Had an interesting little lesson over the weekend.
A UOA was performed on one of our vehicles a month ago, as I was worried about fuel dilution with a mechanical fuel lift pump failure.
The fuel levels were fine, and most wear metals appeared near normal, excepting that the PQ index was up nearly double of previous figures. This didn't raise a flag at the lab, as they don't have an upper limit for the PQ index, only a maximum Fe level of 90PPM.
I put the increase in the PQ index down to the new plunger bedding in to the cam lobe, and the raised silicon as a result of Hylomar on the gasket.
Delvac 1 used throught.
Date 30/8/05 31/5/04 11/2/02
Km 168233 128084 121149
oil km 7000 17935 11000
oil add 0.6l 1.5l 1.5l
Al 4 11 7
Cu 2 7 3
Fe 16 34 19
Pb 5 7 5
Sn
Si 9 8 6
Fuel 1 1 1
Soot % 0.5 0.9 0.6
PQ Index 45 27 b>
Unfortunately I was wrong.
During a routine rocker check over the weekend, I found the valve stem cap on No 4 inlet valve disintegrated. All other caps are fine, all other valve/rocker clearances are fine, and haven't needed adjusting in over 60,000km.
Of course I'm replacing all the caps, but I'm not very enamoured with the thought of all that schrapnel through the system. I inspected the entrails of the OE oil filter, and the tell tale specks/chuncks of steel are there.
Anyway, just thought I'd pass on that a failure doesn't necessarily raise a flag at the lab.
A UOA was performed on one of our vehicles a month ago, as I was worried about fuel dilution with a mechanical fuel lift pump failure.
The fuel levels were fine, and most wear metals appeared near normal, excepting that the PQ index was up nearly double of previous figures. This didn't raise a flag at the lab, as they don't have an upper limit for the PQ index, only a maximum Fe level of 90PPM.
I put the increase in the PQ index down to the new plunger bedding in to the cam lobe, and the raised silicon as a result of Hylomar on the gasket.
Delvac 1 used throught.
Date 30/8/05 31/5/04 11/2/02
Km 168233 128084 121149
oil km 7000 17935 11000
oil add 0.6l 1.5l 1.5l
Al 4 11 7
Cu 2 7 3
Fe 16 34 19
Pb 5 7 5
Sn
Si 9 8 6
Fuel 1 1 1
Soot % 0.5 0.9 0.6
PQ Index 45 27 b>
Unfortunately I was wrong.
During a routine rocker check over the weekend, I found the valve stem cap on No 4 inlet valve disintegrated. All other caps are fine, all other valve/rocker clearances are fine, and haven't needed adjusting in over 60,000km.
Of course I'm replacing all the caps, but I'm not very enamoured with the thought of all that schrapnel through the system. I inspected the entrails of the OE oil filter, and the tell tale specks/chuncks of steel are there.
Anyway, just thought I'd pass on that a failure doesn't necessarily raise a flag at the lab.