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Waterpump dismantle tips?

Posted: Mon Aug 01, 2022 12:35
by Oi_Oi_Savaloy
How everyone - how do you dismantle the waterpump so I can change it using the kit. Mine is rock sold (won't turn) - do I need a press to press it out?

Thanks.

Re: Waterpump dismantle tips?

Posted: Mon Aug 01, 2022 16:13
by AndyC
You definitely need a press, you also need to heat it quite a lot to get the aluminium to expand more than the steel, else you'll be pulling some of the ali with the bearings and the pump will likely fail in the near future.

Re: Waterpump dismantle tips?

Posted: Mon Aug 01, 2022 18:24
by Esprit2
Follow this link to a PDF file on how to rebuild the water pump:
https://tinyurl.com/565eaeay

Early seals were over-molded with black rubber, while modern seals are stainless steel. They're easy to tell apart at a glance. Presuming any modern rebuild kit will include the stainless steel seal, you will need a special 'pusher' to press it into place. It's easy to make, a local machine shop can make one for you in short order. Better Lotus parts vendors willl also have the tool... ask.

The stainless seal's main body is cylindrical with a flange around one end. You simply press it into the pump housing until the flange bottoms out against the housing.

Then there's a smaller diameter, longer secondary housing that is a press fit into the main housing. That secondary housing also ends with a flange/ rim, sort of like a 'top hat'. After the main body is pressed into the pump housing and seated, the secondary housing is pressed into the seal's main housing until it's flange is 0.340" / 8.64mm out from being fully seated.

The special tool does both pressing operations at once. Install the new bearing in the housing first. Then place the seal loosely in position on the exposed end of the shaft/ in the pump housing, set the tool in place over the seal, and press it home until fully seated. Remove the tool, and you'll see that both flanges are where they're supposed to be.

Back-up a bit... it's best to dress the bottom of the seal's main flange, and the mating face in the housing with Hylomar AF prior to installing the seal. Wipe off any excess that oozes out after the seal is pressed into the housing.

Follow this link to a PDF drawing/ sketch on how to make the special tool.
https://tinyurl.com/ymya2uxb

It's very important that the V-belt pulley's groove be in the same plane as the mating groove in the crankshaft pulley. The official method is to measure the distance from the forward face of the hub (it's pressed onto the shaft, the pulley bolts onto it) to the rear face of the pump housing (the face that contacts the engine block). That's a little difficult to measure, unless you have a caliper with long jaws. Then, when the pump is in the hydraulic press having the hub pressed on, it's difficult to impossible to also get in there with the caliper. You can go in stages... press & measure, press & measure, or...

I find it easier to measure the gap between the hub and the nose of the pump housing with a stack of feeler gauges BEFORE disassembly. Then, while pressing the hub back on, lay the same stack of feeler gauges on the nose of the pump housing, and press the hub on until it lightly touches the stack.

The hub and impeller were both (should have been) pressed on along with an anaerobic retaining compound, like Loctite 640 or 680. You will have to heat them with a propane torch or heat gun (hair dryer on steroids) to about 425F / 218C in order to kill the Loctite before pulling either of them off. Don't attempt to remove the them cold. And during assembly, do not forget to use an anaerobic retaining compound.

As has already been mentioned, heat the pump housing to about 225F / 107C before pressing the bearing out of, or into it. Pressing the bearing cold can permanently damage the housing's bore beyond being useable. But be careful not to over-heat the housing, or you risk annealling the aluminum. A heat gun is not as hot as a propane flame, and safer to use for this task. No matter what you use, proceed in careful steps, stopping periodically to spritz a little water on the surface. A 'little'. Like dip your finger in some water, then flick it at the aluminum. When the water droplets spit & sizzle, and dance on the surface, the temperature is right. Proceed with pressing the bearing out/ in.

When the impeller is pressed onto the shaft, you're supposed to stop when there is a spec gap between the vanes and the housing (see the instructions PDF). The easiest way to get that right is to lay a feeler gauge of the spec thickness between the vane and housing, then slowly, carefully press the impeller on until it 'just' touches the feeler gauge. Go too far, and the difference between loose and pinched hard is very small. If you pinch the feeler gauge hard, you can still 'abuse' it out, but you will have ruined it. I find it easier to start with a step or two thinner feeler gauge. Press the impeller on until it's very close, but not touching. Then stop and check the gap with the correct feeler gauge.

Again, the impeller is installed with a retaining compound, like Loctite 640 or 680. Something strong. Heat is required to remove the impeller (and the hub).

When you have done the job before, know what you're doing, and have all the parts & tools lined-up, it takes about 45 minutes to rebuild a water pump.

Regards,
Tim Engel

Re: Waterpump dismantle tips?

Posted: Mon Aug 01, 2022 18:45
by Esprit2
The impeller used in the 907 pumps had very few, short vanes. That may (??) also apply to the 912LC. The 910 Turbo and 912HC pumps use an impeller that has more, much longer vanes. That, plus a deeper scroll housing portion of the pump housing means the later pumps can move a lot more coolant for better cooling.

If your 907/ 912LC runs a little hot, and you run a cooler thermostat to help the engine stay cool, then consider installing the impeller from a 910/912HC pump during the rebuild. It's obvious at a glance that the length of the nose on the two impellers is very different... the 910/912HC impeller being longer. As is, it will not fit into the 907/ 912LC pump housing. But take both impellers (short & long) to a machine shop, and ask then to shorten the long one to match the short one. Then the rest of the pump assembly is as per the instructions.

Also, the front engine cars use a 5.25" OD pulley on the water pump. The mid-engine Esprit doesn't get the air-blast into the engine bay that the front-engine cars do, so the engine tends to run hotter. So Lotus installed a smaller, 4.5" OD pulley on the same pumps when they're used in an Esprit. The smaller pulley spins the pump faster so that it pumps more coolant.

If you install both the 910/912HC impeller and with the smaller OD, 'Esprit' pulley, the pump willl move a lot more coolant, and the engine will run cooler. Now install a proper, higher temp thermostat to keep the engine up to normal operating temp. Consider the greater flow rate to be an insurance policy held reserve for those hot days, or congested traffic situations when the engine might otherwise be prone to over-heating. The big impeller and small OD pulley make a significant difference.

Regards,
Tim Engel

Re: Waterpump dismantle tips?

Posted: Tue Aug 02, 2022 18:11
by Oi_Oi_Savaloy
Absolutely fantastic replies to this topic - thanks guys. Very, very much appreciated.

Re: Waterpump dismantle tips?

Posted: Tue Aug 09, 2022 17:19
by HypnoToad
Hi,

My water pump has also seized also I'm also looking at refurbing mine. This thread is great, thanks for posting the guide and extra info.

I was wondering is anyone has tried any of the rebuild kits avaliable, and if so how did you get on?

So far I've found these, they tend to vary in price and also with what parts are and are not included:

https://www.thelotuscentreonline.co.uk/ ... ebuild-Kit
This is the most expensive I've found but comes with both the pulley hub and and the impellor.

https://qedmotorsport.co.uk/product/qed ... -impellor/
This comes without the hub, and is a little less expensive. I guess I need to get my old pump apart first in order to see if it's short or long impellor.

https://www.ebay.co.uk/itm/274634296799
This one doesn't come with the impellor, but it does come with an installation tool which looks handy.

I think I'm probably going to order the ebay one as it comes with the installtion tool. Are there any kits avaliable that are worth looking at?

Thanks

Re: Waterpump dismantle tips?

Posted: Tue Aug 09, 2022 17:33
by Pete Boole
I bought mine from Lotusbits - it comes with new impeller, pulley flange and installation tool and has a good set of instructions.

Pete

Re: Waterpump dismantle tips?

Posted: Fri Aug 12, 2022 12:47
by HypnoToad
Pete Boole wrote:
Tue Aug 09, 2022 17:33
I bought mine from Lotusbits - it comes with new impeller, pulley flange and installation tool and has a good set of instructions.

Pete
Thanks, sounds like the one to get, I'll get in contact with them and see if they have any available.

Re: Waterpump dismantle tips?

Posted: Sat Oct 08, 2022 15:46
by PrecisionMike
Esprit2 wrote:
Mon Aug 01, 2022 18:45
The impeller used in the 907 pumps had very few, short vanes. That may (??) also apply to the 912LC. The 910 Turbo and 912HC pumps use an impeller that has more, much longer vanes. That, plus a deeper scroll housing portion of the pump housing means the later pumps can move a lot more coolant for better cooling.

If your 907/ 912LC runs a little hot, and you run a cooler thermostat to help the engine stay cool, then consider installing the impeller from a 910/912HC pump during the rebuild. It's obvious at a glance that the length of the nose on the two impellers is very different... the 910/912HC impeller being longer. As is, it will not fit into the 907/ 912LC pump housing. But take both impellers (short & long) to a machine shop, and ask then to shorten the long one to match the short one. Then the rest of the pump assembly is as per the instructions.

Also, the front engine cars use a 5.25" OD pulley on the water pump. The mid-engine Esprit doesn't get the air-blast into the engine bay that the front-engine cars do, so the engine tends to run hotter. So Lotus installed a smaller, 4.5" OD pulley on the same pumps when they're used in an Esprit. The smaller pulley spins the pump faster so that it pumps more coolant.

If you install both the 910/912HC impeller and with the smaller OD, 'Esprit' pulley, the pump willl move a lot more coolant, and the engine will run cooler. Now install a proper, higher temp thermostat to keep the engine up to normal operating temp. Consider the greater flow rate to be an insurance policy held reserve for those hot days, or congested traffic situations when the engine might otherwise be prone to over-heating. The big impeller and small OD pulley make a significant difference.

Regards,
Tim Engel
[/quote

Hi Tim....I've been trying to locate the impeller with the longer canes here in the uk. SJ advise that it's no longer available....Any ideas please.
Also some clarification if I may: is it ok to use the longer vane impeller with the canes that almost spiral to the middle, with a 907 pump. I know the nose will have to be shortened but my concern relates to the length of the vanes that will NOT be in close proximity with the angled surface. (The 0.5 gap)
Thankyou in advance