Low Coolant, Smoking On Start Up.

[Z71JB3]

2004 GMC Sierra Z71 90,000 miles. Been noticing drop in coolant as of Sept. About quart every month or about 600 to 800 miles. No sign of leaks, oil clean, no white smoke or white under oil filler cap. With in the last couple of weeks blue smoke in morning start up. Put quart of Lucas in at first seem to help. Went shopping Tue. and drove about 100 miles, started truck up couple of hours later a puff big blue cloud of smoke. Think I'll pull the plugs and look at them. What test can be done to check head gaskets? And is there any change of doing damage to engine diving this way? My only transportation. Any help would greatly be appreciated. This is my 3rd Z71 and the worst gas mileage of all them 14 to 15 on good day.

Thanks

[txab]

2004 GMC Sierra Z71 90,000 miles. Been noticing drop in coolant as of Sept. About quart every month or about 600 to 800 miles. No sign of leaks, oil clean, no white smoke or white under oil filler cap. With in the last couple of weeks blue smoke in morning start up. Put quart of Lucas in at first seem to help. Went shopping Tue. and drove about 100 miles, started truck up couple of hours later a puff big blue cloud of smoke. Think I'll pull the plugs and look at them. What test can be done to check head gaskets? And is there any change of doing damage to engine diving this way? My only transportation. Any help would greatly be appreciated. This is my 3rd Z71 and the worst gas mileage of all them 14 to 15 on good day.

Thanks

 

Check thoroughly for external coolant leaks. You can add a dye to the coolant and use a black light to aide in finding leaks. There was TSB issued about the certain heads developing cracks and causing leaks. See below.

 

You can have oil tested to see if you have signs of water/antifreeze in it.

 

Smoke on startup is probably valve guide seals leaking.

 

Document ID# 1986750

2004 Chevrolet Chevy C Silverado - 2WD

 

 

Subject:Information on Gradual Coolant Loss Over Time with No Evidence of Leak Found #06-06-01-019B - (06/12/2007)

 

 

 

 

 

 

Models:2004-2006 Buick Rainier

 

 

2001-2006 Cadillac Escalade Models

 

 

2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models

 

 

2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models

 

 

2001-2004 Oldsmobile Bravada

 

 

2005-2006 Saab 9-7X

 

 

with 4.8L or 5.3L VORTEC® GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z -- RPOs LR4, LM7, LH6, L33, L59)

 

 

 

 

This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

 

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

 

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

 

Important: If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

 

Refer to the following illustrations on how to identify Castech casting and/or the very specific areas of the cylinder head(s) for a coolant leak from porosity.

 

 

Cylinder head(s) location of the Castech manufacturing casting logo (1).

 

 

Close up view of the cylinder head(s) showing the Castech manufacturing casting logo (1).

 

 

If the cylinder head(s) is a Castech casting (1), inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time (2).

 

Important: If No evidence of coolant loss is found on inspection of Castech casting cylinder head(s), follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

 

 

The crack location can be found in any of the five cylinder head(s) oil drains. This can be seen as a clean or shiny area, on an otherwise stained surface (1). Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. If inspection reveals evidence of coolant witness marks (1), replace the entire cylinder head(s) assembly.

 

 

 

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

 

© Copyright General Motors Corporation. All Rights Reserved.

 

 

Document ID# 1986750

2004 Chevrolet Chevy C Silverado - 2WD

[Z71JB3]

I have change oil, put some high mileage oil in and some restorers, seem to be better on the smoking. The coolant lose is the one I'm concern about. Put dye in the coolant system and see no visible external leaks. Read the G.M. bulletin and decided to pulled a valve cover off to try and identify the casting mark for these heads, but it is under the rocker arm assemble and didn't want to go that far.There is sighs of coolant under the valve cover. Put some Bar's leak for head gasket and crack heads in that does mix with antifreeze. If that doesn't do it will try some Blue Devil, or Bar's leak that require draining all antifreeze out, will not mix with antifreeze. Also heard about some pellets the dealer my have. My question is where or how do I get my oil check for antifreeze and want is possible damaged to rod & main bearings if I been running antifreeze in oil. Time to trade in?

[txab]

http://www.blackstone-labs.com/

 

They will send you a sample container free by mail if you request it from their website.

[Blackwell]

2004 GMC Sierra Z71 90,000 miles. Been noticing drop in coolant as of Sept. About quart every month or about 600 to 800 miles. No sign of leaks, oil clean, no white smoke or white under oil filler cap. With in the last couple of weeks blue smoke in morning start up. Put quart of Lucas in at first seem to help. Went shopping Tue. and drove about 100 miles, started truck up couple of hours later a puff big blue cloud of smoke. Think I'll pull the plugs and look at them. What test can be done to check head gaskets? And is there any change of doing damage to engine diving this way? My only transportation. Any help would greatly be appreciated. This is my 3rd Z71 and the worst gas mileage of all them 14 to 15 on good day.

Thanks

 

I've been having the same problem with my wife's '04 Yukon for a month or two; our mechanic pulled up that same TSB about the cracked head, and we took the vehicle and the TSB info to the local GMC dealer. They confirmed that the head is cracked, and wanted $2000 to replace it. I wasn't interested in paying for GMC's manufacturing defect, so the service mgr. called GMC, who offered to split the cost. It was a nice gesture, but I'm still not happy about paying for a well-documented manufacturing mistake. My next step will be to call GMC directly.

I'd suggest taking yours to the dealer to confirm the head problem. Then go from there to see if you'd rather trade it in, or see if GMC will offer to pay for part of the repair. Good luck!

[KillerKnife]

I had a problem loosing coolant a couple months back and it was a bad head gasket cost just shy of $2000. I know for mine they only detected it by running a cylinder pressure test.

I think I read that you had signs of oil and coolant mixing in the covers I would defiantly get it looked at.