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Mini_Lund

Original Poster:

1,651 posts

93 months

[news] 
Wednesday 7th May 2008 quote quote all
Hi PH,

I have posted my problems on the Classic mini’s section in my thread, but it’s a little inactive! http://www.pistonheads.com/gassing/topic.asp?h=0&a...

I have recently been having trouble with my Mini. It’s a 1979 British Leyland, Mk4 Mini City (850). She is reluctant to rev and runs rough, when driving there are lots of flat spots but then she'll pick up. It’s a standard engine, air filter and carb (HS4). The carb has recently been refurbished by myself with a new jet and float chamber needle. The standard needle still remains. The Mini seems to warm up quite fast, today she squirted water out of the overflow pipe all over my drive?

I drove the mini down to my friend’s workshop to be timed with a strobe light. I couldn’t manage to move the dizzy at all It had seized to the block somehow. Rockeze did the trick

Timed the dizzy to factory standard setting, and put the points back on. She doesn’t like the electronic ignition, as soon as you press the accelerator she doesn’t rev, just knocking noises from the block! So put the points back on.

Driving home, she is full of flat spots, wont go, it feels as if the engine is restricted, rocking back and forth. I am also rocking in my seat to, eager to go!

I decided the timing wasn’t correct and unbolted the distributer and tried timing it by ear. Whatever position the dizzy was put in, I still had the same problem. So now I'm thinking, it isn’t the timing at fault and I've just buggered my nicely timed dizzy.

From time to time she also has a misfire, running on 3 cylinders. I run her on minimum oil as she burns the oil if there is plenty in - blue smoke. I suspect the valve oil seals and head gasket. Oil is getting through somewhere.

I’m guessing quite a few of you will have had experience with minis in the past or even currently, so can anyone help me out?

Thanks in advance

Tom banghead






wolf1

2,617 posts

133 months

[news] 
Wednesday 7th May 2008 quote quote all
Burning oil and overheating i'd suggest getting the head gasket checked

spikeyhead

8,588 posts

80 months

[news] 
Wednesday 7th May 2008 quote quote all
It could be so many things.

I suspect that there's more than one problem.

If its the same with electronic ignition and points then its unlikely to be the distributor.

You need to do a head gasket rest, though if its been ban for a while then it would probably be showing in the oil or water. Its more likely to be valve seat regression, try a compression test.

What do the plugs look like? are they the right colour, right gap? Are the HT leads in good condition?

Does the electronic ignition run of the same coil as the points? use the same condenser?

That's where I'd start but there's still plenty of other places that could be causing the bad running.


NiceCupOfTea

22,827 posts

134 months

[news] 
Wednesday 7th May 2008 quote quote all
I'm no expert but my gut feel reading that would be coil / leads / plugs.

Change them and at least you can take them out of the equation thumbup

Fire99

8,581 posts

112 months

[news] 
Wednesday 7th May 2008 quote quote all
I'll 2nd the advice already given...

I would be fairly organised about it... when working on Chevy V8's i was always told to get the ignition right first (after compression etc) before looking at fuelling... as the 1st has a dramatic affect on the 2nd.

Id check compression first.. then go through plugs, leads, points, dizzy & timing etc and ensure they are 100% then only then look at the carb / fuelling..

Im surprised electronic ignition has been troublesome as its a very simple device when replacing points.. Just make sure you double check your timing again after fitting an electronic module as it can kick the settings out...

good luck mate.
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vrooom

3,514 posts

150 months

[news] 
Wednesday 7th May 2008 quote quote all
dizzy could be 180 way out...

Hooli

27,355 posts

83 months

[news] 
Wednesday 7th May 2008 quote quote all
any oil in the dashpot? they run REALLY crap when thats empty. thats the little black lid on the carb btw, fill it to the line (about 2cm below the top IIRC) with engine oil.

Dogwatch

3,801 posts

105 months

[news] 
Wednesday 7th May 2008 quote quote all
Fuel pump delivering properly? Obviously not going to be responsible for oiling up but if the beast isn't getting sufficient go-juice, then go fast(ish) it won't. rage

Periodically whacking the fuel pump with a spanner (or worse) to get it to work for a while is an ancient ceremony, usually followed eventually by replacing the damn thing (car or pump). grumpy

52classic

1,303 posts

93 months

[news] 
Wednesday 7th May 2008 quote quote all
I'd say dashpot piston binding and crankcase breather blocked.

There are also some iffy repro points sets that are prone to earthing through the spring.

Any oil in water/water in oil? May be head gasket but nevertheless should run better than you describe.

Mini_Lund

Original Poster:

1,651 posts

93 months

[news] 
Wednesday 7th May 2008 quote quote all
Thanks for all of the feedback.

The spark plugs are set to 0.0025" thou with points on. HT leads are in good condition and engine note changes when each lead is taken off.

If we leave the Electronic Ignition out of the equation, I'll keep it on the points!

Plugs look normal colour, quite black but with copper deposits.

I also agree that its possbile that the distributer could be 180 degrees out, but it runs!?

Dashpot oil is topped up nicely.

As for the reluctant reving. I took the petrol lines off and hose connections and blew through them with a bicyle pump, also connected the petrol pump to the line and blew that out. I then forced air down the line and into the tank. It seems for that moment, she revved fine when all connected back up...

Crankcase breather is breather fine, I also suspected this and took the tube off the carb and blocked it with my finger. Engine then stalled, suggesting that it needs to breathe!

Also, I removed the vacuum advance line from the carb with the engine running, but it made no difference to the engine note what-so-ever, am I right in thinking the engine note should drop?

Many thanks so far guys, its a big help.

Tom



Edited by Mini_Lund on Wednesday 7th May 23:16

x 7usc

1,208 posts

78 months

[news] 
Wednesday 7th May 2008 quote quote all
you say she warms up quick? does she run fine when cold or is it all the time, its just i had this on another make of car had a couple of mechanics stumped, turned out to be a faulty spark plug tracking to ground when warm.

shouldbworking

3,998 posts

95 months

[news] 
Wednesday 7th May 2008 quote quote all
Whats the compression check say?

Mini_Lund

Original Poster:

1,651 posts

93 months

[news] 
Wednesday 7th May 2008 quote quote all
x 7usc said:
you say she warms up quick? does she run fine when cold or is it all the time, its just i had this on another make of car had a couple of mechanics stumped, turned out to be a faulty spark plug tracking to ground when warm.
She runs hot or cold, just not very well. However when she got hot, she wpuldnt rev, knocking noise could be heard from the engine and thats it, didnt sound healthy at all.

Unfortunately I dont have a compression tester so cannot complete a compression test, unless there is any other way of doing it?

xllifts

3,720 posts

86 months

[news] 
Thursday 8th May 2008 quote quote all
Change the coil and The ballast resistor, also check the dashpot oil level and that the cap isn't broken/split, if its pinking your timing is retarded, it may well be 180 degree's out as suggested.

My first port of call would be the coil and resistor.

Also worth checking the condensor on the dizzy along with the cam that the points open on you may have one lobe that is worn or has a high poit on causing irregular opening of points.

Patience when setting the dizzy and points up is the keywink

Hooli

27,355 posts

83 months

[news] 
Thursday 8th May 2008 quote quote all
Mini_Lund said:
Also, I removed the vacuum advance line from the carb with the engine running, but it made no difference to the engine note what-so-ever, am I right in thinking the engine note should drop?
you can see in the dizzy through the grill cant you? (been a while since i looked)
if so take the dizzy cap off & while watching the points suck on the vacuum tube, you should see the baseplate in the dizzy move. also if you can suck & suck on that plate then the vacuum advance is duff, you should suck & not be able to suck anymore as its a sealed system at the dizzy end.


your comment on the breather sounds odd to me too, it shouldnt stall if you block that.

Ribol

9,266 posts

141 months

[news] 
Thursday 8th May 2008 quote quote all
If we are going to guess then I would have gone for a coil on its last legs or a week mixture.
I wouldn't get too hung up about the timing being out, it would have to be a long way out to make much difference.
It won't run 180 outwink
At the risk of insulting you, are you using the right points gap?

Another thing that might be worth doing is looking under the bonnet in the dark, if it looks like Blackpool Pier under there it might give you some clues.

52classic

1,303 posts

93 months

[news] 
Thursday 8th May 2008 quote quote all
I'm a bit worried about the 'knocking noise' and we don't seem to have investigated it so far.

Top of engine or bottom? Could be pinking which AIRC can be cured by retarding the ignition and removing the vac advance temporarily.

Is there smoke to accompany the knocking noise? I'm thinking a sticky or weak valve.

Mini_Lund

Original Poster:

1,651 posts

93 months

[news] 
Thursday 8th May 2008 quote quote all
Hooli said:
your comment on the breather sounds odd to me too, it shouldnt stall if you block that.
Hmm thats interesting. Okaym so when I remove the pipe from the carb, the car wants to stall, if i block it, it does stall.

The points are set to the correct gap with the feeler gauges.

Carb and dashpot all looks grand.


Mini_Lund

Original Poster:

1,651 posts

93 months

[news] 
Thursday 8th May 2008 quote quote all
52classic said:
I'm a bit worried about the 'knocking noise' and we don't seem to have investigated it so far.

Top of engine or bottom? Could be pinking which AIRC can be cured by retarding the ignition and removing the vac advance temporarily.

Is there smoke to accompany the knocking noise? I'm thinking a sticky or weak valve.
There might be a sticky valve, as sometimes it runs on 3 cylinders...and with high revs it sometimes cures it. I've got a 998 unleaded head to fit, going to get it skimmed and then investigate when I fit it, got a genuine top end gasket set also. Knocking noises sound dreadful, sounds like its from the block, as if the pistons were bottoming out.

When the vacuum advance is removed, there is no difference in engine note.

Tom

Edited by Mini_Lund on Thursday 8th May 08:31

Elan159

1,755 posts

100 months

[news] 
Thursday 8th May 2008 quote quote all
Mini_Lund said:
The carb has recently been refurbished by myself with a new jet and float chamber needle. The standard needle still remains.
Did the rough running coincide with your work on the carb? If so I'd concentrate here first - does the piston rise and fall easily? You may not have centered the needle correctly.
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