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Discussion Starter · #1 ·
My second Davies-Craig electric water pump just crapped out. This one gave good warning at least: it got more and more noisy, and finally started drawing more amps and blowing fuses. I installed the first a number of years ago and promptly put 4-5k miles on it... That one died suddenly. Davies Craig sent me a new one and offered to reimburse me the cost when I sent the first one back in... Never did get around to it. I know that was kinda stupid. Totaled all of 8-9k miles in two pumps. Anyway, just wanted to put a little warning out there for anyone considering it. There is another company making a EWP that is supposed to be the cat's pajamas by all I have heard from it.

I never was satisfied with the original install... Mark J. (the guy with the Geocities 99 EWP install site) helped me a good bit, and I made some valuable improvements; it was just so messy underhood- hose clamps everywhere. I DID NOT have the controller which I think is part of the reason for the premature failures. I set it up so it could circulate the head and heater core even with the thermostat closed. The thermostat was drilled out to allow some reduction of head pressure on the pump until it opened. I can only assume it was still too much for the pump. Both failures occured after the motor was thoroughly warm.
I have to say: when it worked, it worked very well. It warmed up quickly, and sat right in the middle of the gauge all the time. On some extended full boost runs the needle might climb it's own width, but ony just. As soon as I remember who made that other pump and order one, I intend to re-work the whole set up. Have my radiator end tanks swapped out with a cross flow style and plumb it more like a 900. Report will follow, but don't hold your breath- it will take a while. ;)
I'll be driveing the 900 until I get the 99t back on the road.

C
 

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For my sins, I'm a washing machine engineer. I can tell you with absolute certainty that electric pumps which run but can't pump fail in pretty short order. In a business capacity, this is caused by blockages. If the thermostat is closed, the system is effectively blocked.........

In your case, rather than buying a bespoke controller set up, I'd be looking at a trimmable thermostat (Kenlowe do one for their fans) and setting it in the 80c range (99 stat - 83c or 86c) and running it through a relay to take the load.

You'll get faster warm up due to the initial lack of circulation and the pump will only run when it can actually circulate coolant.

Penguin45.
 

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Discussion Starter · #3 · (Edited)
Penguin,

I hear ya- no flow means it won't go for long... I barely recall how I did the setup, but the pump could circulate water through the head/block by a restricted line that returned right before the pump. Once the thermostat opened up, this restricted line was largely ignored since it offered more resistance than flowing straight through the head. To quote the Davies-Craig rep when asked about running it like this with no controller: "no worries, mate."
In theory, it would allow the pump to circulate without overload even with the thermostat closed. In both instances of failure the heater control valve was wide open too. There definitely is flow there, especially with the heater on. I am sure this is the cause of failure; I am just dissapointed it came so soon.
I did find the other company that I am going to look into: EMP Stewart. This one is good for 10,000 hours as opposed to D-C's 2000 hours. More details to follow.
 

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Don't take this the wrong way, but you believed the salesman.........? :D

Seriously, the pump is designed to deliver a certain volume of water per minute to allow it to cool itself and run freely. If you look at the flow diagram for the engine (Bentley and Haynes both have one), it has to run through the thermostat for full circulation.

Load it up and restrict the flow and the pump will cook itself.

Honest.......

Penguin45.
 

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Discussion Starter · #5 ·
OK, ok. you convinced me. :cheesy:

I wouldnt say I believed the sales guy; it just made me feel better. :cool:

Regardless, I am reworking my whole system.


C
 

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Well I guess I should pop in and add some words in defense of Davies-Craig. For the record, I am still running the original EWP I bought in 2001, with controller. I drive my 99T almost every day. The temp guage has never gone above 'N'. No leaks, no problems.
No thermostat in my setup. Plenty of flow. Hot heat.
I don't know why some pumps fail but my guess is constant running. In this Saaber's opinion, the controller is what makes an EWP conversion reliable for the long-term, regardless of manufacturer.

- Mark
1985 SPG
1978 99T
 
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