Remember my Bad Fuel Economy?

and that shows why maintenance, especially oil changes is vital.

I doubt it would make much difference to economy though

more like black tar !!!

lack of oil changes.

The message from Simon Dean contains these words:

I once serviced a Pinto engined minibus. No one who drove it had actually complained, perhaps it had lost power so slowly that none of them had noticed, but it was obvious they all preferred driving some of the other buses.

The cam lobes were almost round, max lift on three of the cylinders was about 2mm, with the fourth a bit more. New shaft and it capered off down the road like a frisky lamb. Well - comparatively, anyway.

So is there no point, or is it too risky to clean the gunk off? Or will you just leave debris in your sump, filter and other pipes?

Regards,

Tim

Mm, well, I could probably leave the gunk in situ. As long as it's not doing anybody harm and it doesn't start flaking off in clumps. I've heard a bit of ATF is the better thing to use for cleaning as it dissolves the gunk rather than having broken off lumps clog your filter.

I guess too much sludge can lead to things clogging eventually, as what happened with the oil rails causing the cams to squeal at me in excitement.

Having taken the rocker box cover off, Im inclined to think that the head has maybe been rebuilt before I had it. I can't quite put my finger on it, just lots of little things.

Ideally I'd like to change the cams, but on a rusty 94 primera with possible imminent work required on various bits of the front road wheels (bearings or cv joints and other suspension bits like anti roll bar links (it seems to roll heavily in one direction - maybe I'm just too fat)), I do wonder if its worth it.

Cya Simon

What about worn camshafts? Do worn camshafts not alter economy? Must affect the running of the engine? Too much sludge can lead to (I would imagine), oil rails becoming blocked and cutting off the feed to the camshafts.

Cya Simon

Back when Adam was a lad, I looked at an A-series engined car that was only running on three, and rattled a bit. When I removed the rocker cover I found that the whole valve train was so worn, a push-rod had jumped out of place!

The owner was going on holiday a couple of days later, so I adjusted all the valve clearances, changed the oil and filter and sent him on his merry way.

It was still running OK a year later, and I'm sure had no further work done on it.

Chris

It will if the lobes are half warn away!! Pumping losses will be much higher...

tim. .

The message from Chris Whelan contains these words:

I had an LDV with the 2-litre O-series(?) petrol engine. Ran like a complete pig - it was months before I realised the cambelt was two teeth out.

it does not look as though there is much gone from the cams, which is why I said I doubt it would make any difference to economy. Worn cams make the engine lose its edge, but I seriously doubt it would make more than a percent or two difference to its economy.

You get a massive loss of power which means you use more fuel as you have to keep your foot down.

Would that account for uneven running, iffy timing?

Cya Simon

Deffo uneven running.