Since posting about the intermittent acceleration problem, I found that my turbo was no longer functioning since I have zero boost. My 97 F-350 only has 78,000 miles and has an intercooler added. I have checked and was unable to find any leaks in the circuit. Since I am unfamiliar with a turbo I have some questions that hopefully someone can answer.
1. What is the normal failure mode of a turbo?
2. Should I be able to examine the output side by removing the intercooler pipe?
3. I assume to examine the exhaust side would require totally removing the turbo.
4. Are there any other steps I can take to determine the if the turbo is bad?
TIA

pbgsho2

 

What are you using to measure your PSI of the turbo?

Is there turbo end play?

Does the turbine free spin if you spin it? Drag on the edges?

 

Still sound like its spooling under load/higher rpm's? If you have a mechanical boost gauge ur line may come loose/out. I thought something was up with mine, but it just turned out my line had blown out, the boot was cracked and allowed it to. Just a thought, hope it isn't ur turbo though, but possibility to upgrade if it is.

 

As far as the turbo is concerned, yes you can visually inspect it by removing the intake plumbing and the rubber boot that connects to the intake side of the compressor. Visually inspect the wheel on the turbo. Is it nicked and dinged? Bent or have missing fins? You can then try to wiggle the wheel up and down and in and out. A little up and down movement is not an issue as long as the fins are not rubbing on the turbo housing. In and out play in the shaft is not a good thing, though and you will most likely need to rebuild the unit if this kind of play is found.

Just curious as well, like Talyn asked, what are you using to measure boost? Can you still hear the turbo spool when you push the truck hard? The other things to check for would be a leak in the up pipes which is usually evident because there would be soot on the pipes and firewall wherever it is leaking, a malfunctioning EBPV (but I would think you would be hearing some noise form that), a bad MAP sensor will affect the amount of boost you're getting, or even a very dirty air filter.

Just a few things to check on before you go to the expense of replacing or rebuilding the turbo:

-Check the air filter.
-Unplug the electrical connector on the MAP sensor (passenger side on the heater box with a rubber hose that goes to the intake) and drive the truck. The CEL will come on, but it will go out as soon as you plug it back in. If the truck spools better with the sensor unplugged, you need a new sensor.
-Look for leaks around the up pipes (this will really kill your boost)
-Double, even triple check for boost leaks in your IC pipes, and your intake plenums on the head.

That should keep you busy for a while, but these turbos are pretty resilient, and not too prone to totally quitting on you like this.

 

I first reported my problem in a thread entitled "Intermittent Poor Acceleration". My problem is that I have no boost. Today I removed the intake pipes so I could check the compressor side of the turbo. I can easily spin the compressor rotor and it appears to be quite clean with no missing or nicked vanes. There did not appear to be any play in the shaft either up or down. After starting the engine I can see the compressor vane spinning. I have checked all of the hose connections on the intercooler and all appear to be intact.
My boost gauge reads boost in the pipe connected to the output of the compressor so I feel that I am getting a valid reading. Curently I am looking for a way to generate some smoke which allowed to enter the intake side in the compressor may give some indication of the location of any leaks.
There would seem to only be two components where the flow is leaking that being the intercooler and at the intake manifold.
I drove about 25 miles and consumed about 1/4 tank of diesel so this is consistant with a very rich running engine. Did not notice if there was a black cloud following me but would have expected to see one.
Please suggest if you have any more ideas.

TIA

pbgsho2

 

the intake pleniums are a good place these trucks like to leak.

gotta get the good RTV from ford though to seal them, other stuff will blow out.

Could be an exhaust leak as well.

 

If your boost gauge is showing boost pressure in the pipe on the outlet side of the turbo, you are either losing your pressure in the intercooler somewhere or you have a serious obstruction in the system. Is it possible that the port you are putting the sensor into on the (Y-pipe) is blocked somehow?

The only other thing I can think to check is that if you have a 7.3 IC out of an SD truck, did you get one with the aluminum tanks or does your have the plastic ends? Is it possible that one of the ends of the IC is cracked or broken?

I guess I am going off your quote above and thinking that your turbo is working as it should be, you're just leaking somewhere after the turbo and before the engine. Any chance your plenums are leaking badly?

 

After some investigation it was found that the bearing in the turbo was bad. A split in the boot on the compressor side allowed crud and other foreign debris to bypass the filter and enter which destroyed the bearing. Fortunately I was able to find a lightly used turbo on ebay which is now installed so my truck is back to running properly. It is amazing which functions are impacted by the problem including a very harsh shift which is now quite smooth.

pbgsho2

 

The harsh shift could have been do to the lack of power. The computer saw certain parameters high and shifted. When in realty there was much less power there which could have given the hard shift.

 

Midnight Mods: OBS Intake Boot Replacement

Sounds like you need an intake boot then also. =)

 

Talyn, you are correct and it was replaced with the new Ford kit to correct the problem. Cost was about $125.00.

pbgsho2