Any GM tech's here? long..

[Tony]

About a few months ago my 03 6L SilveradoHD started to lightly surge at idle, so last month I took it to the dealership and they ran a scan and told me the intake gasket was bad, so I had them fix it. They also told me that they just happened to notice my surpentine idler pulley was bad, I didnt belive it since I had just replaced it 20k miles earlier but since I was planning a 3500 mile trip, I had them go ahead and replace it anyway. Halfway into my trip I start to hear a loud sqealing in the motor. After a few close up earshots and the fact that the "new" idler has a fair amount of slop in it, I decide the sqealing is coming from the new idler. I had an appointment next week to have it fixed.....

When I left the house this morning I made it about half a mile when, I heard 2 small clunking noises the engine misfired a few secconds then lost oil pressure, I instantly shut it down and coasted off the road. I check the oil level and its fine, then had the truck towed back to the dealership, I called the dealership to let them know it was comming and fully explained the problem.

Im thinking the timing chain, distributor gear, or oil pump let go. I get a call from the dealership and they say we have bad news, we only had time today to do a quick scan and your engine showed a misfire on a few cylinders on the scan and your engine needs replaced. I ask how they can possibly come to such rediculous conclusion from a simple misfire scan.

...The response, well we ran it for a minute and that squealing you heard was the crank bearings. YOU RAN MY TRUCK WITH NO OIL PRESSURE??? Silence on the other end of the phone......

Is my thinking way off, or did theese guys just lunch my engine?

[Chris]

Yes, they did.

[Buoy]

sounds like the brain surgeons at the dealership put the fork in it.

That sucks.

[cigdaze]

Wow...morons! Dude, sounds like you have a good case to have them replace your motor. That's BS!! Who the fvck runs an engine with no OP?!

[Tony]

I will be there to speak to the service manager as he steps out of his vehicle Monday A.M. Its extremely ironic that this motor has such a "premature" catastrophic failure within 30 days of them doing an "open heart" repair.

Hell I think that will be a great first question to ask. So um how many doccumented cases of theese uhh motors have oil pump failures within 30 days of intake manifold removal @ 100k miles?????

[HaxbySpeed]

Just make sure you're there when they pull that rag out of the lifter valley!

[macjazzy]

Just make sure you're there when they pull that rag out of the lifter valley!

That's obviously a possibility but more likely would be that the tech used a gasket cleaner air tool that has pads that look like mini scotch brite pads. All the manufacturers have stated specifically to not use them as it leaves a lot of grit in the engine that eventually takes out the bearings or in a worse case scenario clogs up the oil pump screen.

Lots of techs still use them because they work so easily and fast.

If there is any question ask for an oil sample to be taken and shipped to someone who can analyze it. That is a pretty cheap process that has a quick turn around. Lots of places can do it, just do a google search.

In fact first thing in the morning call and make sure they pull a sample before it gets drained out and its too late

[sledge]

FWIW, the 6.0L has a sealed cover over the valley. And the intake "gaskets" are rubber orings that fit into grooves in the plastic intake manifold. Intake manifold removal is pretty simple and generally doesn't entail much of a mess.
Also FWIW, the oil pump on these motors is crank driven, behind the front cover. Very different than previous SBCs.
I'm being devil's advocate here, but don't get your hopes up that they did something wrong. Of course it's possible that the tech will fess up and admit he did something. But reading your description of events, if they performed the service you describe, and they didn't drop something down the intake port, their work wouldn't have caused this.
Final FWIW: LS oil pumps have a reputation for just quitting for no reason. And you experienced the pressure loss yourself.

Do the oil sample for sure. Be there, or if you're not familiar with the particulars, higher someone that knows the engine to be there. At least LQ4s are pretty cheap at the salvage yards.

Best of luck. Let us know how it goes.

[HaxbySpeed]

That's obviously a possibility but more likely would be that the tech used a gasket cleaner air tool that has pads that look like mini scotch brite pads. All the manufacturers have stated specifically to not use them as it leaves a lot of grit in the engine that eventually takes out the bearings or in a worse case scenario clogs up the oil pump screen.

Lots of techs still use them because they work so easily and fast.

If there is any question ask for an oil sample to be taken and shipped to someone who can analyze it. That is a pretty cheap process that has a quick turn around. Lots of places can do it, just do a google search.

In fact first thing in the morning call and make sure they pull a sample before it gets drained out and its too late

I was kidding about the rag.. GM, FelPro and others have put out service bulletins for years on those high speed abrasive pads. The main reason being that they round the corners around any port or passage and cause sealing issues. I think you could probably crush a couple of them up in the oil pan and still keep running though. As for oil samples.. Let them know what has happened and give as much detail as possible. The tests are not great other then determinig viscosity and fluid contaminents like gas and antifreeze. I have sent in samples for insurance claims with actual chunks of metal in the oil and had it come back "all good"...

[Tony]

Thanks for all the replies. I'm still floored that an ASE tech would start and run an engine that had no oil pressure.

[HaxbySpeed]

He was probably reading his trouble-shooting flow chart when the thing locked up.

[torrent]

What I gather from your post it sounds like the damage was done before the tech looked at it. The noises you heard before you lost oil pressure was probably what caused your loss of oil pressure.

How many miles are on the vehicle? The reason I ask is GM has a goodwill program, you may get off just having to pay for labor. If your under 70,000 the area service manager from GM may be able to assist.

[NOMOGOFAST]

Hey Tony,

Let me know what happens. I have alot of options for Duramax engines that will save you some $$$. We sell reman, new as well as used.

Don
Factory Engine Exchange
800-764-5040

[SunTime]

How many miles are on your 6.0 out of curiosity?
Does G.M reccomend a pump change at certain intervals on the 6.0?

[torrent]

I have never seen an oil pump fail on a 6.0. The oil pump on this engine is crank driven. It is possible if the harmonic balancer bolt loosened up. The balancer bolt needs to be torqed down tight. Insufficient torque will cause low oil pressure.

[Tony]

I tore it down yesterday and the only thing I could find wrong was a mangled cam bearing. The oil pump was fine, I couldnt even find any evidence of damage from lack of oil pressure, cylinders and bearings all looked fine. Thanks SO member NOMOGOFAST for quick delivery and lots of options for a replacement egnine.


The culprit:

[NOMOGOFAST]

Glad I could help you. I think we have all been there before.......even me. Hope everything works out for you. Did the motor get there ok?

Don
Factory Engine & Transmission Exchange
800-764-5040

[FULL FORCE]

I tore it down yesterday and the only thing I could find wrong was a mangled cam bearing. The oil pump was fine, I couldnt even find any evidence of damage from lack of oil pressure, cylinders and bearings all looked fine. Thanks SO member NOMOGOFAST for quick delivery and lots of options for a replacement egnine.


The culprit:

Wow! I have never had cam bearing failure, they usually live through issues, it is wierd that you lost oil pressure that much from the #2 cam bearing, I could see it at #4-5 closer to pump. I am wonderinig what could have caused it, besides just bad luck, iti is not common to lose cam bearings.

[Tony]

From what I read on the GM forums cam bearing failure does occasionally happen on this model engine. The oil pump is on the front of the engine right behind the balancer inside the timing cover, it caps the front of the crank, thats how it is driven.

[FULL FORCE]

From what I read on the GM forums cam bearing failure does occasionally happen on this model engine. The oil pump is on the front of the engine right behind the balancer inside the timing cover, it caps the front of the crank, thats how it is driven.

Oh... I guess that engine is totally different then a regular small block.. did you get the new engine in yet?

Good thing you have a Ford to bail you out!!