13 replies to this topic

[carl84]

Hi I have bought a 1990 Mayfair 998cc to do up the car has been off the road for 8yrs. 1st time mini owner. I have cleaned out all varnish in carb and done engine oil flush as was rough idling. all though she starts without choke and fires straight away and sounds a lot quieter I was still lacking power so did a compression test and got zero reading on two cylinders and 120psi on other two. Valves seem free and no water in the oil when I did flush and no creaming under rocker cover. Ant suggestions will be helpful. Thanks  

[Fast Ivan]

if the two that have zero compression are next to each other then I would suspect the head gasket

how are you valve clearances?

[Carlos W]

Cylinders 2-3 by any chance?

 

 

Minis don't tend to mix water and oil when the head gasket goes.

 

Oh, and welcome to TMF

[Cooperman]

Check:

 

Valve clearances, should be 0.012" cold.

Head gasket if the low cylinders are adjacent.

Vale sealing with valve seats.

 

If none of these identifies the problem come back on here for more help.

[richmondclassicsnorthwales]

Hi, if you have no compression on the first 2 cylinders,(The 2 Closest to the radiator), then I had this myself and it was head gasket failure and was due to a faulty thermostat which cooked and burnt the head gasket out.
This was in my early daya when I had just started off with Minis. As I remember it all started with a heavy pinking sound with no over heating problems showing, but obviously it was to me unknowingly. It was only upon the gasket giving up and going through every thing after it all came to light

[carl84]

if the two that have zero compression are next to each other then I would suspect the head gasket

how are you valve clearances?

will check valve clearance tomorrow thanks..

[carl84]

Cylinders 2-3 by any chance?

 

 

Minis don't tend to mix water and oil when the head gasket goes.

 

Oh, and welcome to TMF

No its 3-4 Cylinders and thanks 

[carl84]

Check:

 

Valve clearances, should be 0.012" cold.

Head gasket if the low cylinders are adjacent.

Vale sealing with valve seats.

 

If none of these identifies the problem come back on here for more help.

Thanks will check clearances tomorrow..

[gazza82]

Back in the 80s our Midget was down on power and would run with plugs 3 & 4 disconnected .. both exhaust valves were damaged.

Edited by gazza82, 05 October 2014 - 10:34 PM.

[carl84]

Hi I have bought a 1990 Mayfair 998cc to do up the car has been off the road for 8yrs. 1st time mini owner. I have cleaned out all varnish in carb and done engine oil flush as was rough idling. all though she starts without choke and fires straight away and sounds a lot quieter I was still lacking power so did a compression test and got zero reading on two cylinders and 120psi on other two. Valves seem free and no water in the oil when I did flush and no creaming under rocker cover. Ant suggestions will be helpful. Thanks  

Thanks for advice have checked the valve clearance and thats fine so think its take head off and investigate. Thanks will keep you updated

[sledgehammer]

My money on head gasket blown on fire rings between cyls

 

how long was it run like this ?

 

they can burn / crack the block sometimes if run  like this

Edited by sledgehammer, 06 October 2014 - 08:46 PM.

[Cooperman]

Almost certainly a blown head gasket. Don't run it until you have changed it.

[carl84]

My money on head gasket blown on fire rings between cyls

 

how long was it run like this ?

 

they can burn / crack the block sometimes if run  like this

Hi its been off road for 8yrs and bought it as a project to do up so will be stripping head off and getting it sorted thanks for advice will disconnect batt so nobody starts her up...

[Ben_O]

Good luck!

Hope you sort it

Edited by Ben_O, 07 October 2014 - 01:56 AM.