LS head gasket repair, any advice or what to look fors?

[BarryB]

Yeah a good friend of mine asked me to replace the head gaskets in his 04 silverado. I'm pretty sure its the 4.8 V8. reason for headgaskets, It has never overheated,but its loosing water somewhere, runs fine other wise..anyhow.
I've never had one of these motors pulled down that far. I've got 3-4 weeks to do it so I can somewhat take my time.
Does anybody know of a laman term instructions for doing this type of repair. Or just some good, heres what I did type of advice.
Thanks in advance.

[crazy longhorn]

Maybe you should have one of the mods move this to the other board? I am new to the LS engine, so cant give much help(still learning) One thought tho....they do have a plastic intake? Best of fun,crazyL

[D13]

Best recommendation is to spend the bucks to buy the CD-ROM of the service manual.
Head bolts are not reuseable. Keep lifters and pushrods in order if you pull them. check the steam pipes under the intake (if so equipped), they like to corrode. Get a fuel line quick connect disconnect tool, disconnect the lines at the intake and then take the intake off complete with rails and injectors. Other than that it's just like any V8. In general leave the manifolds on the heads, unless the heads need work.

[truckdude239]

sounds like its time for s 5.3 or 6.0 swap its a direct bolt in don't have to change anything

[swb85]

It's not all that different of a repair compared to doing the same job on a sbc. The LS motors have blind head bolt holes, so you need to be 100% sure you get all of the holes completely clean and dry before putting the heads back on. Cracking the block would really ruin your day.

[usmcchevy]

Easyier than a SBC IMHO. The head bolts are torque to yeild and are one time use. Check the water pump gaskets real close before you tear into it, last head gasket job I was asked to do turned into Water pump gaskets.

[BarryB]

Well he dropped the truck off here last night. He bought a new waterpump for me to swap out while I have it.
He brought me new gaskets, and new headbolts also. I'll check the steam pipes since it has been mentioned that they can corrude.
Do you need to adjust the lifters like the older SBC?

Well anyhow, its going to be a learning process for me. I've had a bunch of SBC torn apart and put back together with no problems. So I'll just take my time and make sure all gets done properly.

[cableguy0]

They dont usually blow head gaskets. I would look really hard at the water pump and thermostat housing. How many miles are on the engine? Have you done a combustion gas test? A 60 dollar tools might save you from pulling the heads or at least verify 100% the problem. This style works great. I have an electronic sniffer at work but it would eat most of your profit if you werent going to use it much. Dont just blindly pull the heads hoping to find a problem.

[crazy longhorn]

This old man is still watching....got a 5.3 on the stand for the old 69 I still have time to learn...crazyL

[LEEVON]

there is a certain head casting that is known to develop cracks, Castech 706's I think? Do some research before replacing gaskets and reusing the heads. Use the GM MLS gaskets (multi-layered steel) and get new GM head bolts because they are torque-to-yield. Also, goes without saying but make sure it's not the waterpump first...

[clinebarger]

X2, On the Castech castings, Heres where they leak/crack (2), Castech mark (1).

I would also check the waterpump gaskets FIRST...VERY common issue...They leak with the engine cold NOT hot, If the engine is warm they will pass a pressure test

[cableguy0]

The heads cracking there would cause a milkshake in the oil. If it has no milkshake I would search for another leak.Also if you do end up having to replace the head gaskets. Do your buddy a huge favor and replace the plastic intake not just the gaskets. The plastic intakes warp up pretty badly and will cause vacuum leaks and make the engine run bad. I use the Dorman replacement intake because they fixed the factory weak points.

[clinebarger]

Originally Posted by cableguy0

The heads cracking there would cause a milkshake in the oil. If it has no milkshake I would search for another leak.Also if you do end up having to replace the head gaskets. Do your buddy a huge favor and replace the plastic intake not just the gaskets. The plastic intakes warp up pretty badly and will cause vacuum leaks and make the engine run bad. I use the Dorman replacement intake because they fixed the factory weak points.

The crack is so small that it doesnt visually mix the coolant & oil, A oil analysis will tell for sure. Or pull the valve covers and look for clean spots where they crack.

I had this happen to a customers 04 Suburban a few years ago, It never "milkshaked" the oil.

[dwcsr]

Because the coolant is different in these new engines the oil looks like molasses and is slightly reddish looking leaving reddish stains on the aluminum under the valve covers when the heads crack. As said above it doesn't milkshake like the old antifreeze and oil. I would have them crack checked regardless before putting new gaskets on. The Castech heads had a mark that looks like a D cell battery between the first and second cylinder. Mine were 706's

[BarryB]

Thanks guys for the advice. I talked with my friend, he said he had water in the oil. I haven't had much of chance to dig into it yet. That tells me it most likely more than waterpump gaskets. It wasn't leaking a bunch of water, Every couple of tanks he was having to top off the coolant. He then told me he had put some if that stop leak in the system, and it stopped using water for awhile.

[KQQL IT]

My brothers 01 burban had same thing. No milkshaked oil after time the oil turned to sludge. The lifters began ticking.
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[BarryB]

I started pulling this motor apart today. I seen on the head if looking from the front left head front near the valvecover. 706 casted in the head. So from what some of you are telling me its possible the heads have cracks.. since they are aluminum can they be welded back or will they need replaced??

[truckdude239]

if they are cracked ti time for a replacement head no point in tryingt o weld them

[usmcchevy]

Originally Posted by truckdude239

if they are cracked ti time for a replacement head no point in tryingt o weld them

X2, 706 or 862 heads go pretty cheap, not worth welding.

[BarryB]

Originally Posted by truckdude239

if they are cracked ti time for a replacement head no point in tryingt o weld them

Originally Posted by usmcchevy

X2, 706 or 862 heads go pretty cheap, not worth welding.

Do you guys have a good source for heads if they are cracked? I just checked rock auto to get an idea. 450.00 a piece plus a 150 core charge.

[usmcchevy]

www.car-part.com or www.performancetrucks.net There's a complete 4.8 that needs a crank on my local craigslist for $200.

[BarryB]

I finally got the heads removed today, like said been working on it as I can. I didn't see any of the symptoms of a crack. I'm either going to drop them off or have them dropped off at the machine shop this week. hoping they"ll be able to crack test them,a nd give them a good cleaning if they aren't cracked. Heck They may be able to fix them if they are.. from what I read, you buy heads send in your cores. So in my mind, that tells me they are being repaired, and then resold as reman.

Once I get them back can somebody post up the torque sequence and how to torque per yield.

[clinebarger]

Originally Posted by BarryB

I finally got the heads removed today, like said been working on it as I can. I didn't see any of the symptoms of a crack. I'm either going to drop them off or have them dropped off at the machine shop this week. hoping they"ll be able to crack test them,a nd give them a good cleaning if they aren't cracked. Heck They may be able to fix them if they are.. from what I read, you buy heads send in your cores. So in my mind, that tells me they are being repaired, and then resold as reman.

Once I get them back can somebody post up the torque sequence and how to torque per yield.

Measure the head bolts......04 is a split year, Though most have the 1st design "long-short" head bolt. All 05 & up have the 2nd design "short-short" head bolt.

""First design engine blocks have different drill and tap depths using both medium length 100 mm (3.94 in) and long 155 mm (6.1 in) M11 cylinder head bolts. Second design engine blocks use only the medium length 100 mm (3.94 in) bolt with a common drill and tap depth""

[edhtrd71]

Make sure to use new bolts for the exhaust manifolds.

[BarryB]

I've had alot of drama in my life last few weeks, so just now getting back to working on this truck. Got the heads back from the machine shop. They weren't cracked so they were serviced given a good once over and cleaning. So now to put this motor back together.

can somebody tell where this bracket goes. I know it goes to one of the heads but not sure which side. front or back?