AJP engine noise - I found the cause - warning XXXX content!
Discussion
Having stripped down my AJP for what sounded like a "top end" noise, I even thought timing chain, I have found a fairly decisive reason for my rattle.
Seems fairly conclusive
The worrying thing is that 2 out of 8 have cracked like this
The engine was only rebuilt 9,000 miles ago and they are genuine AE pistons (and therefore I assume gudgeon pins). Looking at them I can only assume that they have been over hardened and got brittle. Whatever, it certainly looks like a production fault and one that I intend to raise with AP - any legal eagles on here who can guide me on the liklihood of me getting another set of pistons out of them?
Anyway, I must say that, overall I feel incredibly lucky that I trusted my instincts and pulled the engine out rather than just risking it. What will be a few hundred quid now would most definitely have run into thousands had I let this go on any longer. I also found a couple of other little faults that I can rectify along the way and will know that I'm putting an engine back together which will provide me with miles and smiles not worry and bills.
Seems fairly conclusive
The worrying thing is that 2 out of 8 have cracked like this
The engine was only rebuilt 9,000 miles ago and they are genuine AE pistons (and therefore I assume gudgeon pins). Looking at them I can only assume that they have been over hardened and got brittle. Whatever, it certainly looks like a production fault and one that I intend to raise with AP - any legal eagles on here who can guide me on the liklihood of me getting another set of pistons out of them?
Anyway, I must say that, overall I feel incredibly lucky that I trusted my instincts and pulled the engine out rather than just risking it. What will be a few hundred quid now would most definitely have run into thousands had I let this go on any longer. I also found a couple of other little faults that I can rectify along the way and will know that I'm putting an engine back together which will provide me with miles and smiles not worry and bills.
Edited by itiejim on Monday 7th September 21:25
Edited by itiejim on Monday 7th September 22:40
as you say, its a good job you didn`t let it go, and bothered to investigate, dissapointing in some ways, but a very big relief overall.
ridds said:
That's not good. Who are AP, I'm either being a little dim as I don't remember hearing of them.
Looks like you'll be needing some new little end bearings too.
Are the pins all free in the rods and pistons?
I'll definitely need little end bearings! I'll do all of them and the pins plus I think I'll need a couple of pistons due to the cracked pins scoring them slightly. All the others seem fine.Looks like you'll be needing some new little end bearings too.
Are the pins all free in the rods and pistons?
Edited by itiejim on Monday 7th September 22:41
sk7ine man said:
Holy sh*t. You;ve done well to diagnose it before it really let go. What was the noise/symptoms?
Can't really say I diagnosed it until I found this today.I was just sure that I wasn't happy driving it as it was!Symptoms were a tapping noise just like a loose valve clearance, the only difference being that this noise was load related - quieter under load and louder on the overrun. Also it was most pronounced between about 2000 and 3000 rpm. Over that it was hard to hear and at tickover it was a very light tap.
Holy moly batman! Impressive sleuthing to boot.
Could pinking / predet have contributed? The shock loading could maybe cause some sort of failure like that.
Hope you manage to get hte parts sourced and engine reassembled ASAP + take lots and lots and lots of photos pls
EDIT: also looks like a small bit cracked off the end of one pin. Make sure you clean the hell out the sump + change oil filter (sure you will, but making sure!) etc incase a couple of particles are lurking down there
Could pinking / predet have contributed? The shock loading could maybe cause some sort of failure like that.
Hope you manage to get hte parts sourced and engine reassembled ASAP + take lots and lots and lots of photos pls
EDIT: also looks like a small bit cracked off the end of one pin. Make sure you clean the hell out the sump + change oil filter (sure you will, but making sure!) etc incase a couple of particles are lurking down there
Edited by stuthemong on Monday 7th September 21:59
It never pinked at all, I think the pin has just been over hardened. They should just be case hardened to allow a little bit of give, these are rock hard all the way through and consequently have shattered like glass!
Don't worry about swarf, the whole thing will be stripped down and washed professionally!
Don't worry about swarf, the whole thing will be stripped down and washed professionally!
itiejim said:
ridds said:
That's not good. Who are AP, I'm either being a little dim as I don't remember hearing of them.
Looks like you'll be needing some new little end bearings too.
Are the pins all free in the rods and pistons?
AP as in the clutch people.Looks like you'll be needing some new little end bearings too.
Are the pins all free in the rods and pistons?
I'll definitely need little end bearings! I'll do all of them and the pins plus I think I'll need a couple of pistons due to the cracked pins scoring them slightly. All the others seem fine.
detonation would be my guess for that kind of damage. The clue will be in the big ends and piston crowns, if they show damage then start thinking about a timing or weak mixture problem, if not then I agree with the faulty pins diagnosis. One other pissble cause it that the little end bore is worn or has been reamed to large and there is slop in the fit to the pin causing hammering.
Jon
Jon
Good old AJP.
I also had what I thought was the rear CV knocking noise, each time I came out of a island. Kept jacking her up and checking them and found nothing, even got my Dad to sit in the car while I went round in circles in a car park. In the end decided that I would leave it until the noise got loud enough to trace it.
It got real loud coming out of an island in Bristol. Shame I live over a 100 miles from there!
That was in July. Just got the heads back on this weekend and will be timing them up (thanks to Clive F for all his help so far) next weekend.
Good luck with yours, hopefully not too much damage.
I also had what I thought was the rear CV knocking noise, each time I came out of a island. Kept jacking her up and checking them and found nothing, even got my Dad to sit in the car while I went round in circles in a car park. In the end decided that I would leave it until the noise got loud enough to trace it.
It got real loud coming out of an island in Bristol. Shame I live over a 100 miles from there!
That was in July. Just got the heads back on this weekend and will be timing them up (thanks to Clive F for all his help so far) next weekend.
Good luck with yours, hopefully not too much damage.
Edited by APB_V8 on Tuesday 8th September 15:17
Piston crowns are perfect, as are the big ends, so I'm going with the manufacturing thing.
I only ever had one noisy bearing - not all 8, so I suspect that the little ends were reamed OK.
I only ever had one noisy bearing - not all 8, so I suspect that the little ends were reamed OK.
fatjon said:
detonation would be my guess for that kind of damage. The clue will be in the big ends and piston crowns, if they show damage then start thinking about a timing or weak mixture problem, if not then I agree with the faulty pins diagnosis. One other pissble cause it that the little end bore is worn or has been reamed to large and there is slop in the fit to the pin causing hammering.
Jon
Jon
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