no turbo boost till 3000rpm

[jbezaire]

Hello
I have just purchased my excursion 7.3 litre turbo diesel!! Love it!! I am having problems with the turbo. I have a loud hissing sound comming from behind the turbo (can feel the air when reaching behind it) and my banks turbo boost gauge only reads 10 psi at 3000rpms but nothing at all before this. I noticed that the hissing goes away when the truck warms up but still not registering the boost until 3000rpms. I purchased a new seal kit for the turbo thinking it may be the o ring but would like some other opinions for what it could be before I start the tear down for the o rings.
Thanks

[mbahr22250]

Your leaking intake or exhaust? If it's intake you probably just blew one of the intake boots or a clamp holding one of the boots. If it's exhaust leaking then it's probably just the v-band clamp that holds the downpipe to the turbo.

[jbezaire]

this is my first diesel so not too sure which it is (intake or exhaust) but with the smell of the exhaust in the cab I am going to assume it is exhaust. would the exhaust cause the boost loss?

[jbezaire]

forgot to mention that I have a engine light on and the code is for boost pressure. I am assuming that this is all in relation to each other. The ford dealership wants 800 bucks to fix but only quoted on replacing seal, anything above and beyond of course is extra. I would prefer to do the repair myself to use it as a learning experience.

[Black&Gold]

where are you located? The exhaust leak will cause a low boost conditions if it is not allowing the exhaust gases to spin the turbine wheel.

[99bluoval]

Or like mine, you've got the silly donut seals in the up pipe from the manifolds to the turbo leaking. It's worse when the exhaust back pressure valve is closed at warm up. And yes the exhaust can cause boost loss, it drives the turbo if not all the pressure is getting to it it won't make boost.

[mbahr22250]

Originally Posted by jbezaire

this is my first diesel so not too sure which it is (intake or exhaust) but with the smell of the exhaust in the cab I am going to assume it is exhaust. would the exhaust cause the boost loss?

Not really. It sound to me like you blew a boot. When you look under your hood you should see some blue or orange (not sure what color exactly for 7.3's) hoses that are about 3" in diameter. One near your turbo, two on either side of the front of the engine compartment coming out of what looks like a radiator (your intercooler) and one going into the intake of your engine. One of these probably has a hole in it or the clamp that holds it on broke and pushed the boot off the tube. From what you describe it's probably the one coming out of the compressor side (the aluminum, non-rusty side) of the turbo. Hope this helps.

[jbezaire]

Originally Posted by Black&Gold

where are you located? The exhaust leak will cause a low boost conditions if it is not allowing the exhaust gases to spin the turbine wheel.

I am in Tillsonburg. I see you are in norfolk somewhere! I am going to check all the clamps and hoses to start but then will start on the seals.

[mbahr22250]

Originally Posted by 99bluoval

Or like mine, you've got the silly donut seals in the up pipe from the manifolds to the turbo leaking. It's worse when the exhaust back pressure valve is closed at warm up. And yes the exhaust can cause boost loss, it drives the turbo if not all the pressure is getting to it it won't make boost.

Okay so if it is leaking ehaust before it gets to the turbo (like the up pipe) it will cause a loss of boost.

[Mikey's250]

I had/have the same problem. If you cant visual find any leaks then you might want to buy or make a leak detector. Google boost leak detector and you will find how to make one. I did this and found a leaking intake boot, replaced the boots now I can barely hit 16 at WOT. So now I got to check the donuts on the up pipes.