BXProject

[Philhod]

Went to Rigbye's Thursday, for some more paint. Kept the Picasso to the speed limit all the journey (mostly 30 some 40) According to the computer (I used cruise) it averaged 53.4.

[mat_the_cat]

Not bad! Do you know if the computer correlates well with actual mpg? Lana's old Megane (the only vehicle we've had with an economy display) showed a best of 46mpg but was a true 37mpg (still not bad for a 2 litre (shhh) petrol!)

Took the van for a test run this evening (before drinking commenced) and power was noticeably up, so economy should follow.

[Philhod]

Yes it does, pretty well anyway.
Did the trip to Stratty last year and got stuck in traffic on the way down.
Computer she say 49.6. Tank top to tank top said 51.1. So it err's slightly on the cautious side.

[Father Ted]

I dont believe the MPG computer on the C8,

On a motorway run it can say we are getting 60 mpg at a constant 75, drop that to 65mph and the consumption drops to 36mpg.

Take my foot off the accelerator and coast and my MPG goes to 999mpg!

The C8 is getting 36 to 39mpg on a tank depending on how much motorway driving it does.

[mat_the_cat]

Take my foot off the accelerator and coast and my MPG goes to 999mpg!

It'll shut fuel off on the overrun, giving infinite mpg.

[Philhod]

Mine is really sensitive. Sticking it in cruise shows it best. As you travel along the M/way, slight rises and falls are shown on the screen almost instantly.
A slight downgrade will give 70-80 mpg, whilst uphill it can drop to low 30's.
After you switch off and re start you can select to view your average of the last journey

[mat_the_cat]

Quick update - seems to pull better and more smoothly. But best of all, it no longer sounds knackered! (Apart from the gearbox maybe, the bearings in it are a little noisy. Maybe next year's job?)

[docchevron132]

dont talk to me about fucking gearboxes...

[mat_the_cat]

Is having sex with a gearbox a bit of a taboo subject for you then?

[Philhod]

I don't know why.....He's probably fucked quite a few.

[docchevron132]

just one..

[mat_the_cat]

And the saga doesn't end here...

After a couple of weeks of being fine (albeit only 100 miles or so) the tapping has come back just the same as before. I still don't think it's oil pressure related, as it does it less at idle. If anything it does it most on the overrun. But what could be causing it and why did new lifters cure it temporarily?

[docchevron132]

interesting.. It doesn't have a filter in the head for the oil feed does it?

[mat_the_cat]

That's a good question - I don't know, and I don't know how I could find out!

I'm half thinking about putting in the engine from a Volvo 7 series - same basic lump but an extra 25bhp. Not sure if the torque characteristics will be unsuited to dragging a heavy van around though. But then that seems like giving up, and I'm always impressed by this engine's ability to sit on the red line for ages, without complaint. Seems a bit of a shame to just throw it out!

[Philhod]

If it aint broke Don't fix it

[mat_the_cat]

But it is broke (to my eyes)! It goes tap tap tappity tap all day long and it's damn annoying, plus if a valve isn't opening fully then surely I must be down on power?

[Philhod]

If it aint stopped don't fix it then.

The amount of power you would lose by that would make you say I "must" be down on power. Coz you sure as hell wouldn't notice it

[mat_the_cat]

I think it might not have been the lifters after all. Not 100% sure at the moment, but the noise may be coming from the vacuum pump, which seems to be driven via a pin off an extra lobe on the cam.

My theory is that if this pin is worn, then it would cause cam speed related tapping. I suspected it happens more on the overrun, which may coincide with barking and hence more load on the vacuum pump.

But why would it go away briefly with new lifters? Maybe because if the pin is worn, it would be worn in a concave shape at the end and hence be shorter. If it was rotated 90 degrees (such as when the cam was out) then it would effectively be back to its original length. A lot of ifs, but should be easy to prove if I pop the pump off and temporarily remove the pin completely.

[Philhod]

Even if the pin did get rotated, it's free to rotate so would have re seated it's self more or less immediately.
Secondly. If I remember correctly there is a strong spring on thet pin, so would compensate for any wear

[mat_the_cat]

Hmm, maybe that's my armchair plan out the window then! But I will try running it without the vac pump, just to see.