Lotus Elan

Dave Bean Water pump

PostPost by: woodcock » Fri Jul 21, 2023 11:23 am

Does anyone have a Dave Bean removable water pump assembly that they never used? Ken told me yesterday he sold the last one & estimates about a year till a new shipment.
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PostPost by: rgh0 » Fri Jul 21, 2023 11:27 am

mmm. maybe I bought the last one, they shipped to me a few weeks ago !

Currently lost in the post between the USPS and Australia Post. If it was the last one hopefully it gets found !!!

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PostPost by: woodcock » Fri Jul 21, 2023 2:34 pm

Rohan, When I spoke with Ken yesterday he mentioned he shipped the last one earlier this week. Could be yours!
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PostPost by: woodcock » Fri Jul 21, 2023 2:40 pm

Mountune, also in southern Calif, lists one made in Europe & they say popular. Lets see what the Elan crowd from the other side of the Atlantic has to say.
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PostPost by: rgh0 » Fri Jul 21, 2023 2:50 pm

I have used the UK / Burtons cartridge pump. I did not like some of the details which is why I wanted to try the Bean one
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PostPost by: alan.barker » Fri Jul 21, 2023 2:53 pm

Hope it's not a Burton pump
I fitted an AKS many moons ago not too bad.
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PostPost by: woodcock » Fri Jul 21, 2023 3:07 pm

What did you not particularly like about the Burton pump? I'm now desperate. Getting ready to put a McCoy Webber head on a Federal Sprint I just acquired, so if I'm going to replace the water pump now is the time.
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PostPost by: woodcock » Fri Jul 21, 2023 5:33 pm

I went back in Elan.net history, as far back as 2009, re. the Burton pump, got all the answers I need. Thanks
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PostPost by: elancoupe » Fri Jul 21, 2023 9:55 pm

Tony Ingram sells the Burton unit, says he has sold over 125 without issue.

A friend has a Bean unit in his just rebuilt motor. He put water in it for the first time last week - water ran out of the bleed hole. Ken told him that a seal may just be sticking a bit, run the car up to temp and it should relax. Hopefully so.
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PostPost by: rgh0 » Sat Jul 22, 2023 1:40 am

woodcock wrote:I went back in Elan.net history, as far back as 2009, re. the Burton pump, got all the answers I need. Thanks


Yes I presume you found your research that there is a fair bit of casting variation versus the groove location for the serpentine O-ring that seals the front cover from the back plate. This can result in insufficient aluminium left in places to support the O-ring properly. On the one i fitted it was just OK but Burtons really need to improve that aspect of the design.

My understanding is the Dave Bean design seals the front and back plate differently so does not have this design weakness.

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PostPost by: 2cams70 » Sat Jul 22, 2023 9:55 am

There’s no real design weakness as far as I’m aware with the Burton pump. The issues with it are lack of quality control in production and Burtons no care attitude toward customers. Once fitted and working however I’m not aware of any problems with it.
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PostPost by: rgh0 » Sat Jul 22, 2023 10:41 am

2cams70 wrote:There’s no real design weakness as far as I’m aware with the Burton pump. The issues with it are lack of quality control in production and Burtons no care attitude toward customers. Once fitted and working however I’m not aware of any problems with it.



The fundamental design weakness is to not allow for the practicalities of the core shift tolerances in the casting combined with the limited space around the pump mounting bolts for the serpentine O-ring and the tolerancing of this CNC machined groove with the casting and the CNC refernence points used for the machining. A fundamental tolerancing problem that any design engineer should recognise and work to ensure does not occur during production and there is unfortunately plenty of evidence that it does occur. It is not in reality a production quality control problem but the outcome of a design problem when put into production.

But that just my personal opinion. Also always happy to work through a detailed analysis of the tolerancing issues to discuss further but I dont think many people would be interested in these details

Yes the Burton pumps work "most of the time", but the problem exists and the casting has failed in documented cases due to this and operating pumps will fail in the future due to corrossion of the very thin remaining metal. There are better ways to design the O-ring seal that would overcome this problem but as observed Burtons or whoever designed and makes it are not really interested

Incidently this sort of problem is common in many German cars (and maybe others ?) in the last 20 years where plastic housings sealed with O-rings fail after time due to the designed thin walls between the O-ring and the fluid being sealed (usually oil or coolant) failing and the o-ring then failing. The VAG VR6 engines .thermostat housing from the early 2000's is an example of this

The Dave Bean pumps have not always been perfect either. While I have not purchase one of them, a friend of mine did early on and had porosity in 2 of the front cover castings. He fixed these using vacuum impregnation of the castings loctite sealant.More recently I have not heard of any issues with their castings which is why I ordered one to see what it looked like currently

The standard front cover castings are not immune from problems either.. I bought one a few years ago when I could not get a cartridge front cover from anyone ( not Burtons, ther UK suppliers or Dave Bean) That casting was also porous around the bearing mount area.

I have a bunch of cracked and porous castings that I am going to have a go at repairing using low temperature aluminium brazing when I have time to see if they are recoverable

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PostPost by: 2cams70 » Sat Jul 22, 2023 11:36 am

Whilst it isn’t good where the wall where the O-ring sits along a small section of the groove is a bit thin I doubt it would could serious issues. Where it is thin is on the coolant (ie high pressure side) not the low pressure side facing outward. Collapse of the wall here would not have much effect because it’s not on the low pressure side facing outward. I have not seen a Burton’s pump fail because of this and virtually every modern car uses o-rings to seal things like thermostats and coolant outlets these days not just VW.

The original design is perfectly fine too if you don’t overtighten the belt too much especially given the limited mileages of these cars these days. The same basic bearing, pump, impeller and seal were used in millions of Anglias and Cortina’s without issue.

Where a lot of people stuff up is thinking that the bearing can cope with the belt loads needed for an alternator. It can’t. It was designed for belt loads associated with a generator. When Ford changed to using alternators they increased the bearing size on their pushrod engines. The Lotus engine did not get this change in bearing size. Run the belt loose like you do for a generator and it will last.
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PostPost by: rgh0 » Sat Jul 22, 2023 1:10 pm

Yes i agree its not good and if it fails it will result in a coolant leak into the sump,

Just as an aside I discovered recently when a bore cracked in my race engine (and hence my current new engine build) that a small coolant leak into a hot race engine results in all the water in the coolant evaporating rapidly and neat ethylene glycol sitting in the bottom of the sump with none of the expected brown mousse oil mix being present

The issue with the Lotus designTwin cam front cover assembly is that the belt tightens signficantly as the engine gets hot due to the alloy housings expansion compared to the original Ford design. It is not the use of alternators versus generators thats the issue but the thermal expansion. The Belt on a twincam needs to be very loose as you oberserve when the engine is cold. You should be able to turn the Gemerator / Alternator pulley by hand with
some effort on a cold engine. Once the engine is hot you will see the belt has tightened signficantly and the pulley cannot be slipped. Setting the belt to what people expect is correct tightness when cold results in excessive tension when hot and more rapid pump bearing failure as a result. Maybe an alloy housing alternator also expands more thna a generators but the lucas generators had an alloy front flange assembly which would see similar expansion to an alternator. The torque and belt load on a typical alternator used on an Elan is similar to a generator as they operate at higher RPM to generate the greater output power due to their smaller diameter pulley and higher efficiency

I have used all sorts of front covers over the years, orignal, orignal covers modified with larger bearings, orginal covers modified with a cartridge insert and larger bearings, new castings to orginal pattern, the current engine I am building will have a burton cartridge cover, next engine will have a bean cartridge cover if I can ever find it in the postal system :(

Never had a bearing fail in 45 years of Twincam engine building or seen one fail when the belt tension is set right. I have had pump seal failures which is the most common issue in high mileage pumps, front covers crack which is a common issue in race engines with the high vibrations at 8000+ rpm and front cover porosity which is a problem with all versions of new after market castings.

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PostPost by: 2cams70 » Sat Jul 22, 2023 2:34 pm

The more amps you draw from a charging device the more torque you require to drive it. That’s why you need a tighter belt for an alternator that has a higher output all else being equal. The rotor in an alternator is of larger diameter and heavier than your typical generator armature. It’s more inertia to accelerate and decelerate. That’s why Ford changed the design of the water pump bearing around 1970/71 when they went to standard alternators. A larger bearing allows you to run a tighter belt tension with greater reliability.
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