2004 truck 4.8liter cracked head slowly leaking coolant

So I noticed my temp was high and checked my coolant which required a gallon of fluid to be added. Around the same time there came a light clatter from the engine when I would start it. The clatter would persist for a minute or so then fade away. I changed the oil and the clatter quit.
The engine light also came on with a code indicating one bank was running too lean. Cleared the code and it hasn't come back on.

1,600 miles later (just at one month) engine hot again requiring another gallon of coolant and valve clatter is back.

I'm at the dealer now getting this diagnosed. They have ruled out the intake gasket with a pressure test and are saying it's either a cracked head or a head gasket. They are estimating repairs at $1800 for a head gasket and have not mentioned a price for a new head. They are currently popping the valve covers to look for cracks.

Does this sound like bull? Are the heads relatively easy to do by one's self (I've got more auto experience than most peoeple, but I'm not a mechanic - I've replaced lower intake gasket, control arm bushings, transmissions, etc)? OR does someone here know of some secret problem with this engine that would be a likely culprit?

04 gmc 1/2 ton with the little 4.8 "v" engine

thanks







So it turns out the right head is cracked. apparently this is a well known problem and I get to spend $3,000 on the project of they said I could have a brand new engine for $5,000 haha. It really made me want to punch the guy.

Any ideas where to buy heads for a reasonable price? Apparently the key is to avoid Castech heads, as they are the ones experiencing this failure. The dealer wants about $450 per head for them, but I have a sneaking suspicion that a motivated individual could do better than that.

Anyone know of a good place to get quality heads for a more reasonable price?

When I worked at the dealer that was a service bulletin, never saw it, as it was in very few heads, but sounds like you. There are a few porous casting heads out there, as you said castech. My advice to you is to look at some salvage yards around. I am a mechanic, so it is no step for me to replace heads, it may be to you though. As far as other engines go, these are easier to replace heads on I think, because the intake manifold is easy to take off on these engines, the valley is covered by a plate, and you do not have to take it off to pull the heads on these things. It is not a hard job by any means, no timing of anything or any of that, just simple remove and reinstall, just gotta tourqe some hardware along the way.
as for the money, yes that is insane. You could probably get a pretty good set of aftermarket heads and install for that money. If you do it yourself, I would think that a set of heads from a salvage yard, and new gaskets (heads and intake), total package should at the most cost you around 800 bucks. I am in not saying the dealer is out of line at all, at the going flat rates, plus parts they are probably right on. If it comes down to it, trade the truck in, it is not worth a 5 grand repair if you ask me. A reputable dealer should still give you decent trade in, even tell em whats wrong with it. I am sure they can get it fixed and saleable for about a grand, so knock that much off trade in value and don't take less. Do not let them bs you, you fix for 3 grand, they fix for a grand, don't let em push you around, but honestly if you aren't doing the work yourself, not saying you drive a log wagon at all, but with currrent values of things I would be hard pressed to put that much jingle in your truck.

Hey, thanks for the info. Greatly appreciated. Do you know if the heads from a 5.3L would be the same on my 4.8L?

I found a place locally that has used, loaded, factory heads for a much more reasonable price, but they don't know if the heads from a 5.3 are going to be the same as mine. They are wanting me to bring my heads in to match up, but the problem is I need to drive the truck down there to get them. The problem isn't catastrophic enough that the engine is inoperable, it just needs to be dealt with soon.

And yes, that service bulletin you mentioned is exactly what the problem is. The write up and the pictures both depict my problem precisely.

those heads as you now know are the defective heads...you can get heads for this 4.8l ...call around ...use a car rental to pick up the parts if necessary...you can get this installed for under 500.oo..
this is not a very hard time consuming job....

the most important thing to also replace is the head bolts...these must be replaced...

if the truck is in good shape it is worth fixing, in my opinion...but not at a dealership..too expensive...

Jasper already found the problem,found out the heads were casted at 2 differant foundries and there is a way to tell.

ya, pull the valve cover and look at the casting number.....the SIB is by the casting numbers. Any updates?

What is "SIB"?

I am still searching for some heads. Trying to figure out if the ones from a 5.3 are going to be the same as the ones for my 4.8.

I'll definitely replace the head bolts. I understand they stretch when installed and are good for only one install. I also ordered a big fat shop/repair manual from Helminc.com - if it's as comprehensive as the one for my Olds Bravada (also ordered from Helminc) it should have all the torque specs and sequence and such.

Will I need to replace the valve cover gasket when I remove the valve cover to look at the markings on the head or is that something that can kinda be popped off and put right back on without damage?

service information bulletin. I am pretty sure the heads should fit fine. The salvage yard should have a cross reference book as to what fits what. If they don't I don't know how they expect to sell anything.