99 4Runner no brake boost when really cold ?? (1 Viewer)

[Duane]

It was 30 below here the other morning. I drive down the block and first time I apply the brakes it's like I'm pushing on a solid rock of a pedal. Very little give and very little for brakes. A few more pushes and releases and then suddenly the pedal pushes down a normal distance and my brakes are as usual. This has happened to me a couple more times in the last couple weeks now on quite cold mornings.
It's as though I'm not getting any mechanical help from the brake booster or something is obviously sticking when cold.
Has anyone experienced anything like this and know what to look for? Someone mentioned to me a Corolla possibly having a problem with mositure collecting in a low spot in the vacuum line to the booster and freezing.
It does have antilock and is an automatic.
thanks

 

[raydouble]

It was 30 below here the other morning. I drive down the block and first time I apply the brakes it's like I'm pushing on a solid rock of a pedal. Very little give and very little for brakes. A few more pushes and releases and then suddenly the pedal pushes down a normal distance and my brakes are as usual. This has happened to me a couple more times in the last couple weeks now on quite cold mornings.
It's as though I'm not getting any mechanical help from the brake booster or something is obviously sticking when cold.
Has anyone experienced anything like this and know what to look for? Someone mentioned to me a Corolla possibly having a problem with mositure collecting in a low spot in the vacuum line to the booster and freezing.
It does have antilock and is an automatic.
thanks

Does you rig have a vacuum booster w/abs on the pass side fender or is it the hydro boost/abs all in one setup?

 

[Duane]

Does you rig have a vacuum booster w/abs on the pass side fender or is it the hydro boost/abs all in one setup?

vac booster with abs on passenger side... I took the vac line off to the booster and no moisture in there. Higher probability on the abs unit then? Time for a fluid change maybe although to get enough moisture in seems pretty unlikely. ??

 

[raydouble]

I'd be real hard pressed to think it was the ABS or that your brake fluid absorbed enough water to freeze.

I would assume the cold is the issue and a high hard pedal is indicative of a non functioning booster.

I wonder if the rubber diaphragm in the booster is the issue?
Moisture in the booster?

If the engine starts you've got the vacuum to operate the booster (as long as the hose to the intake is clear)

Seems like most the ABS system problems if heard about result in soft pedal or one that goes to the floor.

 

[Duane]

Thanks for the input raydouble. I am of the same thinking as your comments. I asked the local Toy dealer and their oldest techs initial opinion was the booster freezing up.
I had never heard of this happening before nor ever experienced it on any vehicles. I find it hard to believe that a person can get enough moisture into the booster to cause this problem. Then again if people use a power washer maybe..
Maybe I should dig into the booster and how it is built to see if this is a scenario worth checking.
thanks for the help

 

[raydouble]

Thanks for the input raydouble. I am of the same thinking as your comments. I asked the local Toy dealer and their oldest techs initial opinion was the booster freezing up.
I had never heard of this happening before nor ever experienced it on any vehicles. I find it hard to believe that a person can get enough moisture into the booster to cause this problem. Then again if people use a power washer maybe..
Maybe I should dig into the booster and how it is built to see if this is a scenario worth checking.
thanks for the help

I can't remember can you just pull the check valve out of the booster?

I was thinking you could dip something into the bottom and see if you have a little puddle at the bottom.

 

[Duane]

I can't remember can you just pull the check valve out of the booster?

I was thinking you could dip something into the bottom and see if you have a little puddle at the bottom.

I'm not sure what check valve you referred to?
I think the booster is basically a can with a diaphragm in the middle and a shaft running through it to connect the master cylinder spools to the brake linkage in the cab. I'm thinking that short of removing the master cylinder and then the booster off the firewall I might try getting a small flexible line through/into the vacuum fitting on the master cylinder side to see if I can pull any fluids up with a vacuum.. a small hose as a stinger to try lifting fluid out of the bottom of the booster.
Or I was thinking drill a small hole on the bottom of the booster and plug it after.. maybe not I'd better sleep on it before i get any more lame ideas.

 

[raydouble]

I was thinking if you can get the plug check valve thing out of the booster pic below, but I'm not sure if it comes out....

I wouldn't go the drill route ...probably not the safest thing.

 

[Duane]

I was thinking if you can get the plug check valve thing out of the booster pic below, but I'm not sure if it comes out....

I wouldn't go the drill route ...probably not the safest thing.

Yep sort of kidding on the drilling idea.. guess I shouldn't as somebody might think.. "what a great idea"
I'll look into the fitting where the vacuum line connects onto the booster.

 

[raydouble]

Yep sort of kidding on the drilling idea.. guess I shouldn't as somebody might think.. "what a great idea"
I'll look into the fitting where the vacuum line connects onto the booster.

I figured but....you know.
I'll be interested to find out about the valve.

lol....wookies

 

[Duane]

lol....wookies

Yes I foolishly asked the mud gods quite a while back as to how long one keeps the rookie status... and therefore some clever chap gave me the "wookie" level now.

 

[Geckeo]

Same problem

Duane. I have had the same problem that you have described. I live in saskatoon and I only get this issue when it is -30 or colder. I would be very interested to know what you did to solve the problem.

i will keep an eye on this thread.

 

[96r50]

The brake booster check valve freezing up in low temperatures seems to be pretty common in a lot of Toyotas. Usually replacing the check valve (not the whole booster) solves the problem. Mine only does it when really cold, and I keep forgetting to buy the valve.

 

[raydouble]

The brake booster check valve freezing up in low temperatures seems to be pretty common in a lot of Toyotas. Usually replacing the check valve (not the whole booster) solves the problem. Mine only does it when really cold, and I keep forgetting to buy the valve.

So the check valve does pop out of there......I was hoping so, Good info.

 

[Thuri]

Add Another too the list, my 2000Runner does this in cold temps, hadn't thought much of it as a few pumps usually 'warms' her up. but will be following this thread if there's an easy fix.

 

[Duane]

The brake booster check valve freezing up in low temperatures seems to be pretty common in a lot of Toyotas. Usually replacing the check valve (not the whole booster) solves the problem. Mine only does it when really cold, and I keep forgetting to buy the valve.

I have not fixed my problem as of yet. So this check valve is the part that raydouble circled in red in the picture above? Basically the part that the vacuum line attaches to on the booster? I should look at my 96 as it has never done this even down to - 40

 

[Sno bored]

I would say brake check valve too. There was a thread in the 80 section where people were having the same problem.https://forum.ih8mud.com/80-series-tech/346354-brake-line-freeze.html. I just push on my brake pedal a few times while my truck is warming up in the driveway, and it's good to go.

 

[pepsilvr]

Same problem on my '97. It only happens if it is near or below 0 degrees F. I just wait a minute and give it a couple pumps and it's fine. At least my accelerator pedal doesn't stick too

 

[SteveH]

My '98 is doing this at 0 or below. If the problem is moisture, why not dry out the check valve, rather than replacing it? I also may put a dropcord light beneath the booster, with the valve removed, and see if I can't drive some moisture out of the booster housing (if that's an issue).

 

[Duane]

Well SteveH maybe that will work ???
I only had this one 99 that did this to me. I live in a dry climate so any moisture should be dissipating I would think.

At any rate I sold this 99 to friend of mine and he currently has a new check valve ordered to try as it has left them without brakes a few times this winter.

I will post up if this remedies the problem.