Thread: 300tdi water pump gone again - HELP!

Hi Dom

I hope that I don't put my foot in it again after that posting in another thread, when I didn't read the OP properly and proceeded to explain to everyone how to check for poor earthing on a mechanical temperature gauge.

Let's assume that the water pump's were good one's that you had installed and there is something else acting on them to cause those failures.

The first thing to ask is after fitting them, was the serpentine belt noisy, was the belt the correct length and is the idler tension correct in it's working position?

Then the external conditions that can cause premature failure are;

1. heat-------------------not likely, unless the coolant wasn't purged properly of air
2. excessive speed--------again not likely, unless the brakes failed going down a steep hill
3. static belt tension------if the idler is working in the correct position, the static load should be correct
4. dynamic belt tension -- ok if all the bearing are running free. However the belt load would soon increase if another bearing in the belt train is seizing as it warms up
5. alignment ------------- use a straight edge against the bottom harmonic balancer, and using a pair of dividers or Vernier calipers, measure between the straight edge and the first ridge in the pulleys multivee's, check all of the multivee pulley's to confirm that that distance is the same and for the flat pulley's use feeler gauges between the face of the driven flat pulley's and the straight edge.
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Hi Arthur

Firstly, thanks for your help, i appreciate it.

Yeah i have have a '97 TDi 300 so it has a small alternator pulley & the 1580 belt. I tried the long belt but the markers on the tensioner were aligned when it was fitted indicating that it was too long.

I fitted a new belt & tensioner, both Dayco. The belt chirped a little at idle but i figure a bit loose is better than a bit tight.

1. Heat... i filled as per the manual so i should be ok there
2. Speed.... hahhahhaha
3. Static tension... new Dayco tensioner
4. Dynamic tension... I have changed the tensioner, the alternator bearings & the PAS pump. The PAS pump though was changed 10000ks ago when i bough the car cause it was running out & tearing up the serpentine belts. It is starting to move in & out as you rev the engine though....
5. Alignment... Hormonic balancer?.. sorry, is that the bottom / crank pulley? or is that the pulley closest to the air con? sorry at the edge of my knowledge here.

I shall measure all the distances in the morning although the belt definately runs at the back of the PAS pump pulley...possible cause or another symptom of the same problem?

I will take her for a good run then whip that belt off & wiggle the pulleys.

Thanks for your time.

Dom

Originally Posted by Bushrunner

[snip]

i am going for a drink!

cheers

dom

Hope you had a couple Dom !

I'm snookered and I feel your pain as I have ongoing P gasket problems, but at least my P gasket isn't a game stopper, it just weeps when the engine is cold.

Originally Posted by Bushrunner

......................................... I had the head gasket changed & head overhauled the week before the first pump failed. I cant see how but is there anything in that procedure that could have gone wrong causing this problem?

.........................................replacing the alternator bearings opened a whole other can of worms

........................................The belt chirped a little at idle but i figure a bit loose is better than a bit tight

dom

Hi Dom, Unless you've got the market cornered on crook waterpumps the problem appears to be excessive or uneven tension on the waterpump pulley. You've had the thing in bits so often now you're unlikely to have missed anything obvious.

I've plucked the above comments out of your posts looking for a common thread, sort of grasping at straws so to speak.

Is it possible that the crook alternator bearings was a cause of uneven tension on the waterpump (as well as a crook tensioner on the other side) ? Was it refitted correctly after the rebuild ?

When re-assembling/re-fitting the alternator did it all go back exactly as it was re-assembled/removed. Is the drive pully in exactly the same position on the shaft as it was before dis-assembly ? A mm or so out here may be enough to skew the drive belt on the adjacent water pump.

Why was (is) the belt chirping with all new bits ? Perhaps a few discretely applied drops of water on to each pulley in turn will identify the culprit ?

I'm not picking on you or your processes here Dom , just trying to add it all together.

Did you replace the tensioner bolt ? If its bent or worn it would skew your brand new tensioner.

That's about all I can come up with.

Deano

Can we get a collective measurement of the face of the water pump hub to a decent straight edge held against the face of the harmonic balancer*?

There are tolerances in manufacturing those water pumps and the setting of the face of the hub in respect to the pumps mounting face. That tolerance, combined with age distortions in the aluminium bracket-coolant pump support and the varying thicknesses of the P gasket, can place the pump pulley out of line enough to cause the belt to run off and try to climb the side of the multivee's.

If the belt is squealing or squeaking, watch the idler to see if it is bouncing, as if it is even slightly, that is conformation that the belt is running off due to misalignment.

There is another variation that can occur and that is the position of the crankshaft protrusion. The crankshaft thrust washers are responsible for limiting any end float, locating the the crankshaft in a fixed position fore and aft.
Apart from rebuilding the bottom end each time, it is best to measure from the face of that pulley called a harmonic balancer.
To smooth out vibrations that pulley is constructed with three sections; the inner hub that is held onto the crank, the outer pulley that has the multivee's for the belt and a rubber ring that absorbs the vibration and locks the other two components together.
There again, there are tolerances in the build of the harmonic balancer, which could allow the hub to be forward or back slightly in respect to the multivee position.

* I was taught a few years ago that the pulley was a harmonic balancer, but according to the Land Rover parts manual it is called a Torsional vibration damper - engine crankshaft.
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A excellent description and diagrams of shaft and pulley alignment.


click on this link. The Importance of Shaft Alignment - Flow Control




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[QUOTE=DeanoH;1765679]
market cornered on crook waterpumps...

Was it refitted correctly after the rebuild ?...

re-assembling/re-fitting the alternator did it all go back....

Why was (is) the belt chirping with all new bits ? Perhaps a few discretely applied drops of water on to each pulley in turn will identify the culprit ?

Did you replace the tensioner bolt ? If its bent or worn it would skew your brand new tensioner.....

Hi Deano

yeah i definitely cornered some sort of market... I am fairly confident i got it all back right but will check, obviously something is off.

I shall have a go at the water drop technique & see what that shows up. I havnt really considered the odd chirp under the bonnet to be a problem.

I didnt change the tensioner bolt, but didnt show any sign of wear. I will check it for square though, with the tensioner off it does stick out waiting to be bashed off square.

As for picking at my technique... fire away. Any and all points of view & help are appreciated. If i did things right i wouldnt be in this pickle

Cheers

dom

Originally Posted by wrinklearthur

........................................To smooth out vibrations that pulley is constructed with three sections; the inner hub that is held onto the crank, the outer pulley that has the multivee's for the belt and a rubber ring that absorbs the vibration and locks the other two components together....................................

Hi Arthur, on my 1995 Tdi 300 the harmonic ballancer/crankshaft pulley is just one solid lump of steel.

Deano