Loss of drive - diagnosis?

[huwp]

Car is a Sigma 125 with a 5 speed box.

 

Towards then end of a 50 mile drive today I was exiting a 30 mph zone in 3rd. Accelerated up through 3rd, 4th and then into 5th. After approximately 30 seconds in 5th I lost drive. The car coasted to a halt. The speedo stayed at the indicated speed when drive was lost.

 

Cue lots of swearing and wondering what breakdown outfit I'm with.

 

Then after a couple of minutes I started the car. The speedo re-settled and off I went. Drove the remaining 7 miles home with no incident.

 

Thoughts?

 

Huw

 

 

[CharlesElliott]

The car cut suddenly and the engine stopped running? If so, it must be electrical.

[huwp]

Engine carried on running but drive was lost. The car remained was still in gear as I began to slow. A stab of throttle and the car revved. Then put it in neutral until I coasted to a halt - still with engine running. Then waited a couple of minutes and off I went.

[ChrisC]

The speedo is also electric, connected to a sensor on the rear off side drive shaft.

[CharlesElliott]

Struggling to think of an explanation for this one. Unless it jumped out of gear, but looked as if it was still in gear?

[Frying Pan]

Agree with Charles - jumping out of gear seems the most logical explanation

[huwp]

Yes, remained in gear.

[Nigel Riches]

Go on you just don't want to admit it's an AUTO, and the computer glitched 😬

But seriously, I'd be checking the gear selector, make sure it is engaging fully, Ford Type 9 boxes have a known problem with jumping out of 5th gear, the fix was to change the synchro blocker bars for a later, larger version.

Regards Nigel.

[elie boone]

Also make sure the lever don't touch the hole in the tunnel preventing it to fully engage. Also make sure there are no objects in the gear lever gaiter.

[Jonathan Kay]

I don't understand what the speedo was doing: was it showing the (approximate) road speed correctly throughout as you slowed down?

 

Jonathan

[huwp]

Quoting Jonathan Kay: 

I don't understand what the speedo was doing: was it showing the (approximate) road speed correctly throughout as you slowed down?

 

Jonathan

 

No, as I slowed it was stuck at the speed when drive was lost.

[John Vine]

Hmm....bizarre.

 

Let's see if I've got this right so far...

 

1. You were motoring along in 5th (at X, say) when suddenly the car began to slow down.

2. While you were slowing down, you "stabbed the throttle" and the engine revved.

3. You then selected neutral and coasted to a halt.

4. The engine remained running after you had stopped.

5. Throughout 2 and 3, the speedo continued to display X.

 

Perhaps you could expand on a few points:

 

Re 1, was the car behaving as though you had simply taken your foot off the gas?

 

Re 2, when you say the engine revved, was it as though the car was in neutral (or the clutch dipped)? (In other words, did the engine speed increase sharply, even though the car was slowing?)

 

Re 3, was the engine running at tick-over speed at this point?

 

All bar 5 suggests to me that the car had jumped out of gear. What's truly bizarre is 5, as that points to an electrical problem. Trying to reconcile the two is a challenge.

 

JV

[huwp]

Quoting John Vine: 

Hmm....bizarre.

 

Let's see if I've got this right so far...

 

1. You were motoring along in 5th (at X, say) when suddenly the car began to slow down.

2. While you were slowing down, you "stabbed the throttle" and the engine revved.

3. You then selected neutral and coasted to a halt.

4. The engine remained running after you had stopped.

5. Throughout 2 and 3, the speedo continued to display X.

 

Perhaps you could expand on a few points:

 

Re 1, was the car behaving as though you had simply taken your foot off the gas?

 

Re 2, when you say the engine revved, was it as though the car was in neutral (or the clutch dipped)? (In other words, did the engine speed increase sharply, even though the car was slowing?)

 

Re 3, was the engine running at tick-over speed at this point?

 

All bar 5 suggests to me that the car had jumped out of gear. What's truly bizarre is 5, as that points to an electrical problem. Trying to reconcile the two is a challenge.

 

JV[throttle.

 

John

 

2-5 were certainly as you summarize. With regard to the first, and upon reflection, I either lost drive whilst in 5th or I selected 5th and got no drive.

 

The engine was running as it should throughout not racing as in a slipping clutch but rather responding to stabs of throttle.

 

With no drive the car just coasted to a halt - initially in gear (But with no drive) then in neutral.

 

My own thought process is of suspecting some sort of failure in the gearbox?

 

Huw

 

[John Vine]

I guess the trick will be to demonstrate the symptoms again -- it's difficult to diagnose further from a distance. If indeed you had selected 5th but got nothing, there's a thread here describing a similar problem. Words like circlips and selector pins get a mention. And someone here had your symptoms too.

 

Just a thought....check that the gear lever/ball-joint housing is firmly attached (three bolts) to the top of the gearbox. Even if it is, it might be worthwhile removing it and having a quick look inside for broken bits.

 

Your speedo behaviour remains a mystery.

 

JV

[Birkin S3 ZA.]

I think you will have to pull the box out and remove the tail housing, I suspect its the fifth gear selector or syncro ring/sleeve.

 

There is a circlip that holds the parts on the shaft in the correct place, if it moved it would loose drive without to much grinding.

 

Chris.

 

 

 

[huwp]

Thanks chaps.

 

Will book the car in...

 

At least I can replace the crappy radiator with a Radtec alternative at the same time - which is the other thing on the list.

 

Huw