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passed the MOT but still got some issues


Dano
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My landy finally passed the MOT an is on the road for the first time in over 4 years, driving it about I have some observations and wonder if there is any advice

1) Even though I have had the gearbox apart, mended what was required and didn’t observe and major issues in the components 2nd gear is pretty poor, when changing from 1st to 2nd and 3rd to 2nd there is a crunch (unless the revs are exactly right) also it jumps out of 2nd on the backlash, double-d-clutch doesn’t seem to have much affect, do you think this will break or is just one of those idiosyncrasies that I will have to live with?

2) When driving on the motorway and on long uphill stretched I can hear what I think is pinking, the timing has been set by ear, would this be a timing issue i.e. requiring a slight retard of the timing? (That would be anti clockwise on the dizzy right?)

3) Even though the engine seems to run fairly well the MPG seems shocking, I have not measured it yet but I had filled the empty tank with a jerry can full of petrol then put approx 38 litres in at the pump to fill it up, I have done 57 miles and the tank is just above the half way make, it has a new sender but I am not so sure the instrumentation is that good as its got a bit of a wobble, next time I fill it up I will calculate the MPG but does seem a little low?

I am getting various other moans and groans out of it but I still have to stick in the one-shot grease and change the fluids in the diffs, this may help on the MPG also

Thanks

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Is it a SIII? Earlier ones didn't have synchromesh on 1st & 2nd. Crunching can be caused by the clutch not releasing fully or drag between the input shaft and flywheel bush.

Pinking is a symptom of over-advanced ignition. Make sure the vacuum advance and bobweights are working. To retard turn the body of the dizzy in the direction of rotation of the rotor arm.

I got 18mpg from my 2.25 SIII SWB overall, about 16 around town. I managed 24.9 on a long run driving very carefully using a vac gauge. Don't forget doubling the speed quadruples wind resistance.

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Is it a SIII? Earlier ones didn't have synchromesh on 1st & 2nd. Crunching can be caused by the clutch not releasing fully or drag between the input shaft and flywheel bush.

Pinking is a symptom of over-advanced ignition. Make sure the vacuum advance and bobweights are working. To retard turn the body of the dizzy in the direction of rotation of the rotor arm.

I got 18mpg from my 2.25 SIII SWB overall, about 16 around town. I managed 24.9 on a long run driving very carefully using a vac gauge. Don't forget doubling the speed quadruples wind resistance.

Thanks for the reply, its a 1977 SIII I would have though it should have a Synchro, I guess its worn, hope it doesn’t fail!

How do I check the bob weights? Check for advance with a timing light with the vacuum pipe disconnected?

I used to get 22ish out of my last SIII 109, I just did a rough calculation and its about 9mpg or worse, although the gauge may not be accurate and there could be other factors, I will know when I fill up next and then check fluids and tyres etc and keep checking the MPG on every fill

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If you disconnect the vac tube and set a timing light up you should see the timing move as the engine is revved up. Then let it tickover quickly and suck the open end of the vac tube, you should see the timing shift again.

If you're getting 9 mpg you should have black smoke coming out of the exhaust!

Have you got the correct speedo for the tyres? are the diffs standard? does the choke cancel fully? Does the engine run at the correct temperature? Are the brakes dragging?

Gearbox crunching won't fail an MOT

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If you disconnect the vac tube and set a timing light up you should see the timing move as the engine is revved up. Then let it tickover quickly and suck the open end of the vac tube, you should see the timing shift again.

If you're getting 9 mpg you should have black smoke coming out of the exhaust!

Have you got the correct speedo for the tyres? are the diffs standard? does the choke cancel fully? Does the engine run at the correct temperature? Are the brakes dragging?

Gearbox crunching won't fail an MOT

Thanks I will do as you say with the advance

No black smoke, does smell a bit rich, calculations may be wrong and the gauge may not be linear so will have to see when I fill up

Its on 205/80r16's presume the Speedo is correct

No idea if diffs are standard, I presume so

Choke seems fine, got a brand new zenith (copy)

Temp seems fine, just under the "N"

Brakes are adjusted, don’t seem to be dragging

It already passed the MOT yesterday, by fail I mean is the gearbox likely to break? I have to trip from Kent to Wales next weekend and hope I wont see a recovery truck for some time to come

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2nd gear synchro is the most common failure on these gearboxes in my experience. Needs a re-build and a new 1st 2nd synchro, and quite likely a new 2nd speed gear as well as the dog teeth wear. Surprised you didnt check these and replace if you had the box apart anyway.

Check the timing with a timing light, and also check that the vacuum advance is working. Timing it by ear is good enough to get it running, but it needs setting correctly.

Get the mixture checked on an exhaust gas analyser, but get the timing sorted first!

Pinking is usually cause by timing but could be a combination of timing and fuelling.

Jon

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Seems my estimation was a bit off, just filled up yesterday and I got 16.25MPG, considering that I have had it running on the drive at idle for long periods, the tyre pressures need adjusting and the drive train fluids need replacing, plus the back is full of tools I guess this is not too bad, I hope to push this up to over 20MPG eventually, I will also monitor the before and after effects of adding the ignition amplifier from Maplin that I purchased, I will post the results up

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