9 replies to this topic

[Maisy87]

I have yet another problem with my poor Maisy. I did try a search on this but i'm not too sure what i'm searching for so hopefullly someone will shed some light for me!

I have an 87 mayfair and she's just recently had a full service, I topped up her petrol yesterday and fitted a new flasher unit and drove her home. I then went out about an hour later and everytime we slowed down she cut out. Once we restarted her we were on our way again, until the next set of lights hen she cut out again. The ignition also gets stuck, so I may need a new one. I turn the key to start her, she starts but the key doesn't go back to the 'drive' position, so she keeps trying to start when sh's already started. Thats not too much of a problem as I can get a new ignition. I also can't leave her running on the drive as once I put the choke in or take my foot off the acelarator the revs go down and she stalls.

Any help would be gratefully received as it's not long till L2B and I still have welding to do!

Thanks

Chel x

PS. I should also mention that 3 years ago my father-in-law loaded her up with unleaded petrol and she's been using that ever since, on the assumption from him that 'it'll be ok'. I'm not so sure. I've heard of a block of lead, much like a toilet block I think, that you can put in the petrol tank. Anyone heard of this?

[Dan]

"Block of lead in the tank" yeah, good one that. Loads of people fall for it, it doesn't do anything at all. You need a proper lead additive like Castrol Valvemaster. It's not just 'some lead' that's been chucked into the petrol, it's a very carefully measured mixture of petrol and tetra-ethyl-lead. Some plain lead in the tank will do nothing other than break your fuel sender when it lands on it.

Cars with cast iron valve seats and plain valves NEED LEAD. 'Lead' was added to petrol from the twenties onwards because manufacturers wanted to avoid the costly process of putting hardened steel valve seats in their cast iron side valve blocks and overhead valve heads. These also were troublesome to fit and unreliable using the machining technology of the time to fit them, so some other way of avoiding valve seat recession was needed.

There were tests to look into this around 2000 when lead started to be withdrawn from forecourts but all these tests were pointless as any car manufacturer had done them all already many years ago due to the Japanese market. Japan has never allowed the use of tetra-ethyl-lead in petrol so any car sold there had to be compatible with unleaded and BMC prooved when the A series first came into use that it definitely needs valve seats fitted to use unleaded. All A series engines for Japan have always had hardened valve seats and unleaded type valves fitted. You can't just stick unleaded into an A series and hope it will work.

A car which has been running on leaded for a long time will have a lead memory. That is a thin coating of lead covering the valve and it's seat which will last for some time after lead stops being used.

In your case, it could simply be that your car is out of tune (and that is what it sounds like to me) but if it's gone out of tune very suddenly and is otherwise regularly serviced then it could well be that your lead memory is finally exhausted after three years of use and so you have started to get some valve recession. Get a good Mini garage to do you a leakdown test and check over your engine to assess it's health. But the only real way to asses how much recession (if any) has happened is to lift the head.

[Maisy87]

Thanks for the info. Do you think it's to late to buy some Castrol Valvemaster and start using it now? Before the service a couple of weeks ago she hadn't been serviced for a long long time (due to her spending most of it off road). I think taking her to a garage will land me with a huge bill and after spending £300 on her in the last couple of weeks I'm not keen. Obviously if that is the only answer then I guess i'll have to.

'lift the head' Is this something I could do and if so what would I be looking for?

Do you think my lead supply might still be ok, she's only done around 1000 miles since last Spring and before that she's only ever been driven locally to the shops and work. I guess I need a cheap option to try first before I go to the garage yet again.

Thanks for all your help so far

Chel x

[1984mini25]

everytime we slowed down she cut out

what is the tick over when stationary? if it's realy low you could try adjusting it on the carb.

[Dan]

Definitely start adding some lead additive to your fuel right now but if it is damaged then you can't do anything other than get new seats and valves fitted to fix it.

There is one way to check if there is severe damage without taking it apart, but it won't reveal minor damage or the beginnings of wear. If you take off the rocker box you can check the relative closed heights of all the valve stems. They should all be about the same but if the exhausts are all sitting noticably higher than the inlets when they are closed then they are receeding into the head.

Having said that, the tuning issues you are having now could well be completely unrelated to any such damage, give it a check over and make sure everything is as it should be and try to tune it up. If it won't come into tune then there is possibly damage but if you can tune it and the valves look OK then it could be allright. As 1984Mini25 says, give it a tune. Basic tuning is pretty well covered in the Haynes book.

[clarks.2006]

Id say try adjusting the idle on your carb too (Its just a simple turn of a screw posydrive) clockwise to make it idle higher and anti to lower the car should be idleing at around 750 - 1000rpm.

[Maisy87]

I'll have a look through the Haynes Manual and see what I can find. I'm not too techie so not sure how i'll get on. I'll glad that adjusting the carb thingy to just a turn of a screw, that sounded complicated till you said that! So thanks!

I started her up again earlier and had the choke out but normally with the choke out for just a few minutes you can put it back in and she'll stay around 1000rpm, but now once the needle drops to 1000rpm she cuts out.

Thanks for the advice so far! I'll read up about tuning and that carb thing. I'm quite hands on (when I know what i'm doing!) so i'll try all this before taking her to the garage.

It was also a struggle to get her started, took a few tries and she normally starts first time (with choke of course).

Chel x

[1984mini25]

The way I've been tuning mine to run just so I can have it set up properly is

With the engine running (full warmed up) lift the piston-lifting pin till it hits the piston and then a further 1 mm on the side of the carb and listen to what happens,
If it cuts out the mixture is too lean, if the idle increases the mix is too rich and if nothing happens the mixture is about right.

The haynes manual goes into much more detail, Pages 4A .15 and 16 fuel systems .
But at least you can get some near right for it to run and stay running.

[Maisy87]

Oh wow! I can't believe I've actually fixed my own car! Thanks for all the advice it solved my probs Really grateful for all the help!

It's idling at around 1500rpm and when driving it's 2000rpm, is that right or should I lower it a bit? Around 1000rpm maybe? It also runs ona bit actually so I best lower it a bit.

[Jammy]

Yea, probably best to lower it, fast idle should be about 1500rpm, normal idle should be between 6/700 and 1000rpm.