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Discussion Starter #1
On the way home from a trip in the mountains of Colorado today, my truck just quit making boost and I had to accelerate with the swiftness of a fully loaded 18 wheeler just to keep my EGT's below 1200. I hadn't been driving it like I stole it or anything, and I am not sure how to troubleshoot this issue. I looked under the hood when I got home and didn't see anything that jumped out at me. How do I go about confirming my turbo is junk? It is the original HX35 I believe.
 

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Have you checked to make sure there is no issues with the intercooler boots? Where they connect to the intercooler are real close to the inner fender and have had one rub a nice cut into it.
 

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Pull the intake hose off and check to see if the blades rub the housing.
 

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Have you checked to make sure there is no issues with the intercooler boots? Where they connect to the intercooler are real close to the inner fender and have had one rub a nice cut into it.
Also they are 20+ year old rubber if they've never been replaced (and they likely have not -- Old ones are perfectly good... right up until they aren't). Would expect to start seeing increasing numbers of failures of them here on the forum over the next few years. I replaced mine this past winter as I had the front end all apart anyway, and the originals definitely were starting to look a little cracked/rotten in a couple places.
 

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Discussion Starter #5 (Edited)
How does that pertain to a loss of boost? I thought the intercooler was for keeping the transmission cool.

Edit: Wow I should've looked that up before replying, I apologize. That's my next thing to check.
 

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Discussion Starter #6
The blades are not rubbing the housing, they spin just fine by hand.
 

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Discussion Starter #7
Have you checked to make sure there is no issues with the intercooler boots? Where they connect to the intercooler are real close to the inner fender and have had one rub a nice cut into it.
I checked all 4 boots. The top 2 look to be aftermarket and in good condition, the bottom 2 look original. I test drove the truck and hear an air sucking/blowing sound different from the intake when I put a little foot in the pedal. I assume one of the bottom boots is bad. I plan to replace all 4 just because that's what most kits seem to have. Will update after I do so. Thanks for the help!
 

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You know you can pressure test the system to look for leaks. A smoke machine is optimal, but most people don't have one. Some PVC and a schrader valve is all you need. I'm still running the original boots, but a very long time ago an experienced owner clued me to the inner fenders cutting them so I bent the sheet metal away with a pair of pliers. If you are hearing air escaping from the intake I suggest you make sure that every bolt is in place on the cover.
 

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I plan to replace all 4 just because that's what most kits seem to have.
Tip: A little hairspray on the boots can help get the clamps on. Huge pain with the clamps sliding off and swiveling around on the slick new silicone when trying to tighten them down. Found that tip on some ricer forum, I think, and it'd have saved me a lot of time.

Of course I'm bald as a cue ball so I don't know what the heck else I'm gonna do with this bottle of hairspray.
 
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Discussion Starter #10
Update:

After too much time unavailable to do any physical troubleshooting and much time for thought put in to the issue, I decided the smart thing to do would be to pressure test the system prior to any random parts purchases. I built a pressure test cap and I found a leak (the bubbles are kinda hard to see), but I have no idea what the fitting is called. The link below includes 3 pictures and shows the fitting from 2 angles, I believe the other end of the hose connects to the waste-gate actuator but I can't see. I appreciate any help!

https://imgur.com/a/NBGQP8I
 

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There has to be more of a leak than that to cause a no boost situation. You need to remove the brass elbow and put some teflon tape on it if its leaking.
 

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Discussion Starter #12
Is there a trick for the pinch clamp? Can I reuse it?
 

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Maybe the wastegate is stuck open?
 

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Discussion Starter #14
Update:

I pulled the turbo off the truck for further troubleshooting and have decided to replace the internal wastegate actuator. I have found 2 different oem looking replacement actuators online, 1 with a 5"-6" arm and 1 with a 7"-8" arm. I measured the length of the old arm at 6 3/8". Any suggestions?
 

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Well ur in luck I just replace the wastegate on a 96 I bought the 7-8 one it was way to long I had to cut it down.
 
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Discussion Starter #16
Well ur in luck I just replace the wastegate on a 96 I bought the 7-8 one it was way to long I had to cut it down.
Thanks! I decided to rebuild the turbo with the Turbolab of America kit and leave the wastegate actuator alone for the time being. It functioned normally when i tested it after I had the turbo on the bench.

Here's my new obstacle...I put the turbo back on the truck and decided to pressure test it before I connected the oil inlet and outlet. When I attempt to put 20lbs of air in the system the gauge gets up to almost 20lbs and I hear air leaking from what seems like the oil outlet port. This doesn't seem right to me, is this normal? I double and triple checked my rebuild vs every video and document I can find and I can't see any differences in how I rebuilt mine and how everyone else has done theirs.
 

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I've never tried an air pressure test on an inter-cooler and piping system, but I've rebuilt turbos before and I would fully expect air pressure to leak back into a "dry" turbo...and in your case...out the open oil feed and drain lines. All that seals the oil to air pressure is a split steel ring seal and a bronze bearing and these would not seal air pressure very well until there is oil in the bushing and oil "pressure" on the back, or oil side, to counter the boost pressure. Spinning up to 150,000 rpm and surviving ...they are amazing little mechanical devices.
 

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Discussion Starter #18
I've never tried an air pressure test on an inter-cooler and piping system, but I've rebuilt turbos before and I would fully expect air pressure to leak back into a "dry" turbo...and in your case...out the open oil feed and drain lines. All that seals the oil to air pressure is a split steel ring seal and a bronze bearing and these would not seal air pressure very well until there is oil in the bushing and oil "pressure" on the back, or oil side, to counter the boost pressure. Spinning up to 150,000 rpm and surviving ...they are amazing little mechanical devices.
Thanks, this is my first turbo rebuild. I felt confident after rebuilding it, but that leak threw me.

Secondly, I'm curious...with air able to leak back into a "dry" turbo, how can I accomplish a successful system pressure test? All the oil drains from the turbo when the engine shuts off, creating a "dry" condition, and it's impossible to hear/feel air leaks with the engine running. I found a few leaks at boot clamps and a leak at the boost elbow before narrowing down the leak at the oil port, but I want to make sure I have no additional leaks. All I can hear is the leak from the oil port right now. Is this a situation where I just need to fully reconnect the turbo, take the truck for a test drive, and rely on my in-cab boost gauge to see if the system builds boost like it should?
 

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Discussion Starter #19
Update:

I reconnected the oil lines and exhaust line and pressure tested the system. I guess I was confused before thinking that if air was leaking at the oil port I wouldn't get any pressure, that was wrong! I can build 20lbs no problem. I used soapy water and found a few leaks, guess I am getting new boots! It takes about 30 seconds for the pressure to drop to 0lbs. Went to start it to make sure the oil port seals were good and the battery is dead. :doh: I'll update after a test drive.
 

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This would also be a good time to check the cat. My 97 plugged at 19k. I gutted it and got the boost and power back. Craig
 
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