Jump to content


Photo
- - - - -

Smoke And High Compression On A Late 1275

engine

  • Please log in to reply
12 replies to this topic

#1 need4speed

need4speed

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 83 posts
  • Location: Occitanie, south of France

Posted 28 May 2018 - 03:13 PM

I've got good compression on all cylinders but no. 3 is 10% higher than the other three. I've also got smoke - lots of it - from the tailpipe with anything more tha idle speed, and oil on the of piston no. 3. So, as this engine sat around abandoned for a long time (with the rest of the car) am I simply looking at valve stem seals, or guides as well? The engine's only got 70,000 miles on it and is quite quiet. It's a '92 1275 single carb model.



#2 Dusky

Dusky

    Crazy About Mini's

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 5,322 posts
  • Location: Belgium

Posted 28 May 2018 - 04:39 PM

The colour of the smoke will determine the answer.
Doesn't sound like valve stem seals.
White could be coolant or brake fluid ( via the servo).
It could also be burning off loads of condensation after sitting for a while. Have you driven the car recently for a good distance? Rings can gum (and free) up.



#3 need4speed

need4speed

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 83 posts
  • Location: Occitanie, south of France

Posted 28 May 2018 - 05:01 PM

The smell of the smoke says engine oil to me and there is fresh engine oil on top of piston no.3. I would expect ring problems to cause a loss of compression. I can eliminate a brake fluid issue by disconnecting the vacuum hose. I haven't driven it far because it's leaving a smokescreen behind it. I'm in the south of France and the car's in my garage, we don't have condensation :proud:



#4 Spider

Spider

    Moved Into The Garage

  • Admin
  • PipPipPipPipPipPipPipPipPipPipPip
  • 13,844 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 28 May 2018 - 06:30 PM

Explore all other options first, but at a guess, I'd say, given that it sat around for a while, one of the valves for No. 3 cylinder was open during that time and the bore got a little rusty, damaging the rings on that piston.



#5 cal844

cal844

    Crazy About Mini's

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 9,482 posts
  • Location: Ballingry, Fife
  • Local Club: TFMOC

Posted 28 May 2018 - 06:47 PM

I'd say a head rebuild at least, possibly a bottom end refresh too, however what I will say is that my Clubman Estates engine sat around for 3 years.

When we fitted it we primed the oil pump, fitted a new clutch(and primary gear seal), water pump and a general service) If left for more than 48 hours it would let off a plume on initial cold start up (lasted for about 500 miles of daily running, at approx 20 miles a day) then cleared, it runs sweet ? it was simply dry valve stem oil seals.

Post edited for clarity and my wild guess...

Edited by cal844, 28 May 2018 - 06:48 PM.


#6 need4speed

need4speed

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 83 posts
  • Location: Occitanie, south of France

Posted 28 May 2018 - 07:04 PM

Hmmm. This engine wasn't run for about 8 years. I'm still puzzled by augmented compression if there is cylinder damage of any sort.



#7 carbon

carbon

    Up Into Fourth

  • Members
  • PipPipPipPipPipPipPipPipPip
  • 2,590 posts
  • Location: UK

Posted 29 May 2018 - 07:01 PM

What compression readings did you get?

 

Just possible that number 3 has been oily for a while, and you're seeing increased pressure because of more carbon build-up in that chamber than the others.

 

Also the head chambers are rarely exactly the same, I have seen differences of between 0.5 - 1.0 cc on a standard head.



#8 need4speed

need4speed

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 83 posts
  • Location: Occitanie, south of France

Posted 29 May 2018 - 07:18 PM

1-4, 155psi, 150psi, 170psi and 155psi (the calibration of the gauge may be a bit out but the error is consistent). I can dip a piece of paper on to piston 3 through the plug hole at tdc and get remarkably fresh looking oil on it.


Edited by need4speed, 29 May 2018 - 07:18 PM.


#9 need4speed

need4speed

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 83 posts
  • Location: Occitanie, south of France

Posted 08 June 2018 - 02:44 PM

Took it out on the road today - the first time that car has seen a road for 10 years and the smoke problem has disappeared. First time I've driven a Mini for 35 years - what a hoot! It just shouts "faster" at me.



#10 germini30

germini30

    Super Mini Mad

  • TMF+ Member
  • PipPipPipPipPipPip
  • 658 posts

Posted 08 June 2018 - 03:25 PM

Sometimes I think that a good drive/thrash is the best remedy

#11 need4speed

need4speed

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 83 posts
  • Location: Occitanie, south of France

Posted 08 June 2018 - 03:30 PM

In this case it appears so.



#12 panky

panky

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,776 posts
  • Location: Cheshire
  • Local Club: Northwest Casual Classics

Posted 08 June 2018 - 03:33 PM

The old Italian tune up method :D



#13 Thelowrider

Thelowrider

    Stage One Kit Fitted

  • Just Joined
  • PipPipPip
  • 90 posts
  • Location: Nottingham

Posted 08 June 2018 - 08:49 PM

If there is oil present on cylinder 3 this may well be the reason why your compression reading appears to be higher than the others slightly. The oil will be creating a ‘better seal’ so will give you a higher compression.





Also tagged with one or more of these keywords: engine

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users