Hi, I have had my Bypass wired open for the last year or so due to the rattle issue. I've just had the engine out service and got a friend to engineer a bracket and lock nut so that the butterfly doesn't fully close. This has fixed the rattle, but I have a question on the valve operation. Having took the car out for a blast, I stopped and checked the valve and was surprised that the valve was in the open position (vacuum applied). Switching the engine off, the valve slowly closed over about a minute. I restarted the engine and the valve remained closed. If I rev the engine the valve opens and then at idle starts to close again but very slowly (over a minute). Is this normal? I thought that the valve would shut off much quicker than this. I have checked the vacuum line and it looks fine. I know the tension on the valve is correct. Cheers
The valve should close rather quickly. Probably less than a second between open and closed if I had to guess. If you remove the vacuum line from the actuator and open the valve by hand does it quickly return to closed? If not it sounds like it is dragging/sticking mechanically.
Thanks... If I pull the vacuum hose the valve closes immediately. Its not catching anywhere. Looks like the vacuum is incorrectly being applied when the engine returns to idle. One thing I noticed is that once I pull the vacuum line to shut the valve and then reconnect the valve stays shut until I rev the engine. Any ideas anyone?
It's possible that the solenoid which controls the valve is leaking (never seals closed) and holds the valve open. Once you pull the hose the vacuum reservoir pulls in ambient air through the valve depleting all vacuum so the valve does not immediately re-open when you re-connect the line.
Rifledriver - I think your right. The Bypass valve is currently connected via a 15 cm plastic pipe direct to the main metal pipe that runs between the two manifolds. There is a small bore metal pipe (about 3 cm long) that T's off from the wider metal pipe. I thought the bypass would be connected directly to a solenoid . I'm sure that before the garage wired the bypass open the vacuum pipe was not connected in this way. Could anyone tell me where the bypass gets its vacuum from. PS . this is a UK car
The bypass valve does connect to the metal tube. Then if you look at the vacuum lines over to the right, you will see two hoses. One connects from a vacuum control valve to the metal tube. The other goes from the other control valve up to the motor. It sounds like your control valve may be bad, so you always have high vacuum.
My bypass valve takes about 2.5-3 seconds to close as the system is wired, and less than 1 second if the vacuum line is pulled. At my last major I took pains to make sure all the components were lined up just right for low friction operation opening and closing (i.e. no rubbing.)
Thanks everyone. http://www.eurospares.co.uk/userImages/003/Large/003_008.gif I noticed this morning that pipe 35 was not connected to the steel tube. Now that this is connected, the bypass opens when I rev the engine and stays there for good. A couple of times I notices that after a few minutes at idle the valve snaps closed all of a sudden. Investigating further, it looks like someone has been doing some replumbing. The canister has only one pipe connected and the other connection has been sealed with sealant (looks like this connector may have snapped at some point as its only 5mm long) . It also looks like a Y connector has been added. The bottom of the Y is piped to the left solenoid, the other leg goes to somewhere in the centre of the engine. I am really confused. Has anybody got any pointers as to why this has been done. I guess this is why the its not working. Also, if anyone could explain how the vacuum system works I'll feel more comfortable trying to resolve. I really appreciate all your help Image Unavailable, Please Login
Hi Guys, The other connection to the vacuum canister has just snapped off as I tried to remove the pipe - the plastic had perished. However if I clamp off the pipe that went to the canister, the bypass valve opens under load and closes at idle. I assume the canister is there to provide vacuum storage. So whilst I wait for a replacement canister is there any problem driving. Will the bypass close unless I'm accelerating and is this a problem? Cheers
Thinking about this a bit more, I am thinking that the solenoid for the bypass is stuck open thus vacuum always applied. Now that the tank is out of the equation, the bypass opens and closes based purely on the engine vacuum coming and going. When the tank was connected, the valve remained open as there was always vacuum in the tank. Does this make sense? Could I swap the two solenoids over to test this ?
The solenoids are the same so you could swap them for testing purposes. Have you looked at the electrical contacts for these solenoids and in the connectors themselves? They seem to have a higher rate for "growth" or corrosion than some of the other electrics on the car. This is something I'd look at first, especially in your location.
I have just pulled both pipes from each solenoid and attached a hose to blow through. I could blow air through both solenoids with the ignition on or off. I was expecting that the valve would be closed not open. Is this correct or are both solenoids broken? cheers
sounds like the bypass valve is mechanically ok. It also sounds like the vaccum lines and tank are ok. Take off the OEM solenoid valve and test it by applying 12 volts to it. Connect up some tubes to the solenoid valve, and suck on the tube that goes to the vaccum tank. You should not be able to suck air through it. Now apply 12 volts, and you should be able to suck air through it now. Remove the 12 volts and now suck on the tube going to the bypass valve, you should be able to suck air freely through the pipe. I did this test with my solenoid valve and found it to be faulty.
Thanks guys. Done a few more tests this morning. I repaired the vacuum can and refitted with correct pipework. With this configuration, the bypass opens but does not close as before. I then swapped the solenoids over and now the bypass will not open at all regardless of revving. I checked the voltage to the solenoid and its only 6 volts. Revving the car made no change to the voltage. So there is a difference between the two solenoids. The original one seems to be stuck open. But from the comments so far, I should have seen 12 volts. The car was warmed up before I carried out the voltage tests, but could there be another reason for the voltage no changing. It looks a nightmare to trace the wires back - any advice what I should try next Cheers
take off the solenoid valves and do the tests. Make sure they are working properly. When i changed my bypass valve to the capristo one, it came with a different solenoid valve. I tested this one and it worked exactly how the oem one should, except opposite ie 12 volts = closed, 0 volts open.
I'm having the same problem with the valve getting stuck open after revving, did replacing the solenoid fix the problem?
