Loss of power, coil suspect (Mini question)

Post by **jojax64** » Thu Jul 24, 2008 7:05 pm

1991 Mini 1000 (Auto).

The car was running sweetly last week. Today there was a distinct lack of power, like the car just can't be bothered. Feels very much like a coil problem I had a few years ago, so I did a quick inspection. Used a meter, and read 6V between +ve terminal and earth, so I'm assuming the coil is of the ballasted type. A few things I need to know:

(1) If the coil is marked ELECTRONIC, is this the correct one for a ballasted system?

(2) Where exactly is the ballast resistor?

(I had a Ford Transit an eon ago which developed a coil problem. The ballast resistor was bolted to the inner wing. I bypassed it with a piece of wire and used a standard 12V coil. It ran sweet us a nut for years after that.)

(3) So, is there an external resistor, or is it built into the coil itself?

Thanks folks, and forgive me for making (another)

non-Moggie post.

EDIT: The coil is not marked "electronic"...sorry for the red herring.

Post by **Matt** » Thu Jul 24, 2008 8:30 pm

I would expect a '91 mini to have a ballasted coil. Have you changed the coil in the past?

From your post about the transit I guess you know how to fit a 12v coil and bypass the ballast resistor?

But there are lots of reasons why an engine can become sluggish

Post by **jojax64** » Thu Jul 24, 2008 9:40 pm

Hi Matt,

"But there are lots of reasons why an engine can become sluggish"

Yep, I realise that. Just seems so sudden. One day it's a flying machine, next day it's a shopping trolley.

I suppose it's going to be a case of starting from the ground up, ie. points, condenser, etc before going to the expense of buying another coil.
With regards to the ballast on the Mini, I believe it uses a "ballast wire" as opposed to a physical resistor that I had in the Transit.
Incidentally, the Mini's poor performance co-incided with a mundane event. The car is kept in a high-crime area, and the LT -ve coil lead was being disconnected at night to render the car immobile. My son forgot about it one morning, and tried to start the car with the -ve still off.....nearly flattened the battery......then realised his mistake. Put the LT -ve wire back on, the car started OK, but ran poorly. It's got gradually worse since then.
Surely trying to start it with the LT -ve wire disconnected couldn't cause damage to the coil....or could it?

Post by **alex_holden** » Thu Jul 24, 2008 10:03 pm

Is the points gap OK?

Post by **jojax64** » Thu Jul 24, 2008 10:35 pm

Don't know. My son and I live 70 miles apart, I don't often get the chance to help him with his car. He WAS supposed to bring it to my home and leave it for a few days to let me tinker with it, but it's running so poorly it would never make it!

Post by **bmcecosse** » Fri Jul 25, 2008 10:31 am

The ballast feed on a Mini is built in to the feed wire!! It won't be the coil - they generally either work - or don't work, sometimes (but rarely) failing when hot and ok again when cold. Check the carb - is there any oil in the damper chamber ? Does the piston move up/down easily? Is the choke stuck on ? Are the brakes stuck on !!

Post by **jojax64** » Fri Jul 25, 2008 1:08 pm

I'll get him to check all of the above.
Incidentally, it turns out the car had a knackered battery. I took him up a new one, brought his to my house and stuck it on the charger. It's a pretty old looking battery, with the 6 top-up holes in the top. I topped it up with de-ionised water and gave it a good charge. 5 of the cells were bubbling away merrily, but one was not. Guess what, put the meter across it this morning and it's only reading 10V.
I suppose what I'm asking is...can a knackered battery cause other electrical problems?
He's running with the new battery now, but the car is still sluggish as before.

PS: regards the ballast wire....is this why there are 2 wires on the coil +ve feed?

Post by **bmcecosse** » Fri Jul 25, 2008 9:54 pm

Yes - one is the resistor feed and the other comes from the starter relay to deliver full battery volts during starting.
No -low battery won't affect running - provided the engine starts of course!

Post by **jojax64** » Fri Jul 25, 2008 10:55 pm

I spoke to him tonight, and asked him exactly how the car was running. Bearing in mind it\'s an automatic, he says that whereas before he gave it some gas..it changed down and took off like a good \'un. Now when he does the same, the wee car just refuses to pull away...sluggish as hell.

This got me to thinking about the actual transmission. I once had a Nissan 120Y auto, which was a lovely wee car. One morning I selected reverse to pull out the drive...gave it some gas....and.....nothing.

After the initial panic I checked the fluid level dipstick, which showed very low. Off to Carparts and bought some fluid. Topped it up, and normal service was resumed.

My elation was short lived, of course. It proceeded to run dry almost every day. Don\'t know where the fluid was disappearing to, but I got rid of the car soon afterwards.
I\'m just hoping the same trouble hasn\'t occurred in the Mini. He\'s only just bought the thing, and this would be a real sickener.

Told him to check the fluid level tomorrow, I can only hope the transmission is not the culprit in all of this.....

Post by **bmcecosse** » Sat Jul 26, 2008 10:51 pm

Ah well. It could indeed be the trans -first step is to change the oil (2-W50) and filter! But could also be that the 'kick-down' arrangement is not working. Get him to stick it in 1st gear - now does it go ok ?

Post by **jojax64** » Sun Jul 27, 2008 8:54 am

Hi,
Are you saying that the trans is lubricated by the engine oil, and not by a seperate trans fluid?

Post by **bmcecosse** » Sun Jul 27, 2008 10:53 pm

Yes indeedy! Hence ultra important it is a) clean, b) filter is working c) 20W50 and d) up to the mark!

Post by **bigginger** » Mon Jul 28, 2008 12:04 am

Is that right? A genuine question, btw - I know the manual one is, but is the auto as well?

Post by **Packedup** » Mon Jul 28, 2008 12:47 am

bigginger wrote:Is that right? A genuine question, btw - I know the manual one is, but is the auto as well?

Yep, the auto Mini box does indeed use the same oil as the engine, in the way the manual does.

Post by **jojax64** » Mon Jul 28, 2008 8:58 am

I never knew that.

I suppose indeed that a swift oil & filter change should be the first course of action. My son did remark that the oil looked "bogging" when he topped up, but he (like me) thought he was merely topping up the engine, not the auto box as well.

Another question: when you drain the oil from the engine sump plug, does that drain the gearbox too....or is there a seperate plug?

Post by **paulk** » Mon Jul 28, 2008 5:12 pm

Mini gearbox is bolted to bottom of the engine, sort of like a complicated sump pressing.
So yes when you drain the oil there is only 1 drain plug
(BTW I've only played with manual Mini's but believe Auto's V.similair with regard to the basics)

Post by **Matt** » Mon Jul 28, 2008 5:46 pm

Yes, just the one drain plug...

Also you should run the engine at a fast idle for 15 or so seconds before measuring the level! This is to make sure the torque converter has the correct amount of oil.

Becuase the 'box runs on the engine oil you need to make sure the oil is changed regularly (at least every 3000 miles). Missed oil changes are not good!

Post by **jojax64** » Tue Jul 29, 2008 12:19 pm

Cripes!

Post by **bmcecosse** » Wed Jul 30, 2008 8:03 pm

So - what's the news on this item ??

Post by **jojax64** » Wed Jul 30, 2008 9:02 pm

Still waiting to hear from my son. Will keep you posted.