I think my brake booster on my 2000 4Runner is going out. I'm getting a hard pedal after startup, at low idles in parking lots, and pretty soon after I turn the vehicle off. I found some threads where people mentioned to check the vacuum line, check valve, and grommet for the valve. I've done all these and bought a new grommet with no change which leads me to think it's the booster going.

OEM is north of $1K and the Seiken people recommended is only available at a few places for just under $700. Is this the best option these days? I am hesitant to purchase a junkyard part as it's going to be just as old as mine and I hear the aftermarket options are junk as well.

The Seiken part number I found is W0133-1741918-SEK. One amazon listing says it replaces Toyota part number 44610-3D700. It doesn't help that it seems to only be sold mostly on amazon and ebay. I don't normally order parts there.

Some also say check/replace the master cylinder and gasket while I'm doing this swap. If I do that do people have a recommendation for that part as well?

These only seem to fail in places like Az--I immediately thought you were in AZ when I saw this thread before even looking. You could do a used one from somewhere with a more mild climate through ebay or something, or try rockauto. My truck came from AZ and the shop put in some sort of aftermarket one which has been working great. I think the price on my invoice was $465 or so. Good luck!

I’ve been running a Cardone reman for about 5 years with performance equal or even superior to OEM. I may have gotten lucky, as some reviews will say the cardone units are junk.

But for $200, as long as you have a free and easy return policy, it might be worth a gamble to end up with a good one.

Other than that, the seiken is your best bet if you don’t want to fork out for OEM Toyota parts - which do seem a bit overpriced for this particular part.

Thanks to you both. I wonder why the AZ thing is an issue, just hot and dry causes cracking/leaking? I am leaning Seiken even though it's still $$$. I am a little concerned I may also need to replace the master cylinder in case there is a small leak that led to my original failing. I guess I won't know until I get in there. I will get a new gasket for the interface and start with the booster and hopefully that'll be all that's needed.

No need to replace the master pump.


I'd recommend try a used booster from a yard as it is way cheaper. Make sure before you pull it check whether it holds vacuum by pulling some vacuum from the tube going into the intake.

I am a little concerned with this option as the part will be as old as the one I'm replacing. I can get a used one for $100 and the Seiken is $630 plus tax right now (partsgeek is the best price I can find) so the used option is tempting.

Try Cityracerllc . com has brake boosters for 00-02 4Runners. Used one for my 100 and works fine Lots cheaper than dealer ($280) and new See Ih8mud forums

Thanks for the tip but I didn't see any for 4Runners there. They don't mention the brand either. Maybe I'm overthinking this but there have been a lot of threads mentioning aftermarket boosters not lasting long or performing very well which is why I was leaning used OEM or new Seiken which I think is basically OEM.

Look under 100 models and brake booster. They are the same

01-02 use a different master/booster than 96-00. OP has a 2000.