Irregular running

[Dru]

Hmm, I'm not even sure if this is electrical, but anyway...

I did a run down the motorway to London yesterday in the Trav, and went straight into almost stationary traffic at Hammersmith. As one does...

After a little while, the tickover became v irregular. I parked up soon after, and had the same problem going out of town again a few hours later; but it was alright again after a bit of fast(ish) running on the open road.

The engine does seem to get quite warm; I certainly haven't had any of the problems keeping warm with the heater that I read about on here. Temp gauge reading (for what the figure's worth) is about 82C on normal running.

I'm thinking that maybe I should try changing the HT leads and plugs; the plugs are a few thousand miles old, and the leads about 14000 miles old.

Any advice, suggestions or comments?

[Orkney]

before looking at the plugs & leads (although changing them will never be a bad thing) maybe its worth checking the timing & then the points?

Whens the last time you checked the coolant? maybe it could do with a backflush & replacing with new?

[Stig]

Could be fuel rather than sparks if it happens after sitting in traffic. Was the fuel pump ticking quickly and erratically?
I know it's winter so you wouldn't expect fuel vaporisation to be a problem but I'm told that winter petrol is a more volatile blend than summer petrol.

[Dru]

Thanks for your replies:

Orkney: I set the timing by backing it off from the pinking point. At least I hope it was pinking I ws hearing... -but maybe it's time to try out my nice new strobe. when it stops raining enough to lie in the gutter again.

Ignition is electronic.

The engine was rebuilt by the people who sold me the car, and, while you never know what went on unless you were actually there, I just assumed that sludge woudn't be a problem. Perhaps naively.

Stig28: yes, there was a bit of fast ticking going on, now you mention it; but it didn't seem much more than the occasional bout of quick-ticking that it's sometimes prone to. Good idea, though; thanks

[bmcecosse]

The fast ticking does usually indicate fuel supply problem - strange to have it in winter!! Look to see if the fuel supply pipe from rear of car is unusually close to the exhaust pipe - and in any case - try wrapping it with some insulating material or creating a barrier of some kind between the exhaust and the fuel pipe. You could also wrap the exhaust with insulating material - most speed shops sell it although I have in the past just used heavy glassfibre tape.

[Dru]

Thanks for the suggestion, bmcecosse

...the fast ticking does come and go; it doesn't seem worse than it ever was. I checked the route of the fuel pipe yesterday, and it's pretty clear of the exhaust.

I also changed out the plugs and the HT leads. The old plugs were v sooty and norrible. It's running more evenly now. Maybe it was as simple as that; I'll know after I've been stuck in traffic again.

Now working up enthusiasm for taking the head off; one of the rockers seems very slack on the shaft. Why in winter? Hey ho...

[bmcecosse]

You can change rockers without slackening any of the head nuts. But maybe it just needs the valve gaps setting. If the plugs are sooty - you must be running rich - check the choke is going off completely - and then adjust the idle mixture to get best idle.

[Dru]

The rocker clearances are all pretty much in spec; but no. 1 rocker is so slack on the shaft that it can waggle about the lateral axis ...if you see what I mean. That's good news about not having to take the head off. I'll do some more close reading of the manual.

[bmcecosse]

Oh you wont see it in the manual!! But lucky since it's #1 - just slacken the adjustment right back and wiggle the push rod to the side. Then undo the circlip at the end of the shaft - and pull the rocker off the shaft! However - in fact it's likely to be shaft itself which is worn - it can be replaced by doing all the above on all the rockers - then undo the littl fixing screw that locates the shaft in the pillar - and then slide the rocker shaft out of the pillars - catching each rocker and the springs etc as it is released. Only snag may be (this is often done on a Mini where there is room) that on the Minor the shaft may hit the radiator before it comes clear of the last pillar - in which case you will need to pop the rad out - but that's just three hose clips and 4 bolts - much easier than lifting the cylinder head! You then slide the new shaft back in -assembling all the bits back in place as you go - and finally turn the shaft till the fixing screw can locate it - and tighten the screw. Adjust valve gaps - and job done!