GM Certified Techs or anyone with help

[oreo57]

I have a 2003 Silverado 4.8L with Castech 706/lr4  heads, How rare have you found the the heads getting a prolific crack vs a head gasket being bad..any help would be appreciated. Mine is losing antifreeze into the heads but not sure why.

[austinado16]

I'm not a GM Certified Tech, but I do spin wrenches.

At this point, it doesn't matter if the head(s) are cracked or if you've blown a headgasket.  Both heads have to come off, no matter what.  If it is sucking coolant into the combustion chambers, you risk bending a connecting rod and/or ruining the catalytic convertor(s) if you continue to drive it and the coolant usage becomes worse.

If you don't find a blown head gasket(s), then have both heads pressure checked by a competant machine shop like "Tuttle's" in Buena Park.

[brainpause]

Just curious...How many miles?

I'm putting shocks on my Silverado today. Hope it is as easy as my Frontier was.

Larry

[oreo57]

Just curious...How many miles?
 
I'm putting shocks on my Silverado today. Hope it is as easy as my Frontier was.
 
Larry

81,000, the shocks easy.
 
 
Thanks, Austinado16

[wavery]

I have a 2003 Silverado 4.8L with Castech 706/lr4  heads, How rare have you found the the heads getting a prolific crack vs a head gasket being bad..any help would be appreciated. Mine is losing antifreeze into the heads but not sure why.

Austin is right.

How did you determine that you are, "losing antifreeze into the heads"?

If you've found antifreeze in the oil or exhaust......... or exhaust gas in the radiator, I would not start that engine again until I found the source.

If (God forbid) you've got antifreeze in the oil, you may need a complete engine overhaul. Antifreeze will destroy bearing surfaces in a short time.

If you have signs of antifreeze in both exuast pipes, it could be something as simple as a bad intake manifold gasket. I still wouldn't start the engine again until I found out. Cat converters are very expensive these days.

[bhauber]

I will second the intake manifold gasket. Chevy V8 is known for that. Check it out at //www.chevytalk.org. My 1996 5.0 liter had it go at 120,000 miles

[oreo57]

Austin is right.
 
How did you determine that you are, "losing antifreeze into the heads"?
 
If you've found antifreeze in the oil or exhaust......... or exhaust gas in the radiator, I would not start that engine again until I found the source.
 
If (God forbid) you've got antifreeze in the oil, you may need a complete engine overhaul. Antifreeze will destroy bearing surfaces in a short time.
 
If you have signs of antifreeze in both exuast pipes, it could be something as simple as a bad intake manifold gasket. I still wouldn't start the engine again until I found out. Cat converters are very expensive these days.

Wayne , Pulled the valve covers, I'm getting a very small amount of leakage into the left valve cover creating sludge, So its been going on for awhile. The oil pressure dropped (40ibs max) the other day and the valves started knocking a bit loud so I flushed the block and put in fresh oil and its stopped knocking pressure back up ,I'm pulling the heads tomorrow after work and take them down to be magnifluxed to see if theres any crackes, new heads aint cheap but neither is a new truck !!
 
Thanks, everyone
 
PS I have been on the differant chevy boards all week looking for answers and even the dealer was no help.

[wavery]

Wayne , Pulled the valve covers, I'm getting a very small amount of leakage into the left valve cover creating sludge, So its been going on for awhile. The oil pressure dropped (40ibs max) the other day and the valves started knocking a bit loud so I flushed the block and put in fresh oil and its stopped knocking pressure back up ,I'm pulling the heads tomorrow after work and take them down to be magnifluxed to see if theres any crackes, new heads aint cheap but neither is a new truck !!
 
Thanks, everyone
 
PS I have been on the differant chevy boards all week looking for answers and even the dealer was no help.

YUK!!!! That's not good. Not very common for a head to be cracked and leaking into the oil galley. Cracked heads usually occur around the valve seat or less commonly in the exhaust port. I have seen cracks that go up the valve guide casting, intrude into the cooling casting then seep into the oil from there, if the crack goes far enough. Not very common though. If that's the case, you will usually have gas in the radiator. You might want to do a "Block-Check". That's a tool that goes on where the radiator cap attaches. It has a green chemical in it that will turn blue if there are exhaust gases present.

Water is heavier than oil. Any water leaking into the engine oil will go to the bottom of the pan then eventually be picked up by the oil pump and distributed throughout the engine block, distributed on the crank, and cam bearings. These bearing surfaces break down fairly quickly under antifreeze because the antifreeze will coat the bearing and oil can't get to the surface.

I used to be Service Manager at Felix Chevrolet in Los Angeles, then later Parts & Service Director for an AutoNations used car mega store. Whenever we had a vehicle with signs of antifreeze in the oil, we opened up the engine and replaced all of the bearings. We'd also inspect the camshaft and lifters very carefully. I'm also talking about low mileage vehicles that are under warranty. In fact, it was required by the factory.

[flyfisherman]

I have a 2003 Silverado 4.8L with Castech 706/lr4  heads, How rare have you found the the heads getting a prolific crack vs a head gasket being bad..any help would be appreciated. Mine is losing antifreeze into the heads but not sure why.

I also am running the 4.8 V-8 in a '02 GMC Sierra and have just passed the 100,000 mile mark. I'm curious to know what your refering to as Castech 706/lr4 heads ... are these factory or something you've added?




Fly

[flyfisherman]

Just curious...How many miles?

I'm putting shocks on my Silverado today. Hope it is as easy as my Frontier was.

Larry

That's a chore I've got to be looking into. My Sierra has begun that boat ride effect with my last outing with thye PU hitched. Tells me it's about Shock time at the 'ole corral.

Let me know how it goes and what kind of shocks you installed.




Fly

[oreo57]

I also am running the 4.8 V-8 in a '02 GMC Sierra and have just passed the 100,000 mile mark. I'm curious to know what your refering to as Castech 706/lr4 heads ... are these factory or something you've added?
 
 
 
 
Fly

No full factory, the 4.8/5.3l LR4 motors, the 706 is the casting #. Apparently they had a very few of these heads develope porosity cracks. You wont notice a leaks just that your adding antifreeze every 2-3 weeks as the coolant get released into the valve cover thru a crack normally around 1 of the head bolts, then your oil gets sludgy and the filter plugs up and you loose oil pressure, found very little on this and SM at the dealer didnt seem to know or care as the trucks out of warranty, But I do know that it is a very rare condition, but I'll find out tomorrow when I pull the heads.

[oreo57]

Engine - Coolant Loss With No Visible Leaks
Bulletin No.: 06-06-01-019B
Date: June 12, 2007
Subject:
Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found
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(R) GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z - RPOs LR4, LM7, LH6, L33, L59)

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.

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

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. 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, replace the entire cylinder head(s) assembly.

[flyfisherman]

No full factory, the 4.8/5.3l LR4 motors, the 706 is the casting #. Apparently they had a very few of these heads develope porosity cracks. You wont notice a leaks just that your adding antifreeze every 2-3 weeks as the coolant get released into the valve cover thru a crack normally around 1 of the head bolts, then your oil gets sludgy and the filter plugs up and you loose oil pressure, found very little on this and SM at the dealer didnt seem to know or care as the trucks out of warranty, But I do know that it is a very rare condition, but I'll find out tomorrow when I pull the heads.

Thanks for the heads up. If you will, how about posting the results of pulling those heads. What would you do .... replace them?

[wavery]

Contact the Service Manager at your local Chevy Dealership before you pull the head. If he goes into, "It's not under warranty", ask for a meeting with the factory rep. (do it in writing). He has to meet with you if you request it.

You may find that they are willing to help. If this is a recognized factory defect, they may well help you out. I know that I would have. GM is very concerned about customer loyalty.

BTW......if it's that rare, I wouldn't be concerned about the other head unless you just want to do a valve job anyway.

One other thing....."KW Block Sealer" is amazing stuff. I once used it on a cracked cylinder block. There was actually water seeping out of the block in a steady stream. I put in a can of "KW Block Sealer" and drove that truck for 2 more years before I sold it. It doesn't gum up your colling system either. Do a Google search on it. I'm not even sure if it is still on the market.

[oreo57]

Contact the Service Manager at your local Chevy Dealership before you pull the head. If he goes into, "It's not under warranty", ask for a meeting with the factory rep. (do it in writing). He has to meet with you if you request it. [/size]

You may find that they are willing to help. If this is a recognized factory defect, they may well help you out. I know that I would have. GM is very concerned about customer loyalty.

BTW......if it's that rare, I wouldn't be concerned about the other head unless you just want to do a valve job anyway.

One other thing....."KW Block Sealer" is amazing stuff. I once used it on a cracked cylinder block. There was actually water seeping out of the block in a steady stream. I put in a can of "KW Block Sealer" and drove that truck for 2 more years before I sold it. It doesn't gum up your colling system either. Do a Google search on it. I'm not even sure if it is still on the market.

[/size]
 
Wayne, thanks for the info, but since this is Toni's daily commuter and also the TV and theres a trip to SP in 2 weeks, I think I'll go ahead and fix it now and then see what GM can do for me. I've been driving it to work this week as I only go 4 miles 1 way so not much use plus since I changed the oil and have gone thru 4 oil filters in about 12 days its running great, but needs to be fixed right so I can trust it for another 80,000 miles or more.