Zero boost pressure - Ford Powerstroke Diesel Forum
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Old 03-17-2013, 12:27 PM
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Zero boost pressure

My OBS has been sluggish lately (running smooth - just no "get up" even after warming up. I have sampled the oil for testing every 15k or so and I recently got an oil sample back that said I likely had a turbo bearing going out (or a valve guide). So I have been doing some investigating.

I cleaned out the EBP sensor line and I can feel the stock EBPV cycling on cold mornings.

I bought a boost gauge and tee-d it into the MAP line as others have done. No boost pressure at all. So I pulled the hose off the manifold Y and put a low pressure compressed air on it (5-10 psi) - my boost gauge responded nicely...so it is working and no kinks in the line from the manifold to the gauge.

I then started the truck up with the MAP hose disconnected and I have zero pressure on the manifold. I can't get the faintest hint of pressure.

I have stock exhaust (I know I need to uncork the downpipe eventually) but I am feeling normal exhaust flow at the tailpipe. There are no restrictions in the inlet air system and I don't see or feel any leaks in the manifold Y connections (orange hoses or clamps). Most sides of the turbo have a slight "something is whirring inside" vibration so something is spinning. And I don't see damaged fins on the inlet side when I look in.

Am I looking at a total turbo failure or is there something else I should be looking at? Obviously I am concerned about the oil sample which suggests turbo bearing wear. I've got about 180k miles on the truck.
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Old 03-17-2013, 01:01 PM
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I hope you're not running 15k OCIs.
But if you pressure tested the charge air system and no leaks, then I'd look for exhaust leaks. Are your EGTs high? I'm wondering if maybe your wastegate is stuck open
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Old 03-17-2013, 02:04 PM
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update

I took it to higher RPMs. Fully warmed up on the freeway. 55mph start headed up a hill, WOT I can get almost 5psi before I back off to avoid getting a ticket. I never get it to above 5psi. So I am getting some turbo - perhaps not factory levels.
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Old 03-17-2013, 02:07 PM
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Nope - I over-change the oil. They keep encouraging me to spread the change interval because numbers are so go, but I haven't - I just don't sample every oil change due to cost.

And I don't have a pyro (yet) - it's coming with a new downpipe!
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Old 03-17-2013, 04:01 PM
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If you can go WOT and not blow black smoke and have to back off like that then I'm thinking your MAP hose has a leak in it.
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Old 03-17-2013, 04:24 PM
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Nope - no black smoke and no significant boost.

Great thought on the hose. In the process of adding the boost gauge to troubleshoot the lack of power problem, I replaced the MAP hose - so I actually eliminated that potential problem source by accident (the old one was hard and getting brittle so I decided it needed a replacement). I know the new one is on there tight and I have hose clamps keeping it there. When I put low pressure compressed air in to test my gauges, I went through the MAP hose as well.

I am thinking my exhaust may be partially clogged (cat?) and/or my turbo has seen the last of its days. Either way, it's looking expensive and not a quick fix. Someone also suggested I look at the seal between the turbo and the Y-manifold - I'll have a look at that next.
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Old 03-17-2013, 05:01 PM
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I am in the same boat as you. Right down to steps you have taken. My turbo looks and sounds good, just no boost and sluggish. I have 280k on mine. I'm thinking hoop or injectors or both. Post your results when you fix it. I have just decided to enjoy poking around slow. Good luck
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Old 03-17-2013, 07:44 PM
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You can feel the turbo, make sure there's very little slack in the shaft.
You make a good point on the exhaust plugged. Can you monitor EBP?
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Old 03-18-2013, 05:44 AM
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Quote:
Originally Posted by jesilvas View Post
I hope you're not running 15k OCIs.
But if you pressure tested the charge air system and no leaks, then I'd look for exhaust leaks. Are your EGTs high? I'm wondering if maybe your wastegate is stuck open
No wastegate on obs turbo's.
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Old 03-18-2013, 05:50 PM
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I always do that. Offer SD reasons on OBS when no one else offers solutions. Then everyone says I'm wrong
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