Hey all,

I've searched on this until I'm close to blind and can't find the exact problem I'm having. I have a 97 F350 7.3 Turbo Diesel that is completely stock with 150k on the odometer. Lately, I have been hearing a low pitch whistle coming from my truck after it warms up. It sounds just like one of those toy whistles with the slide you move out and in to change the pitch. At first it only happened while holding steady on the throttle or speeding up. When speeding up the whistle got a deeper tone. Then, it started happening when I was coasting until the motor finally dropped to idle. Now here's the kicker......lately I can hear it best when coasting in reverse down hill on my driveway. I still cannot even pinpoint the area it's coming from and my rotten kids refuse to ride under the hood while coming down the drive. I've read about the EBPV but am having trouble as to why it doesn't do it at idle but it does when coasting down hill backwards unless it's trying to apply back pressure because I'm coasting. But then why would it be trying to engage when I'm on the throttle? The EBPV does move freely.

Any help or suggestions would be GREATLY appreciated!!!!

Jeff

 

Could be a vacuum leak, does the heater controls switch from defrost to floor OK.
Boost leak is another place to check....especially the small black hose going to the MAP sensor mounted on the firewall.

 

Jeff. It sounds like you need to put a few snickers bars and a pop down in the engine bay. Maybe that will coerce them into doing it.

 

I'll check those places for vacuum leaks. I did disconnect the brake booster and drive it around but it still continued. It's getting quite embarassing!

Here's another thought. My turbo has been missing one of the bolts since shortly after I bought it in '97. I've tried everything to get it back in but can't get it started to save my life. When this noise started I found a second bolt had come out. This one I was able to get back in and tighten down but it didn't change the noise. These bolts are 12 point thad look as if they hold one half of the turbo to the other. I would have expected a different noise from there but do you suppose it got looser and blew some gasket material out? Is there a gasket in there in the first place? I am hoping to do the down pipe in the near future along with removing the cat and would like to go through the turbo with orings and gaskets while I'm at it.

Jeff

 

Talyn,

If there was a Snickers bar in it, I'd figure out a way to drive and be under the hood at the same time. I'm currently having great success with the beer and Snickers bar diet!

Jeff

 

I think its metal on metal.
I had one coming out when I had my turbo off. was like that when i bought it.
I had to keep working it back and fourth to get it tight. took me a good 30 mins to get it back in there.

If its been out for a while, there will be rust in there, and good luck getting it back in without the right tap.

 

Do you still have the original red boot to the turbo intake?
They have been known to collapse when sucking air.

 

Jeff,

I swapped housings on my turbo and the last bolt p*ssed me off so I left it out and it doesnt make any noise. Guess I could have pulled the entire turbo off but didnt. The housing seals metal to metal like Talyn was saying. You dont have a pin hole in your exaust do you? Can you tell if your loosing boost at all or performance?

 

Thanks for the replies!

Hmmm, I didn't think about rust being the problem with getting the bolt back in. Even without rust I still can't get the bolt to turn back there hardly at all. It's the bolt in the lower rear position. Of course it might go better with a 6 point bolt as you can't get a box wrench on the 12 point bolt until it's a good ways in. It sounds like that all needs to come out for a good inspection when I do the down pipe. I'd just like to be sure somehow that it's not a vacuum leak first which should be easier to fix.

I do have the original red pipe going to the turbo. I really haven't changed anything on this truck except the fuel pump and vacuum pump since new. I only changed the CPS recently because Ford did it as a recall. The original was still working fine. Are you saying that that red tube gets weak or is something else causing it to collapse? I'm still confused as to why it whistles when coasting in reverse AND when on the gas as I'm not really up on exactly how these diesels work as opposed to a gasser. Would that valve just after the turbo be closing when coasting down hill?

Just generally clueless here. I sure wish I'd have problems that also occur when idleing! My last one was the trans tailshaft housing causing a vibration but only when on the gas.

Jeff

 

I'm baaaaaaaack!!!

I made some progress in finding my whistle but still need help. I don't have much time to work on this at this time and it's not a daily driver so I do what I can.

First of all, I verified that the vents were opening and closing as they should for the AC/Heat/Defrost so it looks like a vacuum leak is out.....maybe.

I decided to try and unplug what I hoped was the EBPV. It looked as if it was a plug near the valley on the drivers side. It ended up getting rid of 80% of the whistle I've been hearing. Problem is, that makes no sense to me. From reading here it looks as if the only time the EBPV should be closed is on cold startup. Is that correct or does it close at other times too? Also, with that unplugged the brake pedal had an affect on the whistle.

If the EBPV should be open once the truck warms up why does my whistle only start once the truck is warmed up? Shouldn't unplugging the EBPV make it always open?

The only thing I can come up with is that maybe it's not opening all the way and causing high back pressure on the intake system forcing a leak. Does that sound reasonable. I saw another thread about making a PVC cap with a valve stem to check the intake for leaks. I may give that a try next. In the mean time any suggestions would be most welcome!!!

Jeff

 

The EBPV works on a hydraullic type system.
there is a cavity with a piston in it which fills with oil when a sensor on the back of the pedistal opens up.
if the sensor fails, then the oil is allowed into the cavity. Probably enough is getting in to keep it partway closed, or the EBPV is leaking and causing your whistle.

if you dont need it, gut it out.

 

i believe you may have whistle tips!

YouTube - The whistles go.... whoo whoo!

 

That's is, that's the noise coming from my truck! Do you suppose they've gone from stealing Cats to installing whistle tips??? I'll check first thing To think I was sinking in my seat all embarrassed by that aweful sound when I was just ahead of my time.

Jeff

 

the whistles go wooo woooo!

 

man, i've watched that video so many times. haha