Boost leak? I can't tell....

Robert6401 · #1 Wed, March 10th, 2010, 11:15 AM

Hey guys,

I just got back from a week long trip down to Florida pulling the 5th wheel. This was my first time towing since I installed the PHP chip and I am very happy with what I gained. I did end up with some sort of problem though and I'm hoping y'all can help me figure it out.

On the way out of town last week I noticed some increased noise coming from the engine bay but the truck seemed to run fine. I was able to pull all the way down to Florida in OD no problem and was getting about 20psi of boost going up some hills holding just under 70mph, not really trying to get any more. I noticed that around 15psi the turbo seemed to have a pronounced flutter to it rather than just the normal high-pitched whistle, but once it got above 15psi it went away.

Well, we got down to Florida and I didn't drive much while I was there but the little bit I did drive the noise from the engine bay seemed to get a bit louder. The best way I can describe this noise is like a throaty exhaust sound like you would hear from a gasser.

Then, finally, I was able to tell that there is definitely something wrong on the way home yesterday when I could only get about 15psi of boost, the EGTs were a little higher, and the truck definitely felt like it had less power. The condition also seemed to get worse throughout the 9 hour drive.

Of course I have heard of many people on here having boost leaks, but I wasn't sure if it was normal for it to start out small and just get worse and worse like mine did?

Also, if y'all do think it's a boost leak, I need some specifics on where to look because I glanced around a bit last night and didn't see anything I could pin-point as being loose.

Thanks a bunch!

***907DAVE*** · #2 Wed, March 10th, 2010, 12:35 PM

Check your up pipes for leaks, sounds more like a exhaust leak than a boost leak. Boost leaks will produce more of a high pitched squealing, or a loud hissing sound.

Good Luck

Robert6401 · #3 Wed, March 10th, 2010, 12:43 PM

If it is an exhaust leak? Is there anything I can do besides replacing the up-pipes? Those puppies are expensive.

***cleatus12r*** · #4 Wed, March 10th, 2010, 02:19 PM

Actually, the Ford replacements will run you about $100 in parts. The labor is pretty intense (turbo r&r at 1.8 hours plus the time to do the pipes).

Quote:

Originally Posted by Bob

I noticed that around 15psi the turbo seemed to have a pronounced flutter to it rather than just the normal high-pitched whistle, but once it got above 15psi it went away.

That's turbo surge and it's very bad for the turbo. Just sayin'.

Robert6401 · #5 Wed, March 10th, 2010, 02:24 PM

Cody, I was able to get what I thought was turbo surge around 25psi just playing around in the perf tune, but it was more of a *chirp chirp* sound. The sound I was getting at 15psi was more like the sound you would hear if you blew into a table fan. Why would the turbo surge at 15psi? Isn't that really low psi for it to do that?

Robert6401 · #6 Wed, March 10th, 2010, 02:34 PM

YouTube - 7.3 powerstroke turbo surge, turbo stall, compressor surge, or normal wastegate blowoff???

This is the closest sound I could find to what I was hearing at 15psi. Go to the 1:00 mark like he says in his description.

Robert6401 · #7 Wed, March 10th, 2010, 02:53 PM

Wow, now I'm worried! If in fact, that was turbo surge, and I drove the heck out of it not really thinking it was surge, what kind of damage might I have done? How would I check for damage?

***907DAVE*** · #8 Wed, March 10th, 2010, 03:39 PM

Check compressor wheel for "in and out" movement. Also check to make sure it is not scraping on the compressor housing.

hayjayhorses · #9 Fri, March 12th, 2010, 09:08 AM

my '00 F550 surges real bad with no tune a stock turbo, 4" turbo back and the wastegate hose un hooked, It will boost to 29 psi and EGT will get to mid 1200s. No surge with the waist gate hose hooked up, It will boost to 17-19 psi, but EGT get to almost 1400.

any sugestions?

Robert6401 · #10 Fri, March 12th, 2010, 09:25 AM

Wow, it's interesting to me that you can get 29psi without tunes! The rest of those numbers sound normal. The only way to eliminate the surge is to do some upgrades on the turbo.

Here's the latest on my situation, I spent a couple of hours up at the shop searching. There really wasn't any sign of built up soot on the top part of the up-pipes near the baby's butt, but there was a bunch of crap around the area where the bottom of the up-pipes connect to the exhaust manifold. Not really ON the pipe or manifold, but on all the other components right around the connection. And it seemed to be kind of spread out all around the connection. I just changed my oil a couple of weeks ago and would've noticed all of this crud then, so it has to be new.

I also checked all of the boots and clamps and everything really seemed alright there.

I also checked the turbo and it seemed fine. No play really at all that I could tell in any direction (My fingers did get the turbo wheel oily, but the oil came from the CCV crap since I haven't done that mod yet so I figure that's ok).

The truck runs pretty well right now without hauling a load, which is more-or-less what I expected. Still louder than I think is normal though, just a sort of loud drone or moan.

So, after all this, what can you guys tell me? Would a leak down near the connection of the up-pipes and exhaust manifold cause the boost problems I was having towing my camper? And would it cause the extra noise I have been hearing for a while? I really appreciate all the help guys.