Ian, Thanks ... now that is interesting. I was only thinking about the power loss aspect, I hadn't thought about the fuel efficiency part of it. OK, this is getting serious. I think I now have a waterpump with a sheared impeller, which is precisely what I need to undertake this project. (Yes, I know I need to dismantle it to remove the sheared impeller, which I am half-way towards doing already.) Other parts needed to complete: a thermostatic control system (not hard to conjure up), a power supply (again, easy to find under the bonnet) and a suitable pump. What sort of flow rate would the pump need? Oli.
Overheating
- Thread starter zcacogp
- Start date
There is no such thing as a genuine Porsche pump, Porsche build cars not components, all you are paying for is a £300 cardboard box, the vast majority of porsche pumps were by Laso, if you compare your OEM pump with the new one, they will be identical even down to the cast in part number. I have one in my S2 and just fitted one to Stuart (scam75s) turbo. Very good and go straight on. Oli, I get them from ECP for about £160 plus the VAT, the price has strangley came down on them in the last wee while for some reason Alasdair
peanut
Active member
sorry to hear your bad news Oli. I read the first post and immediately thought your WP impellor had slipped on the impellor shaft which is apparently quite common. Haven't read all the rest of the posts but I was wondering why it isn't possible to refurbish our own waterpumps. It can't be that hard surely ? Mmmm just read your post about a remote electrical water pump ...... brilliant idea. ...keep us informed .. i hope you're up to snuff on the mathematics lol
peanut
Active member
[link=http://www.torquecars.com/tuning/electric-water-pumps.php]http://www.torquecars.com/tuning/electric-water-pumps.php[/link] interesting article on electric water pumps. Think I might go for this option when I change my belts. heres all the maths and physics stuff wow...[8|] [link=http://www.youtube.com/watch?v=nrfux_-6RVw]http://www.youtube.com/watch?v=nrfux_-6RVw[/link]
Peanut, Thanks. There is actually quite a lot of discussion about electric waterpumps around, but I have decided that I'm simply going to go with a replacement standard one. While I think there is gain to be made from an electric one, there is also risk; risk of failure and risk while experimenting to get it working as it should. And, as I have only one car (the sciroc isn't mine - it's borrowed from a friend while my S2 is off the road) then I don't really want to be driving around in a mobile experiment. I will however keep the idea of an electric water pump on a back-burner for later consideration. (Here's a ready-made solution, complete with controller. You'd just have to work out where to put the pump and how to do the plumbing: http://www.mawsolutions.com/html/ewp80.html ) I now have the old pump off. It's precisely as you say Nick - the impeller is loose on the shaft. Plastic impeller, knurled shaft, not sure how they were meant to be attached but the attachment is now history. Refurbishment of it would be pretty easy if you could identify a suitable adhesive to stick the two together with again. The snag is that removing the pump is quite a large job, and therefore if your re-stick of the impeller failed it would be a nuisance to tear it down again to re-stick it. I'll keep this thread updated. Oh, one last question. Should I just use the gasket which (I am told) is supplied with the waterpump when bolting it on, or should I try and get hold of some Hylomar Blue (or similar) as well? (If so, do Halfords sell it?) Oli.
peanut
Active member
if you have already bought the pump you have little option Oli as you say. Besides its always more reassuring to have someone else try something new out first lol[
] I cannot believe that these pumps have the impellor 'glued' on . Beggars belief really. I'd feel far happier with some sort of mechanical advantage like a woodruf key or spline. Maybe the intention is for the impellor to slip in a frozen coolant situation to prevent damage to the chamber and pump housing but frankly if the engine froze up it would probably be toast annway. I'd look at the possibilty of threading the spline and lock the impellor on with a lock nut. Re the Hylomar I'd never recommend using that stuff after having ruined an engine once. When you close and tighten the joint any excess Hylomar gets squeezed into the internal chamber where it sets into rubbery lumps free to circulate your oil or coolant system eventually blocking small openings . I'd recommend the mating surfaces are given a careful dressing with a fine flat file and use engineers blue to highlight high and low spots and maybe use some gasket red hermatite with a gasket if the mating surfaces are poor. good luck .
] I cannot believe that these pumps have the impellor 'glued' on . Beggars belief really. I'd feel far happier with some sort of mechanical advantage like a woodruf key or spline. Maybe the intention is for the impellor to slip in a frozen coolant situation to prevent damage to the chamber and pump housing but frankly if the engine froze up it would probably be toast annway. I'd look at the possibilty of threading the spline and lock the impellor on with a lock nut. Re the Hylomar I'd never recommend using that stuff after having ruined an engine once. When you close and tighten the joint any excess Hylomar gets squeezed into the internal chamber where it sets into rubbery lumps free to circulate your oil or coolant system eventually blocking small openings . I'd recommend the mating surfaces are given a careful dressing with a fine flat file and use engineers blue to highlight high and low spots and maybe use some gasket red hermatite with a gasket if the mating surfaces are poor. good luck .
TTM
Well-known member
I knew 928 water pumps have had a plastic impeller for a long time - perhaps even from the beginning - but I thought such a miserable solution would never have found its way on our water pumps, this is totally new to me! Oli, could you please post pictures of both pumps when you receive the new one?
Nick, Thanks. The surfaces seem to be excellent on the block, and the ones on the new pump should be ... well, as good as new. So I don't anticipate any problems. The old pump sealed fine with no sign of any product being used on the gasket. (It took a reasonable shove to dislodge it from position once the bolts were all out.) I'll save the pennies then and just keep stuff clean. Thanks for the recommendation. TTM, yes, I'll post some comparison photos of the new pump and the old when it arrives. For now, here are some photos of the old pump, grubby as it is.
(I know there are parts attached to this which will need to be swapped to the new pump; they are there in order that I can remember where they belong.) Yes, the impeller is plastic. A hard, engineering-type plastic (don't know enough about plastics to identify it precisely), but certainly not metal. I'm not sure how it was held on - could have been glued, could have been an interference fit. Here's some photos, showing clearly the clearance between the impeller and the shaft. (Bear in mind that this pump did the thick end of 100 miles after failure, so the shaft-impeller clearance will have become significantly greater.) I'll be interested to see whether the new (Laso) item is metal or plastic. I can only imagine that a metal one would be superior in many ways. In the world of VW's, aftermarket pumps were available cheaply with plastic impellers or more expensively with metal ones, and the plastic ones were renowned for falling off, and the advice was always to spend the extra and buy the better all-metal pumps. (But then, last time I did a water pump on a VW it cost me £15 and took less than 20 minutes. Worlds apart from the current situation.)
Also, here's a picture of some white-chocolate brownie Mrs zcacogp made yesterday - apparently it is called a 'blondie'. It tastes utterly divine, and if I eat any more of the stuff I will - literally - pop. (The slice in this picture - taken just 5 minutes ago - is long gone I'm afraid. But I would draw your attention to the reasonably-sized lump of milk chocolate, nestling in the middle. It tasted particularly good. Recipie available on request.)
Oli.
Al, Sure. 200g unsalted butter 150g white chocolate (can use a mix of white with milk for 'lumps') 300g light muscovado sugar 3 eggs 200g plain flour 1/4tsp salt 1tsp vanilla extract (not flavouring) 125g raspberries 1. Heat oven to 180c/gas4. Butter, then line, a shallow baking tray approx 22x25cm. Melt the butter in a pan and cook gently for 5 mins or so, until the white solids turn golden and the butter smells sweet and biscuity. Cool for 5 mins then add half the white chocolate and set aside for a few minutes for the chocolate to melt. 2. Using an electric whisk, whisk the muscovado sugar and eggs together until thick and pale (approx 2 minutes). Tip in the flour, salt, cooled chocolate/butter mix and vanilla and fold with a metal spoon or spatula until even. 3. Put the mix in the tin, then scatter with the rest of the chocolate (cut into suitable-sized lumps) and the raspberries. Bake for 40-45 minutes until it is risen all over, with a dark golden crust. Cool completely in the tin, then cut into squares. Keeps for about 3 days in a sealed tin (although it never lasts more than 1 here ... ) The version pictured above is baked without raspberries (couldn't get hold of any), but works just fine. You could probably substitute blackberries or blackcurrants or any other soft fruit if you wanted as well. Happy baking! Oli.
peanut
Active member
barsteward [&o] I'm on a strict diet because I've already gone pop.! What would be the first class rate for a piece of utterly devine blondie cake ?[ORIGINAL: zcacogp Also, here's a picture of some white-chocolate brownie Mrs zcacogp made yesterday - apparently it is called a 'blondie'. It tastes utterly divine, and if I eat any more of the stuff I will - literally - pop. (The slice in this picture - taken just 5 minutes ago - is long gone I'm afraid. But I would draw your attention to the reasonably-sized lump of milk chocolate, nestling in the middle. It tasted particularly good. Recipie available on request.)Oli.
] Well done Oli for doing it yourself. Its one job I have never done and although my S2 urgently needs belts I've been putting the job off . Whatever you go to do on a 944 the job always seems to escalate in direct proportion to one's rapidly depleting financial resources .
appletonn
New member
Thanks for the recipe Oli (or rather Mrs Oli!) and fingers crossed for the water pump replacement. My dad has just bought a 924S (2.5 944 engine model) with a view to us using it for some trackday/sprinting fun - a whole £950 from Ebay with 12 months MOT! We're doing the belts at the weekend, so I may well get a water pump from ECP, as Dr Sodt's Law will inevitably strike if we only change the belts and leave the pump?! Thanks again!
Just called my Indie about this particular issue. (They are very helpful and gave me advice last week when it happened, and booked it in to have the work done as well - which is why I called them today.) They think that a pumpt every other belt change is sensible as well. And asked whether I had yet got the old pump off - apparently the bolts can often seize. (Mine had come out fairly easily, so no big deal there.) I'll take it into them when I have done the job to get the belt tension checked. Nick, a 924s for that money has to be a bargain - and would make a fantastic cheap toy to play with on the track. Keep it well serviced (belts and pumps are a good idea) and some decent rubber, align it carefully and have a load of fun. My only comment is that I am currently so fed up with ECP that I'd probably rather burn the money than give it to them, but that's by-the-by. Peanut, I'd love to send you some blondie but it's all gone now! FWIW, I was very nervous about doing the belts on my S2 last month, and sought a lot of advice from this forum. However, (as with most jobs on the S2) it proved to be easy, although longwinded. There is quite a lot to take off before you get to the belts, and this takes time. However, a 10mm and 13mm spanner, a good supply of tea and a few hours will see you through without any issue. The instructions from Clarks Garage are very helpful, and I don't think you would struggle with it. OK, you also need a 24mm spanner and a long extension bar to get the crank pulley bolt off, but that was no drama at all when I did it (it sounds much more dramatic than it really is.) Oli.
OK, the waterpump has arrived, and there were questions asked about a comparison between the old and the new. I suspect that the one that came off wasn't the original one (plastic impeller being a clue), but it isn't the same as the replacement. The new one is made by Laso, came in an opened Laso box and is brand new. It is clearly from a different casting to the one that came off, but doesn't seem to be an any way of lower quality. Pictures are thus: Old and new, alongside each other. (Note German newspaper, used to wrap the new pump!)
View into the thermostat.
Note the differences in the marks on the casting.
Metal vs. Plastic impeller. Note the difference between the bottom edges of the chambers around the impeller.
And another point where there is a clear difference - deep in the thermostat housing. The new one seems to have the thermostat hole cast slightly offset, and has been reamed out. The original one seemed to be straight from the outset.
Fitting due tomorrow morning. Outside. On the road. The first person to point out that the weather forecast is dire will incur my eternal displeasure. OK? Oli.
Its not as bad as todays was!
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