Stepped piston ring installation?

[arfee]

I have a Petter AVA 1 diesel engine which I am reconditioning.
I have a new set of piston rings one of which is a stepped ring. The book I have does not show which way up the ring should be installed on the piston. Due to conflicting advice I hope someone can give me a definitive answer. I am inclined to think that the step of the ring should be uppermost ie nearest to the top of the piston

 

[david and julie]

Yes you are correct in you assumption.

Although I have never actually worked on this type of engine fitting rings this way is common practice. The rings would normally have a "t " or say top on them.

The reason for the step is that if you were fitting new rings to an slightly worn bore they would hit the wear groove at TDC.

Although not always done on as much modern engines, it is also good practice to put a the rings in the bore then push down about an inch with the piston. You would then check the gap in the ring and file with a swiss file if below spec.

The usual practise is to de-glaze the bore with a glaze buster or emery paper and engine oil, clean away any rubbish, then equi-space the rings on the piston. This helps running in and reduces oil consumption.

Coat piston, rings and bearings with new oil. And don't worry about the smoke on first start up.

Hope that helps.

 

[pipme]

Yep, stepped ring to the top .... fitted 'Cord' oil control rings to Healy once .. ok .... They had stepped upper ring to clear the wear ridge ... glaze busted using wet and dry with brasso, by hand.

When I rebuilt a Renault 16 engine .. circa '78 (wet liners etc) I was advised by a very experienced mate, helping, to coat the bearing parts with .. axle or gear oil, EP90 I think!! I was a little reticent, but followed the advice ... engine was like brand new ... drove 40 miles straight off .. had to reduce tick-over 3 or 4 times !! as she bedded in ... the oil coating did no harm, not enough to cause problems I suppose ... Gave a great boost to the initial lubrication. ... If you are rich and they remain on sale Wynns or STP oil treatment will do .....
BTW we used silicon rtv gasket cement on all oil sealing new gaskets, throughout.. never leaked a drip !!
P

 

[arfee]

Thanks David & Julie and also Pipme
Engine rebuild progressing well now.
Thanks again.

 

[david and julie]

Thanks for the update.

If you can,before starting, turn it over a few times with the injector out just to make sure everything feels OK.

Just curious it is quite a nice old engine is it a from a genny or a boat?

Good Luck.

 

[pipme]

 

[arfee]

Thanks for the update.

If you can,before starting, turn it over a few times with the injector out just to make sure everything feels OK.

Just curious it is quite a nice old engine is it a from a genny or a boat?

Good Luck.

The engine is from a genny circa 1952. The set was made by Dale Electric (Yorkshire). I got it when we had no mains electric. It is automatic start when a light switch is put on in the house and swithes off when the last light is put out. 2.5Kw. It is a good standby when the mains fails at times.