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Clutch Fluid Flush

17K views 16 replies 10 participants last post by  FJ-6MT 
#1 · (Edited)
I was checking under the hood the other day and saw my clutch fluid is looking pretty dirty. My FJ is about 4 1/2 years old so I figured it could use changing. Brake fluid absorbs water from the atmosphere and that water will cause any steel in the system to rust. That's why I think it's a good idea to change brake & clutch fluid once in a while.

I was surprised when I did a search (on here and google) and didn't find any info on how to do that on an FJ so I thought I'd share how I did mine. If I've just missed something or if anyone knows a better way, please let me know.

First thing I did was use a vacuum pump to suck all the fluid out of the resevoir and clean the inside. It was filthy. After that, I refilled it with new fluid.

Next, underneath the FJ, if you look just above the front driveshaft on the clutch bellhousing, you'll see a slave cylinder bolted on. It has a 10mm bleeder screw just like on your brakes so if you know how to bleed brakes you're set right? Well, maybe.

At first, I used the vacuum pump to try to pull the new fluid through but it wasn't coming through very easily so I closed the bleeder and had my wife come out and push the clutch pedal down while I cracked the bleeder open and plenty of fluid came out. I tightened the bleeder as the flow slowed down and thought everything was good now. That's when my wife said, "Oh great, the clutch pedal's just sitting on the floor now."

In my several years of marriage, I've realized this is the time to act like nothing's wrong. I think I just let some air into the system when I couldn't get fluid to come out of the bleeder. So, I had her pull the pedal up (it will stay up by itself) and tried again with the vacuum pump. This time the fluid came out much faster. I guess all the debris clogged something (bleeder screw probably) and using the pedal forced it out?

Anyway, keep a close eye on the resevoir while you're pulling fluid through. It doesn't hold much and will run out quickly.

After refilling the resevoir a couple times, the fluid coming out looked clean so I closed the bleeder and the clutch worked fine again.

That's all there was to it. Hopefully that helps someone out.
 
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#4 ·
Every hydraulic clutch I have ever bled has been a two person job

Me underneath getting all dirty, a clean person - preferably a woman - shoving in the clutch pedal and then pulling it back up again

I also love how most woman think we actually know what we're doing!
 
#7 ·
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Brake fluid absorbs water from the atmosphere and that water will cause any steel in the system to rust. That's why I think it's a good idea to change brake & clutch fluid once in a while.
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That's true, but there is a brake fluid that does not absorb moisture. This would be silicone brake fluid (DOT-5). A great deal of the classic car guys use it (mainly because of the infrequent use of most of these types of vehicles). It also has a very high boiling point and it won't damage the paint job on your vehicle if you get a little sloppy.

I have been using DOT 5 silicone in every car I've owned since the late 70's. You don't even have to totally flush a system. I have, in some cases bled out most of the old stuff, while in other cases, I've just topped up a DOT-3 filled system with silicone. Cars serviced by me in this fashion have stopped perfectly from speeds well over 100 mph (drag strip stuff). I've never had a stuck caliper (or wheel cylinder) piston since making this change universal in all my vehicles (especially in cars stored for long periods of time).

I haven't had the chance to research the type fluid used in our FJ's. Is it just the old standard DOT 3 stuff ?

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#9 ·
DOT 5 may be ok for a clutch, but how would it work with the electric assist power brakes, traction control, and ABS of the FJ? DOT 5 is compressible that may confuse the electric assist
 
#11 ·
DOT 5 may be ok for a clutch, but how would it work with the electric assist power brakes, traction control, and ABS of the FJ?
I stayed with DOT 3 for a few reasons.

1. I have an extended warranty so I don't want to go against the owner's manual recommendations.

2. Flushing every few years isn't hard or expensive.

3. I've read that DOT 5 is not compatible with ABS and I'd rather just use one type of fluid in the FJ.

4. I've also read that when converting to DOT 5 you should completely disassemble the system and clean out all traces of DOT 3 or you'll risk formation of sludge in the system.

I guess you could use DOT 5.1 which is compatible with DOT 3 but there don't seem to be many advantages to it.
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I was never wondering about silicone fluid for the brakes in an FJ, only for the clutch fluid because the OP was concerned with moisture in the hydraulic clutch system (which is a ridiculously simple system compared to the elaborate brake system on these trucks).

Certainly the old classic vehicles I mentioned don't have anything resembling ABS (heck, most of them only have drum brakes at all 4 corners). In these applications I have no reservations whatsoever about silicone fluid in the brake systems. The advantages here vastly outweigh the disadvantages. The majority of members in the couple antique car clubs I belong to all use it with no horror stories ever having surfaced.

Also brake fluid specs are covered in detail in Federal Motor Vehicle Safety Standard section number 571.116 (part of the Code of Federal Regulations). Sub-chapter S6.5.4 addresses miscibility, specifying that the fluid being tested must mix with a standard type fluid, and this miscibility test applies to all DOT 5 fluids (can't gel, swell cups, etc.) when mixed.

Dow-Corning, the leader in silicone brake fluids (only true USA manufacturer ?), did a detailed study 30 years ago. One of the tests included a system that was swapped from DOT-3 to silicone, with the intent of leaving a significant portion of the original DOT-3 fluid still in the system. The tested system passed all the DOT test specs easily.

I agree about the warranty issues. As long as my truck is under a warranty I'd just stick with whatever the manufacturer says (esp. considering the cost of repairs). However, after that, if I find that moisture is a culprit in the clutch fluid, I'd certainly try out a different fluid.

A further item of interest is the fact that U.S. armed forces have made standard the use of silicone brake fluid since the 1990s. I wish all the auto manufacturers would have done the same. This would have eliminated the need to F&F fluids unless the system has been disturbed (ie: component replacement).

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#10 ·
I stayed with DOT 3 for a few reasons.

1. I have an extended warranty so I don't want to go against the owner's manual recommendations.

2. Flushing every few years isn't hard or expensive.

3. I've read that DOT 5 is not compatible with ABS and I'd rather just use one type of fluid in the FJ.

4. I've also read that when converting to DOT 5 you should completely disassemble the system and clean out all traces of DOT 3 or you'll risk formation of sludge in the system.

I guess you could use DOT 5.1 which is compatible with DOT 3 but there don't seem to be many advantages to it.
 
#12 ·
Reviving a really old thread I know but for anyone that sees this, I just moved to a new home that has a proper garage so I took as a task to go over the truck and do a bunch of things I have been neglecting to do because I had no place to work on it.

With that said, I flushed the clutch fluid this weekend and what a difference!! Old fluid was filthy and honestly looked pitch black like coffee (had not changed it since I bought the truck in '09). I also noticed that a problem I was having with the clutch got fixed. I thought I was going to need a new clutch given that early in the mornings when engaging 1st, the truck would be all jumpy; like as if the clutch was slipping.

Well I do not have that any longer. It now starts rolling without issues and without slipping. I also noticed that the system had a bit of air as few bubbles came out when I opened the bleeder.

Thought I could post this in case anyone else has this or similar issue.
 
#13 ·
... when I opened the bleeder.
Since this is a job that should be done every few years, there must have been many people here who have bled the clutch line. How exactly do you open the bleeder? What tool specifically?

I've tried several 10mm combination wrenches - the don't fit in the area due to the clutch cover. I've tried to get a deep or regular socket on the bleeder - there just isn't quite the room needed at the angle that the bleeder screw. Today I bought a 10mm offset wrench - it will get on the bleeder screw, but won't turn because there is no space to turn the wrench when it is engaged on the bleeder screw

The service manual just says "Bleed clutch pipe line" and that is after the manifold stay and the no.1 clutch housing cover is put on. The bleeding is the last step with everything assembled so it is clear that it is intended that the clutch can be bled with everything in place but I can't seem to get a tool to work on the bleeder screw.

Twice I've paid the Toyota to change the clutch fluid and when I get the FJ back, the reservoir fluid looks brand new, but the dust cap on the bleeder screw looks untouched so I'm pretty sure that they didn't bleed the line.

Is there a special service tool that is specially shaped to reach? The service manual references 09023-00101 to fit the pipe fittings but this is just an line wrench to socket adapter. I don't think it would work on the bleeder. The Toyota special service tool website doesn't seem to show a special tool for this.

What is everyone here using to bleed the clutch line when doing a clutch fluid change?
 
#16 ·
Changing the fluid is the best way to help prevent corrosion in the system, which will lead to having to replace the parts.

Using a turkey baster will help, but the moisture in the fluid will be at the master and slave cylinders, so after turkey basting and refilling with fresh be sure to flush out what's left in the system so its clean all of the way through.
 
#17 · (Edited)
For brake and clutch fluid replacement, I use a 60ml syringe with a piece of 1/16" ID 3/16" OD silicone tubing attached. This makes it easy to extract the fluid and really get into the corners to get all of it. I do change the clutch fluid in the reservoir from time to time if it is discoloured at all so the fluid and the reservoir stays fresh and clean. I think that most of the moisture ingress would be at the reservoir. The cap is vented and the reservoir is plastic and plastics are permeable to water over time. I believe that replacing the reservoir fluid regularly is better than doing nothing and there would eventually be some mixing of the rest of the fluid due to diffusion so there should be some improvement to the fluid quality further down.

I still would like to bleed the fluid right through to the clutch cylinder so if anyone has a good suggestion of how to turn the bleeder screw without disassembly or the appropriate tool to use, please post it up.
 
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