Possible Brake Booster Issue

[d240zx2]

That is as it should be.

[Zs-ondabrain]

That is as it should be.

Which part?

Everything? or the last line?

Dave

[d240zx2]

The last line, Dave, the last line.

[Jennys280Z]

So after Dave and I did quite a bit of electoral work my car is running a lot better. The engine missing is almost completely gone.

Only problem is my engine RPMs are still dropping when I brake, when they start dropping in the 500 area my engine begins to miss.

When I first start the car up and I'm letting it warm up if I push on the brakes i hear a distinct Whoosh/hissing sound. Then my engine rpms drop 100-300. This also happens when I put the car into neutral at stop lights and signs. Which sometimes puts my car into the danger zone RPM wise and stalls the car on occasion.

Does this sound like the symptoms of a failing/leaky brake booster? I never thought anything of the hissing noise until I started searching on here about brake boosters. Couldn't find anyone with the exact symptoms as me and just need a little reassurance before i drop $100 on a new one.

As always thanks for any and all feedback. Hopping to get rid of the last of this running issues so I can finally start on the interior.

I'm having the exact same issue and I see from this thread that it's the brake booster. :paranoid: I seem to have rust on the surface of my brake booster too...where my brand new master cylinder is bolted on. Uggh how messy is this going to be?

I raised my idle to about 900 RPM in the hopes that the extra 100 RPM will keep the motor from dying when I'm on the brakes. I feel a very smooth vibration in the brake pedal when pressing it, hear the same whooshing sound, and my RPM drops 150-200 when I press the brakes. I haven't let the car warm up all the way to see if the problem becomes less noticeable.

I was testing my intake manifold vacuum through the hose that goes to the check valve/booster and this problem occurred soon after doing that. I was wondering if a little bit of twist I was putting on the valve on the other end of the hose I was twisting to remove might have upset it but this is probably wishful thinking at this point

[Zs-ondabrain]

if the smooth vibration in the pedal is while pressing down, your rotors mayneed to be turned or replaced. They may be warped.

One sure way of telling if the booster is bad is to clamp it off with a hose clamp, run the motor, and rapidly press on the brake pedal, (press, release, press, release) if the RPM's hold steady, then the booster is bad. Release the clamp and try it again. If the RPM's raise and lower with each press, then the booster definately shop.

Dave

[torker]

Can you guys tell me if another year booster will work on a 74 260? My son is having problems finding one. Pepboys said it would have to be sent off for rebuild. Seems crazy. I know there are different diameters. Not sure why the auto parts he has been to 3 don't seem to be able to get it.

[Jennys280Z]

Can you guys tell me if another year booster will work on a 74 260? My son is having problems finding one. Pepboys said it would have to be sent off for rebuild. Seems crazy. I know there are different diameters. Not sure why the auto parts he has been to 3 don't seem to be able to get it.

There's remanufactured ones from Centric it looks like...though the warranty is not good. You can opt for an extended warranty from these places but I don't know how much they cost. Still, $93 after the core is refunded is cheap imho.

http://www.partstrain.com/store/details/Nissan/260Z/Centric/Brake_Booster/1974/CE160-dot-88031.html?ptc=S1171391678W45d204bec356b&ptcenissan260z19741974centricce160.8803189384274brbo

[Jetaway]

Can you guys tell me if another year booster will work on a 74 260? My son is having problems finding one. Pepboys said it would have to be sent off for rebuild. Seems crazy. I know there are different diameters. Not sure why the auto parts he has been to 3 don't seem to be able to get it.

According to the Black Dragon catalog, the 1973 through 1978 coupe boosters interchange and the 1974 (first year of the 260Z) through 1978 2+2 boosters interchange. But apparently the coupe and 2+2 boosters do not interchange, even within the same year. So it looks like that at the very least have Pepboys look for one for a 280Z and if you have the coupe model, a 1973 240Z.

Chris

[Jennys280Z]

Early 280Zs were the first models not to have a suggested replacement schedule for their brake boosters. The 240Z especially, had a booster replacement schedule that was crazy short, at least per my '70-'79 Z shop manual.

So if you can buy the 280Z coupe booster, by all means!

[Jetaway]

Early 280Zs were the first models not to have a suggested replacement schedule for their brake boosters. The 240Z especially, had a booster replacement schedule that was crazy short, at least per my '70-'79 Z shop manual.

So if you can buy the 280Z coupe booster, by all means!

When I read this I thought "Huh? Brake boosters as a wear and tear item? Must be writing about something else."

Nope.

The 1972 FSM has a two and four year maintenance schedule for the booster (Master-Vac). I replaced mine about, oh just about two years ago with a remanufactured one from Black Dragon. I have no idea if it is an OEM or aftermarket. Since they somehow figured out how to build a booster that didn't require maintenance within the decade, would aftermarket (or later OEM) boosters incorporate that knowledge and thus now, some 30 years later, not require maintenance?

Chris

[olzed]

Thoughts on brake booster replacement. Iv'e owned my 72 240 for 11 years and havn't had a problem, nor have I ever replaced it. I don't know for sure, but I know the previous owner was not one for maintainenc, so I suspect ,as the booster is at least 20 years old, i'm going to have to do a replacement soon.

I think I will leave it alone and see how long it does last.

Brian.

[Jetaway]

Thoughts on brake booster replacement. Iv'e owned my 72 240 for 11 years and havn't had a problem, nor have I ever replaced it. I don't know for sure, but I know the previous owner was not one for maintainenc, so I suspect ,as the booster is at least 20 years old, i'm going to have to do a replacement soon.

I think I will leave it alone and see how long it does last.

Brian.

I hope I haven't cursed you.

Chris