Correct VCU silicone oil
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it is not silicone oil.
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the VCU doesnt use silicone oil
What he said^^^^
The fluid used in the VCU is a specially made fluid. It is made out of silicone but it most definitely isn't silicone oil.
GrumpyGel
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But its probably as close as you'll get to what went into a VCU.
Quite a few people have used it when rebuilding VCUs 'at home', and its probably what professional reconditioners will use.
Quite a few people have used it when rebuilding VCUs 'at home', and its probably what professional reconditioners will use.
The correct fluid is available.
But for information on the fluids properties, Google "Dilatant fluids"
GrumpyGel
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I have Googled and Wikied so many terms relating to viscous/silicone properties, I can't be tossed to Google any more!
If the 'correct' fluid is available - what is it? Show me a link to someone selling it and get MHM to agree its the right stuff.
It will save countless pages of threads and posts on here!
While you're at it, please confirm how much should go in?
Winu
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facebook group questions ? :monitor_punch:
VCU is NOT a part for DIY service (in general is not serviceable) , Ok, some companies do a recons, but IMO it should be replaced for new unit.
Want 4x4 car? Pay for it.. it's simple especially if you need to do this once for thousand miles.
VCU is NOT a part for DIY service (in general is not serviceable) , Ok, some companies do a recons, but IMO it should be replaced for new unit.
Want 4x4 car? Pay for it.. it's simple especially if you need to do this once for thousand miles.
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LandyMan
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The actual fluids used are.
Dow Corning Viscose Coupling Fluid.
3-9160, 3-9161 and 3-9162.#The different part numbers are for different viscosities.
I believe that Dow Corning no longer make the fluid.
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Over the years we have spent many a happy hour or hundred searching and discussing this very subject (see the numerous posts). the closest we have got is information on the similar VW unit. But even that wasnt very conclusive. I can only remember a couple of peeps that have "Replaced" the fluid, but when asked to verify that it works well, we have heard no more. Make of that what you will!
As for the volume required (and it is critical), the usual suggestion is to measure what comesout and replace with exactly the same amount. No one, to my knowledge, hasresponded with a figure. Much less several people to get a realistic comparison. Unsurprisingly Bell and other refurb houses wont tell us.
GrumpyGel
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I know MHM, over recent years, many of those discussions/posts have been contributed to by me - and don't get me wrong, I've found it interesting - just tends to go round in circles - as do my searches for the terms relating to viscosity etc - hence my previous remark!
I can find only 1 reference to those Dow Corning part numbers on LZ. They were posted by someone who 24 hours earlier did not know what type of fluid was in the VCU and appears to have found a Dow Corning page saying they sell generic fluids for viscous couplings. No confirmation that that its the fluid in a Freenlader VCU - in fact there's 3 different part numbers - so which is it?
However, that member 'jonaf' is I believe 1 of the members who has rebuilt VCUs and if my memory serves me correctly, he (or his 'group' of Freelander mates) have done quite a few and he believes they work well.
I would imagine that those 3 part numbers relate to the cst ratings of their 'silicone fluid' - eg 30.000, 100.000 etc. I would deduce (probably incorrectly) therefore that those part numbers probably equate very similarly to generic silicone fluid of different cst ratings you can buy on eBay.
This still does not confirm what the OEM fluid is.
So, once again circles. At some point - if you want to rebuild a VCU, ****ing and pots comes into the equation and you might as well bung in some generic eBay silicone fluid of X (probably 100.000) cst and monitor it!
I can find only 1 reference to those Dow Corning part numbers on LZ. They were posted by someone who 24 hours earlier did not know what type of fluid was in the VCU and appears to have found a Dow Corning page saying they sell generic fluids for viscous couplings. No confirmation that that its the fluid in a Freenlader VCU - in fact there's 3 different part numbers - so which is it?
However, that member 'jonaf' is I believe 1 of the members who has rebuilt VCUs and if my memory serves me correctly, he (or his 'group' of Freelander mates) have done quite a few and he believes they work well.
I would imagine that those 3 part numbers relate to the cst ratings of their 'silicone fluid' - eg 30.000, 100.000 etc. I would deduce (probably incorrectly) therefore that those part numbers probably equate very similarly to generic silicone fluid of different cst ratings you can buy on eBay.
This still does not confirm what the OEM fluid is.
So, once again circles. At some point - if you want to rebuild a VCU, ****ing and pots comes into the equation and you might as well bung in some generic eBay silicone fluid of X (probably 100.000) cst and monitor it!
Creeeg
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Or just buy a professionally rebuilt one for a couple of hundred quid or so with a guarantee every few years and be done with it. Is it really worth ****ing about with something like this that could end up costing you a grand in parts if you get it wrong?
GrumpyGel
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Absolutely - you only take on a VCU rebuild if you 'want to' as a project.
I think the only way if could do any serious damage is if the fluid you use can change its properties in a short space of time. You'd be very foolish not to test it (1 wheel up) before you install, and foolish not do regular tests, and keep a feel for any binding characteristics.
I think the only way if could do any serious damage is if the fluid you use can change its properties in a short space of time. You'd be very foolish not to test it (1 wheel up) before you install, and foolish not do regular tests, and keep a feel for any binding characteristics.
Creeeg
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Yes, regular testing is the way forward. Then again, it should be that way even with a professionally built VCU too 
Until someone recons one with whatever aftermarket fluid and posts valid side-by-side comparisons with a new OE or good reconditioned (like from Bells) unit then its all just speculation and ****ing into the wind. I think these silicone oils "work" in that they produce a similar effect but whether its the RIGHT fluid that behaves correctly under the various conditions of force and temperature inside the VCU over time is IMO unlikely.
I would want to see side-by-side testing doing an "on the bench" version of the 1 wheel up test - ie one end of the vcu in a vice the other end with a bar and weight on it....repeated tests with different weights and at different temperatures.
Then I would want to see those tests repeated after at least 5k miles.
Then I would consider the results useful. Until then its £200 to Bells every few years, which is a small price to pay, really.
I would want to see side-by-side testing doing an "on the bench" version of the 1 wheel up test - ie one end of the vcu in a vice the other end with a bar and weight on it....repeated tests with different weights and at different temperatures.
Then I would want to see those tests repeated after at least 5k miles.
Then I would consider the results useful. Until then its £200 to Bells every few years, which is a small price to pay, really.
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