pressure in the clutch system. The 825 has a standalone system of clutch hydraulics, not linked with the brake system as some do. A look at the murky old shit in the reservoir revealed that it seemed likely that the car had never had a fluid transplant, so I bought some. My guess was that the master cylinder would have been at fault, possibly the internal seals (a known weakpoint) aren't actually allowing enough pressure to build up. This would mean ether stripping the master cylinder down and replacing the seals, (about £8) or replacing it altogether. (£108).

Against all my usual ethics, I went the £108 route.

So, in usual 800 fashion, the master cylinder is a bastard to get to. It would be fine if there weren't a horrible non-structural crossmember blocking it; non-removable thanks to the inlet manifold, brake master cylinder and ECU being bolted to it.

But at least I'd found it. You're looking at the back of the cylinder, and the damper. The actual cylinder sticks through the bulkhead where the piston attaches to the pedal by way of a short pushrod.

The first stage of the process was to purge the system of fluid. Then, I thought, let's see what a fluid change on its own can do. 

I Went under the car to the bleed nipple on the slave cylinder, employing Dad to stroke the clutch pedal. First stroke and, well, a lot of air came out. This was a good sign. The next couple of strokes brought less air and more fluid and then gradually it switched to fluid only. We fed enough through that I can say the liquid now in the system is new and clean.

Immediately we both saw a big improvement in pedal feel, from fucking hopeless to simply poor. Next step, I thought, was to take it for a drive to see how bad it still was.

Well, there's still a lot of pedal travel, but I no longer have to push it right to the stop to effect a change. I can change gear quickly like I used to be able to.

Thing is, when Dad had a drive he confirmed that, to him, it still feels bloody awful. Thw question is; are Rover 825 KV6 clutch pedals bloody awful generally, or is there a problem, Houston?

A look in the Haynes manual suggests that you adjust the pedal height if you replace the clutch. Hmm, Pedal Height; could this have an effect on the travel? We had a look in the footwell and found the adjuster nut, in the least accessible position it could possibly be. Thing is, I'm 6'5" and have a large cranium and there was NO WAY I could get in there worth a shit. Fortunately my Dad is considerably shorter, so I employed him at the cost of a lovely cuppa.

He gave up, too, cup of tea or none. Bollocks to it.

So, the state of play is this: The car is now completely driveable even though the clutch pedal still has quite a long throw, but I can't remember how it's supposed to feel. I'm going to start driving it again to see if it gets any worse. If it doesn't then I'll probably live with it until I'm in the mood to investigate further.

It it does go downhill again, well, firstly I'll change the master cylinder. I have it, all safe and paid for, so that's the next step. The only thing that frightens me a little is that the symptom of excess pedal travel could also stem from a lack of clutch material. I've dismissed this as the cause so far simply because of how rapidly it changed from good to bad, but have to admit it could still be the culprit. I really don't fancy changing the clutch at all, so lets hope it's the master cylinder. Or maybe there's still some air left somewhere in the system?

Watch this space.

1 comment:

  1. Hi ZSM from hooniverse here. Any update? When I had the black clutch fluid in my Volvo it was cause the seal in the plunger of the slave cylinder had become one with the fluid over 40 some years I guess. It looked good to me, but sure enough when I got a rebuild kit you could tell the difference, the old one looked like it had swelled in the smaller part and gotten smaller in the larger part. Anyway mechimike recommended I hone the cylinder, I did, and everything was great now. About the height adjustment, I just adjust the nut that goes from the slave cylinder to the clutch fork. I just wiggled it around to see where the clutch springs start to offer real resistance. At first the clutch pedal seemed to be too high, I thought I would have to adjust the pedal, but in a few days it seemed to balance out. I think that's a trick hydraulic setups like this tend to do. So anyway, adjust the nuts at the clutch fork first and see how it goes from there.