Engine Knocking
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Junior Member
Joined: Nov 2014
Posts: 10
Re. engine "knock" from lower end. Bad bearings are unusual these days esp. on a low mileage vehicle, but as has been said, you don't know what's happened before you acquired the vehicle. If the age of the vehicle doesn't match the mileage, be suspicious it's been "clocked", and BTW, moderm electronic mileometers can be clocked just like the old mechanical ones. It's just a different method.
The knocking noise could be something else, poss. the clutch or gearbox if you have a manual.
If the knock gets heavier when you put your foot down, bigends are a likely culprit. If it's more of a light rattle, piston/gudgeon pins are likely. Main bearing wear is more of a rumble. A tendancy NOT to knock when the oil is cold and thicker, also points up probable bigends. If the oil pressure us not up to scratch, the bearings will complain. This is a favorite with those engines that have never had their oil changed ever, just topped up. The cruddy overloaded oil blocks up the oil galleries, starving the bearings, esp. the bigends with their impulsive heavy load.
If all seems good with he oil, I would pour a can of that STP "glop" into the engine to thicken the oil, then see if the knock is affected. If it is, you'll defo. know it's the bearings.
Leedsman.
The knocking noise could be something else, poss. the clutch or gearbox if you have a manual.
If the knock gets heavier when you put your foot down, bigends are a likely culprit. If it's more of a light rattle, piston/gudgeon pins are likely. Main bearing wear is more of a rumble. A tendancy NOT to knock when the oil is cold and thicker, also points up probable bigends. If the oil pressure us not up to scratch, the bearings will complain. This is a favorite with those engines that have never had their oil changed ever, just topped up. The cruddy overloaded oil blocks up the oil galleries, starving the bearings, esp. the bigends with their impulsive heavy load.
If all seems good with he oil, I would pour a can of that STP "glop" into the engine to thicken the oil, then see if the knock is affected. If it is, you'll defo. know it's the bearings.
Leedsman.
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Junior Member
Joined: Nov 2014
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Ok got the car up on the ramps and I think the noise coming from the top now.
I took the serpentine belt of and it's any of the ancillaries.
It looks like the rear head has been replaced as it is nice and shiny
I will tKe the rocker covers of and have look tomorrow.
The noise is hardly noticeable at tick over but gets a lot worse as the revs are increased. It doesn't go away if you hold the revs.
As for the mileage, it has one previous owner a engineering company how used it as a limo. The full service history ties up with the MOT mileage's and the lack of wear on the seats peddles and switches.
I took the serpentine belt of and it's any of the ancillaries.
It looks like the rear head has been replaced as it is nice and shiny
I will tKe the rocker covers of and have look tomorrow.
The noise is hardly noticeable at tick over but gets a lot worse as the revs are increased. It doesn't go away if you hold the revs.
As for the mileage, it has one previous owner a engineering company how used it as a limo. The full service history ties up with the MOT mileage's and the lack of wear on the seats peddles and switches.
Senior Member
Joined: Jul 2013
Posts: 885
Sounds good. Could be a lot less expensive than a recon. engine.
Why not take it to the previous engineering company (if practical) and see what they think about the knocking noise? Also, see if you can find it using the old mechanic's long screwdriver trick, used as a listening tool to pin-point the knock. Or a 'tame' mechanic might give you his opinion on the source of the knock. "The noise is hardly noticeable at tick over but gets a lot worse as the revs are increased. It doesn't go away if you hold the revs". It's possible you have a collapsed hydraulic tappet with too much lash if you have top-end noise. This would give a very light but loud "tapping" knock. If it is, you've dropped lucky as these aren't expensive. (Or they shouldn't be).
Leedsman.
Why not take it to the previous engineering company (if practical) and see what they think about the knocking noise? Also, see if you can find it using the old mechanic's long screwdriver trick, used as a listening tool to pin-point the knock. Or a 'tame' mechanic might give you his opinion on the source of the knock. "The noise is hardly noticeable at tick over but gets a lot worse as the revs are increased. It doesn't go away if you hold the revs". It's possible you have a collapsed hydraulic tappet with too much lash if you have top-end noise. This would give a very light but loud "tapping" knock. If it is, you've dropped lucky as these aren't expensive. (Or they shouldn't be).
Leedsman.
Last edited by Leedsman; Nov 24, 2014 at 01:17 PM.
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Junior Member
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Had a tame mechanic look at it and says it's defiantly the bottom end. It sounds like its in the righthand (rear) cylinder head. So just as Leedsman thought.
I will get into it at the weekend and post a update.
I will get into it at the weekend and post a update.
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Ok just to finish this post off.
It turned out to be a knackered crankshaft, the worst journal was knocked out by 0.75mm yes that's right 0.75mm. So it was scrap.
I located a second hand engine with low miles and transplanted it. I have cover over 500 miles and all is well.
In total on buying the car and the replacement engine I have spent £850 so I am a happy chap as I bought the car know there was a problem. I have a couple good cylinder heads if anyone needs one.
Thanks all
It turned out to be a knackered crankshaft, the worst journal was knocked out by 0.75mm yes that's right 0.75mm. So it was scrap.
I located a second hand engine with low miles and transplanted it. I have cover over 500 miles and all is well.
In total on buying the car and the replacement engine I have spent £850 so I am a happy chap as I bought the car know there was a problem. I have a couple good cylinder heads if anyone needs one.
Thanks all
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