7.4 Vortec Head Gasket job in vehicle?

wvukidsdoc said:

Coolant does go down slowly in tank, perhaps 1/4” down a month.

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Greetings wvukidsdoc,

Just the fact that you can tell me exactly how much coolant is consumed each month tells me volumes.
When a vehicle owner can tell me with confidence what kind of MPG vs usage, plus how many miles per
quart of oil, and finally how much coolant is being consumed, now *this* is a person who will not only
appreciate good work, but will take care of that same work, whether they use the wallet wrench or fix
it themselves.

****

Re: Using ebay parts on your machine. A handful of years ago, I was down to a single vehicle, and
I managed to burn one of the exhaust valves on my then DD. (A D15b in a '90 Civic hatchback) Simply
stated, if the car wasn't running, then I was walking. And I had a job with an inflexible schedule that
I had to get to. Paying a garage to do this would cost more than the 28 year old vehicle was worth.
Plus having to rent a car while it was in the shop. And the only solution that allowed me to fix the car
and not run afoul of this schedule was to have a rebuilt/remachined cylinder head in hand so that I
could swap it on in less than a day.

So after a bit of searching I found a small machine shop on ebay who had lots of positive feedback, and
the way they described their work had the ring of truth. Nothing exotic, just solid work. So I bought
the head (see attached) got a set of good gaskets, a fresh timing belt, etc., and on my next day off I
got it done. And my DD was back online running on all 4 cylinders. Felt like I had 2 engines under the
hood compared to chugging down the road on 3.

Point is, I checked the valve seal by pouring rubbing alcohol into the ports and ensuring that nothing
leaked past the closed valves. The little hatchback ran like brand new, all the way to the point where
I traded it in for my current DD.

****

The point I'm trying to make is that if you give those ebay heads a careful inspection there's a very good
chance that you will end up with a smooth-running big block that uses zero coolant. And if you are so
inclined, you can now remachine your original heads without having that 'gotta get this back together asap'
time pressure on your shoulders. My default nature is to minimize risk when it comes to mechanical stuff...
but sometimes you just have to make the best of what you have to work with.

And by all means make a Build Thread of your big block GMT400 and take sharp pics, and in turn I can promise
that I will be pouring over them, living vicariously through your experience. :0)

Best of luck. And Welcome to the forum.

Cheers --

I can vouch for the cherry picker when trying to pull heads off the 454/7.4. I had use mine to get my heads out a couple of years ago. ~75 lbs is pretty heavy considering the relatively awkward position in the truck. Other than that there's really nothing in the way other than normal stuff. You shouldn't need to mess with core support at all for heads (I did pull the core support when I pulled engine a couple of months ago for rebuild). The heads on these are a pretty standard job, aside from the weight.
For reinstallation you'll need an angle adapter or a higher end torque wrench that does angles because stock head bolts are torque + angle (torque to yield). If you need an adapter, get the Lisle adapter, not the Performance Tool garbage. (ARP bolts are about 2X cost, but don't require the angle torque and are reusable.)
As far as the coolant leak, have you checked that stupid heater core hose connection on the intake? Mine was leaking at that 'quick connect' fitting, but it was slow enough and burned off such that it didn't show on the ground. This go around I'm replacing that quick connect with a barbed fitting and replacing that hose.

Given your adequate compression pressures, and very small coolant loss, I'd consider re-torquing the head bolts rather than actually replacing the gaskets.

If re-torquing doesn't help, you're out nothing but your labor, some sealant, and maybe valve cover and exhaust manifold gaskets; and when actually removing the heads, all the bolts will be easy to deal with including those on the exhaust manifold. Since the cooling system has to be opened-up, be sure to pull the block drains so that minimal coolant goes into the lifter valley and then into the pan, or leaks out the head-bolt holes in the block.

It's the exhaust manifold-to-head bolts studs and nuts that would concern me, and they've gotta come off to get to the lower row of cylinder head bolts. The manifold-to-exhaust pipe studs 'n' nuts are likely to break, but you can deal with that once the exhaust manifolds are sitting on the workbench. Manifold-to-exhaust pipe studs get brass nuts when I put 'em back together.

You'd probably want to mill the exhaust manifolds after checking them for cracks. Kinda thinking the manifolds attach to the heads metal-to-metal, no gasket. I may be wrong.

I don't want to sound like a jerk with this rebuttal, but in my experience...

Since these head bolts are torque-to-yield that retorquing is probably futile.

Those exhaust studs and nuts can be removed with penetrating oil and heat. Also, heat and squirting water helps break them loose.

When you put the exh. manifolds back on I recommend using stainless nuts with antisieze (brass is too soft) on the head-to-manifold and manifold-to-pipe studs/nuts. This worked real well for me.

For the exhaust manifold to head, it does use a gasket. I've used Mahle MS16091 MLS gaskets with good luck (so much better than that soft metallic crap-tastic stuff)

Motrhedx81 said:

Since these head bolts are torque-to-yield that retorquing is probably futile.

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They're NOT Torque-To-Yield (TTY). They're not even torque-angle like the small-blocks.

1997 C/K service manual, page 6A-397 lists engine torque specs. Cylinder head bolts are (in sequence) 85 ft/lbs. "Pipe sealant with Teflon" (PST) is recommended. This is almost certainly Loctite/Permatex 592, but custom-packaged for GM with a GM part number (12346004)
www.amazon.com/dp/B0002KKTH2/?coliid=I2C34IAJPLZFEQ&colid=2VLYZKC3HBBDO&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

The manual calls out three torque stages for the head bolts-- 30/60/85 ft/lbs on page 6A-436.

But if merely re-torquing the bolts rather than a head gasket replacement, I'd pull each bolt out one at a time, in torque sequence. Clean the threads, reapply sealer, and torque it back in at 85. Move to the next bolt in sequence.

Motrhedx81 said:

Those exhaust studs and nuts can be removed with penetrating oil and heat. Also, heat and squirting water helps break them loose.

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There's lotsa tricks to getting rusted fasteners loose. Penetrating oil, and heat (from a REAL torch--Oxy-fueled not just atmospheric oxygen; or one of the new-fangled inductive heating coils) seem to be the most-common ways.

But be prepared to twist the studs off. It happens sometimes.

Motrhedx81 said:

When you put the exh. manifolds back on I recommend using stainless nuts with antisieze (brass is too soft) on the head-to-manifold and manifold-to-pipe studs/nuts. This worked real well for me.

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The torque-spec section of the service manual talks about the torque on the manifold bolts. But the actual service procedure shows the manifolds are held to the heads with studs and nuts, with the spark plug heat shields getting their own nuts on the same studs.

Brass fasteners for manifold-to-head would not be recommended. I'd be really careful about stainless fasteners, too. They've gotta hold 40 ft/lbs. Most (not all) stainless fasteners are soft and weak--generally equivalent to Grade 2 "farm use" bolts; some of the better one are almost but not quite as strong as Grade 5. There are stronger stainless fasteners, but you've gotta search them out--you won't find 'em in a typical hardware store. ARP and Grainger have them. Not cheap. But brass nuts on the exhaust pipe studs has been a common upgrade for decades. (22 ft/lbs.)

Many exhaust manifold-to-exhaust pipe stud replacement kits come with brass nuts. VERY recommended.

For example:
www.napaonline.com/en/p/NOE6001817

Motrhedx81 said:

For the exhaust manifold to head, it does use a gasket. I've used Mahle MS16091 MLS gaskets with good luck (so much better than that soft metallic crap-tastic stuff)

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Thanks for that. Looks good.




Whether re-torquing the head bolts, or replacing the head gaskets, the real issue is the exhaust manifold fasteners. If the exhaust manifolds can be removed without breaking the manifold-to-head studs, great. If those studs break, you're perhaps pulling the heads to get the broken studs removed.

I'm thinking we may be getting crossed up here. I think we may both be right about the head bolts. I have a 2000 K3500 454/7.4. The FSM specifically states not to reuse head bolts. They're torque+angle (torque to yield). See manual screenshot below. TTY is a 'newer' thing and I'm betting GM made a change for the 1999, 2000 type models. Based on what I found, the LS engines use TTY head bolts also (same era as my truck). I don't doubt that your manual for that model year says to use standard torque numbers. I honestly wasn't thinking about the potential differences in model year bolt styles, just about what I deal with on my truck.






Agree that the common stainless nuts are made from a generally weaker material. But between the MLS gaskets and stainless nuts I haven't had a problem for the 3 years they've been on there, for either manifold-to-head or manifold-to-pipe. They sure made life a little easier for disassembly this latest go around. I'm sure others have had different experiences, but this is what I've had.

For reference, McMaster-Carr carries the common and high strength stainless fasteners.