5.3 Coolant Loss

[tmicklet]

Bump

[jakeorfo]

Hi guys, how many of you have had problems with cracked heads? I have the 706 casting heads on my 04 gm crewcab. Its using coolant, sometimes smoking on cold start, valve lifter tick on cold start, cream coloured sludge on underside of valve covers. Sound like a cracked head to you guys?? Any info or ideas would be great. Thanks , cheers

 

 

hey man i had the same problem and i researched it and thats what i came up with was the cracked cylinder and we looked around at the cylinderheads and found a spot where u could tell it was cracked and we orderd some new heads and replaced them and now the truck runs better than ever and the heads will only run u about 500 loaded

[chevyman09]

My 05 Sierra had cracked heads. I wasn't getting steam but losing coolant and no leaks. Took it to two dealerships and they couldn't find anything I asked them about the tsb bulletin and they didn't say much. I told them I pulled the valve cover and you could tell coolant was in it. Then they said they didn't have time. Finally I took it to the big city and the tech I talked to opened the hood looked at the head and said yeah probably cracked head. They had it in in two days and both were cracked bad. They did all of it under warranty since I had less than 100k miles. $3200 worth of work.

[Brian in KC]

I have a 2000 silverado 1500 5.3 .I have serious coolant loss ,and slight miss in engine.I'm 100% sure its goin out the tail pipe.Is there any common issues here etc.weak head bolts,bad gaskets ,bad head castings?just want to know before I tear it down.It still runs decent but not like it should .This thing has been serviced,taken care of properly.

[Brian in KC]

I can tell you from personal experience that you most likely have a cracked head. I have/had 706 castings as original equipment. Losing antifreeze, smoke on cold start, tons of sludge. Head cracked around #1 head bolt. The only way to tell is to have them pressure tested by a qualified machine shop. I had one welded at 156,000. I'm at 195,000 and the other one cracked. I scrapped the 706's for some 862's. The knock you're hearing is most likely NOT lifter noise but rather a chewed up thrust journal on the crank. Antifreeze and oil eat the bearings out of it. My entire engine is torn down right now and the crank is at the machine shop to see if they can repair it. Don't kid yourselves. They won't get better. Don't half-heartedly attempt a band-aid repair. Tear it down and fix it right or you'll just be wasting your time and money. Been there and doing that.

[Justinlw]

If you're losing coolant and see it in the oil, or if a combustion gas test shows positive in the cooling system, fix immediately. Proper procedure would be to pull heads, inspect gaskets, and take heads to a machine shop. Any time an aluminum head is removed, take to a machine shop to check deck and pressure test.

 

I used to argue that you could visually inspect and straight edge, and save your money. Experience proved otherwise, and it cost me a lot more than having the heads inspected in the first place.