big end noise?

ormondstreet · May 22, 2008

can anyone describe the sound made when the big end bearings are going? I'v had a noise appeare lately, a load knocking, low down on the engine, but only when engine revs are high, not on tick-over.
If it is big ends, can they be replaced with the engine in situ?

pos · May 22, 2008

Hi Ormondstreet,

First of all (to help us diagnose your problem), which engine do you have? How old is it? How many miles has it done and how often has it had oil changes etc?

If it does boil down to your big end bearings you will have to strip down your engine in order to change them, which is annoying considering that you can get to them by simply draining all your oil and removing the sump, but you need to knock the pistons upwards (which will be stopped by the head) in order for the con rod to clear the crank shaft so that you can change the bearings. Unfortunately I don't know what kind of sound they would make, but I can imagine it being like a washing machine drum out of balance with a heavy load.

The fixing process involves:
1) Removal of rocker cover (usually three bolts / nuts)
2) Removal of rocker assembly (eight bolts)
3) Injectors out
4) Wiring (glow plugs) removed
5) Headbolts out
6) Head off
7) Sump off

And then you can undo the big end caps and knock the pistons up and out of the top of the block so that you can get to the bearings. Ofcourse, at this stage you would be stupid not to replace your piston rings and deglaze the cylinders. It's not that big a job: deglazing tool is about £15 and fits in your drill, piston rings are about £6 per set of three, and your engine will be like new again. You'll need the best part of a three day weekend to get it all in though (unless you're experienced, and you'd probably get it done in a day with all the right tools etc.)

Obviously I can't provide you with any more specific information until I know what engine you have, but it might be something much much simpler that involves next to nothing to fix!

-Pos

ormondstreet · May 22, 2008

it's a 200 TDi 1991 102,000 miles and according to the previous owner has had it's oil changed every 6 months. I have owned it for 10 months and it has had it's oil changed twice since.( it has covered only 2 thousand miles in my owership)

david451 · May 22, 2008

pos said:
Hi Ormondstreet,

First of all (to help us diagnose your problem), which engine do you have? How old is it? How many miles has it done and how often has it had oil changes etc?

If it does boil down to your big end bearings you will have to strip down your engine in order to change them, which is annoying considering that you can get to them by simply draining all your oil and removing the sump, but you need to knock the pistons upwards (which will be stopped by the head) in order for the con rod to clear the crank shaft so that you can change the bearings. Unfortunately I don't know what kind of sound they would make, but I can imagine it being like a washing machine drum out of balance with a heavy load.

The fixing process involves:
1) Removal of rocker cover (usually three bolts / nuts)
2) Removal of rocker assembly (eight bolts)
3) Injectors out
4) Wiring (glow plugs) removed
5) Headbolts out
6) Head off
7) Sump off

And then you can undo the big end caps and knock the pistons up and out of the top of the block so that you can get to the bearings. Ofcourse, at this stage you would be stupid not to replace your piston rings and deglaze the cylinders. It's not that big a job: deglazing tool is about £15 and fits in your drill, piston rings are about £6 per set of three, and your engine will be like new again. You'll need the best part of a three day weekend to get it all in though (unless you're experienced, and you'd probably get it done in a day with all the right tools etc.)

Obviously I can't provide you with any more specific information until I know what engine you have, but it might be something much much simpler that involves next to nothing to fix!

-Pos

Pos yer a fud, the big ends are changed without the head off all yer do is turn the crank away from the con rod leaving it at the top of the stroke.

pos · May 22, 2008

david451 said:
Pos yer a fud, the big ends are changed without the head off all yer do is turn the crank away from the con rod leaving it at the top of the stroke.

Now that's what I'm talking about! An easy fix with nearly nothing to worry about! I am stupid!

pos · May 22, 2008

Suppose what you can do then is get the front end up on ramps, drain the oil and then take the sump off. Undo the big end cap on the con rod that you want to examine and then turn the crank shaft over so that in theory, the crank shaft is as low as it can possibly be at that point, and you can then push the piston back up into the cylinder if it decided to keep hold of the crankshaft.

The bearing shells may decide to stick to the crank shaft, the big end cap or the con rod, but will come out with a little careful leverage (ie. picking at it with your fingers). They go in a certain way, but its pretty obvious from the little notches in the big end cap and con rod, so just make sure that they line up and you'll be fine. You should also make sure that the same big end cap goes back on the conrod that it came off.

david451 · May 22, 2008

pos said:
Now that's what I'm talking about! An easy fix with nearly nothing to worry about! I am stupid!

No never say yer stupid, yer learnin wee man, just keep wurkin at it.

pos · May 23, 2008

yes but that was a daft mistake I must admit. I actually took advantage of that clearance myself when putting my engine back together, because I forgot to oil the bearings before I put them into place. What could have seemed like a 3 day job which might have had him pay to have the job done is actually just a few hours job which he can do with relative ease and save himself a fortune.

david451 · May 23, 2008

pos said:
Suppose what you can do then is get the front end up on ramps, drain the oil and then take the sump off. Undo the big end cap on the con rod that you want to examine and then turn the crank shaft over so that in theory, the crank shaft is as low as it can possibly be at that point, and you can then push the piston back up into the cylinder if it decided to keep hold of the crankshaft.

The bearing shells may decide to stick to the crank shaft, the big end cap or the con rod, but will come out with a little careful leverage (ie. picking at it with your fingers). They go in a certain way, but its pretty obvious from the little notches in the big end cap and con rod, so just make sure that they line up and you'll be fine. You should also make sure that the same big end cap goes back on the conrod that it came off.

Yep bang on , just make sure you dunt get the oil holes in the shells in the wrong place. Mark all the caps wif a notch or a centre dab before yer take them orf.

On fitting make sure the cap and rod are clean of any oil then fit the shells, then lub the shells and refit. Each time yer do one make sure yer can turn the engun free, it's not uncommon to lock up the engun if the shell aint right.

But do an oil pressure check furst coz low oil pressure might have fooked them in furst place

big end noise?

ormondstreet

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ormondstreet

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