Turbo problem - Isuzu NPR

[VicHanson]

I need some help from you experienced Isuzu owners/mechs. My 2001 NPR has 78,800 miles on it and just recently it started making unusual noises. It started as a whistling noise when I would accelerate or was pulling a little harder, not at a steady speed on level ground. As soon as I would let up on the throttle it would stop. I talked to a diesel mech and he said there was an air leak in the hoses between the turbo and the intake manifold, to check for a hole or loose clamps. I couldn't detect any leaks but tightened the clamps. Of course it didn't make the sound when I just revved it up while sitting still.

That seemed to help some for awhile but then I noticed a similar noise when I let off the throttle, and then under some conditions it sounded more like a squeal than a whistle. Today when I first started it there was a definite squeal, couldn't pinpoint it for sure but guessed it was coming from the turbo. When I increased the RPMs a little it would stop, but then would start again when idling. After blipping the throttle a few times the noise stopped. I did loosen the clamps and wiggle the hoses around to try to seat them a little better and then tightened them all good. I haven't driven it since to see if it is the same as before under normal conditions on the road.

I also talked with a guy who said he drove one for years at highway speeds of 70 mph and had to replace the seals in the turbo a couple of times because of high speed driving. I rarely drive over 55 mph but do spend time at higher RPMs in lower gears when going up hills and mountain passes.

I know in Peru they rebuilt turbos all the time, do they do it in the US as well or just replace them? Is this something that any mechanic can handle or do I need to take it to an Isuzu or Chevy truck dealer? Any idea on costs?

Thanks much for any help or recommendations you can provide.

Vic Hanson

 

[alan]

Hi Vic,
I would be checking the shaft free play in the turbo, disconnect hose at turbo and move the shaft up and down there should be very little movement may be 5-10 thou tops!

 

[FusoFG]

if it's anything like the mitsu, it might be the turbo waste gate actuator or the over boost relief valve on the intake manifold.

That whistles like blowing across a pipe sometimes.

You haven't mentioned any performance issues associated with the noise. Are there any?

Have the boost pressure checked. Any diesel mechanic should be able to do that.

Mitsu manual calls for not driving until water temp gauge moves off zero and idling engine after driving for 3 minutes before shutting down to protect turbo bearings.

my 1994 turbo is rebuildable, my 2004 turbo internals are single non rebuildable replaceable unit.

don't know about 2001 isuzu.

have a manual?

 

[VicHanson]

Thanks for the info guys. I ended up taking it in to a repair shop today and just got the bad news from them now, it is a problem with the turbo, probably the waste gate I think he said. He also said it is not repairable, the whole unit needs to be replaced. He estimated about $2500 to replace it, including the diagnostic work they have already done. Ouch!! They are going to try to get a better price on the turbo tomorrow and then will call me again.

 

[VicHanson]

I was told by a mechanic friend that the price I received was way too high, so I called an Isuzu dealer and they said the turbo by itself was $1311. I was first told $1800 by the repair shop. Those were both with a core exchange so they do rebuild them! They gave me a final price of $2300 total so I went and picked up my truck, had to pay $221 for the diagnostic work. I was about ready to order the turbo from the dealer when I decided to check again at Turbocharger Pros online. I had called them earlier and gave up waiting on hold. They said $675 for a new aftermarket one or $850 for a rebuilt Garrett. I decided to go with the new, should have it by Tuesday, and will replace it myself. Hoping that goes OK!

 

[whatcharterboat]

HI Vic,

Well done. Fingers crossed.

Regards John.

 

[kerry]

Shouldn't be a difficult job. Just for the record, in the USA, Busbee's Truck Parts is the best supplier of used Fuso, Isuzu and other cab over trucks I have found. They ship anywhere and are prompt. They specialize just in cabover trucks.

 

[VicHanson]

Time to bring you up to date, hopefully my experience will help someone else! It took me 3 days to replace the turbo. The bolts were really rusty so had trouble getting the old one off but finally got it. Then I ran into problems trying to put the new turbo in, just couldn't get the bolts and holes to line up correctly. Finally gave up about 7:30 pm. Tried a new approach the next day (after much thought and prayer!). Not having a manual or any instructions to follow, I had done things in the wrong order. Started over from the beginning and got the right sequence for putting the pieces together and it worked! All installed correctly, no parts left over.

Everything sounded good at start up, let it warm up good and then took the truck out for a test drive. It seems to make the same noise as before! I paid $220 to confirm that it was a turbo problem, $675 for a new turbo, 3 days of learning how to do it, and it didn't fix anything. I wasn't a happy camper! The repair shop was closed for the weekend so had to wait until Monday to take it back and see what they had to say. They said that because I had done the work, they couldn't take any responsibility for it not solving the problem, I might have done it wrong!

I wanted to get heading south so drove down to Portland and took my truck to an Isuzu dealer there (FMI - Fleet Maintenance Inc.), the service manager looked at it and immediately determined that the whistling noise was caused by a broken bolt on the exhaust manifold. He said that is a somewhat common problem for trucks that are in areas where salt is used, or other rust prone areas. The chassis of my truck was very rusty, not sure if it was the salt air in Florida or if it was from a snow area originally. Repair estimate - $1000, which included a new manifold and labor. I dropped it off there on Thursday about noon and it was ready the next afternoon. Runs and sounds perfect! The total cost was about $50 more than the estimate but it was done ahead of schedule. Very good service, they went out of their way to have it done early for me. They have two locations, the one I went to only works M-F, till 5:00pm. Their other location works Saturdays as well, and they are open till midnight, so they took it over there to make sure it got done right away! The problem was at the front of the engine, right behind the AC compressor. The original repair shop said that the compressor was making noise and needed to be replaced as well. Not a sound now so I'm thinking they were just totally incompetent. Just before taking it to the Isuzu dealer, I had been trying to pinpoint the noise, which did seem to be coming from the area of the compressor. But it was hard to tell because I had to be on the other side of the engine to rev it up. However at one time I did see a slight puff of smoke that came from the front of the engine on the other side from me. That was exactly where the broken bolt was (which wasn't easily visible behind the compressor mounting bracket), so I was pretty sure that he had found the problem.

Anyway, other than being $2000 poorer, I'm very happy to have the problem solved. I think I will stick with Isuzu dealers from now on!

 

[SkiFreak]

That's quite some saga Vic.
Happy to hear that you finally have it all sorted but empathize with you about paying for and getting crappy advice. I had the same sort of thing happen to me some years back.

I must say that it is hard to find good tradesmen these days, in any area. I am lucky that I can put my hand to most things but when I do get stuff done by other people I normally find myself asking why I did not do it myself when it is a below par job.

I am just about to get a 3" exhaust fitted to my truck.
I went to six shops before I met a guy that looked like he had good skills and cared about what he did. I must add that I have made all of the exhaust hangers and brackets, along with getting heavy duty flanges made, so all he will need to do is run the exhaust pipe along the path I have created.
It goes into the shop this week, so we will see how it goes.

 

[TriStateTurbo.com]

Isuzu NPR Turbo Rebuild or just a Broken Exhaust studs? TriStateTurbo NJ NY PA CT

Isuzu NPR NPI NQR Turbo Owners might find this information helpful as we service Isuzu NPR / NPI turbochargers for our fleet customers here in New Jersey.

We see our fair share of NPR NPI NQR turbochargers and typically they are in bad shape from the elements. Most of the Isuzu turbochargers are Garrett
and commonly produced by Garrett in Japan and for some reason the Asian iron doesnt seem to weather the east coast elements very well. Typically there are broken studs that require considerable time to remove.

We have plenty of walk in clients that bring NPR - NPI - NQR turbochargers into our Bergen County, NJ workshop for a rebuild often times customers hear a high pitch scream coming from the engine in the turbocharger vicinity. This high pitch whine sounds very much like a turbocharger failure but often when the noise is isolated it turns out to be a broken exhaust stud.

Typically broken exhaust manifold studs can be a simple repair or a major expense depending on the break and the technician aptitude. During tear down customers will experience additional broken studs due to the fact most of the material is corroded and rust-welded.

If the turbocharger is accessible it might be in the owners best interest to inspect or have a mechanic inspect the turbocharger for shaft play. Most Isuzu turbochargers are worked very hard and typically benefit from a turbocharger overhaul during the process explained above. If the turbocharger shows signs of excess play now would be the correct time to quote a turbo rebuild price or to be 100% certain of the exact price ask for a turbo core exchange. Keep in mind sending your own turbo in for service will be more economic compared to a core exchange. Exact price & time frame may not be furnished until your turbocharger is inspected at our workshop.

Moral of the story, small problems may seem HUGE use a cool head and make the right decisions. If you have questions regarding turbocharger related issues feel free to contact us direct.

Thank you,

TriStateTurbo
80 Greenwood Avenue
Midland Park, NJ 07432
888-292-7001

 

[carisam]

Hello everyone!
Just reaching out to see if anyone has any ideas. I have a 06 NPR with the 5.2L RV conversion . I am getting a low turbo bust pressure code if I drive above 50 mph for a few minutes (code 0299) . If I clear the code the engine comes right back up. I have had to drive her home a few times now in limp mode. I am wrapping up my project and surely don't want any trouble when my wife and I head out for our new life style.

I am also talking to some suspension people because I have flattened out my springs due to the conversion. Any suspension suggestions would also be welcomed.



I have installed the following into my conversion:

1 made a patio deck out of the 8x16 ft roof along with inside swing down ladder
2 elevator queen bed
3 24 volt 360 amp hr lithium batteries
4 24 volt 150 amp secondary alternanter
5 Washer and dryer
6 Victron multiplus 3000 inverter
7 42 gal fresh and 32 gal grey water under the floor between the chassis
8 1 ton mini split A/C with WIFI
9 I have a 1600 lb tuck away lift I want to use to carry a motorcycle on the back just for fun.
10 32 inch one piece shower.
11 12 volt 10 cu ft refrigerator
12 induction cooktop

Solar panels coming next
We hope to be out there soon.....................

Gary

 

[kerry]

I'd try to get a direct reading of boost pressure, either via a software program which provides a readout or installing a manual pressure gauge. It could be a problem with the sender but knowing the actual pressure and how it varies at various speeds could get you looking in the right direction. Do you have a clean air filter on it? A dirty air filter could reduce boost pressures.

 

[kerry]

How are you powering that fridge?

 

[carisam]

I'd try to get a direct reading of boost pressure, either via a software program which provides a readout or installing a manual pressure gauge. It could be a problem with the sender but knowing the actual pressure and how it varies at various speeds could get you looking in the right direction. Do you have a clean air filter on it? A dirty air filter could reduce boost pressures.

Yes the air filter is new. I have an obd2 ( blue driver ) but it doe not support (live mode on the truck) I am looking for the IDSS isuzu software but it is pricey.
I went thru it today. Removed hoses, and ckecked actuators. As far as I can tell seems ok. Mas sensor voltage changes when I give it gas.
Turbo gate valve feels good I guess I wont really know unless I put a gauge on like you suggested.
Thank you

 

[carisam]

How are you powering that fridge?

The refrigerator is a 10 Cubic Ft. Made by Unique.
It will run on 12 or 24 volt . The say 300 watts of solar panel will run it.
I have 360 ah at 24 volts of lithium batteries.