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Glad you got your rack back! 
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We're not quite done with this round yet. I've been smelling fuel and decided to look at it carefully today. I couldn't really see anything but it was pouring out a lot of fuel on the driver's side about dead center front to rear of the engine. I took him back to Rackley's and after a lot of climbing about they found that the plastic fuel filter base is leaking - evidently a crack. So it has nothing to do with the repairs they made but needs doing.
I noticed when I picked it up after the head work that I was down a few PSI on fuel pressure. After I had it back a few days I then noticed some Diesel fuel smell (never had that before) then it was hard to start after it sat a bit. Now I realize that the fuel was leaking out of the canister and it had to refill before it would fire. So - annoying but we're finding stuff that comes from old age...... I can relate!
DanComment
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Awaiting the part. Hope I can get the ol' boy back soon - I love driving that ruck.
DanComment
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Truck is back home. When they dug into it the filter canister turned out to be OK but there was a bad line in that area as well as a failed fuel thermostat housing. With the virus thing it took a while to get parts but now he's back up and running great. I picked him up last night and haven't been very far yet but I'm taking the ol' guy to lunch and I'll have a chance to get a foot full of accelerator pedal. Looking forward to it.
DanComment
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OK - I'm several iterations behind. I've noticed that when the engine gets fully up to temp the boost drops from about 20ish to about 12ish PSI. After some troubleshooting I pulled the turbo and send it off to Tim Scott at Tim's Turbos, my turbo guy. So he found some funky stuff (understandable at almost 270K miles), did a rebuild, and sent it back. Pics:
Pic with the turbo in VA for a rebuild:
And an hour and a half later:
It's a pretty easy turbo to remove and replace!
The only trouble is that it still loses boost when the engine comes up to temp. I'm about to do an Internet search and see what I can learn. Either way, the turbo needed freshening up so at least I can check that off the list.
DanLast edited by DanStokes; June 13, 2020, 08:22 AM.Comment
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Looks like the IAT sensor might at least be a possibility. Not too pricey from Rock Auto so I have a fresh one on the way. It'll work or it won't.
DanComment
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what does IAT have to do with boost control?Doing it all wrong since 1966Comment
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Dan I have absolutely no experience with turbos - are you saying that they typicially need to be freshened at 30K?Originally posted by DanStokes View Post
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OOPS - my crappy typing strikes again. That should have been 270K miles. Somewhere around 250K it's probably time at least on the Cummins. I have no clue on a gasser as I think they run hotter but that's not really an area of my expertiese.
DanComment
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The ECM uses various inputs to make decisions about fueling and, subsequently, to a limited extent, boost. From what I can learn by reading up, basically it pulls out fuel to limit boost if it thinks the inlet air temp is too high and that lowers boost. If the engine coolant temp were reading high it would also impact fueling but my dash gage (same sensor) reads OK so I don't think that's the culprit. The good news is that it's a fairly cheap and easy thing to try so try it I will.Originally posted by SuperBuickGuy View Post
DanComment
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A bit of turbo info if you're interested.Originally posted by cstmwgn View Post
A look at the top pic with the turbo removed shows the connections. Turbos run REALLY fast (20K RPM and more depending on application) so they need oil to the center bearing which is where the whole thing spins. At the top of the oil filter housing there's a round port and that's the tap for the oil supply. Straight down from that is a tube with a 2 hole flange - that's oil return. I never heard of a turbo with a self-contained oil supply like some of the Pro Charger style blowers.
Other than that the 4 hole flange off the exhaust manifold is the exhaust inlet to the turbo -all of the exhaust gas goes to the turbo. Most (at least Diesel) turbos bypass some of the exhaust gas to control turbo speed and this one has an "internal" (built in") wastegate unlike Mutt's new setup with an external WG. The only other connection is the exhaust pipe which you can see at the far left of the pic. The inlet air, of course, comes into the inlet in the center of the compressor (cold) side of the turbo so it's shown at toward the front of the engine in the second pic.
So the turbo squeezes the air (but you knew that) but depending on application the engine may or may not use a series of sensors to make decisions based on boost. Newer Cummins use an electronic wastegate and control boost pressure with it. Mine does not have that but can mess with fueling to cut back exhaust heat and therefore the turbos' ability to make boost effectively controlling boost. Mutt has none of that so boost is a matter of the turbo hardware and exhaust heat.
This brings up a major turbo theory. Many folks think a turbo is spun by exhaust gas velocity but in truth that's a very minor player. What really matters with a turbo is exhaust heat - as exhaust gasses exit the port they begin to cool rapidly and therefore expand greatly. It's the expansion of the gasses that impart energy into the hot side and thru the center shaft to the cold (compressor) side.
Sizing a turbo properly for the engine and its application borders on voodoo but the basics are pretty simple. Tim and I have been searching for just the right size of turbine (hot side) and compressor (cold side) to get Mutt to do what I want him to. More proven setups like the Dodge Cummins have lots of development so turbo folks can pick something off the shelf that will work pretty well.
Hope I didn't tell you more than you wanted to know!
DanLast edited by DanStokes; June 13, 2020, 11:47 AM.Comment
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I bit more info: I started digging around under the hood to see where the IAT is located. It turns out that there is both a MAP sensor and the intake temp sensor at the left rear of the engine in the intake manifold. Why they buried them back there is anyone's guess...... Anyhow, I found that the MAP sensor is broken right off at the plug! While my symptoms don't match what I've read for a bad MAP maybe having the whole deal broken off gives different issues. Anyhow, I have a MAP on the way.
DanComment
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hopefully that guides you to a solution....
Doing it all wrong since 1966Comment
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Me too! It'll get changed tomorrow.
DanComment
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well, you should since you will have a map. I'd almost feel bad about that but I know I'm a amateur punner compared to you.Originally posted by DanStokes View PostDoing it all wrong since 1966Comment
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