| Bleeding out the DOT 5 [message #250209] |
Tue, 20 May 2014 17:50  |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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For my brake problems I rebuilt a spare combination valve and replaced the original one on the coach. Now I have to bleed the brakes and was wondering if DOT 4 would mix with the DOT 5 or would it just push it out. Anyone have experience with mixing the two.
I plan on using a color brake fluid so as I can when the brake fluid in a brake line has been replaced.
Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: Bleeding out the DOT 5 [message #250217 is a reply to message #250209] |
Tue, 20 May 2014 18:55  |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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DOT 5 brake fluid will NOT mix with any other type of brake fluid. Including DOT 5.1. Any mixing with DOT 5 will result in a major problem. If currently Dot 5, keep it Dot 5, unless you are ready to replace the entire system. Yes, it is that bad.
Tom, MS II. With Dot 5 courtesy P.O.
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Bleeding out the DOT 5 [message #250246 is a reply to message #250209] |
Wed, 21 May 2014 00:44 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Bruce Hart wrote on Tue, 20 May 2014 15:50For my brake problems I rebuilt a spare combination valve and replaced the original one on the coach. Now I have to bleed the brakes and was wondering if DOT 4 would mix with the DOT 5 or would it just push it out. Anyone have experience with mixing the two.
I plan on using a color brake fluid so as I can when the brake fluid in a brake line has been replaced.
If you are talking about dot 5 silicone fluid I flushed mine with 2 large cans (quarts ?) of dot 3 . I siphoned the master cylinder refilled with dot 3 and just pumped the remaining fluid thru the lines and out the wheel cylinder and caliper bleeder valves. That was a long time ago and I haven't had a problem since. I don't see any reason to take the system apart to flush it out. When I converted my 1932 ford street rod the other way from dot 3 to dot 5 I did the opposite and no problems for 35 years till I sold it. Ditto for my 1948 ford street rod no problems for more then 35years. I will add I switched the GMC from dot 3 to dot 5 by the same way didn't like it after 5 years because of isolated water in the caliper and expense of dot 5 replacement so I just flushed it back to dot 3 then finally it is now dot 4. No problems what ever I think gloom and doom is over rated.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Bleeding out the DOT 5 [message #250291 is a reply to message #250209] |
Wed, 21 May 2014 20:23 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
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While I can understand folks not wanting to mix the two fluids, I do wonder what is the actual problem of the mixture. I once put some DOT 5 and DOT 3 brake fluid in a test tube, and they seemed to separate into two layers like vinegar and oil. I wonder if the combination of the two becomes somehow corrosive or precipitates over time. I let the test tube sit for quite a few weeks and it didn't seem to change visually.
Perhaps one of our engineers can explain the warnings more clearly.
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: [GMCnet] Bleeding out the DOT 5 [message #250295 is a reply to message #250291] |
Wed, 21 May 2014 20:33 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
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The question comes up as what happens when heat is applied to the mixture.
Will it separate or does it form a third gooey compound.
On Wed, May 21, 2014 at 7:23 PM, George Rudawsky wrote:
> While I can understand folks not wanting to mix the two fluids, I do
> wonder what is the actual problem of the mixture. I once put some DOT 5
> and DOT
> 3 brake fluid in a test tube, and they seemed to separate into two layers
> like vinegar and oil. I wonder if the combination of the two becomes
> somehow corrosive or precipitates over time. I let the test tube sit for
> quite a few weeks and it didn't seem to change visually.
>
> Perhaps one of our engineers can explain the warnings more clearly.
> --
> George Rudawsky
> Chicago, IL
> 75 Palm Beach
> _______________________________________________
> GMCnet mailing list
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>
--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: [GMCnet] Bleeding out the DOT 5 [message #250316 is a reply to message #250295] |
Thu, 22 May 2014 00:14 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Bruce Hart wrote on Wed, 21 May 2014 18:33The question comes up as what happens when heat is applied to the mixture.
Will it separate or does it form a third gooey compound.
On Wed, May 21, 2014 at 7:23 PM, George Rudawsky wrote:
> While I can understand folks not wanting to mix the two fluids, I do
> wonder what is the actual problem of the mixture. I once put some DOT 5
> and DOT
> 3 brake fluid in a test tube, and they seemed to separate into two layers
> like vinegar and oil. I wonder if the combination of the two becomes
> somehow corrosive or precipitates over time. I let the test tube sit for
> quite a few weeks and it didn't seem to change visually.
>
> Perhaps one of our engineers can explain the warnings more clearly.
> --
> George Rudawsky
> Chicago, IL
> 75 Palm Beach
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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[/quote. Anyone merely adding dot 3 or 4 to dot 5 to top off the master cylinder is foolish. If they do it in a pinch it shouldn't cause a problem as long as they flush out the system with one or the other when they get home.when dot 5 first got popular (early 70's ?) the instructions that came with the dot 5 said not to add it to your existing dot 3 system but to flush the dot 5 thru the system till the dot 5 was coming out of the bleeder valves at the wheel cylinders. If this is done you shouldn't have a problem non of my vehicles have had any adverse reactions and we are talking 35 years plus in the cars and 25 in the GMC and I'm towing more then 3000 pounds in the Sierra Nevada mountains. If a problem arises after fourty years in the car or 30 in the Gmc I guess I loose but may 'not be still driving them. I don't bother to replace the dot 5 in the car only if I do a major repair in the brakes.it keeps the system realy clean and moisture free . In the GMC I replace the dot 4 fluid every 3 or so years as I don't want to worry about a loss of brakes in these mountains even tho the humidity here in cowboy country is nill.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Bleeding out the DOT 5 [message #250415 is a reply to message #250295] |
Thu, 22 May 2014 19:42 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Bruce,
Every document I have ever read from any knowledgeable source notes not to mix Dot 3, 4, and now 5.1 with Dot 5. Below you will find
some examples:
http://en.wikipedia.org/wiki/DOT_4
http://en.wikipedia.org/wiki/DOT_5
As far as changing from one DOT 4 to DOT 5 or vice versa, I for one; would err on the safe side and disassemble, flush, clean; and
dry the system completely to make sure there was no residual fluid left anywhere.
Regards,
Rob M.
-----Original Message-----
From: Bruce Hart
The question comes up as what happens when heat is applied to the mixture.
Will it separate or does it form a third gooey compound.
Bruce
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Bleeding out the DOT 5 [message #250426 is a reply to message #250415] |
Thu, 22 May 2014 23:42 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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Thanks Rob.
t
On Thu, May 22, 2014 at 6:42 PM, Robert Mueller wrote:
> Bruce,
>
> Every document I have ever read from any knowledgeable source notes not to
> mix Dot 3, 4, and now 5.1 with Dot 5. Below you will find
> some examples:
>
> http://en.wikipedia.org/wiki/DOT_4
>
> http://en.wikipedia.org/wiki/DOT_5
>
> As far as changing from one DOT 4 to DOT 5 or vice versa, I for one; would
> err on the safe side and disassemble, flush, clean; and
> dry the system completely to make sure there was no residual fluid left
> anywhere.
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Bruce Hart
>
> The question comes up as what happens when heat is applied to the mixture.
> Will it separate or does it form a third gooey compound.
>
> Bruce
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: [GMCnet] Bleeding out the DOT 5 [message #250757 is a reply to message #250426] |
Tue, 27 May 2014 16:42 |
GMC_LES
Messages: 569
Registered: October 2009
Location: Montreal
Karma: 0
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Senior Member |
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My experience with converting to/from DOT 5 is similar to Roy Keen's. I've had several vehicles that I converted to DOT 5, and whenever possible, I've always done a complete teardown, cleaning and re-assembly of the systems prior to adding DOT 5. On the vehicles where I just did a flush, I didn't detect any difference in performance, but I had previously done a flush with a DOT 3/4 fluid several weeks before the conversion as a first step. The reason is explained below.
When I first obtained some DOT 5, I contacted the manufacturer and asked about mixing or flushing without a full teardown. I was told that if the old DOT 3/4 fluid was not moisture laiden, that there were no problems with performing just a flush. The problems begin when the old fluid contains excess moisture. Doing a flush does not remove 100% of the old fluid and any that remains will migrate to the end points of the system such as wheel cylinders ans calipers. This old moisture laiden fluid can then cause corrosion, and severely lower boiling points. DOT 5 will float on top of DOT 3/4, so without lots of turbulent flow, it is very hard to get all the old DOT 3/4 out of a system with a flush.
I have seen suggestions online that say to use an alcohol flush to remove the DOT 3/4 fluid, then follow with compressed air and a DOT 5 flush. Alcohol is also hygroscopic, so I wouldn't use it for the same reason as specified above. We can't be sure that we have removed any reminants unless we fully dis-assmble the system.
For converting from DOT 5 to a DOT 3/4 type fluid, My personal opinion is that any remaining DOT 5 won't cause an issue, but I am not a chemist that is well versed in what the long term effectas could be.
A partial dis-assembly of calipers, wheel cylinders and master cylinder for cleaning would be the minimum if you need to be sure.
Les Burt
Montreal
1975 Eleganza 26ft
A work in Progress
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