Head removed - wet areas in zylinder 3 & 4

[mopetta]

I recently checked the temperature on the exhaust, when I realized that there was huge difference between 4 and others. So I removed the head to check the condition. Not the perfect Christmas present...

I have some wet areas in bore 3 & 4. I have attached a couple of pics. I'm a bit uncertain on how to proceed. 

What is the problem, just a bad gasket ? What is your advice ?

   

   

   

   

   

   

   

thanks
Oliver

[Reckless Rat]

That looks like oil to me, not water which suggests that your engine is worn, allowing oil past the piston rings into the combustion chambers, hence the carbon build up. It is a phenomenon exacerbated by the late 37 head design which places the spark plug right on the circumference of the bore and directly in line with any oil coming up from below.

Turn the engine over by hand and see if there is any movement of the piston relative to the bore when at the top of its stroke (repeat for all 4). If there is, then you're probably needing a rebore and a set of pistons.

Clean up the top surface of the pistons to see what size they are.

[Howard Wright]

Hi Oliver

Good to see a set of clear photos with a request!

As Reckless says looks like oil and the first thing to do is clean it up and check for any slop between the pistons and bores. 

Do you know the history of the engine?  Has it been rebuilt recently?

You put a recent thread on the forum regarding manifold sealing.  I’ve been told that it is possible that a badly sealed manifold could contribute to carbon build up (although I’m not sure of the mechanism for this).

Good luck

Cheers

Howard

[Colin Reed]

Hi Oliver,
As Reckless has said it is a Oil problem,
The Only way to fix is remove Engine, because it looks like a rebore and new pistons and Rings also the Block & Head will need to be faced.
If you look at the Head gasket you will see that it is ready to go between water jacket & cylinder in two places.
Regarding head gasket do not be tempted to just clean head and block as you will allready  be having Machine work done so the Facing will not add much to the bill

Do it once do it right less pain in the long run

All the Best
Colin
NZ

[mopetta]

Thanks for your advice. Now, I took the engine out and checked the piston size - it's +0.40.
There is some ply when the piston is at top - but I don't know what is still considered ok. I can put the 0.2mm gauge between piston and bore when I push the piston to one side. Same with valves, there is some ply when not under pressure.

see video: https://youtu.be/GMGEhofQvIU

   

[Reckless Rat]

I would suggest that your engine is badly in need of a rebore. It is very badly coked up, due to burnt oil collecting in the combustion chambers. With the current pistons at 0.040" there is scope for a re-bore, fitting a set of 0.060" pistons and rings, which are available at our cherished suppliers. I would invest in a complete overhaul of the block while you're at it, valves, seats, guides, studs, surfaces. It will be worth it in the long run. Throw the oil baffles away (if they're still there) and fit a silicone base gasket.

[Howard Wright]

Hi

Again Reckless has said it all.

Invest in a copy of “The Austin Seven Manual” by Woodrow. Essential companion for a first foray into an A7 engine rebuild.

Cheers

Howard

[Bob Culver]

It certaiinly seems uncommonly oily. My engine used prodiguous oil at one stage but never appeared that wet.Depends a bit on what it did before shutdown. It is difficult to assess wear without a mike. A large lip is a give away but may have been removed. Wire or nails can be filed to length and used as an internal gauge to get some idea of taper but measuring inside cyls requires some patience and skill. Wear is usually very local under the lip.
The fact that all cyls same does suggest wear as othr faults not usually common to all cyls.

[Andy Bennett]

Also worth closely checking particularly between 2 and 3 by head stud for any cracks in the block before paying out for work.
Might just be muck or an optical illusion but your pics do look like they have a 'line' to the stud.

Also earlier pictures suggest water way between 3 and 4 is completely blocked, exactly where both cylinders appear to be allowing oil past. Those with more knowledge than I will know if this might have caused damage to the block through overheating/distortion and so the cause of your problems and whether or not it is wise to proceed with spending money on this block.

Andy

[Hedd_Jones]

Bet that oils plugs, particularly with the H/C head on it!