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08-09-2011, 11:40 PM | #1 |
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Location: Prunedale California
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4.8 with a cracked head question...
Hey guys Im looking at a 4.8 that seems to be in good shape but the drivers side head is cracked where the exhaust manifold bolts on because of an accident, would this be an easy repair as for just buying a good head and bolting it on? Are the 4.8 and 5.3 heads the same? The number casting on the heads are 862 if that helps.. Any advice is welcome, thanks in advance.
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08-10-2011, 02:49 AM | #2 |
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Location: Midvale, Utah
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Re: 4.8 with a cracked head question...
I think that you could just find another 5.3/4.8. They are so cheap to come by. To fix it, you'll be another 300$ on top of the price . Just buy a different one.
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08-10-2011, 09:54 AM | #3 |
1965 Chevy C10, 2005 4.8L/4l60
Join Date: Aug 2004
Location: DFW Texas
Posts: 8,546
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Re: 4.8 with a cracked head question...
I wouldnt buy it unless it was like <$100. if not, then I would agree with Chris above, move on to a known good motor. if the accident caused the head bolt hole to crack, what other issues are you facing?
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08-10-2011, 04:35 PM | #4 |
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Location: Ashland, KY
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Re: 4.8 with a cracked head question...
It's ultimately up to you but the 5.3 and 4.8 heads are the same. But if the engine is early 2007 and older then you are looking for 862 or 706 casting heads. The newer engines run the 243 and 799 casting numbers which are the same as ls2 corvettes and LS6 engines. If you look around older 5.3 and 4.8 heads can be found for around $50 a piece or if you get lucky a buddy may even give you one. You will then need head gasket and head bolts to complete the job. Another option is take the head and have the area welded.
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08-10-2011, 08:30 PM | #5 | |
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Location: Prunedale California
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Re: 4.8 with a cracked head question...
Hey guys thanks for your replies, the engine or I should say drivetrain comes complete with tranny, all the accesories, harness and ECU, even the exhaust flanges with the oxigen sensors, all this for a pretty good deal, owner didnt know head was cracked till we unbolted the exhaust manifold (two bolts were broken, so I had to inspect)...
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08-10-2011, 09:18 PM | #6 |
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Location: Ashland, KY
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Re: 4.8 with a cracked head question...
The 862 and 706 heads all have the same cc on the combustion chambers and have the same size valves on the intake and exhaust. The heads are also interchangeable side to side. So if you find a head from a pre-2007 5.3/4.8 engine you will be good to go. Just a reminder the head bolts on these engines are torque-to-yield bolts and should only be used one time. The bolts also have a specific tightening sequence and it is not a ft-lbs type of tightening. If you purchase ARP bolts they are torqued to a specific ft-lbs rating. There are no Dumb questions especially when trying to learn a new type of engine configuration!!!! I'm just lucky a couple of my friends have a chassis dyno and perform swaps and tunes for our tri-state area. So my knowledge was gained from the time there and my own trial and error.
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08-11-2011, 10:58 AM | #7 |
1965 Chevy C10, 2005 4.8L/4l60
Join Date: Aug 2004
Location: DFW Texas
Posts: 8,546
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Re: 4.8 with a cracked head question...
May I ask what he is asking for the motor? with all that stuff included, it might be worth picking up if he is willing to deal.
The 4.8/5.3 heads are pretty easy to find, so it might be quite do-able.
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08-13-2011, 02:28 PM | #8 | |
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Re: 4.8 with a cracked head question...
Quote:
I ended up buying the drivetrain from the guy, he let it go for $800 (originally asking $1200) drivetrain has 84k original miles... |
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08-13-2011, 04:32 PM | #9 |
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Location: Ashland, KY
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Re: 4.8 with a cracked head question...
Getting the 706 checked out is up to you. I have a couple of good buddies that have machine shops so I always take them in and have them cleaned and looked over. Your other question about installing you need head gasket, head bolts, and tightening sequence for the type of bolts you use. That should really be all for installing the head. You can reuse the rocker arm bolts and get the proper torque specs for those it's around 22-24 ft-lbs.
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08-17-2011, 04:04 PM | #10 | |
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Re: 4.8 with a cracked head question...
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08-17-2011, 10:35 PM | #11 |
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Join Date: Jul 2009
Location: Russellville, Arkansas
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Re: 4.8 with a cracked head question...
Sounds like a good deal with everything. You'll like it in your truck. Big difference. Jim
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