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

[Duane]

Well my friend has recently changed out this check valve assembly and had several days in the - 20 deg C range ( -4 deg F) and no more problems for now.
Hopefully this is the fix.
This removed check valve looks fine and I suppose I will hang onto it until next winter is over to see if it did fix the problem for sure. Then I might take it apart to see what is really inside this thing. There are at least 7 parts which look to be mostly pressed together made of at least 4 different materials.

Our 96 has never done this so I wonder if theses assemblies were different for newer model years or what.
What are the years of the vehicles you guys have experienced this with? 99, 2000 and any other years?

 

[bkg]

interesting... my Lexus IS will do this from time to time when first started... 30 seconds later it's fine. Young car, low miles... always thought it odd. Might have to try this fix.

 

[Gerdo]

I had this issue last year. It was the check valve. Replaced it and haven't had any problems since.

 

[fyaajster]

Yep! happen to my 98 4runner as well.
Question do you use any special tool to removed the check valve, can you write a how to or show some photos of how to remove.
Thanks

 

[smokey0066]

my '00 has done it for the last 3 yrs or so. It usually only happens after work when my truck has been sitting outside for 8+hrs. I will be picking one of these up before winter hits!

 

[SteveH]

Can I just pull the check valve, and place it in warm sunny spot for 8 hours and dry it out? Is the failure due to moisture in the valve or a worn-out valve?

Mine has frozen several times.

 

[Duane]

My friend had the dealer replace it so I'm not sure how it comes out.
I wonder if anyone has had this problem since new or after quite a while. ??

 

[Kroll]

Wow, just stumbled upon this thread...

I had this exact issue happen in the 2000 4Runner, last winter when the vehicle sat outside in -30C weather for 6+ hours.

 

[jacklany]

97 runner. I live in Montreal Qc, so it's basically minus one thousand every morning for 7 months a year here. Issue happens every day when I start it up to go to work.

 

[haryv]

sounds like a famous design defect "did Toyota test these trucks in these temperatures? I guess not"

I imagine the part is pretty inexpensive. Good info for me to know if I have a call from some one with the same problem.

 

[Duane]

Yes my friend who bought my black 99 4Runner changed this out late last spring. We recently had a week of very cold temperatures and he reported no problems.

The wife mentioned our 2000 did something odd the one day so I am thinking I will be getting a new check valve installed on it as well. Oddly enough our 96 has never done this..knock on wood.

I wonder how many accidents this little sticky part has caused?

 

[drcoffee]

WD40 is a water disapator lubricant. Has anyone tried just squirting some in the check valve to lube and clear the water?

Its usually safe for most rubber and seals.

 

[CodeMan47]

Me too

I have this same issue with my 97 in MN... only when below 0
Anyone ever decide for sure if it's caused by a faulty valve or moisture and/or replace the valve on their own?

 

[Jetboy]

My 96 4runner does this very rarely. So it does happen on older ones too. It has probably done it 3 or 4 times in 5 years, and only when outside overnight in cold weather and not every time. Usually by the second push of the pedal it's back to normal.

 

[CodeMan47]

That's how mine was, but the last few days (very cold) have been worse. When sitting for about 4 hours at work, if I forget to warm it up before I leave, I can end up driving a mile or more before it starts acting normal.
I try pumping the brakes, but it seems to have to warm up quite a bit before acting ok.

 

[drcoffee]

My 96 4runner does this very rarely. So it does happen on older ones too. It has probably done it 3 or 4 times in 5 years, and only when outside overnight in cold weather and not every time. Usually by the second push of the pedal it's back to normal.

Im sure you know this, but it is not affected by pumping the brake pedal. The vale is on the booster and until the ice inside thaws, the valve wont open to the vacuum source.