10 replies to this topic

[Zlevin23]

Hello on my 93 1275 Mini I’ve got smoke pouring from the oil fill cap on the valve cover. I did recently have an over heat occurrence happen it didn’t get extremely hot but it did get up there and while that happened oil covered the right back side of the engine bay. After cleaning it up and filling it with oil and flushing the cooling system I find the smoke build up. Any ideas? I know I’m looking at definitely pulling the head but what could be the problem? Thanks!!

[sledgehammer]

Just my opinion -

What is the mileage on this engine , and what work done on it previously ?

are you using breather to carb - or open to atmosphere , are pipes & breather clear?

Do a compression check before pulling the head

 

no plugs in with throttle open , charged battery , dry , then put some oil down bore , record pressures .

 

also check head torque settings - look for one a bit looser than the rest

 

look for oil on the plugs

 

sounds like a piston ring may have gone or picked up in the bore

 

but there are loads of other things it could be 

 

cheapest is a fire ring gone thru to oil return hole on head gasket , or breathers blocked
 

most £xpensive is a rebore & pistons / rings

 

hope it's cheap to fix

others will be along with more idea's ,
 

best of luck

Edited by sledgehammer, 23 July 2024 - 08:46 AM.

[Cooperman]

It does sound like a broken piston ring or rings. I note that you say smoke is 'pouring' from the oil filler cap, which indicates more than just a bit of bore/ring wear.

It could be a head gasket, in which case you would be lucky, but that seems a bit unlikely.

I had a 1990 Cooper which I bought for restoration a while back and the engine was smoking and using a bit of oil. That turned out to be two broken piston rings, but the smoke was not 'pouring' out of the filler cap. It could, of course, be a damaged piston.

I think you will end up pulling the engine out and stripping it right down for a proper look.

[Zlevin23]

I’m going to start with compression test and go from there. No smoke is coming out of the exhaust and last I looked the plugs were clean. But let me check compression first. Thanks you!

[KTS]

is it smoke or water vapour ?

[Zlevin23]

is it smoke or water vapour ?

Great great question. Looked like smoke but let me get a wiff of it next time I fire her up.

[Zlevin23]

So after doing a wet compression test results are 9-5-5-9 bar. I’m thinking blow by between two and three on the head gasket. Held pressure just fine in each test so I’m hoping the rings are fine.

[Zlevin23]

Also just pulled the valve cover. Smoke is coming from the rod tubes on 2 and 3.

Edited by Zlevin23, 27 July 2024 - 10:25 PM.

[timmy850]

If the head gasket is blown into the pushrod holes it'll be pushing a lot of pressure through the crankcase/rocker cover

[sledgehammer]

Any update on this ?

 

Hope it was cheap

[coopertaz]

whenever ive had head gaskets fail it's always between 2 and 3 check block and head for any damage here if this has blown through had it knacker an old engine when i had to limp it home with this blown