Squishy brakes after m30 swap.

[Doughnut]

So my brakes are squishy after finishing my m30 swap, this is my brake check valve:



(old m20 one)

What check valves do you guys use?

Help would be much appreciated.

[euroshark]

That one should work fine. Make sure it works and make sure you have the correct reinforced hose since cooling or hose hose can collapse under vacuum. If everything appears to be in order there I'd look at brake hoses if they have not been done recently, and of course the master cylinder.

Edit: That's funky looking. Usually the check valve is just in-line. What's the second loop for?

[Doughnut]

Edit: That's funky looking. Usually the check valve is just in-line. What's the second loop for?

That is the valve that I'm using currently, and it does not work.

That particular check valve is from my old 1984 2.3l m20 (l-jet) engine. What is the part number on your single in - out check valve euro? Gimmi part numbers?

[euroshark]

12 NON-RETURN VALVE 1 05/1982 34331151532 $14.08

That's the part number for the 6 series valve that I used.

[Autobahn Sport]

Even so, if your brakes are "squishy", you have something else going on. Did you drive the car prior to the swap?

-Joe

[euroshark]

Quite true, you should probably check your master and your flexible lines.

[Doughnut]

Nope brakes were fine before swap. (no air was induced into the brake system either)

I drove the car out of the shed with no brake check valve and the pedal sprung back out fine, even though it was very heavy to depress.

I have done this to the valve (for now) removed top hose (off black top section of valve, which used to go to the intake boot on the old engine) and the pedal springs back fine now.

Germans and their over engineering ftl :(

[Doughnut]

So, is this what your check valves look like for the m30 swap? If so, where do I connect the other end of the small hose (blue arrow) on the b35 engine?



Yep, I'm still running that old check valve...

[SoopaGhetto]

you tried bleeding the brakes? if the brakes are "squishy" doesnt that mean you are getting sufficient vacuum to assist your foot during brake depression? i have squishy brakes now; i found out i have a leak in one of my brakes.

[E30SPDFRK]

So, is this what your check valves look like for the m30 swap? If so, where do I connect the other end of the small hose (blue arrow) on the b35 engine?



Yep, I'm still running that old check valve...

That is the one I am using and it works fine. The little vacuum hose looking thing is just a plug- it's not connected to anything.

[canyoncarver]

keep it simple, any generic vacuum brake booster check valve will work, as "euroshark" mentioned, its best to use reinforced hose to prevent collapse under vacuum. a short length from the vacuum port on the b35 manifold to the booster is all thats necessary............

"squishy" sounds more like air in the lines than a booster issue...tried bleeding the brakes again ?

[Doughnut]

That is the one I am using and it works fine. The little vacuum hose looking thing is just a plug- it's not connected to anything.

Thanks for confirmation mate!

"squishy" sounds more like air in the lines than a booster issue...tried bleeding the brakes again ?

Yeah, reason why I say it's this valve is because with no check valve (no vacuum to booster) the brakes, although hard to press, work fine I didn't crack any bleeder nipples while I did my swap and nothing seems to be leaking. Also the brakes were fine before the swap aswell.

Any more ideas are greatly appreciated, I'll get the proper valve. (one pictured)

[Kerrath]

Does it creep down when you're at stops? Like if you try coasting forward a bit (if it's an auto) does the pedal descend? If that's the case then your MC is probably bad even if it still works most of the time. (Happened to me.)

With your engine off, press the brakes. After you purge the vacuum from the booster, if the brakes are still squishy, you've probably got a bit of air in the system even if it's almost nothing. (Happened to me after I bench-bled the cylinder and installed it.)

Could also be a bad slave cylinder but only if the pedal doesn't build resistance if you let off lightly and press again.

I'm using an M50 booster line which is straight line with a valve. Before that it was just a tube with no valve. I feel like the valve keeps the vacuum in after the engine is off, but kinda hazy on recall of what it was like with the straight line.