johnny5.9

I know this is dodge site but I didn't want to go to the trouble of setting myself up on dieselplace just to ask a question. I figured somebody here would know just as much. I recently drove an 01 d-max to see how I liked it. I know this is the first year for them and so I want to be careful. Previously I have only driven LBZ's but this sounded much different. The truck has 81K on it. The truck fired right up and sounded fine. However when taking off and putting even a slight load on the engine it develops this knocking sound. I usually know the diference between a good knock and bad and I can't think of what would knock like that in a HPCR system. The truck ran fine and had plenty of power it just sounded wierd. Any thoughts? Should I run?

96_12V

What's an LBZ??

Personally, I think far too many people skip a $100 test for a truck that ought to be standard practice. Take it to a qualified diesel tech (maybe even the dealer for the brand) and let them do a complete check on it. They can tell you what to expect - and this one sounds like at least the injection system (or more) may be on that list soon. I would let a dealer look it over. If they have bad news, take the truck back, and walk away.

if the seller won't let you visit a repair shop - I would run away from it.

Common

Did the CES light come on?

rjm022

duramax engines are known by lb7,lly,lbz and lmm (depicts yearly engine/design changes,etc )

wannadiesel

If you think it sounds funny, skip it and go on to the next truck.

torquefan

On the LB7 trucks (01-early 04) injector problems were VERY common. So much that GM extended the warranty on the injectors to somewhere around 200,000 miles and eleven years. Not too bad for standing behind their product.

99DodgeGuy

Had one like that, at the logging company I was working at, I never experienced a knocking noise, so much as timing rattle somewhat similar to my dad's 04 dually, just while accelerating as the computer is putting in more timimg... however that one also had problems where it would go into limp mode and wouldn't go over 40km/h, til you shut it off and restarted it... good times...

pretty good truck took quite a bit of logging roads in it's 250K kms of life til the block heater caught fire in the middle of winter, just too bad it didn't have more ground clearance (took a boulder or two)

johnny5.9

Good advice. No, the CES didn't come on. That's what I thought was kind of wierd.

John_P

johnny5.9:

Without knowing the history of that Duramax (what the prior owners might have done to the truck performance wise) I would be real careful about buying it! I know that the Duramaxes that have been heavily modified have had some problems with "shrinking" rods. I know that Clint Cannon at ATS Diesel has seen this with his Duramax and they are now recommending billet rods to all owners who plan on really cranking the power up on any of their Duramaxes. I am not saying this is what the truck is doing you drove, but it could be a possibility!

Anyway, be careful and good luck.

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John_P

Common

So the Duramax does have a CES light?

(Change engine soon)

duratothemax

pilot injection shutting off.

either that or bad injectors. what does the oil smell like? Can you tell the difference between timing rattle and an actual "knock"?

ben

LOGAN

usaully when one is run to the limits as in boxes and programming, you will shrink all the rods, rarely its only 1. take it to a dealer and have them check the injectors, its a TSB/recall thing so it worth getting it checked. and if you dont feel safe, just walk away from it. thats low mileage for a 2001, make sure its got the factory dash cluster in it too with the right miles, i know alot of guys that will swap another cluster into it and drive it til they get ready to get another truck and put the stock one back in.

Lil Dog

Problem is that even if the injectors are going bad, you don't get a CES light. You have to get the tech II hooked up to the engine and measure injector pulse width time (IIRC) to see if you have a bad injector. I think they call it "Balance Rates". Basically the ECM is trying to compensate for a bad injector by adjusting pulse width.

Thats the problem with todays plug & play uploaders, you would never know if the truck had a 200Hp upload with a tranny full of debris..

Skip it, find a grandpa truck if you can.

PoorMansCat

The check engine light on my company truck NEVER came on.... thru many sets of injectors. It would come on every time I lost an injection pump though. Only light I got when the engine let go was the low oil level light... I think GM/Isuzu has most of their problems worked out on the LBZ engine....but I would steer clear of the LB7 engine all together. JMHO!.
The block on my LB7 had dark burnish marks on the upper ends of the cylinder walls at 97,000 miles. After the engine swap, I talked to the dealership once GM had inspected it, they said the burnish marks (actually burnt spots in the walls from fuel) were due to engine being used at heavy loads on a continous basis. I believe the LB7 was a steep learning curve for Isuzu... but I think they may have it figured out now.

Grit Dog

You don't have to worry about the instrument cluster/odometer being switched out. It's not that easy. All the run time data is stored in the ECM. You could change out the cluster everyday and it will still read actual mileage.
Injectors are covered 7yrs OR 200k mi on 01-03's.
A "knock" is hard to diagnose over the 'net. My '02 does have some injector noise or timing rattle occasionally. Usually after a long drive, towing, but then it quiets down again.
Other than injectors being close to out of warranty on time, just get the truck checked out and buy it. 01's had reportedly some head warping problems, but that seems to be rare. One of my subs has an 01 w/ over 200k mi on it w/ a full Banks setup, stock Alli, and he's still on orig injectors, cp3 and trans.