4.0 OHV Head Replacement

cal74 · Nov 25, 2016

Opinions on re-manufactured heads vs new ones?

Looking at picking up two new heads, one vendor on feebay has a three year warranty. Specs sound good, but who knows?

Think the other one is clearwater something or other, believe those are new heads with the valves/springs installed. About 70.00 more for the pair.

I'm already into this for more than I want, but ??

Thanks

RonD · Nov 25, 2016

Are both old heads cracked?

All 4.0l OHV heads will have the weak point in the casting, between valve seats.
So any can crack there, if overheated.

New or used/reconditioned wouldn't matter unless the used head was overheated, but didn't crack, was just weakened more.

I cracked a 4.0l head from over heating, I only replaced the cracked head, with reconditioned.
Haven't had any problems with either head since, 100k miles, I half expected the remaining original head to fail by now because it was over heated like the one that cracked.

So up to you really, new head won't have been over heated, ever, used may have been but in my experience it doesn't seem to matter.

cal74 · Nov 26, 2016

Neither of the current heads are cracked, passenger side has a burnt (cracked) exhaust valve on number 2.

I haven't priced out any machine shop work, just kind of presumed that it would be cheaper buying a rebuilt/new head.

I have not taken the drivers side off yet either, didn't know if I should mess with something that is not broke or not but also presumed as long as I was in there I should pull it.

So Ron, since you've been such a help up to this point. What would you advice?

150,xxx on the truck.

Burnt valve (no cracks/leaks) on the passenger side, everything else looks good. I'll be replacing a couple of the rockers and believe I'll order all new push rods. Drivers side is good as it stands right now.

Thanks

RonD · Nov 26, 2016

Well we are only talking about pulling out 8 more bolts to remove the other head, + exhaust manifold, lol, can be a PITA

And when you buy gasket sets you will get 2 head gaskets
And have to buy new head bolts so set of 16
So the parts are the parts, cost is the same 1 or 2 heads

So I would pull the other head

Burnt exhaust valve can be caused by a few things that are common to the whole engine, i.e. insufficient EGR flow or lean conditions, both of which heat up cylinders enough to cause exhaust valve issues.
So examining the other head would be warranted IMO

I would check with local machine shops; cleaning, pressure test and surfacing of a head is about $60, give you a little piece of mind.
They also often have good prices on replacement heads, worth asking.

But you can, of course, just do the one head, "if it ain't broke don't fix it"
I have done that before on other engines, don't recall any problems.

ratdude747 · Nov 26, 2016

I'f you're getting heads decked pull both. The shop will deck the bad one first until it's good, then deck the second to the same amount of cut. That way everything is nice and balanced.

4.0 OHV Head Replacement

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