Leak Test On Valves

[smithy 1]

Currently rebuilding xu9 engine I have cleaned head up and lapped in valves.

The valves and seats all looked good with a nice clean greying from the cutting paste.on this head for some reason I thought I would do a leak down test,in all the heads I have rebuilt I have never bothered.anyway I poured some paraffin on the valves with head upturned and after a while I got some leaking back through the valve seats.

Would you expect to have a 100% seal or is it normal to have a weap over time using this method?

[rallysteve 22]

Did you have the valve spings fitted when you did the test?

 

Steve

[smithy 1]

Yes mate springs and the rotation shims are fitted

[smithy 1]

all sorted now i had all valves back out yesterday and gave them another good lapping in,3 course and 3 fine.

 

done the test again and left overnight 99% of paraffin was still sitting on top of the valves with only a slight weep past the valves.