2004 5.3L Silverado Losing Coolant

rdnkcpa · February 17, 2011

How can defective heads pass a pressure test? If the head is cracked it will not hold pressure.

The bare heads were sourced by a local machine shop. He got them from an outfit in Canada.

This is what I have in mine so far:

bare heads and machine work $780.00

Lifters $140

Valve grind kit

New head bolts

New exhaust manifold bolts $23.00

water pump $150<--Thanks to Rich, AKA MS3DALE.

Spark plugs ~$70.00

Wires $65

Serpentine Belt

upper and lower radatior hoses

All SS hose clamps

GM Shop Manual $135.00

Snap-On torque angle gage $83.00

Anti-freeze

6 quarts mobil 1 & new filter

Those that I did not put prices next to, I could not remember what I paid.

All my labor is free. I'll let you know if it turns into a oil burner. A new crate engine is about $4k, plus labor.

jmilana · February 17, 2011

Didn't mean to alarm you. He was talking about buying "remanufactured" heads. Says that some of them never crack, just leach coolant through the porosity but pass a pressure test.

rdnkcpa · February 18, 2011

Didn't mean to alarm you. He was talking about buying "remanufactured" heads. Says that some of them never crack, just leach coolant through the porosity but pass a pressure test.

Not alamred. Mine were not cracked, they had the porosity problem. However, they did fail the pressure check. My heads are essentially remanned heads. Old valves were reground and put in the new head castings.

sicutlass455 · May 26, 2011

I'm having similar problems w/ my 2002 Silverado 4.8L w/ 120,000. I'm trying to get assistance from GM as we speak. First I have to have the Chevy Dealer's Service Department diagnosis the problem and confirm that it is the Castech heads and issue. I'm very nervous that this dealer is going to screw me... I brought him my truck along w/ the old oil filter(full of tar, burnt, sludge oil) and this is what he states..

He sticks his finger in the oil filter and smells..he states "Nope I don't smell any antifreeze in the oil. The might be antifreeze leaking, but maybe outside the engine."

I say what explains the condition of oil in my filter.

"To tell you the truth. It's a 120K engine, I would say normal engine wear."

I almost jumped over the counter and wanted to choke the guy. I've changed the oil personally w/ syn oil every 3K for the life of the engine. The filter looked like it fell in tar!!

If GM screws me on this one, I'm switching brands. I've owned only GM cars (14 vehicles) and worked as an Engineer in the Linden Assembly plant for 7 yrs. I hope they do the right thing.

KMGZ400 · May 26, 2011

I'm having similar problems w/ my 2002 Silverado 4.8L w/ 120,000. I'm trying to get assistance from GM as we speak. First I have to have the Chevy Dealer's Service Department diagnosis the problem and confirm that it is the Castech heads and issue. I'm very nervous that this dealer is going to screw me... I brought him my truck along w/ the old oil filter(full of tar, burnt, sludge oil) and this is what he states..

He sticks his finger in the oil filter and smells..he states "Nope I don't smell any antifreeze in the oil. The might be antifreeze leaking, but maybe outside the engine."

I say what explains the condition of oil in my filter.

"To tell you the truth. It's a 120K engine, I would say normal engine wear."

I almost jumped over the counter and wanted to choke the guy. I've changed the oil personally w/ syn oil every 3K for the life of the engine. The filter looked like it fell in tar!!

If GM screws me on this one, I'm switching brands. I've owned only GM cars (14 vehicles) and worked as an Engineer in the Linden Assembly plant for 7 yrs. I hope they do the right thing.

what are your symptoms? are you sure its not your water pump going?

sicutlass455 · May 26, 2011

Symptoms:

1. Antifreeze constantly needs topping off, but the last one more than usual. No external leaks found.

2. The oil pressure dropped (I think off the result of the sludgy oil clogging the lines

3. Burnt oil covering the drain plug (even saw some metal very minor shaving on the magnetic tip)

4. oil came out sludgy during last oil change

5. oil came out reddish in color

6. Oil filter full of thick sludge. i mean thick

Can a leak in the water pump cause the anit-freeze and oil to mix??

rdnkcpa · May 26, 2011

Symptoms:
1. Antifreeze constantly needs topping off, but the last one more than usual. No external leaks found.

2. The oil pressure dropped (I think off the result of the sludgy oil clogging the lines

3. Burnt oil covering the drain plug (even saw some metal very minor shaving on the magnetic tip)

4. oil came out sludgy during last oil change

5. oil came out reddish in color

6. Oil filter full of thick sludge. i mean thick

Can a leak in the water pump cause the anit-freeze and oil to mix??

I would think not, the water pump is bolted to the block and covers two water jacket holes. The water pump is seperate from the internals of the engine, meaning no oil passes through the water pump therefore it cannot mix in the w/p. Just my logic speaking there, but I've been known to be loud wrong sometimes.

I would look at the TSB on the Castech heads, I don't recall if it covered the 4.8's. If it is not the heads then maybe a blown head gasket?

If your oil pressure has dropped, it sounds like the coolant has eaten up the main bearings. Maybe time for a crate engine.

My truck had the Castech heads but my oil did not get full of sludge and the oil pressure has been the same since new.

jtstacy77 · June 5, 2011

I would bet it is the castech heads. Oil pressure hardly ever goes over 40. Sludge in filter and if it hasnt happened yet you will have a yellow gel in the oil filler tube. Trust me the sludge in the oil will keep getting worse. GM should really do something about those heads.

kgrigsby · June 11, 2011

I'm having similar problems w/ my 2002 Silverado 4.8L w/ 120,000. I'm trying to get assistance from GM as we speak. First I have to have the Chevy Dealer's Service Department diagnosis the problem and confirm that it is the Castech heads and issue. I'm very nervous that this dealer is going to screw me... I brought him my truck along w/ the old oil filter(full of tar, burnt, sludge oil) and this is what he states..

He sticks his finger in the oil filter and smells..he states "Nope I don't smell any antifreeze in the oil. The might be antifreeze leaking, but maybe outside the engine."

I say what explains the condition of oil in my filter.

"To tell you the truth. It's a 120K engine, I would say normal engine wear."

I almost jumped over the counter and wanted to choke the guy. I've changed the oil personally w/ syn oil every 3K for the life of the engine. The filter looked like it fell in tar!!

This is what I found with my Pickup, read carefully and save $2000.00. 3years and 55,000 km later and no loss of coolant.

Last year my 1999 gmc 4.8l 250,000 km had all the issues with the valve noisy lifters, loss of coolant with no visible sign of leaks on outside of engine.

I checked to see if i had the castec heads and did not.

Another thing I found in regards determining if you have antifreeze in you oil is your oil will not always be ' milky' on the oil dipstick to confirm that antifreeze has mixed with the oil, antifreeze does not like to mix with oil. You have to drop your oil and if it comes out kind of chunky or blobs, you have antifreeze in the oil, it will end up on the bottom of your drain pan.

I found the problem when I pulled the intake manifold off, THE TOP ROW OF BOLTS ABOVE PUSHROD GALLERIES, (11mm, not the main head bolts) ON THE LEFT HEAD HAD LOST TORQUE and subseqently antifreeze was able enter the oil pan via the valve pushrod galleries, there was evidence of corrosion, etc on the pushrods, aft lifter area.

At this point I was 90% sure I found the leak but decided to change the head gaskets, when they were pulled I found no evidence of leakage around the head gaskets gaskets.

So what I suggest, pull your intake manifold off, (only way to get at the smaller 11mm? bolts) check torque, if loose retorque, put intake back on (new gasket), if not and no sign of corrosion etc in pushrod galleries continue on with changing out head gaskets. If you do this it should take, 2-3 hrs versus 4-8 hr for a head gasket change depending on your experience.

If you are looking for a complicated explanation for this problem there is not one, that was all it is. Let us know what you find, Good luck and pm me if you need.

sledr · June 15, 2011

Well I am the latest member to join the Castech club.....

I have an 04 Silverado w/ 5.3. The truck has 173,000 km and I am the original owner. Last month I started losing coolant and consuming oil. Had it at the dealer yesterday for an oil change expecting the worst. The oil came out clean and the filter was OK but the when the tech pulled the valve cover it had the milky residue. So I bought some rad leak stop stuff and dumped it in. Today I begin my search for a new truck.

jeffro360 · June 17, 2011

add yet another castech member to the club. My truck is currently at the dealer, and i'm awaiting my service tech to get back to me on quotes for replacing the heads or or replacing the engine with a new one.

I'm not really sure how to handle this. To put things bluntly, what should i do? Can i use any threating language such as lawyers and class action law suits in combination with the TSB? Should i ask GM/Dealership to give me a discounted rate as i'm the original owner (even purchased from the same dealership in 2001).

I feel completely let down and quite mad that GM is just brushing this off. The repairs are going to cost more than the truck is actually worth. It's my love and i've taken care of her since i've picked her up... i hate the position i'eve been put in and really don't know what to do.

Any tips or advice on how to handle my dealership/service tech? would be very greatful for any help.

jeffro360 · June 17, 2011

Have you pressed any further on the issue of gathering names and contacting GM about arbitration?

Unfortunatly I own the same truck as you do, a 2004 GMC SIERRA Z71 WITH THE 5.3L ENGINE.

Recently, I discover gradual coolant loss over time with NO evidence of any external leaks and no changes in driveability and performance. Even the oil looked perfectly normal... After a little digging, this is what I found:

My truck is affected by GENERAL MOTORS SERVICE BULLETIN ##06-06-01-019B: Information on Gradual Coolant Loss Over Time with No Evidence of Leak Found - (Jun 12, 2007)

I inspected the cylinder heads and sure enough found the tell a tale signs that are indicative of "porosity cracks" in the cylinder heads in a very specific area. I found the cracks in BOTH of the heads in the same location!

I also noted the heavy "butter scotch" sludge that coated the underside of both of my valve covers. I can't help but wonder what damage this has caused my engine and most certainly shortened its operating life.

Currently I am approaching GENERAL MOTORS OF CANADA to urge them the carry out the repair at their expence as this is a blatantly obvious defect in craftsmanship on their part.

I may be gathering names and information of people affected to present to GM and request arbitration on this specific issue if they fail to remedy the problem.

Just look at the attached photo's!!!

1- CASTECH casting mark

2- Porosity crack easily visible with dye added to the coolant3

3-"Butter scotch" sludge unside of valve cover

chip645 · June 18, 2011

Hi all Im new here and found his great site looking for the slow leak with casteck heads . Every thing Ive read point to a cracked head . After pulling the right valve cover I noticed a creamy color in the fill spout . I then pulled the left side and the whole valve cover was a cream colored . My question is , is it always the left head that cracks ? Should I do both sides and is there any feed back on cyl heads Inc ? Thanks for all the previous posts Ive learned a lot .

sledr · June 21, 2011

Well I had the truck towed to my dealer yesterday for the repair. I also called GM Customer Service and pleaded my case. I was told that it was likely I would get some reimbursement given that I am the original owner and the truck has been serviced regularly, etc. However, the only catch is that the diagnosis and repair have to be carried out at a GM dealer - which makes perfect sense. Here is my dilemma - the place I go for service was a GM dealer up until 2 years ago - now they sell used stuff but most of the techs are still there. This is where I bought the truck and had it serviced - I have a 25 year relationship with them. Since my dealer was turfed by GM, I have tried 2 other dealerships in my area for minor service or recall items. One tried to scam me for new rear brakes telling me everything was "rotting" when they were not (I called them on it and the service manager blamed the girl who called me up pressuring me to replace the brakes. He claimed she must have misunderstood the tech) and the other just provides poor service (repair promised at a certain time but actually completed an hour or more later) and pressures you for more than what you came in for. I always end up back at my old dealer - they treat me very well and over the years have provided good, fair, and consistent service. They even gave me a loaner vehicle to use while the truck gets fixed. I may pursue some form of reimbursement but since it isn't being done at a GM dealer, I may be out of luck.