View Full Version : Stuck Boost bypass valve?

12-10-2006, 11:05 AM
I think I have an issue with the boost bypass valve sticking closed. I have noticed this when the outside air temperature is below 35F. Typically I hear pressure surges shortly after releasing the throttle as if the boost bypass valve is remaining closed for a minute and then releases. The last time I inspected the boost bypass valve (mid summer this year) it was clean (removed the intake plenum when I cleaned the throttle body). This time around I am considering using seafoam and let the idle draw in the chemical through the PCV line. If the fins on the intercooler are in the same condition my throttle body was, does anybody think that seafoam would work in cleaning the intercooler out? I would sure hate to remove the supercharger to do that.

I am wondering if it is the actuator motor and not the valve that is sticking.
The vacuum line connections to the actuator motor are in the stock arrangement as well as everything else except for the cat back. Any idea what could be the issue?

12-17-2006, 12:41 PM
Took a gamble and decided to use seafoam through the PCV valve. Surging noise now gone. Noise was similar to when you shut the motor off. May not have been the boost bypass valve afterall. Everythings is back to normal with a bit more response from the throttle. I did not see any smoke from the exhaust as many others that have used seafoam have reported. I let it cool down for at least 40 minutes before starting it up again. Headed out to the highway and then back again. Got a strange request from a passenger in one of the cars I passed after I slowed down from a quick punch of the throttle, she asked me if I could do it again. :D When changing the oil I decided to install the new clutch cable I had bought when I picked up the car after the clutch replacement. Noticed somethig not good all over the transmission case, transmission fluid. May need to take it back to Ford and hopefully just have the input shaft seal replaced. Fluid was everywhere inside the bell housing :( funny that the clutch was not slipping.....until after I replaced the clutch cable. :rolleyes: . Should have gone aftermarket on the clutch assembly and not bothered with Ford for the guide sleeve and TOB back in April or March of this year. Not too happy with what I found but everything else is back to normal.

12-18-2006, 06:52 AM
spoke too soon, noise still occurs but when moving slowly. Most of time after slight throttle use and coasting. Almost sounds like tire rub on the plastic splash shield. Does not sound like it is comming from the wheels though, more like the back of the motor. When I changed the oil, I went from Amsoil (has same color as the transmission fluid) to Royal purple so if the fluid on the trasmission case changes to purple I would then know it is the rear seal and not the transmission. Since the oil pressure is not changing I would assume the transmission is the source. After cleaning off the case and a few miles of highway driving I did not notice much if any new fluid seaping out from the vent hole in the bell housing. It is very much a slow leak and this time I know it is not water due to the red color. I am still convinced it is the input shaft seal. :( At least I was able to dial out the clutch slip after adjusting the clutch cable tension.

12-18-2006, 07:10 AM
Did this noise just creep up on you or did it suddenly appear one day? I wonder if it's a noise other Terminator owners hear? Nevertheless, at least you found you have a leak!

12-19-2006, 06:59 AM
The noise occured suddenly shortly after an oil change about 3000 miles ago. It may be related to liftinig up the car if for any reason the plastic fender liner got out of alighnment. It will be difficult to track down but I have some thoughts of what it could be. At first I thought it may be the steering rack as it had become loose again but I corrected that by adding some more spacers since the nut was all the way in to the unthreaded part of the bolt.

If the breather filter is clogged on the passenger valve cover, the pressure built up in the block would probable make the noise I am hearing once it surges through the PCV valve. Since the Eaton has a vacuum line connected to the bottom of it and joins the PCV line at a "T" fitting it may be related. I will have to check to see if it is still connected in case it blew off. The noise is comming from the drivers side but yet hard to determine from where. The only time I heard it before was when driving slowly after some hard acceleration which made me think that it could possibly be the bypass valve if stuck closed would probably cause some issues when it pops open. This week while on vacaion I will have to dig into the problem.

As for the leak, I knew about it but at the time it did not seem severe enough to worry about it since I thought it may have been water that may have been splashed up from the road surface since it was wet out when I first discovered it. I probably forgot about it the last time I changed the oil. Since I only have about 27k miles on the odo, time to take it in and have it fixed.

12-24-2006, 11:02 AM
My ride is at the Ford dealer for service. They at least agreed with me that the transmission is leaking but they want to study where and how this leak is occuring. My thoughts on that would be the guide tube since I did not have a leak until after that was replaced. That also may be related to the noise I have experienced. I guess I will have to wait and see what comes out of this.

12-28-2006, 11:30 AM
Problem resolved. The transmission input shaft seal was defective. :thumbsup: Had it replaced under warranty. During my short 30 mile drive yesterday, I did not notice the noise....... If it does not return, more than likely it was related considering the amount of transmission fluid loss, and where it was spewing out.