Water pump Subassembly didn't work out too well

[freshcut]

As mentioned from a previous "hijacked" post.

Well, I got the pump pulled on Saturday, and down to the machine shop on Monday. Talking with the tech for a bit, we determined that the impeller would certainly need heating to come out without damage, however the hub likely could be pressed "cold". Unfortunately that didn't work out too well for the hub as the shop called a said that the hub was pulling nicely but suddenly snapped during the process (dollar signs went flashing through my head at this point). I contacted the guy I got my subassembly from and have been told he does have a replacement hub as they had a few from a run they did for Lotus a few years back. So at this point I'm just going to bite the bullet, order the hub and ship the whole lot over to JAE for a rebuilt unit without attempting to do anything with the impeller. Lesson learned I suppose!

[Günter]

sound like the mentioned problems in the 'highjacket' post ...does it ?!

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Having been in contact with this guy yet more, it seems that they were the original suppliers for the OEM pump. I've got the hub coming to me, which he said was actually "stolen" from a Perkins diesel. He didn't tell me where the impeller was stolen, but he did say that the pump body is specifically Lotus and that when they (Lotus) contacted his company to produce the 918 pump, they requested it be made "as cheap as possible", so only the body was specific to the car and everything else was acquired from other pumps they were building at the time. Unfortunately most of the pumps that the parts were stolen from are no longer current, so they don't have parts laying on the shelves to produce new pumps, only the subassembly which was done from a run that Lotus needed a few years back. They are getting into contact with the manufacturer of the impeller to see about having a batch made up, but said that would be a few weeks, and likely at that time will have a supply of ready to go, OEM pumps (well, OEM as from the actual manufacturer).

On a side note, I finally got ahold of the pump and saw the damage first hand. It certainly appears that all was going well as the hub is about half removed, but it busted about 1/3 of the fixing surface where the pulley bolts on. The tech explained that he was gently applying hydraulic pressure at a slow rate with the hub moving smoothly off the shaft when it snapped into three pieces, the one large main piece still attached and two smaller pieces. However, regardless of how it snapped, it happened. But I guess throughout all of this, I've at least learned a) it's best to buy a complete unit when possible, and b) I got a little background information as to the source of the pump, and some of the parts used for anyone interested.

[Iconic Ride]

Fascinating stuff, Blake. If I go ahead and have my pump replaced when the cam belts are done (see "hijacked" thread mentioned above), I have to assume that the Lotus dealer here has a complete OEM unit on hand, and that it was assembled by someone (God knows when) who knew what they were doing, what with the mishmash of eclectic parts involved as referenced in your post. Makes one wonder just how many OEM pumps still exist in the Lotus inventory world wide.

Just how difficult is it to get at the pump if doing an R&R without doing the cam belts? In other words, if I decide not to replace the pump at the same time as the belts, is it a big deal (labor wise) to do the pump alone later, as necessary?

[Günter]

would gues the pulley-hub is a 'cast' part ?! ..as it broke into pieces, instead of bend somewhere.. . Anyway, just take measurements of your pulley and the pump-shaft and make your own hub in a machine shop. Think you do not need to have a cast, and more simple 'one piece production' on a lathe should do the job as well.. @John, -that's why I say dont change anything that works ! As you never know what you get ..or what will go wrong

[freshcut]

Better yet Gunter, call the guy who built them originally for Lotus, and have him send me a new hub for 5GBP plus postage.

As for how many OEM pumps remain, I'd imagine a few. Roger (the guy I've been corresponding with) is the guy that Lotus came to when they needed a pump designed for the 918 engine. In fact, he claims to maintain a working relationship with Lotus and still designs pumps for engines that Lotus Engineering designs for other manufacturers. He said that Lotus had contacted him about 3 years back to produce a run of additional "OEM" pumps and at this point he's selling only the subassembly, however he recently found a stock of hubs that had been hiding in his shop of which one has my name on. On a side note, he also offers to transfer your old parts to the new subassembly for a nominal fee if you send him your old pump. I suspected at the time I should have done so, but got anxious and didn't want to post my pump to England figuring that there would be competitent shops who could take the proper precautions and transfer the parts locally.

The pump is actually somewhat easy to remove and replace if you aren't a big guy. Reading thought the manual, it didn't really make much mention of the timing belt cover, but for simplicity I loosened and pulled it forward toward the passenger compartment. It's a tight fit and will require the removal of the EVAP solenoid (I'm guessing thats what it was)and for additional room I'd suggest disconnecting the radiator hoses at the thermostat housing. It might be a good idea to replace the thermostat housing o-rings and thermostat while you're in there. I'd say that start to removal of the pump only took about 30-45 minutes at most, and that included removing the front left wheel to gain access to the lower radiator hose and drain the coolant. On a 1-10 scale, I'd say a 2, but only because of the tight clearances to gain access. I'd imagine replacement will be just as easy.

Gunter; yes, the hub is cast. it busted a chunk of about 1/3 off into a total of 3 pieces including the main section still attached to the shaft.

[wookiecj]

Blake, I don't want to prolong your agony on this one but if you have any pictures it would be interesting to see them.

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Not worried about the agony. These things happen. Working in a technical field I'm more than familiar with how something that should be textbook easy turns out to be more than one expects. Fortunately it's fixable. They say hindsight is 20/20, but in this case I'm actually glad it worked out in this way. I've had the opportunity to speak with some very interesting people who have given me, and in exchange by my posts on here, the rest of us some information about the design of one of our parts and the origins of them, mainly the pump hub. Perhaps I'll see if Roger can let me know where the impeller was sourced which will give us a complete picture since we know the subassembly is Lotus 918 specific.

As for the pictures, I'll edit this post in a few minutes with pictures as soon as I get the camera. Unfortunately I don't have the pieces of the hub that were broken off of the main piece still attached as they're likely on the floor of the shop that was unsuccessful.

pictures as requested showing both the damaged hub, and complete impeller.

As you can see, the hub did begin to come free just prior to breakage. Unfortunately it would appear that even the hub must be heated to increase the chances of successful removal.

[wookiecj]

Oops, double ouch! Thanks.

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I will say though that I'm not torn over the whole incident. As I said, I've had the opportunity to chat with interesting people which wouldn't have happened if I'd gone down the route of just ordering a pump and being done with it. True, I'll probably spend a bit more money going this route, but sometimes a lesson in trial and error is a little bit more expensive. Fortunately it's only to the tune of less than $100US rather than thousands.

[Günter]

..as you talk about water pump component conception & design

I know the responsible 'chief of facility' on the *Mercedes auxiliary components production* plant in Berlin-Marienfelde. As he does a course in the university -on which I'm still listed as student. So if it comes on problems with water-pumps and 'variable cam'-actuators and things like these, I know who is to ask.

But from the point of hub rebuild with a part *for 5 bucks* [will you really get the new hub for free ?!] -on your position I still would prefer just to fabricate a hub in DIY on the lathe, as it's such an simple design after all.. .

Or other thought: if an optimising project is in mind for the whole auxiliary-drive. Why not convert to an electric water-pump and new belt drive -wouldn't that be possible for you ?

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I did think briefly about going with an electric WP setup, however, as I've said on here in the past, I prefer to keep things as close to stock as possible when possible. In my experience with electric pumps, mainly fuel, a failure will almost always suddenly occur in which results in zero pressure or flow. From a coolant standpoint, I can't see that as being a good thing at all. In the case of a drive belt driven pump, you'll generally notice the failure coming on either in the form of coolant loss, or the tell-tale sounds of a bearing going. Thats not to say that others haven't had excellent results in using an electric pump, but my experience has resulted in a dislike for electric pumps when a mechanical one is available and works. As for turning a new hub on a lathe, if I had the lathe I might think about going down that route, but since I don't, I didn't and I highly doubt I could get a shop to make one for me for the $12US that the new hub ended up costing including shipping.

[mike_sekinger]

This advert appeared recently on Ebay - it is the same folk?

GB Autopumps on Ebay

Would be a cheap replacement if a safe and reliable method of swapping the necessary parts across could be established.

Cheers,

Mike S

[Simon350S]

Cut through the shaft top and bottom the. You can use the fullface of the flange to press against rather than pull using the edges only.

I'd happilly tackle it.

Bit of heat may help also.

Think the failure stems from using pullers on the outer edges which should be a complete no no I'd say.

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That would be the outfit. He does offer the service to swap your old hub and impeller for something like 25GBP (quite a bargain after what I've gone through at this point). My main reason for not going that route was that I had concluded that I should be able to have it done locally and avoid having to ship from the west coast of the US, to England JUST to have some parts swapped from my old pump to the new one. Oh well, live and learn. On a side note, that particular seller has been VERY helpful, and has even posted a replacement hub which I expect to receive later this week. Incidentally, the seller is selling genuine OEM parts since many manufacturers actually contact their company to prototype and mass produce pumps. On a side note, this particular company not only produced the WP for the 918, but also the pulley for the power steering pump.

Simon, I thought about doing that as well AFTER the hub broke. As for using a puller, I don't believe thats what the shop did as he specifically mentioned using a hydraulic press. My guess is that he probably didn't have the press lined up fully center on the shaft which would have put additonal stress on one side. The shop tech did say that he was going slow, using gentle yet smooth strokes, the hub was pulling free with little fuss, when it just snapped. Now I wasn't there to confirm, so can't comment on the validity of the claim, so have to go by what information was presented to me.Hopefully, once I get the hub, I'll have the WP replaced and refilled with coolant by next weekend.

[lotus4s]

FWIW,

There is a very concise procedure written by Tim Engel for rebuilding the 4 cyl. water pump and the same principles apply here. If anyone is interested I would be glad to email it.

To remove the hub you need to use heat and a heavy duty bearing splitter in the press in order to hold the hub as closely as possible to the center without putting pressure on the outside edges.

[Simon350S]

Always keen for more info, feel free to send it across thankyou

If your rebuilding, a bearing splitter would help a lot.

In this case cutting the shaft and moving the press plates closer would have stopped this from happening. More thinking needed by press operator me thinks, schoolboy error!

Edited May 16, 2010 by Simon350S

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Perhaps we should start a thread of what not to do. Fortunately as I said before, it's not the end of the world and will be fairly inexpensive to fix this little hiccup. Just glad I had other avenues to explore and wasn't dealing with something that is rare and unique in which one would want my first born to repair.