diif q and my compression figures

[matt123]

Hi
on way to work yesterday and today i noticed my diff was a rather noisier than usual. got some stands and hoiked up the back end and filled it with gear oil, it took 400ml and it has capacity of a pint so it was only one fifth full  :'( , took it for a quick drive right now and its quiter but still makes more noise than it did, is it toast or will it soldier on and i'll just keep checking the level?

finally got round top checking my compression here are the figures cylinders numbered from front of engine, the last three i popped a smigen of light oil in cylinder than tested again. socan anyone shed any light , are they ok or bad bit worried that the last three are low

         1         2        3           4           5           6
Psi    150    140     150    130/120     130       130
Bar   10.5    9.7     10.5        9            9           9
oil                                    145         175        170
                                         10           12         12


matt

[JohnD]

Matt,
Only time will tell on the diff.   Keep an eye on it - is it leaking?  Is the breather open?  Split pin next to the ?Right output shaft bearing housing.  If that's blocked, heat increases internal pressure and forces oil out.

On cylinder pressures:
No.4 doesn't increase much with some oil, from a lower pressure - that points to a burnt valve, or other problem with the valves.
5 & 6 increase significantly - that points to rings.  But you should compare with the other three.  If they increase as much, this is just general wear.   If 4 & 5 stand out, draw your own conclusions!

John

[Clive]

Yep, redo it treating all 6 cylinders dry and then (the same amount each) oil. Do it a few times and compare. Hopefully results are repeatable!
Compression increases with the oil even on good engines, so everything is as john says comparative. Johns comments about poss problems accurate too, but the figures are not a disaster, and the engine could trundle on for years (my herald did with one dodgy cylinder, neve changed much for about 3 years of regular use)
Thing is to keep an eye on if it does change, or plan a rebuild at a convenient time, SHOULD it be needed.

Clive