Rev Counter

[pgoldsmith]

Has anyone experienced any problems with their rev counter? Mine usually works ok but sometimes when I start the car the needle rises slowly up to around 1500 rpm and stays there even though the car is clearly ticking over at 800 or so. Then if I drive off and accelerate as normal it may go above 1500 to say 2000 and if I then stop it will slowly fall back to perhaps 1200. After a while driving it sometimes resumes normal operation.
Conversely it can be fine first thing in the morning but after driving 8 miles to work and then stopping and switching the engine off it sometimes sits on 1500.
I’ve had the instrument cluster out on three occasions for a speedo problem and whilst it was out I checked the rev counter needle wasn’t fouling the facia and it seems to move freely. Could it be a bad connection ?
Any thoughts would be appreciated as I sometimes have to rely on the rev counter to gauge my speed – my speedo doesn’t always work – and I don’t like being ‘blind’ especially when Dorset are so keen on mobile speed traps.
Thanks,

i have the same problem, I cleaned up the contacts and checked all connections and it isnt as bad, but still does it. I think the only real solution is to buy a new instrument pod.

I've found that many of these problems are actually due to poor battery connections to/through the body. In my case it was where the + battery lead is bolted through the body of the car (below the battery tray). I used a wire brush attached to an electric drill to clean up the area below the bolt (it was badly corroded). As the bolt is likely to be severely corroded, I would suggest soaking the area in releasing oil for several days before you attempt to remove it. I would also recommend giving the top of the bolt a few sharp jolts with a hammer and drift. Prior to doing this, I had intermittent problems with my speedo and rev counter. No longer!

[pgoldsmith]

Thanks for the tips.
I took a look at the earth strap underneath the battery tray and it was badly corroded - or at least the shake-proof washers were!
Took it off, cleaned it up, replaced the washers and took it for a test drive.... no change !
I then decided to take off the earth strap from the gearbox to the chassis and cleaned everything up .... but again no change.

Finally decided I'd take the instrument cowling off, disconnected every connector I could see, sprayed switch cleaner (which i bought from a local electronics shop for £2) on all of them - paying particular attention to the large connector block on the lhs of the speedometer, reassembled the cowling and took it for a drive.
This seems to have done the trick, the rev counter hasnt stuck yet, the speedo has kept on working even whilst unduring bumps in the road which normally makes it stop. So fingers crossed !!

Even the fuel gauge seems to be giving a sensible reading too.

P.