Classic cars forum & vehicle restoration.

[arossco]

I've stripped down the engine from my 1956 Cresta, and I'm happy to see it is generally in good condition.

It has only done 31,000 miles from new, so it's been sitting still for a large amount of time !

There is no noticeable wear on the cylinder bores apart from number one, which has a small rough area about 1 cm across where the surface is slighty pitted.

Will it be safe to fit new piston rings and run it as it is, or does it need a repair or rebore ?

Thanks
Ross

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[Kelsham]

Difficult to tell from a photo, can you feel it with your fingernail as a pitting of the bore?

If you can I would advise a rebore, slight marking , you could try polishing the mark out.

Kels.

[V8 Nutter]

I would guess that is water corrosion. The main concern is where did the water come from? When I worked at the engine reconditioners we would have pressure tested the block to make sure it was not porous. Any doubts and we would have fitted a liner.

If the corrosion is not very deep new rings should be O.K. but expect to burn some oil

[ukdave2002]

Its a difficult one to answer;

If the engine is out and oversize pistons are available at reasonable cost, then it makes sense to re-bore, you will probably spend £150 more than just replacing the rings, but have an engine that bore wise is good for 50-100K miles.

Bores wear oval, so nice new round rings in oval bores will never be perfect, however if you only plan to cover a few thousand miles a year, so what?

Whenever I have put new rings in old bores; the engine has smoked at first, then been good for 20 -30k miles and then requires a re-bore.

Don't know if this helps!

Dave

[Scotty]

Looks as though its been lying for a while with damp or even head water in the bore.

It all comes down to what you want, are comfortable with and can afford. A re-bore is the safest option, but in a needs-must situation you might get away with it, but I'm sure there'll be members who wouldn't agree with that.

To illustrate - I had an upright side-valve Ford and just couldn't afford a white metal job, so I filled the broken up big ends in with Plastic Padding. I always made sure I changed the oil regularly and the 'bodge' had lasted 5 years when I sold the car to a friend who was completely aware of what I had done as he originally helped. That wee car is still going strong after nearly 10 years, with a small rattle on first start up in the morning that vanishes a few seconds later.

So there you have it, sometimes life is a gamble which pays off despite the odds.

[arossco]

Thanks for the replies - I feel a lot happier after reading them !

I can feel the mark with my fingernail, but it is only a slight depression.
There is no sign of water anywhere else, apart from a slight amount of rust on the corresponding piston ring.

I've had a crack in the block repaired by Lockstitch Ltd. who did a great job - they pressure tested it after the repair.

I have decided to put in new rings and assemble the engine and see how well it runs - in the worst case I'll have to strip it down again, but as this is a hobby I won't mind doing it !
Annual mileage will likely be less than 2000, and I'm never going to sell the car.

Can anyone recommend a good supplier of piston rings ?

Ross

[norustplease]

Has the car been sat for a long time? Atmospheric moisture can get into a cylinder if it is left with the inlet valve open and if there is rust on a cast iron ring locally, that may be what has happened.
Have you honed the bores to remove any oil glaze? That may help.
_________________
1953 Citroen Traction
1964 Volvo PV544
1957 Austin A55 Mk 1
Boring Tucson SUV

[arossco]

Yes ! I sold the Cresta in 1982, and found it again in a damp railway arch garage in 2006 ... in that time it had only covered 8000 miles.

There is every likelihood that the engine could have been static for a long time. That would explain why only one cylinder is affected, and only a small amount of rust on one piston ring.

On the bodywork though rust is another matter entirely !

Ross

[Farmer John]

Hello Ross
I have been contemplating your bore since your post and have been trying to evaluate the likely performance of the rings if no repair is made. It seems that two rings will pass the pitting, that would be the first concern, but impossible to know without measuring. Just the top ring crossing is risk enough, particularly if the height of the pitting is greater than the thickness of the ring. In that case combustion could pass the top ring and enter the space between the top rings, the bore, and the cylinder wall.
Combustion pressure builds to a peak when the piston has travelled half to three quarters of an inch down, so the pitting looks to be in the worst possible place unfortunately.
Ross I support absolutely your decision to throw it together and drive on, if the bore turns out to be the biggest headache the rest is going to be easy!
The only thing is that it is cheaper to do it now.
Just my opinion for what it is worth.
Good luck with the rebuild, have always thought that model being near the end of the EIP was one Vauxhall's best.
John

[arossco]

Hi John - thanks for your detailed comments. I've measured the distance from the top of the bore to the pitting, and it is about level with the 3rd ring (oil control) so I guess this is not ideal !

It's going to be a long time before the car is restored, so I may try a test rig like this one on YouTube - though without the cigarette !

http://www.youtube.com/watch?v=QlQG75fNbX8

I'm glad you like the E series - we had one when I was a kid in the fifties - I must see if I can dig out a photo or two !

Ross

[colwyn500]

That idea of using plastic filler instead of white metal is great...just the sort of "bodge" that I like. Ben, an old friend of mine, now sadly passed away, told me of his exploits when running a taxi business, I guess the fifties. He once bought an Austin 12 at auction about 150 miles from home. In no time at all he realised that a white metalled big-end was gone. He removed the sump and the piston and connecting-rod, wrapped a rag tightly round the oil-feed drilling in the crankshaft and drove home on five cylinders. And they ask us what it is we like about old cars!!!

[Churchill Johnson]

First thing to do is hone the bore you should do this every time the ring's are replaced, after this i think you will find the marks a lot less dominant.