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Wet spark plugs and cylinders
https://www.ausmini.com/forums/viewtopic.php?f=2&t=91335		 Page 1 of 1
Author:  Mjk738r [ Mon Dec 21, 2015 1:17 am ]
Post subject:  Wet spark plugs and cylinders
I am new to Ausmini. I have searched for my problem but I have not be able to understand the problem.
I have an early Mini 850 that has not been used for a few years. The engine starts ok but lacks power on the roads. I was eliminating possible problems and I checked the plugs. After running the car for 15 minutes, I was surprised to see they were wet, not sure if it is water or fuel. I put a tissue in all four cylinders through the spark plug holes and the cylinders are slightly damp. Not really wet but not dry. The tissue was slightly marked.
I don't think it is the cylinder head gasket because I have done a compression check and all four cylinders are between 130-140.
The plugs are new and all four are firing and sparking. I have tried another set of plugs but didn't change anything. The points are set up correctly, coil is new. The timing has been set up correctly.
The carb is in good condition. I am not sure if it is the original carb, it has a su hs4 fitted, not sure if it should be a hs2.
Any help or advice would be greatly appreciated
Author:  Convertible Mini [ Mon Dec 21, 2015 5:51 am ]
Post subject:  Re: Wet spark plugs and cylinders
With radiator cap off do you see any bubbles in the coolant with engine running?
Author:  drmini in aust [ Mon Dec 21, 2015 6:22 am ]
Post subject:  Re: Wet spark plugs and cylinders
Check the plug and coil H/T lead resistance. Old suppression cables increase their resistance with age, until they go open circuit. Too much resistance gives a weak spark.
If buying new ones I suggest inductive core leads, Bosch or similar. These don't have the problem.
Author:  DavidE [ Mon Dec 21, 2015 6:33 am ]
Post subject:  Re: Wet spark plugs and cylinders
drmini in aust wrote:
Check the plug and coil H/T lead resistance. Old suppression cables increase their resistance with age, until they go open circuit. Too much resistance gives a weak spark.
If buying new ones I suggest inductive core leads, Bosch or similar. These don't have the problem.


I would also advocate buying Bosch leads individually and getting the shortest ones that will comfortably go from the dizzy cap tot he plugs/coil.

Cheers
Author:  9YaTaH [ Mon Dec 21, 2015 7:57 am ]
Post subject:  Re: Wet spark plugs and cylinders
When you say damp...is the tissue wet with unburnt fuel? smell?

If you replaced the points and didn't clean the preservative oil off their faces...that can cause what you describe (they quickly blacken)
Author:  Mjk738r [ Mon Dec 21, 2015 3:48 pm ]
Post subject:  Re: Wet spark plugs and cylinders
Convertible Mini wrote:
With radiator cap off do you see any bubbles in the coolant with engine running?


I checked but there are no bubbles.
Author:  Mjk738r [ Mon Dec 21, 2015 7:13 pm ]
Post subject:  Re: Wet spark plugs and cylinders
9YaTaH wrote:
When you say damp...is the tissue wet with unburnt fuel? smell?

If you replaced the points and didn't clean the preservative oil off their faces...that can cause what you describe (they quickly blacken)


I can't be sure if it is fuel or water. More likely to be fuel.
It is only damp.
Author:  9YaTaH [ Tue Dec 22, 2015 3:31 pm ]
Post subject:  Re: Wet spark plugs and cylinders
Mjk738r wrote:
I can't be sure if it is fuel or water. More likely to be fuel.
It is only damp.


"Only damp" means no fire in the belly or a firing problem...noting that fuel evaporates fairly quickly...
Author:  robbyasti [ Wed Dec 23, 2015 4:38 pm ]
Post subject:  Re: Wet spark plugs and cylinders
9YaTaH wrote:
Mjk738r wrote:
I can't be sure if it is fuel or water. More likely to be fuel.
It is only damp.


"Only damp" means no fire in the belly or a firing problem...noting that fuel evaporates fairly quickly...


It could be coolant seeping in, the head gasket could be on its way out.
Author:  peterb [ Wed Dec 23, 2015 5:30 pm ]
Post subject:  Re: Wet spark plugs and cylinders
Do a dry comp test then wet, see what you get. Then start and run engine till its well and truly warmed up. Grab a bit of glass and put it at exhaust, see if you get any condensation on it. Is there any custard in the rocker cover?
Author:  Mjk738r [ Wed Dec 23, 2015 6:10 pm ]
Post subject:  Re: Wet spark plugs and cylinders
peterb wrote:
Do a dry comp test then wet, see what you get. Then start and run engine till its well and truly warmed up. Grab a bit of glass and put it at exhaust, see if you get any condensation on it. Is there any custard in the rocker cover?

I did a comp test and all is ok, around 135 psi on all 4. The rocker cover is clean, no custard. There is some seeping at the front edge of the head gasket. A small patch of water, not drops. It could well be the coolant.
I will check the exhaust for condensation. Good tip, thanks
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