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Old 08-06-2013, 07:14 PM   #1 (permalink)
orangespot
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6.5 turbo loses power as it heats up.

1993 Chevy k2500 6.5L turbo diesel.
I've been dealing with the problem since last summer (2012), but I have a little car that I drive so the truck wasn't really top priority.

The car died. Need the truck. And the problem is worse than ever.

It started on long trips, 60+ miles, I would notice loss of power. Now it's more like 20 miles, I think.

About 3 weeks ago a mechanic friend (he doesn't know much about diesels) noticed that the clamp on the hose from the air filter to the turbo was missing, so he put one on. Then the truck wouldn't start, even though the engine was warm. We opened the air filter housing and saw that the filter was filthy. Since we were at the auto parts store, we replaced it. It still wouldn't start. Then I popped the clamps, so air was bypassing the filter and letting a bit of air in. It started.

Since then, I've been using the air filter clamps like a "choke" so to speak. There seems to be no rhyme or reason on how this choke works. When the engine is cold, it might require that I open OR close the clamps to get it to start.

But that's not the worse problem. The fact that it loses power as the temp climbs is what I'm afraid of. I'm afraid that the temp gauge is not reading accurately because it's not really showing very hot. It only climbs ONE NOTCH (from the second notch to the third - what ever that means).

I always pull over and let it cool down because I'm so scared of what comes next. The engine compartment is obviously much hotter than it used to be, last year before this problem started.

Oh yeah, I also drive around with the hood popped so that air is coming in under the hood. Also, I will turn off the truck and just coast for a few seconds on hills, this helps cool it and restores power pretty fast. It's a crazy way to live though! Power steering and power brakes are gone when the engine is off so that's scary.

Before I noticed that it was temperature related, it had gotten to the point where it wouldn't go much over 25 mph after driving for a distance. Now, I don't let it lose power that way because I'm too worried about the damage. I can actually drive it without losing power if I pull over before the temp gauge hits the third notch -- about every 10 miles.

I did the paperclip thing and got a code 12. No help there.
I pulled the new air filter out to look at it. There was one bumble bee stuck to the back so that indicates that some air is flowing through it right? I stuck my hand in the hole behind it and didn't feel any obstructions. Then I stuck my hand in the other hose, toward the turbo and I spun the turbine a bit, it turned.

I'm not a mechanic but I'm hoping that with some clues, you guys can direct my mechanic friend in the right direction. He's young but he's very good, just not experienced with turbos.

Oh, the coolant overflow was bone dry. I added water and it has helped a bit, but not very much. There is a tiny leak somewhere in the radiator or hoses because it does drip on the driveway.

That's all the clues I can think of right now. Please help!
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Old 08-07-2013, 03:08 AM   #2 (permalink)
suburbank2500
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Do you stillhave the snorkle in the inner fender at pass.side Kennedy Diesel
Are you sure your water pump is ok
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Old 08-07-2013, 08:51 AM   #3 (permalink)
90GMC62L
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When it loses power is there a lot of black smoke? Can you physically hear the turbo spooling? I would maybe add a boost gauge to see how your turbo is acting.

Also, I had a similar problem on my old 6.2 where I could cruise around town it would be fine but once I tried to do highway speeds, it would barely do 35. My injector pump went bad for that situation.

Do you have the stock exhaust yet? Get rid of that junk if you do because it only hurts performance.
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Old 08-07-2013, 11:34 AM   #4 (permalink)
JMJNet
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Welcome!!!

I think you have more than 1 problem.

Whatever you find, you need to troubleshoot it.

There is a Diagnostic Checklist in the sticky on top of this section.
You may want to fill and DO those test and see what comes up.

As with any diagnosis, make sure you check all the electrical like batteries, connectors, etc.
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Old 08-07-2013, 12:31 PM   #5 (permalink)
FloridaHorseman
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Aside from the drip leak in the driveway and coolant loss everything you describe screams "plugged soot trap" or some other type of exhaust restriction. Since the problem gets worse with time (heat build up) it indicates soot trap perforations swelling shut. The OEM soot trap is at the bottom of the down pipe. It looks like a catalytic converter but is not. If it's still there, get rid of it. If the problem persists with the soot trap removed you may have to also check/replace the exhaust crossover pipe. They're double walled and if collapsed internally will restrict the turbo operation. ~FH
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1998 Chevy K3500, 454 horse hauler , 175,000 miles, tuned flow-through exhaust, pillar gauges (vac, trans temp, volts), electric cooling fans, external trans cooler & fan, manual TCC lockup mod, limo tint, front & rear brush guards, B&W G/N flip hitch, spray-in bed liner, chrome wheel inserts


Engine "No Start" Checklist
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Last edited by FloridaHorseman; 08-07-2013 at 12:33 PM.
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Old 08-07-2013, 12:34 PM   #6 (permalink)
Rattler1
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Quote:
Originally Posted by FloridaHorseman View Post
Aside from the drip leak in the driveway and coolant loss everything you describe screams "plugged soot trap" or some other type of exhaust restriction. Since the problem gets worse with time (heat build up) it indicates soot trap perforations swelling shut. The OEM soot trap is at the bottom of the down pipe. It looks like a catalytic converter but is not. If it's still there, get rid of it. If the problem persists with the soot trap removed you may have to also check/replace the exhaust crossover pipe. They're double walled and if collapsed internally will restrict the turbo operation. ~FH
My soot trap was right in front of the muffler. That is why I thought it had been removed when I first looked.
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Fan clutch mod to fix overheating problem
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Old 08-07-2013, 01:22 PM   #7 (permalink)
Diaric
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To trouble shoot coolant drips, need a location. Could be water pump, houses, seals etc.
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well to make your pump retarded, you could let it hang out with me for a day
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Old 08-07-2013, 05:36 PM   #8 (permalink)
turbovanman
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We need more info like trans, modifications etc but first things first- ENGINE OFF, check the turbo to see if she spins, and move the shaft up and down, with a light touch, you shouldn't be able to touch the wheel to the housing. IF this is ok, then install a boost gauge and see what's going on.

Get a vacuum gauge and see if your getting vacuum to the boost control solenoids, engine running.
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1984 G20 Diesel Get a Way Van, 6.2L turbo. Rebuilt 1989 700R4, 3.08 gears. Fluid damper, modified hummer headers, 2.5" mandrel Y-pipe to 3 inch single system, Hooker Max Flo muffler, 3 inch F350 mandrel bent tailpipe-passenger side exit, 6.5L turbo lower intake, 6.5 military IP-5149, open faced injectors set to 2500 psi, HX35W with a super 60mm billet wheel at 22psi, ARP studs, .010" head gaskets, bypass oil system, Dmax van fuel pump/filter combo. REMOTE MOUNT TURBO INSTALLED!!!! Burning hydraulic fluid, jet fuel, WMO and WATF.

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1989 Dodge Caravan ex daily driver, 2.5L TIII DOHC Turbo, GT35R, 12.5@104 mph.

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Last edited by turbovanman; 08-07-2013 at 05:36 PM.
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Old 08-07-2013, 09:46 PM   #9 (permalink)
orangespot
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Thanks for the advice everyone.
Is there a way to edit my posts? I meant to say that my mechanic doesn't have a lot of experience with diesels... (I wrote "turbos" by mistake).

I tried to seat the airbox lid better, then I clamped it shut. This time, I closed the hood all the way and then I drove it to the grocery store in town. This time it didn't lose power until I was almost home. That's a 40 mile round trip. I never had to pull over or turn off the ignition. I even made it up the hill. Though I was only able to go 25 mph by the time I got to the top. So there is improvement but I don't know why.

Suburbank2500, my air conditioner and heater are working great, so does that mean my water pump is also working? Thanks for the Kennedy link, I'll probably do those mods but want to wait until I figure out the problem.

No black smoke. just white when I start it. Also, sometimes a puff of white comes out when it shifts gears. But not always. I think everything on the truck is stock. I've never modified anything. It's a work truck, mostly. Been pretty reliable with minimal problems until last year. 2 starters went out and 2 alternators too.

I don't think I've ever heard the turbo, but then I'm not sure what to listen for. In my old Mitusbishi Eclipse I could really hear it, but the diesel truck is so noisy.

I did stick my hand in the turbine and spun it. Next time, will check for wiggle too.

The problem with finding the leak is that it is running along the frame by the time it drips to the ground. Makes it harder to trace.

We drove it from Seattle to San Diego in 2010 or 2011 (can't remember). It drove great. But in LA, it blew a hole in the exhaust, where it connects to the engine, I guess. The muffler shop repaired it, but I don't remember the details too well, my friend was driving it, so he paid to fix it. It had lots of power on the way back, even loaded up with his books stuff from his storage locker.

Okay, I'll try to get my mechanic to read this thread and troubleshoot from your advice. Where's a good place to get a boost gauge without breaking the bank?
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Old 08-07-2013, 09:54 PM   #10 (permalink)
turbovanman
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Boost gauges are around $30-$50, check any auto store or Ebay.
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1984 G20 Diesel Get a Way Van, 6.2L turbo. Rebuilt 1989 700R4, 3.08 gears. Fluid damper, modified hummer headers, 2.5" mandrel Y-pipe to 3 inch single system, Hooker Max Flo muffler, 3 inch F350 mandrel bent tailpipe-passenger side exit, 6.5L turbo lower intake, 6.5 military IP-5149, open faced injectors set to 2500 psi, HX35W with a super 60mm billet wheel at 22psi, ARP studs, .010" head gaskets, bypass oil system, Dmax van fuel pump/filter combo. REMOTE MOUNT TURBO INSTALLED!!!! Burning hydraulic fluid, jet fuel, WMO and WATF.

2000 VW Jetta TDI, auto, black, leather, fully loaded, wife's new ride.

1989 Dodge Caravan ex daily driver, 2.5L TIII DOHC Turbo, GT35R, 12.5@104 mph.

1993 CBR900RR and 2000 GSXR750 race bike.
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