I've been lurking around for a bit trying to decide what to do with this motor. So upfront I'll say thanks for any feedback and apologize if I"m breaking any etiquette rules for this site.

I've got a GMC Savanna AWD cargo van with the 5.3 (03 with 100K). I haven't actually pulled the heads but it's pretty clear that I've got the castech failure. One of the lifters is starting to tick pretty good two for a few minutes in the morning - so off with it's head

The plan is to just swap the heads for a set of rebuilt 862 heads. Lifters, water pump, plugs, wires and probably drop the oil pan just to check the pickup tube and make sure the pan isn't full of gunk.

So the questions are..

Am I missing anything while I'm in there?
Anyone have a nice kit with with the head gaskets, lifters, bolts ect that would make this easy?

And finally. Are there any easy power gains here that won't kill torque. This is my daily work van. It is also the family weekend hauler pulling a 3,000# camper. Occasionally a race car will also be pulled.

I am not looking to go crazy with custom tunes. So really I think this is just put on the heads and do the tune up so we are back to stock power. But the one thing I was thinking was just to shave the heads for a bit of compression bump. I'd probably have to go to high octane fuel but I figure the tune could stay the same and I'd get a modest power bump without having to worry about ripping the 4L60E apart.

Any thoughts on that ^^

Thanks again. I know this isn't a crazy ***** out project like I have seen elsewhere in this forum. But I'm just looking for a simple repair that will be long term reliable.

 

I've got an 04 Silverado with the same problem. Those damned castech heads. You know what works? The Bars leaks headgasket/cracked head sealer. 1000% stopped my water loss. The problem for me is I caught it too late, so my bottom end got sludged up from the dexcool in the oil. Im still driving the truck, but I'm building another motor to swap in.

I would verify water loss and a sludged up oil filter to confirm the 706 crack.

I actually have a set of 862s to swap in, but I figured I'm halfway there so I'd build another engine. But if I was gonna do a top end swap, I'd use the 862s, mill them to 58CCs, and swap in a 212/218/114LSA/520 lift cam. That would bump the power just a bit, but not require premium gas or a stall converter. Just make sure you use the right pushrods, as LS engines set lifter preload by pushrod length.

 

Your ticking could be from
1) there is some trash clogged up in the lifters

2) the oil you are using is to thick for cold start and takes a while to loosen up the viscosity level by heating up

If you want to keep the stock cam, then I wouldn't mill the heads and reuse the stock pushrods and save your money. You will need new gaskets and head bolts, do NOT reuse the stock head bolts, they are tq to yield and the threads stretch when they get degreed

 

Sorry I didn't respond sooner to these posts. I thought I had set it up for notifications but apparently not!

Yea I think it's just time to put new heads on it with stock cam and let it ride from there. I suspect I'll still get another 100K out of the bottom end. If I have the truck that long it will have earned a whole new motor.

It is very disappointing but it is what it is. I have driven this truck very gently but at 100K I'm in an extensive top end rebuild and the entire front suspension needs to be rebuilt. It is worth keeping though. It's somewhat unique with the 2500 AWD and optioned to the hilt even though it's a cargo van.

 

I never knew they made a 2500 van with AWD, that sounds like an awesome work vehicle.

I know the 2WD vans allowed easy removal of the oil pan, but if you had leaking issues, I would definitely want to pull the pan, clean it out, check the bearings and put it all back together (even maybe throw in a new oil pump for good measure).

I tend to elongate every project I start by over-thinking things like my previous paragraph, so take my advice with caution, as it's usually overkill.

 

Full intention of dropping the pan, whatever it takes, to assess the bottom end.

2500 was a first year thing and a big deal to order. Nobody really new what was the difference and it was gone after the first year. The best we came up with was spring rates about 400# higher than the 1500, larger Dayton diffs than the 1500 and the bigger heavier ply tires from the 2500. I'm not really sure how that compares to the 1500 AWD 04 and up, but in 03 you could order either 1500 or 2500 for minimal $$ difference. We also fought for and got the auto locking diff in the rear which everyone fought me on since it was already AWD.

We really worked over the dealer when we ordered it for where we wanted glass and getting the glass both tinted and tilt out. Heated rear glass, compass mirror, tilt wheel, cruise, power locks, power windows, chrome package, big alternator, big battery, full tow package. To replace this truck now is BIG bucks. We have also now welded a bench seat in with a custom divider behind it and custom shelving for work. Doing the bench compromised my work space a bit, but it's now kind of the ultimate camping mule.

Do wish I had gotten even more options on it like electric seats and rear heat/ac. But again, to order this truck now would be big coin, certainly far more than fixing it.

I would like to find a a decent set of 17" rims for it - and put the full 2500 pickup mechanical in it with the Allison 6 speed

Sorry for the total thread drift already. It's not too often that anyone gives me more than a blank stared when I say I have a 2500 AWD van

But for those of you that have driven vans and know they can get stuck in a flat parking lot on a 1/2" of snow I can tell you it is HILARIOUS when you go cranking through a field with 14" of snow on the ground to get around all the cars and SUVs stuck on the road next to you.

 

A serious question - I did see in my research references to small variations in the 862 over the 706 and cautions about what style head gasket to use.

Otherwise the shopping list is

heads
head gaskets
head bolts
lifters
water pump
plugs
wires
exhaust studs?
and possibly alternator if I can't find someone to press in new bearings.

after that, new suspension and steering.
After that body shop to make it all look new. Should be good for awhile.

 

Most people think the 862s are better casting.

You have to know if it has the notch. Google image search 862 notch and should be a picture of two heads one with and one without.

Graphite gaskets work on both, but MLS only works for the non notch. If you put a MLS gasket on a notch set of heads it will leak.

I have pulled the heads off a motor and 2/3 of the water jacks were clogged, from somebody mixing coolants.

I would buy bolts from the hardware store for the manifolds or re use the stock ones, studs are over kill.

If you want a little extra power to replace milling the heads you could get some shorty headers, everybody will tell you not to waste your time with shorties, but in your situation you are not going to need a tune and shorties work nicely with the stock tune. They will give you a little more tq to help that beast move and probably help fuel millage out a little bit.

 

OK. The shop I'm mostly going to source the heads from says they have 862 or non-castech 706. So I can really do either.

What I really want to do is the cam and forced induction

 

Good deal on the heads, I have had no issues with the graphite gaskets on N/A motors and would prefer to run them over the MLS. I mean now is the perfect time to put a baby cam in it that will work with the stock stall.

Get a 150 shot and get to the jobs realll fast haha

^jk