2004 5.3L Silverado Losing Coolant

txab · June 21, 2011

Look at this TSB. It gives you all the info you need

http://ww2.justanswer.com/uploads/Bluegori...nt_loss_5.3.pdf

absinthminded · June 23, 2011

Crap...my truck has been running low on coolant for a while now. 2003 with 135k/5.3 I'll start digging into her tomorrow. I love this truck...might be time to trade her in.

absinthminded · June 23, 2011

I added dexcool today, checked my oil and inspected the inside of the oil cap and filler neck. The inside of the cap had this brown rusty color build up. You can see it on 2 spots of this wipe. I won't be able to pull the vc's for a few weeks. Just bought another house and I'm moving. Good thing it has a 3rd stall for fun stuff like this.

tc12 · July 4, 2011

2004 z71 bought brand new have the exact same things going on minus the smoke on startups. Mat be doing it and im just not catching it. About 2yrs ago noticed a small wet spot, investigated and found water pump gasket leaking., this was around 125k. Haven't pressure tested yet,but no signs or smell of coolant anywhere. Just changed oil today and found some disturbing sludge, it was alittle overdue but there was some chocolate syrup.that dripped out of the pan. Don’t.know what's up,and a mechanic IAM NOT. When I read the original post it was like I had written it. Your stepdad is not alone. If I stumble on a soluion I'll post it good luck.

walshj57 · September 1, 2011

Mine is an '04 Sierra 1500 with 5.3 liter Vortec/ 4WD/ AT. Just coming up on 90,000 mi. Bought it used 1 yr ago. Outside of towing a 23 ft boat for approx. 60 flat miles four mos ago, I've been easy on her. Early on it's only problem was lifter noise for 10-15 sec on morning startup. Later,began experiencing gradual coolant loss (approx. 1 qt. every gas fill/ 250 miles)-now only slight coolant loss and no coolant odor since I threw in some liquid aluminum last week. Temp gauge staying good also but it never really would go up very noticeably. Also added 1 qt Rislone to my oil change (done 275 mi ago) and noticed oil level down about 1/2 qt yesterday - so I topped it off with more Rislone. Prior to the treatment I would lose at least a qt of oil every oil change depending on how hard I drove her. When I was having the oil changes done soon after I bought the truck the outflow was heavy with sludge and I took to using 89 octane and synthetic oil ever since.Have seen light puff of smoke only occasionally on startup and only after sitting overnight. Oil gauge reading all the way right pointing toward 4 o'clock as if broken- only moves slightly back on occassion or deceleration- it used to read between low end and medium in early months. Having no issues with power but getting some rattling on acceleration (0-25mph,especially if done quickly). So I was developing some concern about the rings but kinda glad that there weren't real bad crankcase problems yet.Was considering I would do a head/head gasket/rings job soon for a more permanent fix.I was honestly going to make my first entry to this website this morning to see if you guys liked my thought process but first I wanted to start her up and get fluid level checks.Well (and I swear this is the FIRST time) it starts rattling like there's you're shakin a large spray paint can. Still turning-no freeze up. Rattled louder with higher accel. but slightly less as it warmed up- I haven't dared get on the road since this started. Slight puff smoke at first but didn't continue.Dipstick clear and up to top level. No leaks underneath. Temp gauge good.The noise does seem to be coming from low in crankcase. WTF. Did I just happen to witness exactly when this thing went from having just moderately bad problems (gasket/rings) to all out disaster (rods/bearings/shaft) right as I'm looking under my hood? Did I F#$@ it up myself with these engine treatments? Is this what they do right before they break and freeze up? HELP!!

cheetoz49er · October 8, 2011

OK it is 6: like I said I went buy what I had to use and was not sure.

Otherwise I can't explain the symtoms you have described. Start with testing for leaks in the cooling system and go from there for now.

Share your results, or any addition symptoms or info that you might find.

I'm having the same issue with my truck. I just bought this used and this is my first Truck. I am losing coolant every 200 to 300 miles. I pressure check it the engine and it stay pressurize for 1 hour. so I don't know what else to look at.

txab · October 8, 2011

Pull the valve covers to find if you have the suspect head and problems. You could be leaking in other locations. Water pump and gaskets are the most common location. They may be hard to find too. They don't always pour water, just a small seep while the engine is hot will evaporate before hitting the ground. You can add a special dye to the coolant, then use a black light to find most leaks. Head gaskets can be another culprit

2manyrepairs · January 8, 2012

I have a 2005 Sierra 1500 CK 4.8L. Bought the truck new and I am another owner whose dealer was eliminated. Truck only has 108,000km (just over 60,000 miles) and had all servicing. Just noticed in the last month problems with the heating system, thought I'd change the thermostat and saw coolant reservoir was nearly empty. Refilled twice. Can't see where coolant is leaking. Oil looks good. Going out to look at the truck and pull valve covers off and check for Castech logos and signs of leakage. I've owned four GM cars and this is my third and maybe last GMC truck. Had the first truck 15 years, second 12 years and had only normal maintenance repairs on these. My current truck has also had wheel bearing replacements, brake problems, tie rod replacement. and is showing rust in more than one location already - my 12 year old Sierra still had no rust when I traded it.

I've already spoken to GM about my dissatisfaction with the truck but they do not appear to care about service after the sale.

DeePa · January 26, 2012

I went through all of this back in june. My 04 sierra 5.3 had the castech issue, fixed it myself for 1500 with 2 brand new head castings from GM, then a shop swapped all of the internals over.

Also did lifters, water pump, hoses, all gaskets, etc.

It sucks but 1500 is better than paying for a new truck.

Any questions, just PM me. My elbow is still F'd from torquing the 30 head bolts in a row...

Mike

RADO_4U2NV · January 30, 2012

Mostly 5.3's came with the castech heads, a few 4.8's had them but very few. Most of you this is going to be your problem. You don't have to replace them with new heads. You can find heads online for around a $100. have a machine shop do a valve job and clean the surface and your ready to go. The 862 off of the 4.8's is nearly the same head just the combustion chamber is a little bigger (around 1cc) do to the 4.8's having flat top pistons and the 5.3's having dish pistons.

The tapping noise is usually piston slap. The LSx series are notorious for this. It only happens on start up, after the engine warms some and the internals swell and tight things up it stops. Another is the lifters do to the aluminum heads and composite intake there is nothing to to absorb the sound of the valve train like on and old iron 350 motor with iron heads and intake.