to replace or not? -piston rings.

[xotcab]

I'm part way through re-building my 1.9 DG engine and have practically changed everything.
I've got to order a set of exhaust valves and i'm considering replacing the piston rings.

Now i've been told that due to possible ovality of the liner it isn't advisable as new part's won't seal correctly. Is this true?
I know that if I do change them the liners will need de-glazing.
From looking at the spark plugs cylinders 1&2 are sooted and dry while cylinder 3&4 are sooted and a bit oily - this is my reason for changing them.

Any advice/opinion would be greatly appreciated.

[ewenmaclean]

Hello,

I did this years ago but on a non-vw diesel engine, so possibly I'm not being much help as I know it's a totally different kettle of fish with a DG. I know that a lot of people seem to use a thing called a flex-hone:

http://www.pacehigh.co.uk/category6767/ ... e-reg.aspx

for de-ridging etc... which is vital if you want your rings to seat well. In the old diesel I did I used slightly oversized rings, and got the cylinders rebored as they were too knackered. Good idea too to see whether something lower down was causing lateral movement and hence the ovality.

To figure out whether you need to rebore or whether you can just hone, I think it's really worth getting the cylinders checked out with proper measurement equipment, which you might have, but if not there are machine shops that will do reboring and measuring for you, and if you ask me it's totally worth it now you've got the engine in bits anyway! Like I say - I'd check the crank and bearings too...

I am too lazy now to do that sort of thing, so am impressed with anyone that has the energy and motivation to do it! Hope it goes well

Ewen

[fairwynds]

I rebuilt my DG 1900 about 3 yrs ago.
I got new rings from VW, and had the bores honed and check by a company called QEP in Sussex. I decoked the pistons too, but some say to leave them (?).
Check that end float on crankshaft, mine was within tolerances and I was advised not to split the case (van only had 50k on clock.
I have lots of pics of the whole rebuild, so ask away should you need too...
Dont forget to check/replace those head studs IF NEEDED (mine were ok due to lots of lovely coolant changs!) and also the exhaust studs. I used a JK mild steel exhaust to tide me over as money was then too tight for s/s one (but I have since put on s/s one - tis lovely!)

Enjoy - it's worth it....

FW

ps - whereabouts are you based?