Cracked Water pump housing

[Defender_300Tdi]

Hi All,

As the title suggests, my water pump housing on my 300Tdi has cracked, or rather appears to have cracked. So I went out and bought a genuine parts water pump and gasket and changed it out, note: I also changed the P-Gasket at the same time as this gets disturbed when changing the water pump.

So re-filled with coolant, ran up to temperature and low and behold the new pump starts leaking in exactly the same place. So I did some more research and found that the aluminum casting that the water pump sits in can warp, well fine I thought, so I went a bought a new casting (part number ERR3637), another new water pump, new gasket and another P-Gasket.

I changed the whole lot today, re-filled with coolant and run up to temperature. The new pump has cracked as well, in exactly the same place! I am at a lose end to explain why this has happened to all three pumps. All the bolts were torqued to 25NM as per the manual. The orginal pump had done in the region of 10,000Km before the crack appear, but the following two didnt even make 1km. The engine was a reconditioned unit from Turner Engineering in the UK.

This was the original first crack:



You can just see the hairline crack to the right of the bolt head:



Aluminum Casting removed (first attempt at repair):



Not very relevant, but shows the new casting all fitted up:



So any ideas what is going on with my engine? Could the acutal block be warped? It's not loosing any water, the cooling system doesn't appear to be pressured and there is no water in the oil.

Cheers

Rob

[Big.Mike]

First off, what a clean engine. It's a credit to you.

1. Did you get all new bolts, those ones are quite long and could be bent, applying a twisting motion when it heats up.

2. Is your torque wrench okay? They can go out of calibration.

3. Have you tried an after-market pump? iirc there was a rib on that bolt hole.

Cheers,

Mike

[Rangy35]

Your photos don't show or tell much.......but it seems there is a high spot forcing the pump to crack.

[Defender_300Tdi]

None of the bolts were bent and they are the newer coated type. All mating faces were checked to see if they were true and all were flat on a straight edge.

The fracture is happening on the same "web" on each water pump (I have now been through three genuine pumps including the original). All bolts were torqued up to 10Nm first, opposite side/alternating, then going round them again up to 25Nm as per the manual.

I have owned 300Tdi's for 10 years plus and I have never seen this type of failure before.

A friend who is a NDT Technician carried out some dye penetrant testing on the pumps and this has confirmed that they have all fractured in the same location. I am at a loss as to why the first one lasted 10,000km and the second and third didn't even make 1km.

Your photos don't show or tell much.......but it seems there is a high spot forcing the pump to crack.

Apologies that my pictures didn't show or tell that much, please see pictures below of None Destructive Testing results, the red line is the crack, I think its pretty clear:

Both the pumps with red marker dye sprayed on, the original pump is the lower one in the picture.

Rear of the pump with the fracture in red (original pump):

Front of the original pump:

Front of the 2nd pump clearly showing the fracture:

Rear the of the original pump, alternator and PAS pump housing (Part no. ERR3736) where it bolts up to the block, no signs of fractures:

Note that the third pump was still on the vehicle at the time of testing, but it has definitely fractured in the same location.

Having had a chat with a friend, we are thinking that the gasket maybe too thick and as the pump is tightened up this is causing it to distort, why this is the case I do not know, because as I have said all the faces as flat. I am going to try one more new pump with just RTV silicon as the gasket. If that fails I am completely out of ideas.

Cheers

Rob

[Big.Mike]

Hi Rob,

The rib is a terrible design, it needs a large radius to the top to stop this sort of fracture... what I'm saying is that this might be nothing to do with you, it might be the part design.

It may even be a flaw in the casing process. The part appears to be sand blasted, which is never a good sign for an aluminium casting of this size.

Honestly, I'd try another OEM supplier.

Why did your first one last 10k, easy, you probably didn't notice it. Now you have, you're looking for it.

I could swear I've seen the castings with a rib around the edge too...

Cheers,

Mike

[Defender_300Tdi]

Hi Rob,

The rib is a terrible design, it needs a large radius to the top to stop this sort of fracture... what I'm saying is that this might be nothing to do with you, it might be the part design.

It may even be a flaw in the casing process. The part appears to be sand blasted, which is never a good sign for an aluminium casting of this size.

Honestly, I'd try another OEM supplier.

Why did your first one last 10k, easy, you probably didn't notice it. Now you have, you're looking for it.

I could swear I've seen the castings with a rib around the edge too...

Cheers,

Mike

Mike,

Thanks for the replies so far. Its all very odd! I like to do things properly and this is extremely annoying.

I have a picture of another waterpump, I believe this to be supplied by Britpart.

http://s795.photobucket.com/user/rcsprason/media/STC1086-300TDI-WATER-PUMP_zpsa25dc575.jpg.html'>

Worth the risk?

Regards

Rob

[CwazyWabbit]

That's interesting what you say Mike,this picture of a genuine pump apears to have a more rounded web http://img98.imageshack.us/img98/8498/lr6eh4.jpg

[CwazyWabbit]

Hi Rob,

Was just having a look at a few pictures of 300tdi water pumps and I notice the design you have been using is the same as the ones supplied by Turner Engineering (who supplied the engine to you). It might be worth giving them a call and asking if they have experienced similar problems at all?

[Defender_300Tdi]

Hi Rob,

Was just having a look at a few pictures of 300tdi water pumps and I notice the design you have been using is the same as the ones supplied by Turner Engineering (who supplied the engine to you). It might be worth giving them a call and asking if they have experienced similar problems at all?

They also supplied the first water pump as well....I will give them a ring later on today and post up the results.

Interestingly enough, the vehicle and I are now located in Australia and my dealer over here has been supplying exactly the same pump. They are definitely genuine and come out of genuine parts box all sealed up.

Regards

Rob

[Big.Mike]

Notice the little circular lumps on the "non-LR" parts, they are ejector/feed points from a tool... the surface finish is glossy too, not sandy. The "LR part" doesn't have them which suggests they are cheap sand castings, not to go into the ins and outs of cast design, these are normally below standard.

The best casting I have seen is the QH brand, which I believe is an OEM part. The ones I have handled have a properly machined inside face, the rib is also flush with the top of the boss...

Personally, I'd try one of these. you'll soon find out if it works or not.

You can then send the rest of them back to LR for a full refund.

Oh and as a tip... you can use cochenille red food dye to find cracks too, my materials lecturer used to swear by it...

Cheers,

Mike

[pat_pending]

They are definitely genuine and come out of genuine parts box all sealed up.

Regards

Rob

The Chinese make some very good copies of original packageing.

The casting in photo of the second pump looks like and old casting that's been sand blasted.

I'd be tempted to say it's an "overhauled" pump, but then why did the original pump fail?

Difficult without seeing the engine in the flesh.

I'd bolt it all back together dry, no gaskets, with some engineers blue on one face of everything. Then strip it back down and see what sort of contact it's all making.