11 replies to this topic

[Joseph-C]

Hi,
Had my mini tuned at Aldon, before getting it on the rolling road he checked the compression:
Cylinder 1 - 165
Cylinder 2 - 165
Cylinder 3 - 140
Cylinder 4 - 165

So cylinder 3 is down on compression - the operator suggested it could be tappets or maybe a "valve" can anyone explain what he meant by valve?
It wasn't down on power and made 65 bhp from a 1275 with a stage 1 kit.

It does usually let out some white smoke on start up so I'm hoping it might just be the head gasket although I thought it would usually drop further and mini's usually go between 2 and 3?

Worst case scenario I think is piston rings - how much could this cost to sort out?

I will be getting it to a garage to take the head off and inspect it soon, but I'd just like to see if anyone else has had a similar problem.

thanks

Edited by Joseph-C, 11 September 2012 - 07:01 PM.

[fattail95]

Could be worn valve seats. If these are worn or damaged, then the cylinder wont be sealed off and some compression will be leaking out. So when you are doing your compression test, it will be clear which cylinder has the dodgy seats. The sure fire way of determining whether they have gone is to remove the cylinder head, lay it on a flat surface valve side upwards, and pour some petrol into it. The valves that are ok will hold the fuel without it seeping out, and the ones that are past it will leak the fuel out very quickly.

[fattail95]

Also, is it a leaded or unleaded head?

[Joseph-C]

thanks hopefully it is the seats so no need for engine out work.

as far as I'm aware its unleaded its a 1993 so should be

[ANON]

get a leakdown test done.

[Joseph-C]

get a leakdown test done.

Thanks; was already planning on it.

[mister bridger]

Pouring a little oil in the bore will temporarily help seal the rings when you do a compression test and show you if thats the problem. If the compression doesn't improve the problem is elsewhere.

[Joseph-C]

thanks will do.

[bmcecosse]

Check the valve gaps before you pull the head.

[Joseph-C]

okay will do.

[Carlos W]

Does it lose any coolant?

[Joseph-C]

Yes but it has a small water leak at the moment as well so if any water was getting into the oil I wouldn't be able to tell
Another problem on the to do list