5.3L Castech head replacement - advice?

[tRidiot]

So I've got the Castech 706 heads, my coolant has been disappearing for a couple of years. It's not horrible yet, but it is noticeable. I don't drive my Tahoe that many miles anymore, having gone from a 150-mile commute to about 1 mile. Or thereabouts.

But, my mechanic has advised I could use a top-half rebuild and will need to do it sometime. A friend of mine warned me in the strongest possible language to do a complete rebuild or complete replacement.

Now... my mechanic is a good old boy. He has saved me many times when other shops have tried to convince me to do moderate "add-on" repairs when I had it in for tires or something. Like... rear brakes that went another 18 months after I was told they needed immediate replacement (this is commuting 20k per year), and a Pittman arm that was supposedly in need of replacement back in... oh, I don't know, 2012 or something. Still hasn't become an issue.

So the bottom line is, my guy looks after my wife and me, has done all our work and maintenance and has been up front in what we NEED and what we DON'T need - and he knew he could tell me whatever and he could have gotten extra jobs - but he works as much as he wants, and runs his own shop on his own schedule, doesn't need to milk his good and loyal customers - like us.

So, the question is, should I go ahead and do a complete replacement? He is telling me we're looking maybe around 2 grand for a top-half rebuild, most of the full rebuilt motors I'm able to get prices on online start at $1700 and go up, most are $2k+. I have read of people finding a smoking deal on one under a grand - but haven't been able to find one of those.

The other question is, what if I decided to do it myself? I mean, I have access to a decent-sized shop, my buddy is pretty mechanically-inclined, and I am smart enough and not un-handy. I mean, I have changed out valve cover gaskets, alternators, water pumps, radiators, done a couple brake jobs with some help from friends, and I have a doctorate level degree (in science, not history or literature, lol). So I'm not stupid, and I know the intarwebz likely has plenty of tutorials - both written and video - that would help... hell, it might even be fun. Would it be worth the undertaking, you think? To save a couple of grand?

So anyways... what do you think? Is a top-half rebuild asking for major problems in 3-6 months with the rest of my motor letting go?

<Edit> Knew I would leave something out - I picked this 2004 Tahoe up in 2010 and have done extremely regular maintenance with high quality filters and synthetic oil - usually Mobile 1. Had around 80k when I bought it, I'm at 265k now. Lots of highway driving. Up until recently. Uses next to no oil, and zero drips.

 

[Big Mama]

I may have missed it but I didn’t see your year and mileage. Also there must be a reason he thinks the bottom end is good for a long time. You don’t want to do this twice. Is it using oil? The coolant is going somewhere it shouldn’t and that’s not usually good for the bottom end. How about a little history of the rig? Lots of experience and knowledge on here. It’s a big decision so let’s see what the others say.

 

[iamdub]

So I've got the Castech 706 heads, my coolant has been disappearing for a couple of years. It's not horrible yet, but it is noticeable. I don't drive my Tahoe that many miles anymore, having gone from a 150-mile commute to about 1 mile. Or thereabouts.

But, my mechanic has advised I could use a top-half rebuild and will need to do it sometime. A friend of mine warned me in the strongest possible language to do a complete rebuild or complete replacement.

Now... my mechanic is a good old boy. He has saved me many times when other shops have tried to convince me to do moderate "add-on" repairs when I had it in for tires or something. Like... rear brakes that went another 18 months after I was told they needed immediate replacement (this is commuting 20k per year), and a Pittman arm that was supposedly in need of replacement back in... oh, I don't know, 2012 or something. Still hasn't become an issue.

So the bottom line is, my guy looks after my wife and me, has done all our work and maintenance and has been up front in what we NEED and what we DON'T need - and he knew he could tell me whatever and he could have gotten extra jobs - but he works as much as he wants, and runs his own shop on his own schedule, doesn't need to milk his good and loyal customers - like us.

So, the question is, should I go ahead and do a complete replacement? He is telling me we're looking maybe around 2 grand for a top-half rebuild, most of the full rebuilt motors I'm able to get prices on online start at $1700 and go up, most are $2k+. I have read of people finding a smoking deal on one under a grand - but haven't been able to find one of those.

The other question is, what if I decided to do it myself? I mean, I have access to a decent-sized shop, my buddy is pretty mechanically-inclined, and I am smart enough and not un-handy. I mean, I have changed out valve cover gaskets, alternators, water pumps, radiators, done a couple brake jobs with some help from friends, and I have a doctorate level degree (in science, not history or literature, lol). So I'm not stupid, and I know the intarwebz likely has plenty of tutorials - both written and video - that would help... hell, it might even be fun. Would it be worth the undertaking, you think? To save a couple of grand?

So anyways... what do you think? Is a top-half rebuild asking for major problems in 3-6 months with the rest of my motor letting go?

I just went through all of this on my brother's '05 Sierra. He bought it maybe 8 months ago with around 170K miles on it and at the time of failure it had about 181K. He's had to add a little coolant here and there ever since he bought it. His oil never was a milkshake but he had a little mustard-looking stuff on the underside of his oil filler cap. We figured it was normal condensation and would burn off as he drove it. Anyway, his oil pressure began to steadily drop over a couple of weeks then one day it suddenly dropped low enough to trigger all the warning lights and tones.

I tore into it to find the whole motor was horribly sludged up. The leak from the cracked head was slow enough that the water in the coolant would steam off so it didn't show in the oil. The remaining chemicals stayed in the oil, turning it into a thick and sticky sludge that built up on every internal surface and passageway of the motor. The drop in oil pressure was from the pickup tube slowly clogging until a chunk broke loose from somewhere and finished it off.

The cylinder crosshatching was still very strong so we decided to let the cam bearings dictate if we were gonna clean and fix or replace the motor. The cam and bearings, miraculously, looked fine. He got some low-mile 243s of Facebook market and I ordered all new gaskets and LS7 lifters and donated the timing set, pushrods and rockers from a past LQ9 project since they only had 31K miles on them. I pulled the motor and de-gunked every accessible surface including bottle brushing the oil galleys. I replaced the oil pump with a high-volume unit but swapped in the included "low pressure" spring.

All said and done, it has great oil pressure and no leaks (previously had a leaky oil pan gasket and possibly rear main seal). It idles smoother than my '08 and pulls strongly through redline.

My point is that you may find your motor to be much worse than you may be expecting once you open it up. It could be fine with a good cleaning and replacing of parts or it may not be worth it. All the parts and supplies I bought for his motor were right around $1,000 and he got the heads for $300. The timing set, pushrods and rockers would've been another ~$200-$300ish had I not had them to donate. Included in that $1,000 of parts was new spark plugs, an $18 catch can, $125 ACDelco motor mounts, new ACDelco oil pressure sensor, all engine seals and gaskets and pertinent bolts, oil, oil filters, many cans of brake parts cleaner and degreaser, antifreeze, etc.

The cheapest of the best salvage yard motors we found were around $1,000. But, they had 706 heads that were possibly (likely?) Castech, so we would've swapped them just to be safe. We also would've replaced everything (oil pump, timing set, seals, etc.) as a precaution. So, fixing his motor was the cheapest and maybe also the best option.

You're gonna have to open yours up to assess before deciding on repairing or replacing.

 

[Larryjb]

I had my oil analyzed which showed all metals were in the normal range, so I went ahead with a top rebuild. I used a machine shop to rebuild the heads but I did the teardown and installation. It was a lot of work, but doable. Here's a link to my procedure which may help you decide.


https://www.tahoeyukonforum.com/threads/5-3l-head-removal-2002-tahoe.108649/

 

[tRidiot]

Good advice here, thanks guys.