Cracked head, now what?

[Sparrowhawk]

I just found out that the head on my '96 Explorer 4 L OHV engine is cracked. I paid $3400 for the rig three weeks ago and they want $3500 to fix it. I'm thinking of changing it myself but don't trust the quality of unknown web order rebuilders / remanufaturers.

Are heads a weak point on these engines? How do I find a head to install that I know will be high quality and last?

Any other ideas or thoughts?

 

[Creager]

Yes the heads are known to be a weak point. Do a search for Alabama Cylinder head, they sell the MHALE castings which are far superior to the stockers.

Installing the heads is pretty straight forward, get a haynes manual, it should tell you exactly what to do. The only think i didnt like about the haynes manual is it tells you to toruqe the head bolts in three steps: First to like 50 ftlbs, Second to 65ish, then the last step the manual says to give them an extra '90 degree turn.' The hell with that, Torque in even steps of 20ftlbs all the way up to 80ftlbs.

Gaskets are going to be the kicker. Make sure you use the Ford lower-intake gasket, and valve cover gaskets. You can use felpro headgaskets and upper-intake gaskets without a problem. Felpro head bolts are OK too.

 

[Sscolax]

The only think i didnt like about the haynes manual is it tells you to toruqe the head bolts in three steps: First to like 50 ftlbs, Second to 65ish, then the last step the manual says to give them an extra '90 degree turn.' The hell with that, Torque in even steps of 20ftlbs all the way up to 80ftlbs.

I was told that method with the extra 90º turn is Ford's spec for the head bolts and is the best way to go. Supposedly it properly stretches the bolts or something like that.

 

[Sparrowhawk]

Thanks, good information. I am finding out the original head was so bad there are literally no remanufactured ones available because there are no cores. So now its go buy a new casting and get to work.

 

[shamaal]

Call an automotive machine shop. Look in yellow pages or ask a competent auto store for a reference. I paid $259 for a new head casting and for an extra $25 he cleaned up the valves and transferred all the parts. I supplied new seals that came with the gasket kit.

How did the shop know a head is bad, say opposed to, say, a gasket? I'm not doubting it's bad, it probably failed compression. I think it's hard to tell without a visual inspection. The point is if you have one head off, you might as well pull the other and inspect it.

I have to agree with the 90º twist. The torque ensures metal mating. The extra 90º, literally stretches the bolt. You can feel it twisting when you turn it. This is also why you must always replace the bolts.

Ask questions about any bits you don't know.

 

[Creager]

Yes, the head bolts are TTY. When you get town to the 90 degree part you will see what i mean. Its not clean as it sounds on paper, to the point where it doesnt even seem right. Atleast not with the engine on a stand.

The problem with the 90 degree method is it becomes too easy to unevenly torque those bolts. Some will go the full 90 degrees, but some wont make it past 30 degrees. It's probably tons easier with the engine in the truck, but vanir's method of stepping 20ftlbs on up to 80ftlbs will seemed more realistic to me.

You might want to save your stock head bolts, just to get an idea for what it takes to make that extra 90 degree turn. It tougher then the 8.8 crushsleeve at this point. Torx bits only take so much until they start twisting themselves. Originally i was going to 'mix' the two method togeather. Torque in steps of 20 all the way up to 60 and do the 90 degree turn. But once i actually got down to the last step, 80 was the tightest those things were going.

Isn't there a special wrench that measures tensil strength for torquing TTY bolts?

 

[Aussie Explorer]

Yeah but TTY method is used as it cancels out thing like Friction or a tight thread, which will cause a toque wrench to click before the bolt has reached it’s specified clamping force.

 

[shamaal]

Creagers right regarding how long the bits last.
My Torx held up well until the last three bolts, when it started slipping unless I had it square on. The last bolt may have only gone 85º
The bits useless now except for loosening.

 

[ma96782]

Yeah but TTY method is used as it cancels out thing like Friction or a tight thread, which will cause a toque wrench to click before the bolt has reached it’s specified clamping force.

IF I remember correctly.........I read once, that you don't torque "dry." Unless it specifically say to do so. There are too many variables.

Haven't read the head section if it says to torque "dry."

When I torque a regular bolt: I clean off the threads and run a clean-up tap through the hole........apply Anti-seize (never, use oil) on the bolt threads.........then torque.

IMHO.........I'd go with the:

method of stepping 20ftlbs on up to 80ftlbs

It sounds reasonable, as "equal torque will be applied"........as opposed to the extra 90 degrees method.


Aloha, Mark

 

[Creager]

Yes definatly tap those threads, and use anti-seize.