|
|
|
#1
|
||||
|
||||
Bad "Non-Return Valve, Brake Booster" ?
I have a situation where I have power brake boost right after I start the car and for 2 or 3 brake applications. Then the boost goes away for a few applications, then returns and is fine all day. This problem seems to have come about this winter.
I haven’t done any vacuum pump testing yet, but I wanted to first ask if a sticking “Non-Return Valve, Brake Booster” can cause these symptoms. Because I have brake vacuum at cold start up I think that means it is working fine at holding a vacuum, but can it “stick” and not allow fresh vacuum until it releases for some reason? I'm referencing part #140 below. Thanks.
__________________
1993 W124 300D 2.5L Turbo, OM602.962 2000 Chevrolet Cavalier, 2.4L DOHC 2002 Ford Explorer, 4.0L SOHC 2005 Toyota Prius, 1.5L http://www.fuelly.com/sig-us/40601.png |
#2
|
||||
|
||||
Answer
Generally this is a symptom of a vacuum pump issue.
|
#3
|
||||
|
||||
Then is seems the first thing I need to test is vacuum pump suction when the engine is cold.
__________________
1993 W124 300D 2.5L Turbo, OM602.962 2000 Chevrolet Cavalier, 2.4L DOHC 2002 Ford Explorer, 4.0L SOHC 2005 Toyota Prius, 1.5L http://www.fuelly.com/sig-us/40601.png |
#4
|
||||
|
||||
Quote:
Minimum is 13 inches mercury. Good is 26 - 30 inches mercury. |
#5
|
||||
|
||||
FYI
The vacuum pump was superseded four times.
Need VIN# for correct part.. |
#6
|
||||
|
||||
Here it is:
VIN WDBEB28E1PB901581 Chassis 1241281B901581 Engine 602962 12 016644
__________________
1993 W124 300D 2.5L Turbo, OM602.962 2000 Chevrolet Cavalier, 2.4L DOHC 2002 Ford Explorer, 4.0L SOHC 2005 Toyota Prius, 1.5L http://www.fuelly.com/sig-us/40601.png |
#7
|
|||
|
|||
you could test the non-return valve by cracking open the flare nut on the booster end of the plastic booster-vacuum pump hose. this is when the car is stopped, but you had power brakes before you stopped. there will a decent bit of vacuum left in this line if the non-return valve is good, so when you crack the nut open it will hiss (sucking air).
__________________
________________ punkinfair |
#8
|
||||
|
||||
I should also mention that I can hear my vacuum pump. Not outside the car but only at idle when sitting in the car. It doesn’t sound bad, as if it ready to self destruct or anything like that. It makes a subtle “chu-chu-chu” noise that goes away if not idling. I can’t say I noticed it before but I am wondering now what a new pump would sound like….or can you not hear new pumps at all?
__________________
1993 W124 300D 2.5L Turbo, OM602.962 2000 Chevrolet Cavalier, 2.4L DOHC 2002 Ford Explorer, 4.0L SOHC 2005 Toyota Prius, 1.5L http://www.fuelly.com/sig-us/40601.png |
#9
|
||||
|
||||
Answer
Quote:
MB# 000 230 31 65 Fastlane: Vacuum pump http://catalog.peachparts.com/item.wws?sku=0002303165 Last edited by whunter; 06-07-2011 at 03:54 PM. |
#10
|
||||
|
||||
Answer
Quote:
|
#11
|
||||
|
||||
Took some measurements
Last night when I got home I took some vacuum measurements…
Hot Engine (all measurements - in Hg) 23 @ Vacuum pump 23 @ Non-Return valve This morning I took measurements after starting the cold engine… Cold Engine 23 @ Vacuum pump 23 @ Non-Return valve Some other observations: -When the vacuum gauge was attached to the shut off valve port on the Non-Return valve, and with the engine running, pumping the brake pedal would make the vacuum eventually rise to 10. After ceasing pumping the vacuum would drop back down to 23 again. Is this the correct vacuum pump capacity when at idle? - Using a mechanics stethoscope on the vacuum pump, and with the engine running, I cannot hear any abnormal sounds coming from the vacuum pump. This morning when I disconnected my shut off valve port / hose connection, I could hear air sucking into the port. This seems to indicate the No-Return Valve is doing its job and that the brake booster diaphragm is not leaking. But, driving down my street again this morning (after doing the pumping thing explained above), I lost power assist to the brakes for a few applications. It returned as it usually does. Conclusions so far… I am thinking my vacuum pump is OK unless one of you guys says otherwise. Now I need to test my brake booster. How do I do that? Any other ideas? Thanks for all your comments so far.
__________________
1993 W124 300D 2.5L Turbo, OM602.962 2000 Chevrolet Cavalier, 2.4L DOHC 2002 Ford Explorer, 4.0L SOHC 2005 Toyota Prius, 1.5L http://www.fuelly.com/sig-us/40601.png |
#12
|
||||
|
||||
Answer
Quote:
http://www.peachparts.com/shopforum/showthread.php?t=142411 |
#13
|
||||
|
||||
Lot's of good reading in the "Brake" link you posted.
After reviewing the threads, it was clear it needed to be verified that the master cylinder was not leaking fluid into the booster. 1) The fluid on reservoir is not dropping. It has not moved appreciably since the brake lines and pads were replaced this summer. 2) To verify #1, the vacuum line was removed from the booster, a thin tube was inserted down the port to point near the bottom and a vacuum drawn on it the tube with a MityVac. No fluid was drawn out. 3) The Non-Return valve does hold a vacuum in the booster. But it should let air flow past it towards the vacuum pump it seems. Blew on it but could not get any air past it. Tried again and air easily went past the valve. Tried again and nothing. Could the Non-Return valve be the problem? Next step is to build a tee fitting to place between the vacuum line and the booster to verify the condition of the Non-Return Valve. Has anyone built one and would share the fittings needed to do this? Thanks!
__________________
1993 W124 300D 2.5L Turbo, OM602.962 2000 Chevrolet Cavalier, 2.4L DOHC 2002 Ford Explorer, 4.0L SOHC 2005 Toyota Prius, 1.5L http://www.fuelly.com/sig-us/40601.png |
#14
|
|||
|
|||
Any luck???? What did you end up doing?????
__________________
92 300D 2.5L OM602 OBK #59 |
Bookmarks |
|
|