hughesy
Well-Known Member
It means your pistons are worn and loose in the bores allowing them to slap about causing noise. You're looking at a rebore, new pistons and rings, so not terminal but a few undred quids worth and probably find some more stuff worn out when it's stripped. If it isn't running too bad though it could go on for ages just being a bit noisy and/or smoky.
yella
New Member
well if yer had piston slap then oil would be making its way into the cylinders and burning with the fuel, causing black smoke. it sounds like yer oil aint getting up to the top fast enough. change yer oil and filters but flush it with half a gallon of diesel before you fit the new, that should clear all the **** out of your oil pump
david451
New Member
Piston slap is usually the skirt of the piston that has worn, and usually on the thrust side, but it's quite difficult to diagnose. I have not really seen many to be honest and the ones I did were on performance engines reving their nuts off. When the skirt wears the piston loses it's ability to travel up the bore square and results in the piston rings and the top end of the piston failing, but it could take a while.
If it's a diesel its slow reving and less likely to do this, and I personally have never had one, but I guess it could happen.
.
Was the person that told you legit, and it's not something else like a diesel knock.
david451
New Member
I think if the pistons were as bad as you say yella, then your right he would be getting more problems than just a knock, and billowing out clouds of blue smoke, with starting probs. He would be chucking gallons of oil in it.
It's also only aparent on idle, usually it knocks when you blip the throttle, a very heavy distinct rattle, unlike the big ends.
I think he needs a second opinion, wonder if it goes away when he presses the clutch?? and it's the crank moving in the thrusts.
david451
New Member
Sometimes if the pump timing is too far advanced it causes the engine to produce a heavy knock, and it sounds if the engine is knackered, you dont seem to be using oil and its fine otherwise.
When the pistons wear to the extent of knocking it burns oil, and you make no mention of this.
Also if your idle speed is too low you get this kind of knock
david451
New Member
Is it not idling too slow??, just a dab higher to take it away, some of the truck engines I have worked on sounded like they were going to explode when the idle was too low.
Adjusting the pump timing requires you to mark it first and then slacken all the nuts at the rear of the timing casing on the pump flange only enough to move the pump a tad. Turn the top of it to the engine to retard it, but the pump has no real proper adjustment and you will be limited, but it will move.
An engine noise in near impossible to diagnose on here, but give these a try.
david451
New Member
How long is a long time, I think yer dads gona get the big slipper out lad.
I think if it's that bad then refer to the chap wif the oil change and diesel to clean it, and good engine oil, not that symphetic ****, it's too thin for an old engun and will run out everywhere.
And yer dads gona get slippered as well for letting you, and diagnosing piston slap with **** oil in it.
Better get yer mom to look next time.
