i just happen to notice this recently. On my way back from a track day, the speedo started jumping up and down and now its just dead. I drove the rest of the way home without it. The next day, I went out to drive it and the speedo still didnt work but once down the block, the car started to rev up and idle at 4000rpms. It scared the crap out of me. So I turned it off and drove it back home and left it.

Its been sitting since (about a month) and I started to take apart the motor because I found out recently that the coolant seals went out. But I'm pretty sure that a coolant seal failure wouldn't cause the bad rev/idle and the speedo to not work. So what could it be?

 

We have a mechanical speedo cable and the only thing I can think of it affecting is the speed sensitive steering. I don't see how it could be related to the other problem.

Cheers

 

as far as the speedo, the cable has become disconnected or broken.

The idle I suppose could be related to your leaking coolant seal.

 

thanks for the reply. The motor is being taken out of the car right now and i'll start from scratch with a rebuild or a jspec motor. We'll see what happens. I think the speedo cable may have broke because it's been getting looser and looser everytime i look at it.