irishminis.ie

Having a issue with the car, I think the rings on #4 are fubard. Symptoms are oil vapour coming out of oil filler cap, when I pull the lines from the breathers it comes from here too.
Car will not run unless on full choke until fully warm, Misfires through the whole rev range , backfires impressivley, feck all power.

Now compression test showed up as pretty much even apart from number 4 which was way below the other 3 which were quite consistant.

My Dad reckons HG Failure but I doubt it as no mixture of coolant and oil, nor is there the tell tale smoke from the exhaust.

Valve Stem seals could also be a culprit but I doubt this.

Piston Rings are my choice due to compression test results.

Anyway of isolating the rings to eliminate the valve stems for sure?

Also that Holts piston seal gick, am I right in saying this is pure crap?

http://www.ehow.com/how_4486238_test-ca ... rings.html

and ive never had a good result from *any* magic potion poured into a car: its pretty much all snake oil IMHO

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Signature awaiting top-coat and lacquer....

coolio, ill give that a try tomorrow, oh the joys of minis , if this is the rings its another enforced leave from the road.
Why couldnt they have gone 3 months ago when id sweet feck all to do and all day to do it!

It sound like ring land failure to me Ciaran, verry common on no:4 piston. normal cause is over advanced ignition, causing the top ring land to faile on the hottest piston which is No4.

Cheers Paul, Im hoping its HG but it doesnt look like it. The lock is bored to 1380...Am I right in saying these cannot be honed much more?
Is the block scrap?

the block should be fine if its a faild piston all you should need is a new set of pistons and a hone,

It could well be a head gasket, when you are doing you compression test are you doing it with all plugs out ? if so and all the other pistons show normal compression then its almost deffently a piston failure.

Yea comp test was done with plugs out on all cylinders. Can I not just change the rings to oversize and hone the block? or is this a waste of effort?
Ive too much on my plate at the moment to e dealing with taking the motor apart. Feck sake.

Hi Ciaran,
If the ring land on the piston has failed there is n point replacing the rings as there is no where for them to sit (the ring land is the botom at top part of the ring grove in the piston). Im afraid its a motor out job for this one Ciaran. maby you could just find a 998 or 1275 engine that would get you out of a hole that way it would only take you a day or so to change them out !.

I think im just gunna leave it till the summer to be honest, last year in college this year, I dont have the time for all this. Im going to buy a cheap banger and use that for the year! (anybody got one??!).
I have a sneaky plan for the 1380

I see what folk are saying here, the backfiring and the very low compression tells me that you might in fact have a valve problem..... has the head been converted for unleaded, and if not did you use an additive..... is the backfiring out through the carb or the exhaust....?

Ian
028 (048) 4481 1688

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Ian
MINI QUIP
http://www.mini-quip.co.uk
028 (048) 4481 1688 (THIS NUMBER WILL NO LONGER BE AVAILABLE SOON)
0044 7703 839 401 (NEW NUMBER)

I presume its been made run unleaded, its a stage 3 minispeed head (whatever spec their stage 3 is i dunno).
Backfiring out the exhaust! nothing from carb, I think ill whip the head off it on sunday and have a look, that will eliminate HG and the I can inspect the valves and seats.

But the vapour coming from the crankcase is BAD

Stage 3 mini sport head is unlikle to be unledded converted as they run a 37mm inlet in them no room !

backfireing is simply an indication of the fuel/air mixture not been burned in the engine and igniting in the hot exhaust.

Valve problems rarely cause excessive crankcase pressure (the valve would litterly need to be falling around in the guide). If blowby has increeced masively from the last time you checked the motor and now the rings or ring land's are your problem.

If you want to be 100% sure simply do the compression test again on #4 but this time put in 10-15ml of engine oil into the plug hole and repeat the test if compression comes up Piston rings or pistons are at fault.

doodoo doodoo doodoo.

If its not unleaded im fucked, its been running 95 for 2 years its only the last 2 months I was putting in the additive because i wasnt sure.

Could very well be the valve seats, right Im going to put oil down the bores later then whip the head off, It be handy if it was the head or HG!

did you get this one sorted?

no one think of a leak down test!?!

what where the results of the pressure test?

there will be some grank case pressure are you aware of what normal is?

what is your timing set to?

EDIT:- is it not sore on the crank having all plugs removed to do a pressure test?

_________________
Stewart

Lucas, the prince of darkness

#1 was 15bar
#2 was 14bar
#3 was 12 bar
#4 was 6 bar

Put oil down the bore this brought compression on 4 up to 8 bar. There is a serious amount of smoke/condensate/oil coming for the crank breather on the clutch cover, pulled the lines from the carb and the car ran alot easier (obv due to the lack of crap messin the mixture up)

Im thinking rings from the results, but im still not 100% as the cyliner didnt raise much more pressure with the oil!

No mayonaise in the oil and now oil in the coolant. I cant see it being anything else other than rings though.

[quote="swalker"]did you get this one sorted?

no one think of a leak down test!?!

what where the results of the pressure test?

there will be some grank case pressure are you aware of what normal is?

what is your timing set to?

EDIT:- is it not sore on the crank having all plugs removed to do a pressure test?[/quote]

I did think of a leak down test but seen as how the car is at Ciarans house and is not driving and seening as it is unlikly for Ciaran to have a 20l/min compressor at his house, I taught it a bit impractical.

It is in NO way sore to have the plugs out when cranking for a compression test infact if anything it is much better for the crank ! and besides the rusults gotton with plugs in is totaly meaningless.

[quote="kona"]#1 was 15bar
#2 was 14bar
#3 was 12 bar
#4 was 6 bar

Put oil down the bore this brought compression on 4 up to 8 bar. There is a serious amount of smoke/condensate/oil coming for the crank breather on the clutch cover, pulled the lines from the carb and the car ran alot easier (obv due to the lack of crap messin the mixture up)

Im thinking rings from the results, but im still not 100% as the cyliner didnt raise much more pressure with the oil!

No mayonaise in the oil and now oil in the coolant. I cant see it being anything else other than rings though.[/quote]

Ciaran it sounds very much like botom end the comreission has come up 2 bar which is nearly 28psi which is a 33% increase not to be sniffed at. your next port of call is to wip off the head its an hour work and will let you know where you stand.

my openion is ring land failure.
regards,
Paul.

??? i run my leak down tester off a 24L portable compressor.

did you try a compression test with No3 plug in to check for inter-cylinder leakage via a head gasket track?

If your head gasket is blown it doesn't automatically mix the oil and water, the most common fail in a Mini is between N0 2 and 3.

pouring oil down the bores may seal up a bore/ring failure but the ring land would be harder.

I hope all this has been done with the engine warm BTW?

_________________
Stewart

Lucas, the prince of darkness

Yup all done with engine warm

Ill whip the head off this afternoon and get pics up

whipped the head off last night, its clear as day there is a notch out of the side of the piston and a little scoring on the Bore.
The head is fine, its certainly a Big valve head as there isnt much metal between the inlet and the exhaust, its been well ported too.
Now that I have a little project on my hands Im probably going to be selling my twin carbs, the inlet manifold , and the stage 3 minispeed head. Gunna make myself a lil monster :p

Good Man Ciaran,
At least now you have your problem found, This is a common problem from over advanced ignition. or running to lean on WOT.

A good lesson for people out there with sporty minis get your fueling and ignition checked if your not sure its rignt get it checked !

Look forward to seeing the new build come on Ciaran best of luck.

Thanks paul,

I cant Imagine it being the fuelling as the needles in the carbs were quite rich, so it must have been the ignition, although It wasnt pinking or anything, but it had a fair total advance on it.

Ah well, be a lil monster when Im finished with it haha. Gunna get cracking asap.