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Repair or replace?

wayne36

By wayne36
in Ask A GM Technician

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wayne36 Enthusiast

wayne36

Posted
Posted

I have a 2004 Silverado with 163k I am going to need to replace valve seals quote is at 900 and I have a problem with coolant leaking into the motor somewhere. So with that mileage should I just replace the valve seals or drop a rebuild in it. No quotes on a rebuild yet but i'm guessing 3k?

citydriver Enthusiast

citydriver

Posted
Posted

That would depend on whether it's worth it to you or not. A few things you need to consider. How long are you planning on keeping the vehicle? What is the overall condition of the vehicle? For example the condition of the transmission, drive line components, suspension, body and frame condition.

 

I've seen these engines go in excess of 3ooK mi with proper maintenance. What is the compression of the individual cylinders? Where exactly is the coolant leaking from? Head gasket, intake gaskets? Is it burning the coolant, or leaking internally into the oil? If it's going into the crankcase, have the rod and crank bearings been compromised? These are things you should consider in making an educated decision, then do the math and do what's best for you. A crate engine may be your best option if you plan on keeping the vehicle for awhile, at least you may get a warranty with it. Again depending on the condition of the rest of the vehicle. A rebuild may be a better option as long as the block and heads are in good shape. In the end it's your wallet.....

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

$6K for a crate??? Holy s**t !!! I used to be able to buy 12 or more cars for that ..... :shakehead:

 

Since your in TN, I'd venture a guess that the body & frame are still there, unlike the ones up here. It's always cheaper to fix what you've got than to pay for another, then registration, insurance, & associated taxes ...... but with $6K crate engines my line of thinking on that might be wrong. I could buy a pretty decent truck for that, even up here!

 

But anyway ... if you can do the work yourself with a buddy or 2, that'll save you a TON of money. Valve seals are fairly easy (well, at least they USED to be ...). Yank the heads, get 2 new head gaskets, install the seals, new valve cover gaskets, and you should be good to go for a while. Whatever you do, DON'T TOUCH that damn timing cover! These days it's integrated into the pan ...and if you've got 4x4, you will open up a can of worms so big you'll be dreaming of shoving your truck off the nearest cliff ... or loading full of lead .... or setting it on fire ... or all of the above!

 

Also another big consideration is whether or not you live in an area that tests for emissions. If not, life will be MUCH easier for you as far as engine options go. Could throw in an old school 350, brand new, for less than a pair of cylinder heads on a LS engine. Lots of options there.

 

EDIT: I missed the $2,500 core charge there - now that price is a little more reasonable!!

02suburbanZ71 Senior Enthusiast

02suburbanZ71

Posted
Posted

Dude go to a junk yard and pull a low milage lq9 for around 2200$. Cam it while its out too piece of cake

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

Isn't the 04 5.3 engine in the area of bad Castech heads? The heads that ended up being porous? If so, and you have antifreeze in the oil, it is time to pull engine and either replace, or have yours rebuilt. Both heads are likely toast if they are porous. Take a look at this thread

http://www.gm-trucks.com/forums/topic/119868-castech-heads

 

There is a link to the TSB on the subject of castech heads being porous.

 

Getting engines from the wreckers can be a good idea, as well as a bad idea. You have to believe them when they say how many miles on the engine, and how long did it sit outside not covered or protected? Wreckers have a warranty for the engine, but, the labour to re and re the defective engine is not covered. Best thing to do is sit down and price the different ways to go, including labour, and add in what it would cost to deal with warranty parts that failed. Not talking about new parts, failure rate is predictable with new parts, but not with used parts. You also need to decide if this truck is what you want for the next 5 years. As others have said, look the truck over, is everything else good enough for you? Paint, interior, all the rest of the drivetrain. At 160,000 miles, the truck is going to need other work.

 

Once you add up the costs, you can then make an educated decision. One thing to remember, your decision if your decision based upon your life and needs. It does not matter what I would do(in regards to final decision), my life and needs are far different from yours. The internet may be a great source of information, but it is a poor source of opinions on what you just did or are considering doing.

Chris Senior Enthusiast

Chris

Posted
Posted

Dude go to a junk yard and pull a low milage lq9 for around 2200$. Cam it while its out too piece of cake

I dont know what junkyards you go to, but the LQ9 was relatively low volume for a truck. And every day get more scarce. i have yet to see one in a junkyard. I had a shop source a wrecked SS to find mine. That truck came from about 10 hrs away.

 

Get a junker LQ4, LS6 cam it and add 243 cast heads. The same if not more power than an LQ9 with lower compression so later eill be more boost friendly than an LQ9. I wish i went that route now.

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

I dont know what junkyards you go to, but the LQ9 was relatively low volume for a truck. And every day get more scarce. i have yet to see one in a junkyard. I had a shop source a wrecked SS to find mine. That truck came from about 10 hrs away.

 

Get a junker LQ4, LS6 cam it and add 243 cast heads. The same if not more power than an LQ9 with lower compression so later eill be more boost friendly than an LQ9. I wish i went that route now.

 

The only difference between LQ4 and LQ9 is the pistons. LQ9 has flattops, LQ4 has dished. Bringing this up just to help people not get taken by wreckers selling a LQ4 as a LQ9. These two engines are identical on the outside.

02suburbanZ71 Senior Enthusiast

02suburbanZ71

Posted
Posted

The engine cover is same for lm7, lq4, l59, l33 but usually the lq9 has a little nicer looking cover [emoji4]

Chris Senior Enthusiast

Chris

Posted
Posted

 

The only difference between LQ4 and LQ9 is the pistons. LQ9 has flattops, LQ4 has dished. Bringing this up just to help people not get taken by wreckers selling a LQ4 as a LQ9. These two engines are identical on the outside.

Yes they do. And they also arent happy if you use regular 87 octane
Chris Senior Enthusiast

Chris

Posted
Posted

The engine cover is same for lm7, lq4, l59, l33 but usually the lq9 has a little nicer looking cover [emoji4]

988d7339e714125040e3411deffb96e9.jpg
02suburbanZ71 Senior Enthusiast

02suburbanZ71

Posted
Posted

Chris i believe they also made a similar cover to yours that said "vortec max" in red letters. Also why do you have the clutch fan shroud with NHT efans?

Chris Senior Enthusiast

Chris

Posted
Posted

Chris i believe they also made a similar cover to yours that said "vortec max" in red letters. Also why do you have the clutch fan shroud with NHT efans?

Pics from different times. Thats before i made the fan swap. And the vortec max cover was limited run. 06-07c

 

I used to have the 06 cover

6b2f48e5bb5f5ab57360ed973763681a.jpg

rdnkcpa Enthusiast

rdnkcpa

Posted
Posted

From the OP's description, it appears he has the Castech problem. The only way to tell for sure is to pop the valve covers off and look. If you see the dexcool/oil sludge then you know the heads are done.

 

I bought new head castings and had a machine shop assemble with existing valves & springs. Machine shop cleaned up the valves, or reground them & put all new guides and seals in.

 

I ended up replacing both heads, lifters, water pump, hoses, plugs, wires, belts, idler pulley, intake gaskets, head gaskets, new head bolts, exhaust manifold gaskets & bolts. I may have done some other stuff as well, but I can't recall. Between the heads, and all the other parts, I think I had close to $1,500-1,600 in parts.

 

The truck just turned 150k and all is well. The engine runs smooth as silk. I never did drop the pan. So far so good.

 

Good luck.

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