LB7: No compression

[x MadMAX DIESEL]

I am posting this for Dean (wdino73)

The truck started misfireing and got the misfire code on #7. Truck white smokes now. Balances rates arent good, think its +15-16 on that cylinder.

The oil pressure is normal, compression check said #7 had none.



Could this be an injector seal? Hoping its not a cracked piston.

Any ideas would be appreciated

 

[x MadMAX DIESEL]

its 15

 

[JOHNBOY]

Remove the oil fill cap with it idling. Are you getting a lot of blow out of it? If so piston is gonzo.

If it is and LB7 it could be a injector cup. But you would pressurize the coolant and blow out lots of it.

If it is an LLY or newer you should be able to see it blow by around the injector if the seal failed.

 

[wdino73]

I'm getting blowby out of the oil fill cap,

 

[x MadMAX DIESEL]

Remove the oil fill cap with it idling. Are you getting a lot of blow out of it? If so piston is gonzo.

If it is and LB7 it could be a injector cup. But you would pressurize the coolant and blow out lots of it.

If it is an LLY or newer you should be able to see it blow by around the injector if the seal failed.

He said he could see some blow by coming out the fill tube IIRC... Its an LB7

He wasn't molesting the truck even, it was on level 10 ppe

 

[LarryJewell]

is this a built motor

 

[x MadMAX DIESEL]

is this a built motor

02 Duramax, LB7 lots of toys, 150 hp Injector and match CP3 from Industrial Diesel, FASS Fuel System, Garrett GT ???? Ball Bearing Turbo, Stage II Port and Polished Heads, Street Cam with Upgrades to Valves, Springs, Push Tubes ect. ARP Head and Crank Studs, Crank and Cam Keyed, 20 over Malhe Pistons, Piston Skirts Coated, and Bowl delipped, Modified Oil Pump, Banks Intercooler, Suncoast with all the triming, Suncoast Transfer Case Bracket, BD Manifold with MBRP 4 to 5 inch Stackes with resonator, Stage III Snow Water/Meth, Bullydog Propane, Twin Electric Fans, EFI LIVE, Maxx Torsion Keys, Firestone Air Ride, Cpeks with Toyo's Open Country.

 

[SmokeShow]

I cannot believe the run of bad luck you are having on this Dean. I thought I had it bad at times. I feel for you bud. That's a pile of heartache under the hood.

Sure sounds like a piston to me. IMO, you have really GOT to buckle down and get someone to tune your truck for the stuff you have on it. PPE is good for stock engine trucks but IMO, custom tuning is needed once you've built the motor. Especially with the big sticks and heads, etc.


Just seen he has 20-over Mahle pistons... are those stock Mahle or the custom aftermarket ones? If the latter, that'd be the first set I've heard of CRACKING.

 

[wdino73]

I believe they were the stock 20 overs, I can't remember, yeah, I'm a upside down horseshoe lol, I really need some help on this one, Ben has really been trying to help, I like about 2 hrs. an I'll have the engine on the ground, I'll know later what happened, hopefully it's just a hole and no damage was done to the cy.wall, would thermal barrier coating helped this from happening,
Thanks for the love I feel like I lost my best friend again,

 

[x MadMAX DIESEL]

We'll get her running :thumb: I'm free after 1:00 tomorrow btw

 

[dmaxfireman]

IF it is a hole i would check the injectors to see if any are leaking (check balance rates) to avoid burning through another one shortly after you fix this one.

 

[x MadMAX DIESEL]

Thats what I was thinking.. Unplug the FPR, pull the injector fuse, crank with the glow plug pulled to check that, correct?

What is the fuse called that needs to be pulled?

 

[dmaxfireman]

not sure on the lb7 on lbz you just unplug both bail connectors and crank it over the the glowplugs out and find the one that makes the biggest mess

 

[sweetdiesel]

20 over Malhe Pistons, Piston Skirts Coated, and Bowl delipped, Modified Oil Pump.

I take it these are LB7/LLY pistons and not the forged? Just geussing since you said delipped??

Either way I feel bad for you!!!! A guy puts so much time effort and money into the built motors and expects it to take a shite kicking!

How much of a fuel shot where you running? If you dont mind me asking


Again sorry to hear that!

 

[Mike_S]

All those goodies and no rods? Seems like a good time to put some in to me...I would.

 

[dmaxfireman]

no factory dmax came with forged pistons. the lb7 lly's came with mahle cast pistons the lbz/lmm came with pos cast pistons that can crack under stock power levels.

rods are not a must..... are they nice, yes, but to save 3k on a budget build they are expendable. i am building a motor over the next few weeks that will be running arp headstuds delipped lb7 pistons and lbz rods and will be pushing hopefully upwards of 600rwhp if all goes to plan. i am going to throw everything i can at it with 40% overs 4094 and a raptor150 ported rail fittings and a shimmed fprv. i think it is going to hold together all right. i am going to beat the piss out of this motor on the sled pulling track and if i can muster up a few bucks for slicks or drag radials and drop shackles shoot for 11's. i expect that this build will be capable of this.

so again rods are not always a necessity

 

[LBZ]

no factory dmax came with forged pistons. the lb7 lly's came with mahle cast pistons the lbz/lmm came with pos cast pistons that can crack under stock power levels. No kidding. We are talking about a "BUILT" engine here but thanks for the info.

rods are not a must..... are they nice, yes, but to save 3k on a budget build they are expendable. i am building a motor over the next few weeks that will be running arp headstuds delipped lb7 pistons and lbz rods and will be pushing hopefully upwards of 600rwhp if all goes to plan. i am going to throw everything i can at it with 40% overs 4094 and a raptor150 ported rail fittings and a shimmed fprv. i think it is going to hold together all right. i am going to beat the piss out of this motor on the sled pulling track and if i can muster up a few bucks for slicks or drag radials and drop shackles shoot for 11's. i expect that this build will be capable of this.

so again rods are not always a necessity

If you think rods are expendable, talk to the guys that have bent them and windowed blocks and ask them how expendable they are. In any build. if your planning to do a budget build and keep the hp below 600 then yes LBZ/LMM rods will work much better than LB7/LLY ones. Which is what YOU are doing correct?

It looks to me this guy did a full build complete with stage 2 heads and a ton of other stuff-DEFINETLY NOT a budget build!! If rods were not done then I am at a loss as to why not. Who puts stage 2 heads on with a plan to keep it under 600hp??

 

[SmokeShow]

Simon, he said he's running PPE on 10 - whatever fuel shot that is.

It sounds like they are the OE mahle lb7 pistons that were delipped.

And I'm pretty sure he has aftermarket rods. This is round two (now will be round three) on a built motor. If you all recall, he first started out on here cause he had problems on his newly built engine that came out to be a busted crank. He tore it down and rebuilt himself and now this after just a few short months.


IMO, he needs to get more appropriate tuning and get his injectors checked. That's way too soon to be having issues.


C-ya

 

[x MadMAX DIESEL]

How much of a fuel shot where you running? If you dont mind me asking

I'm sure he won't have a problem with sharing what it fuels, I just don't want to say without permission. But like Mitch said it was a ppe tune he was running at the time. I will say that looking at the big tune, it would be really smart to back pw down after its fixed though. I never paid much attention to it.

 

[cdbright]

why was he running PPE if he has EFI, that might be a stupid question but i have always wanted to flash my truck back to stock pwr and then run a PPE just to see the difference, is that what you guys do when you run both, not stacking but to compare i would assume you back to stock first right????