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Bibs

Electric Chargecooler Pump vs uprated impellor

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Well mine was still yellow when I chucked the remains away and went over to electric. :)

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Pink antifreeze is higher spec and lasts longer than blue thanks to Organic Acid Technology corrosion inhibitors. It means you can leave it 5 years between a flush and change rather than 2 years with blue as you end up with more corrosion in your system with blue. Other than that, they are the same chemical composition for their role as an antifreeze, Propylene glycol.

Lotus recommend the OAT nowadays, time & technology move on, their suggestion is Halvoline XLC. It's orange but OAT is either pink or orange.

Their are no dark forces in the chargecooler circuit, your impeller was fine at first until it disintegrated and I do exorcise (sic) it regularly!


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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I've never seen something like this happening to a PU (= Polyurethane) impellor.

Cheers

Marcus

I will stae upfront I am not an organic chemist have done part of a chemistry degree in the past and work with medicinal chemists everyday at work so I consider myself and amateur chemist when it comes to stuff like this. If we do have any bona fida organic chemists in the forum please feel free to correct any assumptions and errors I have made.

For chemical stability and Polyurethane CLICK HERE

Ethylne glycol (EG) = propylene glycol (they are the same stuff)

Been doing some reading on this. Depending on the type of crosslinked poyurethane polymer used in the pump will vary the degree of resistance to various organic solvents such as EG. The organics in antifreeze are not able to dissolve cross linked polymerised polyurethane but can cause it to swell up and soften.

I would hazard a guess that your Bibs has swollen, softened and then distorted because of the centrifugal forces.

The above link lists that ethylene glycol can have a severe effect on PU. The effect in a chargecooler pump will be dependant on % concentration in your antifreeze plus what other additives are in there. Its also worth noting that PU refers to a wide range of products which vary in properties from additives in varnish to hard plastics depending on the cross linking and other substances used in the polymerisatin process.

Its not unreasonable to conclude that the type of PU used may not have a wide range of tolerance to various antifreeeze agents.

I found a nice article on the web: The hydrolysis section seems relevant to the story (its in blue see below)

Cheers Alex

Chemical degradation of polyurethane.

There are many ways polyurethanes can chemically degrade. Some of these are:

* Hydrolysis

* Thermolysis

* Oxidation

* Photolysis

* Pyrolysis

n. Decomposition or transformation of a chemical compound caused by heat.

* Microbial

* Solvolysis

n.

A chemical reaction in which the solute and solvent react to form a new compound.

Hydrolysis is defined as the reaction with water. Thermolysis reactions are those which occur due to heat. Oxidation involves the reaction with oxygen. It can be initiated with heat (thermooxidation) or by light (photooxidation). Photolysis are the reactions caused by the interactions with light. Pyrolysis is considered those reactions which occur due to burning. There are also chemical degradations caused by the attack of microorganisms. These are called microbial degradations. Attack on polyurethanes by solvents, alcohols for example, can cause a degradation referred to as solvolysis. Complete papers could be and have been written on each. This article will review the first four: Hydrolysis, thermolysis, oxidation and photolysis.

Typically a diisocyanate and a polyol are reacted to prepare a polyurethane prepolymer. The polyols are usually either a polyether or polyester. That prepolymer then is cured with a diamine.

Hydrolysis

The three bonds most susceptible to hydrolytic degradation are the ester, urea and urethan (figure 2). The ester reverts to the acid and alcohol. This acid further catalyzes ester hydrolysis. This reaction then becomes autocatalytic (Catalysis of a chemical reaction by one of the products of the reaction.)

Because of the autocatalytic nature of ester hydrolysis it is the most prevalent. The urea bond hydrolyzes to a carbamic acid and an amine. The carbamic acid normally isn't stable and typically undergoes further reaction. The urethane, although somewhat less susceptible, undergoes hydrolysis to yield a carbamic acid and an alcohol.

Comparing various polyurethane systems, we can see in figure 3 that polyester-TDI MBOCA systems hydrolyze hydrolyze quite rapidly, two to four times faster than polyether-TDI MBOCA systems. Using the same polyester in an MDI-BD system we can see the polyester also degrades more rapidly than the analogous polyether system. We can also see the influence of environment on the degradation. The polyester in an MDI-BD system was enhanced to a greater resistance than that of the polyether TDI TDI - Transport Driver Interface MBOCA systems (ref. 1).

Another important environmental influence on hydrolysis is temperature. At 50 [Degrees] C the tensile half life of a polyester-TDI-MBOCA system may be four or five months while that of a polyether-TDI-MBOCA appears to be almost two years. At 70 [Degrees] C, however, these half lives fall to two weeks and five weeks, respectively. And at 100 [Degrees] C they become a matter of days.

As we have seen, polyesters do not fare well in hydrolysis situations. If a polyester must be used in a wet environment, carbodiimides help in prolonging their longevity. Carbodiimides act as acid scavengers. As seen in figure 4, the acid and carbodiimide react to form an intermediate which rearranges to give an N-acyl urea. This consumes the acid which can no longer catalyze the hydrolysis.

Figure 5 shows the marked increase in life span of this polyester with a 2% addition of polycarbodiimide. It should be remembered, however, that the carbodiimide is being consumed and eventually will be totally used up resulting in the onset of catastrophic hydrolysis.

Thermostability Thermostability is the quality of a substance to resist irreversible change in its chemical or physical structure at high temperature. (Naturally, the meaning of high temperature will depend upon the type of material.

Heat can cause degradation of polyurethane. The onset of allophanate dissociation is around 100-120 [Degrees] C. For biurets it is around 115 to 125 [Degrees] C. These reactions are dissociations and somewhat reversible. They give back the urethane or urea from which they were formed. The urethane begins its thermal degradation around 140 to 160 [Degrees] C which is prior to the urea which is about 160-200 [Degrees] C. Since the urethane group degrades before the urea, it is these degradation reactions I would like to review. The urethane can dissociate to the isocyanate and polyol from which it was formed. This reaction is reversible as long as the isocyanate is not lost to a side reaction. The second reaction produces a primary amine and an olefin or alkene. The third reaction produces a secondary amine. Since these latter reactions generate [CO2] which is lost as a gas they are irreversible.

Again, which of these thermodegradation reactions takes place and to what extent depends on the structure of the urethane, the reacting conditions and the environment.

Oxidation

Once again, oxidation is simply that degradation which occurs due to the reaction with oxygen. Oxidations may be heat initiated or light initiated. Heat initiated oxidation is called thermooxidation and light initiated oxidation is called photooxidation. I would like to split this subject into these two parts, thermooxidation and photooxidation, and discuss each separately. In the discussion of photooxidation I will include photolysis reactions since they are closely related.

Thermooxidation

Previously we saw the ester to be the weak link in hydrolysis. Now it is the ether that is the weak link in thermooxidation. Thermooxidation proceeds via a radical mechanism. Heat causes a hydrogen extraction at a carbon alpha to the ether linkage. This radical is subject to oxygen addition and forms a peroxide radical. The peroxide radical then extracts another hydrogen from along the backbone to form a hydroperoxide. The hydroperoxide radical then decomposes to form an oxide radical and the hydroxyl free radical.

The oxide radical will cleave cleat, cleave at either of two places . One, it may cleave at the carbon bond adjacent to the oxide radical. If so, formates are formed. If, on the other hand, cleavage is at the carbon-oxygen bond, aldehydes are formed. The order of stability of polyethers to thermooxidation is: Polytetramethylene Glycol

types are more stable than polyethylene oxide glycols, which are in turn more stable than polypropyleneoxide glycols.

Photooxidation

In summary, this article has reviewed chemical polyurethane degradations including hydrolysis, thermolysis, thermooxidation, photooxidation and photolysis. It has shown that there are stabilizers which can help improve the longevity of a polyurethane in use. It has also inferred that selecting the right urethane for a given use is highly important.

References [1.] Pentz, W.J., Krawiec, R.G. "Hydrolytic stability of polyurethanes," Rubber Age, Vol. 107, No. 12, Dec. 1975, p. 39. [2.] Athey, R.J. "Watix resistance of liquid urethane vulcanizate," Rubber Age, Vol. 96, No. 5, Feb. 1965, p. 705. [3.] Schollenberger, C.S., Stewart, F.D., "Thermoplastic polyurethane hydrolysis stability," Advances in Urethane Service and Technology, Vol. 1, Chapter 4. [4.] Matuszak, M.L., Frisch, K.C., Reegen, S.L., "Hydrolysis of lineos polyurethanes and model monocarbamates," Journal of Polymer Science, Polymer Chemistry Edition, Vol. 11, No. 7, July 1973, p. 1683. [5.] Saunders, J.H., Frisch, K.C., "Polyurethanes chemistry and technology, part 1 chemistry," Interscience Publishers, New York, NY, (1964), pp. 106, 107. [6.] Fabris, H.J., "Thermal and oxidative stability of urethanes," Advances in Urethane Science and Technology, Vol. 6, p. 17380. [7.] Mathur, C.N., Kresta, J.E., "Thermooxidation and stabilization of urethane and urethane-urea block copolymers," Polymer Science Technology (Plenum), 26 (Polymer Addit.), p. 135-153. [8.] Osawa, Z., "Photodegradation and stabilization of polyurethanes," Dev. Polym. Photochem., 3, Chapter 6,209. [9.] Rek, V., Bravar, M., "Ultraviolet degradation of polyester based polyurethane," J. of Elastomers and Plastics, Vol. 15, January (1983), p. 33-42. [10.] Hoyle, C.E., Kim, K., "Photolysis of aromatic diisocyanate based polyurethanes in solution," J. Polymer Science, Part A: Polymer Chemistry, Vol. 24, p. 1880-1894.

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Hi Alex,

Does that mean that it falls apart in its basic elements sooner or later like any other object here on earth ... hmmmmmmmmmm ... its not stable

This all makes me a bit depressive ... but I feel this is nature ...

Every element/object/compund wants to settle on a level of the least (chemical or physikal) energy.

Marcus


Marcus

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Some might say it falls apart sooner rather than later. :)

Trying not to be too harsh here, Marcus, because as you know I like most of your stuff and am quite happy buying from you. This one item in your catalogue does seem to warrant a re-think.

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Hi All,

Jokes aside ... today I showed Bibs pictures to the manufacturer of the PU-impellors.

BTW, its a manfufacturer who mainly does impellors for pumps used in the food industry.

He told me that he would like to examine the destroyed one and additionally he offered a free replacement for everybody who has experienced a failure within 3 years.

Bibs, could you please send me the old destroyed impellor ?!

Many Thanks

Marcus

PS: Does anybody know how many of the PU-impellors have failed so far ... is it 2 ?

Edited by Paula&Marcus

Marcus

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I'll post it back to you today, can you PM me your address.

I've no interest in a replacement as I've fitted an electric pump, I'd rather a refund.


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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Hi Alex,

Does that mean that it falls apart in its basic elements sooner or later like any other object here on earth ... hmmmmmmmmmm ... its not stable

This all makes me a bit depressive ... but I feel this is nature ...

Every element/object/compund wants to settle on a level of the least (chemical or physikal) energy.

Marcus

hi Marcus,

basically cross linked PU is stable, but its not impermeable to certain chemicals which will alter its strength and hardness. What I was suggesting is that the PU used in your product may have not tolerated the chemicals in antifreeze solutions very well and so contributed to its demise. In a later post you said these are sourced from a supplier who sells them for use in the food industry where temp and pressure may be high but presence of chemicals like ethylene glycol certainly wont be there. Its likely they are well suited to food industry processes but not antifreeze containing coolant processes. I doubt that different antifreeze products are standardised so what may be ok in yours wont be in another car with a different antifreeze product. The idea of a plastic replacement to the rubber one is good, its just that the PU in yours isnt ideal. Both GKP and Bibs impellor failed very quickly, i would check yours for distortions. The other thing is certian plastics do degrade and change over time so if your orignal batch order has been sat around for a while they may now not be the same as when you first bought themm

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Hi Alex, Hi All,

We carry these impellors for a few years now and there have been 3 batches so far ... The impellors get custom made for us and each batch has around 40 pieces. There have been sold about 100 of these impellors so far.

All impellors we had the opportunity to check after some time (the last one we could check was Stefan Ertler's after quite a long time; you know the one with the Sport 500 project) came out flawless.

But, there was no car I know of, that had the red (organic acid) coolant in it ... maybe it has something to do with it ... or not ... who knows.

Honestly I have never seen one that has failed till I saw the pics from Bibs and heard the words from GKP.

I hope we will get an explanation from the manufacturer once he has the chance to examine one of the two that have failed.

Marcus


Marcus

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I'll take back what I said about the pump, it's ok now I've attached it the other way. It's now sucking from the rad and pumping up to the chargecooler, I thought it would be better the other way as gravity would help but it wasn't getting enough of a head of water to prime correctly. I've also added 6 inches of clear pipe so I can see the flow too and determine if there is air in the system or not.

I'll take it for a drive next week once the wheels are back on with new tyres fitted and see how the MAT gets on, fingers crossed!


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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Good show - that is the way the mechanical pump does it. What score you getting on the temperatures now then ?

What would be interesting so see is if you do a run with the old pump - take some freescans and then when you chop over to the johnson one you can compare the two - it would lay to rest the little indifference between high flow and optimum flow - from what I have read and after being convinced otherwise on hear - fast flow is the way to colder inlet temps.

I know what you were saying about being too cold the other day but remember you are boosting higher and that in itself will add more heat.

Be interesting to find out practically and lay more myths to bed.

Ay, we could all have a 'coldest chargecooler day/event' imagine the fun !


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Hi All,

Please have a look at your plumbing ! For a good efficiency its essential that the pump sucks from the lower radiator outlet (the one at the bottom) and then pumps into to front (in driving direction) c/cooler inlet.

If you mix up the pump connections (= flow direction will get reversed) you will end up with lower efficiency and also with a disturbed header tank function, because the pump pressurises the header tank ... no good idea.

Cheers

Marcus


Marcus

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Hi All,

Two days ago we handed over Bib's "red" destroyed impellor to the manufacturer. We also informed him that the coolant used was the red/pink one with OAT-technology.

Today we got the info that it was actually the red OAT coolant that softened the PU-material and also dyed the whole polymer red.

Now he is checking, if he can modify the PU that it will be also resistant against OAT in the future.

I will tell you what comes out ... very soon.

Cheers

Marcus

PS: All others who use the yellow PU impellors with non OAT coolants (= blue, green, whatever) please dont worry ... the PU will not get attacked.

Edited by Paula&Marcus

Marcus

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Marcus

What will happen to people that have brought them in the past? Can we get a modified replacement FOC?

I am running one with OAT coolant as per Bibs

Edited by internets

1982 DeLorean DMC 12 #16327, 1999 Lotus Elise, 1998 Lotus Esprit GT3 #2272, 2011 Lotus Evora S, 2013 Lotus Exige S,2016 Lotus Evora 400

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It's not a massive surprise that an impeller from a food blender isn't compatible with anti-freeze. Will you be contacting people who have purchased this item from you and removing it from sale Marcus, what are you plans?


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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You might wanna make sure this OAT stuff doesn't wreak the new pump on there as well.

Plastics / polymers etc can be very resistive to chemicals as well as completely reactive with them - luckily the pumps are magnetically coupled so they dont ahve a seal to leak by but never the less you might find this a problem again later in life.

WRT longer lasting coolant - thats all very well but draining the coolant freequently is something which helps the cooling system as well - esp with you metal tankers and the rust they generate.

Always a prob when you try somethign new.


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OAT has been about since 1994, it's not a new technology so shouldn't come as a surprise to anyone. My new pump states it's compatible with antifreeze and by that I would assume that a 15 year old antifreeze is included. It is standard on most cars now as it's better than the older stuff as the very reason it is used is that it doesn't need to be changed so often as it doesn't degrade the cooling system, it's more inert.


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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Hi All,

As soon I have a feedback from the manufacturer if it is possible to make it OAT resistant I will inform you.

BTW Bibs, we had the prototype impellors tested extensively before we had the first batch made ... no we did not use apple juice as a testing-medium ... :( We tested with recommended Castrol antifreeze (actually it was old coolant) and never saw any problem.

I personally would stay away from OAT in Esprits (not only because of that impellor). The Esprits cooling system was designed decades ago and IIRC blue Castrol antifreeze (and similar) was recommended by Lotus. From my experience the blue antifreeze works perfectly and there definitely is no need to use something different - why changing a running system ?

IMHO, its also very important to change the coolant and flush the whole system at least every two years. Not because the coolant itself gets old but you have a horrible material mix in that cooling system and getting things neutral and clean in there is always a good idea.

Marcus

It's not a massive surprise that an impeller from a food blender isn't compatible with anti-freeze. Will you be contacting people who have purchased this item from you and removing it from sale Marcus, what are you plans?
Edited by Paula&Marcus

Marcus

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Lotus now recommend OAT, personally I'll stick with that. :)


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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As soon I have a feedback from the manufacturer if it is possible to make it OAT resistant I will inform you.

Hi Marcus

Any news on this yet?


1982 DeLorean DMC 12 #16327, 1999 Lotus Elise, 1998 Lotus Esprit GT3 #2272, 2011 Lotus Evora S, 2013 Lotus Exige S,2016 Lotus Evora 400

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And my refund :blink:


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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Hi All, Hi Bibs,

We have discussed this OAT-eats-impellor-thing with the manufacturer yesterday. He told us that it probably will be possible to make it OAT resistant ... but what comes next ?

In the end we have decided that we will not change the impellors, because we and the manufacturer cannot tell for sure if this works with all OATs and all future upcoming formulas ...

We know that it is perfectly resistant against good blue Castrol Antifreeze and that is also what is recommended by Lotus.

I would like to add your own words here Bibs (you wrote that in the gearbox oil thread):

"Castrol TAF-X is ideal, it does the job and works perfectly, there is no need to choose another lubricant"

Just swap the TAF-X with Antifreeze and the word lubricant with coolant.

Cheers

Marcus

Edited by Paula&Marcus

Marcus

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hehe I would say the better bet is to swap Antifreeze with Electric pump and Coolant with impeller :)

:getmecoat:

Sorry low ball, but I couldn't resist :P


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If you call Lotus now and ask what coolant they recommend for my 1989 Esprit, they will say OAT. If you ask what gearbox oil, they will say TAF-X.


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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