Water Pump failure

[alan_thomas]

imported post

I thought I would strip down my failed pump (supplied by a 'tier one' as a 'rebuilt pump' one year ago)

Lets play spot the difference!

Ok no marks for guessing which one has failed but notice.

The failed shaft has no 'splines' to retain the impeller

The failed Shaft has no groove to accept the small rubber 'O' ring

The failed shaft has the gear tooth grooves tapering to a point the good shaft are the same width to the end.

I conducted my own simple hardness test see on the failed shaft a distinct 'cut' in the gear section, this was caused my be running the corner ofa square needle file over the gear for 10 stokes. The good shaft has a shiny patch in the same area it is caused by the same 10 stokes of the file but the file 'skated' across the surface and would not 'bite'. Anyone who has tried to use a file on a hard surface will know what I mean the sound is different and you cannot get 'under the surface'. the file bit into the failed shaft on the first stroke.

I will certainly use this file test on all future components, I am fitting new chains with all new sprockets and I will be testing new against old on all the sprockets. Will let you all know the outcome!

- Alan

PS I should have said the 'good' shaft is a known original pulled from a TR7 engine with 80K on the clock

[NickA]

imported post

As I understood it the original "soft" waterpump shafts were made for Unipart so beware any NOS unipart waterpump you see on eBay. Personally I've bought a couple of used TR7 pumps to keep for spares.

The waterpump/jacksaft gears can fail through lack of lubrication. If the front bearing in the block is worn no amount of harding will help. I'm 99% sure this is what caused my pump/jackshaft gears to fail.
http://home.btconnect.com/nickargue/...-jackshaft.JPG
Just my 10p's worth

[DJT]

imported post

Alan,

That is most revealing. Have you contacted the supplier with this information? I don't mean the person who answers the phone but get hold of the main man. This is simply not acceptable.

Dave

[Sheepdip]

imported post

Alan, that failed pump looks like a cornflakes freebie compared to the proper one - thats disgusting and I think should be taken up with the supplier. At least my failed item looks like the originals.

I mentioned, I'm still not convinced as to where the problem lies, jackshaft, pump, oil supply,my workmanship? Apparently the 12 vane is more susceptible. I've also found a difference in the block casting in the waterpump gear area (I reckon my 2 engines are a Mk1 and Mk2) by accident - you can remove the jackshaft without touching the pump ona Mk2 but not on a Mk1 (can't get rear bearing past pump gear) - did this change when the 12 vanes were fitted and affect performance?

I took all my bits to Tony Harte who has seen a few of these -he kindly gave me free advice and said:

1) After pump failures of a few years ago, all new pumps were hardness tested - the stamping on my shaft vindicated the pump.

2) The front block bearing can wear oval, reducing oil supply to the gears. Tony looked at mine along withthe failed jackshaft and agreed the bearing was fine and not worn (apart from the back 1/4 where it seized).

3) Pump covers can be fitted incorrectly, jamming the impeller. There were no marks on mine.

4) Tony was starting tohear ofa few more failures like mine that couldn't be tied to a particular area. Since it was a new jackshaft,he wondered if this could be at fault.

I did explore getting the shafts further checked out for hardness and gear accuracy, couldn't find anyone local but knew it would cost and the club didn't show any interest so decided to fit used parts and repair block.

[Sheepdip]

imported post

Alan, that failed pump looks like a cornflakes freebie compared to the proper one - thats disgusting and I think should be taken up with the supplier. At least my failed item looks like the originals.

I mentioned, I'm still not convinced as to where the problem lies, jackshaft, pump, oil supply,my workmanship? Apparently the 12 vane is more susceptible. I've also found a difference in the block casting in the waterpump gear area (I reckon my 2 engines are a Mk1 and Mk2) by accident - you can remove the jackshaft without touching the pump ona Mk2 but not on a Mk1 (can't get rear bearing past pump gear) - did this change when the 12 vanes were fitted and affect performance?

I took all my bits to Tony Harte who has seen a few of these -he kindly gave me free advice and said:

1) After pump failures of a few years ago, all new pumps were hardness tested - the stamping on my shaft vindicated the pump.

2) The front block bearing can wear oval, reducing oil supply to the gears. Tony looked at mine along withthe failed jackshaft and agreed the bearing was fine and not worn (apart from the back 1/4 where it seized).

3) Pump covers can be fitted incorrectly, jamming the impeller. There were no marks on mine.

4) Tony was starting tohear ofa few more failures like mine that couldn't be tied to a particular area. Since it was a new jackshaft,he wondered if this could be at fault.

I did explore getting the shafts further checked out for hardness and gear accuracy, couldn't find anyone local but knew it would cost and the club didn't show any interest so decided to fit used parts and repair block.

[DJT]

imported post

Sheepdip wrote:

I've also found a difference in the block casting in the waterpump gear area (I reckon my 2 engines are a Mk1 and Mk2) by accident - you can remove the jackshaft without touching the pump ona Mk2 but not on a Mk1 (can't get rear bearing past pump gear) - did this change when the 12 vanes were fitted and affect performance?

This is something I wasn't aware of. When I had my WP/JS problems last year I was able to pull the JS without problem. That was on a Mk1 block (LD10499). Is your Mk1 block a very early one?

Dave

[mad cyclist]

imported post

stustag wrote:

Sheepdip wrote:

Interesting comments guys. I was really hoping Alan had a link here. Can't comment on the shaft hardness (I put the colour down to the use, the one on the left did 1700 miles, right 70k and I hope many more to come......).

I've bored the pants of many people hawking my bits around, I'm not looking for revenge, I just want to know what happened to make sure it doesn't happen again. One supplier thought the jackshaft teeth angle was incorrect, another said the hardness stamp (the numbers on the LH shaft) proved it had been tested and conformed - I hada certificate somewhere.

Re SOCTFL - I had a chat with Mike Allem and Kingpin on this a few months ago, suggesting the club should be interested asthere seemed to be quite a fewfailures costing us a lot of money.There wasn't any interest.......the only suggestion was to use proven parts.

Sheepdip if that stamp was to prove it had been hardness tested their having a laugh as you wouldn't be able to stamp it if it had been hardened!!!:shock:

Stuart

could they have stamped it and then hardened it?

[Kevin Garrod]

imported post

mad cyclist wrote:

could they have stamped it and then hardened it?

Or stamped it and forgotten to harden it:?

[alan_thomas]

imported post

DJT wrote:

Sheepdip wrote:

I've also found a difference in the block casting in the waterpump gear area (I reckon my 2 engines are a Mk1 and Mk2) by accident - you can remove the jackshaft without touching the pump ona Mk2 but not on a Mk1 (can't get rear bearing past pump gear) - did this change when the 12 vanes were fitted and affect performance?

This is something I wasn't aware of. When I had my WP/JS problems last year I was able to pull the JS without problem. That was on a Mk1 block (LD10499). Is your Mk1 block a very early one?

Dave

Came across this, it explains why you cannot pull the jackshaft out without removing the waterpump on early mk1, This 'early' jackshaft has a 'collar' on the shaft of a larger dia than the pump drive gear behind the gear making it impossible to pull out without 1st removing the pump.

[DJT]

imported post

alan_thomas wrote:

DJT wrote:

Sheepdip wrote:

I've also found a difference in the block casting in the waterpump gear area (I reckon my 2 engines are a Mk1 and Mk2) by accident - you can remove the jackshaft without touching the pump ona Mk2 but not on a Mk1 (can't get rear bearing past pump gear) - did this change when the 12 vanes were fitted and affect performance?

This is something I wasn't aware of. When I had my WP/JS problems last year I was able to pull the JS without problem. That was on a Mk1 block (LD10499). Is your Mk1 block a very early one?

Dave

Came across this, it explains why you cannot pull the jackshaft out without removing the waterpump on early mk1, This 'early' jackshaft has a 'collar' on the shaft of a larger dia than the pump drive gear behind the gear making it impossible to pull out without 1st removing the pump.

Sorry. Just re-read you note. I misunderstood and thought it referred to not getting the jackshaft out without removing the OIL pump, not water pump. I guess I jumped to the conclusion that the water pump would be out anyway.

Memo to self - always double-read a posting before hitting keyboard :X

Dave

[Sheepdip]

imported post

DJT wrote:

alan_thomas wrote:

DJT wrote:

Sheepdip wrote:

I've also found a difference in the block casting in the waterpump gear area (I reckon my 2 engines are a Mk1 and Mk2) by accident - you can remove the jackshaft without touching the pump ona Mk2 but not on a Mk1 (can't get rear bearing past pump gear) - did this change when the 12 vanes were fitted and affect performance?

This is something I wasn't aware of. When I had my WP/JS problems last year I was able to pull the JS without problem. That was on a Mk1 block (LD10499). Is your Mk1 block a very early one?

Dave

Came across this, it explains why you cannot pull the jackshaft out without removing the waterpump on early mk1, This 'early' jackshaft has a 'collar' on the shaft of a larger dia than the pump drive gear behind the gear making it impossible to pull out without 1st removing the pump.

Sorry. Just re-read you note. I misunderstood and thought it referred to not getting the jackshaft out without removing the OIL pump, not water pump. I guess I jumped to the conclusion that the water pump would be out anyway.

Memo to self - always double-read a posting before hitting keyboard :X

Dave

My fault, I wasn't clear on which pump I was referring to.

I have seen these jackshafts with the collar next to disi drive which I reckon must be a very early type but neither (or should I say none :X) of mine have it, its the disi drive gear which fouled the water pump gear on removal.

I haven't looked at the casting numbers on my block so am making assumptions. I'm 100% sure my very late Mk2 engine is pukka as I have all the paperwork, the other mk2 had another engine at some point so I'm assuming it was a Mk1 to account for the differences. [nb found out the "Mk1" had dropped its crank thrust washers at some point and the block had an insert fitted].

I only found out when replacing the Mk1 jackshaft. I tried it out on the benched Mk2 block first, with water pump in place I could remove jackshaft without problem. tried it out on other engine in car and couldn't get disi drive gear past water pump so had to remove.

Putting fingers inside the water pump casing I could feel a difference between the two, its not down to casting tolerance.

Re pump hardness, I assumed the pumps were all checked for hardness and then stamped (not stamped and then hardened). The stamping is on the flat at bottom of pump, so could this be subjected to a different hardness criteria than the gear? [its many years since I studied mech eng].

I might try Alans file test on gears and shaft.