Cracked heads

D

Doc Stewart

IH Guru
Overheated an ic sv392 [in a 74 200 4x4 727]. Didn't show on the gauge. Steam rolled out when I shut it down after a 20 minute drive. Let it cool 90 minutes then added 3 gallons of water to fill up the rad! White smoke out of the driver's side of the dual exhaust on the way home. Gauge showed normal operating temp.

Pulled heads: both cracked. My question: what else should I look for in the way of damage?

The motor is in otherwise good shape. Plan is to clean up and lap the valves on a spare set of heads. I will test the cooling system and the gauge & sender before running again.

Suggestions?
 
At least one half (prolly more) of the I-4/sv heads (all versions) I see are cracked also doc! Normally visible immediately, but sometimes only after magnaflux or diecheck...very common! One IH engine core supplier we deal with magnafluxs all heads (especially IH!) before they are shipped to the various engine rebuilders they deal with, they hate shipping scrap iron and their customers hate receiving scarp iron and paying for shipping it around needlessly!

I know...you know...the drill about "ic vs. Non-ic" 392 stuff so you know what to do regarding replacement parts.

Roll the motor over and see if there are any signs of "scuffing" on the cylinder surfaces...especially the cylinder walls that are "siameezed", that is the most likely point of any heat-related damage. If none, then clean up the block deck with appropriate 3m "roloc" abrasive brushes:

3m abrasives : roloc™ bristle disc

And apply the appropriate replacement gaskets

if the cylinder walls aren't scuffed, then drive on! I've experienced this same issue many times with both IH and Ford motors, never had any other damage if the motor wasn't limped along for weeks with water in it and overheated continuously.
 
(edit) sorry...didn't mean to jack the thread....just dawned on me.

This thread probably explains my problem as well. I have coolant leaking from the driver's side of my n/c 392. It pools up in by the #3 cylinder spark plug and also drips pretty rapidly from under the exaust manifold somewheres too, plus it's also burning the coolant(white smoke driver's side exaust) I haven't had a chance to diagnose the issue yet, I will be tearing into on Sunday and am going to start with a coolant system pressure check and go from there. Do you guys have some suggestions as to what else to check? Maybe torque the head bolts first or maybe remove the exaust manifold? Much appreciated always!
 
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Scout-n-josh said:
(edit) sorry...didn't mean to jack the thread....just dawned on me.

This thread probably explains my problem as well. I have coolant leaking from the driver's side of my n/c 392. It pools up in by the #3 cylinder spark plug and also drips pretty rapidly from under the exaust manifold somewheres too, plus it's also burning the coolant(white smoke driver's side exaust) I haven't had a chance to diagnose the issue yet, I will be tearing into on Sunday and am going to start with a coolant system pressure check and go from there. Do you guys have some suggestions as to what else to check? Maybe torque the head bolts first or maybe remove the exaust manifold? Much appreciated always!
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The cracking most often is between a valve seat and plug.
Possible that the watter is coming up the plug threads and draining out from around the exhaust port. Could also be a crack around a head bolt and the water is coming past the bolt head and out by the plug.

One more possibility is a blown head gasket and the water is making its way out the bolt hole.

To many causes without pulling the head and looking. Bad to have the constant water in the engine. Can cause serious cylinder wall pitting.
 
Just an update....found a decent sized crack on the driver's side head right in by the cylinder #3 spark plug, so I pulled both heads, purchased some 345ci heads off a rebuilt motor and will be installing them hopefully tomorrow or sat afternoon depending on when my gasket kit shows up. Cylinder walls look good and the guy who I purchased this rebuilt motor from is sending me a check for the cost of the new heads and gasket kit plus a little for labor time. At least he's willing to work with me.(edit) the 345 heads have a 5 stand rocker, would I be better off using the 9 stand off the 392 heads?
 
Scout-n-josh said:
just an update....found a decent sized crack on the driver's side head right in by the cylinder #3 spark plug, so I pulled both heads, purchased some 345ci heads off a rebuilt motor and will be installing them hopefully tomorrow or sat afternoon depending on when my gasket kit shows up. Cylinder walls look good and the guy who I purchased this rebuilt motor from is sending me a check for the cost of the new heads and gasket kit plus a little for labor time. At least he's willing to work with me.(edit) the 345 heads have a 5 stand rocker, would I be better off using the 9 stand off the 392 heads?
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I prefer the nine stand rocker assemblies on any IH engine. But what is most important is which assemblies you have are in decent condition!
 
chris142 said:
are you putting 345 heads on a ic 392? I was always told that wont work.
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The 392 engine is a non-improved cooling.

Michael, is there any particular signs of wear that I should inspect for on the nine-stand? It does appear like they're in good condition.
 
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Scout-n-josh said:
the 392 engine is a non-improved cooling.

Michael, is there any particular signs of wear that I should inspect for on the nine-stand? It does appear like they're in good condition.
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Disassemble the rocker shafts completely, look for major wear points on the bottom of each shaft where each bushed rocker arm rides. If the shafts are decent at those eight points, the shaft can have the end plugs pulled, the internals douched, and new plugs installed.

Wear on the rocker bushing interface points will be very evident...that will indicate that the rocker at that point has been receiving minimal or no oil from the spit hole in the shaft.

Review all the other threads in this engine tech sub-forum and you should find everything ya need to know about this stuff!

If your shafts are not usable, then post some pics and we'll walk ya through some options for repair.

Also inspect carefully the top of each rocker stand, looking for cracks indicating gross over-tightening of the retainer bolt at some point in time.
 
Thanks michael! Much appreciated! I have been doing quite a bit of reading about the proper oiling and rocker stands and it has been very helpfull. Very good info!
 
Okay, pulled off the heads on my ic 392. Am I paranoid or do these look cracked?
 

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Granted I only see casting marks not cracks, but a visual inspection is not enough to definitively rule out cracks. Magniflux testing can take care of finding all cracks that extend through to the surface.
 
Good news! Had my heads magnafluxed, no cracks! Don't know why I was so paranoid.

I do have a new question. My intake seats are inserts, is that normal? I expect the exhaust to be, but not the intake.
 
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