CCKW GMC 353 Brake Fluid

[JB506]

Hello everyone

Need to pick someone's brains regarding brake fluid for the Jimmy. There are mixed reviews/opinions on what is best to use, silicon or normal brake fluid(the truck currently has silicon in the system).

Any advice on this would be greatly appricated.

Many thanks & kind regards

JB

[John V Cliche]

My opinion.

If you currently have "silicon" stay with it

I have vehicles with both types....and to be honest those with silicon have been trouble free since 2001....the one with "regular dot 4" is a source of constant attention, ( but that may also be to design issues as well )

I'm sure opinions vary
Hope this helps
John

[JB506]

Many thanks John, that is helpful to know.

The truck has also been standing for 6 months, would you advise draining the system and replacing the fluid, or would you say it will be fine just being topped up?

I must say, the brakes did work very well and survived a very long drive through the UK without any problems a couple of years back.

Thanks again

Jason

[John V Cliche]

I believe silicon fluid should be flushed and changed just like the "regular" stuff anyway.
So why not do it now and be done with it for a couple of years.

The plus side of silicon is it won't absorb moisture...that doesn't mean moisture doesn't get into the system....instead of mixing with the fluid it simply stays on top.....and that's where the rust,pitting will occur....so flushing is still a required element of PM

Hope this helps
John

[JB506]

Many thanks for that, it certainly does help.

Just one other thing i forgot to ask, what fluid would you use? we have access to various types, Dot5.1, Dot 4 etc?

thanks

Jason

[John V Cliche]

I think dot 5 is similar to silicon...but you can get silicon in gallon quantities from several vendors that advert. is SL and MVM
Dot 4 is what I use as the "regular" stuff.
Being across the pond you should also have a source for IIRC a Castrol product made specificly for Rolls Royce ...it is gentle on ALL rubber parts and most important PAINT as well.I have tried unsuccessfully to purchase it here.(stateside)

hope this helps
John

[JB506]

excellent, thanks. I'll have a hunt around to see if I can find any of that here.

Many thansk for your advice.

Best regards
Jason

[LITTLEWOOD]

How much brake fluid is needed to flush the system and then fill? This Dot 5 Silicone is scary expensive!

Thanks James

[John V Cliche]

Adirondack Dodge parts is advertizing $30.00 gallons of silicon brake fluid in MVM
I'm guessing by the time you've done all the fittings on your CCKW you should have bled out about a quart of old fluid in your jar/bottle...or about $7.50.... plus shipping of course
I don't consider that to expensive even if you push 2 quarts thru.

Hope this helps
John

[Nick Bombini]

I think dot 5 is similar to silicon...but you can get silicon in gallon quantities from several vendors that advert. is SL and MVM

hope this helps
John

The DOT 5 I buy says silicon on the front of the bottle. I get it from NAPA auto parts at $125/gallon. I'll have to check out some of the dealers for the $30/gallon stuff. I use silicon because that's what was in the truck when I bought it.

--Nick

[dr deuce]

One important point to remember:

Hydrovacs fail. Usually the first way they fail is to start leaking brake fluid into the vacume system which means the motor will "eat it".

A chemist friend of mine told me that when you burn silicon you get basically sand....

An M35 with an airpak does not have this problem

[LITTLEWOOD]

The website that John mentioned is http://www.adirondackdodgeparts.com/prod1.htm it sounds very cheap for silicone but if it works and they will ship to the UK I'll take 2 gallons

1 Gallon of DOt 5 here is £130 so about $188!!

Jason and I are working on the same truck, we took the drums of today and the lining are line new one of the slave cylinders on the rear most wheels will not adjust on one side, the truck prior to stripping braked fine so I think we will leave alone unless you guys think it should be sorted? Also one of the drums was smooth without the rings is this post war?




Thanks James

[dr deuce]

Release the return spring, wire the wheel cylinder cups together and unbolt the wheel cylinder and let it just hang down so nothing is interfering with the adjuster.

Lube it with penetrating oil and let it sit for 24 hours.

GENTLY try to move is a little back and forth. If it will not move, apply a little LITTLE heat.

You will need that adjuster some day and the longer you wait, the more of a problem it will be.

When I do my twice annual grease job, I move all of the adjusters back and forth just to keep them free.

[John V Cliche]

The website that John mentioned is http://www.adirondackdodgeparts.com/prod1.htm it sounds very cheap for silicone but if it works and they will ship to the UK I'll take 2 gallons

I attend several MV events during the year ( The first being Aberdeen )there are always several vendors selling gallons of silicon fluid in the $30.00 price range.

I'm a firm believer in fixin' it right the first time so take car of that adjuster now, cause sooner or later you're gonna wish you did ( probably on the side of the road somewhere )

John

[Fernando Mendes]

At the suggestion of RAM, one of the more knowledgeable MV Experts in the US, We are just two old Farts that have been around GI Trucks a bit, and kept our eyes open, it was suggested I flush the Brake Systems of my 2-1/2 Ton Trucks with Power Brakes. I was surprised at the brown sludge that came out. It is now a 3 year ritual. Whether you use DOT-3 Conventional, or DOT-5 Silicone, you will have similar crud. These systems "breathe" and are subject to condensation, and it has to settle somewhere. Yes, silicone Brake Fluid can be a victim of condensation. Think about it, where is the water going to go? It will puddle in the low spots in the system. Same goes for your Jeeps, too.
Joel
I think it is more one contribution for us.

[Fernando Mendes]

Yesterday I changed all my CCKW brake fluid DOT3(conventional) per brake fluid DOT4(petroleum).I didn't never know about this matter(conventional-silicone-condensation).I thank to this forum for this new knowledgement.

[dr deuce]

With the silicone, you also have the issue of it burning in the engine if the booster starts to leak it (not that uncommon). When the Silicone brake fluid is burned, it creats silica (sand) in your cylinders....