Cracked Heads

[Broosedamoose]

I replaced the head gaskets about six month ago and the other day the truck started “sputtering” and blowing white smoke out the exhaust. Seemed like the head gaskets were blown again. Well, today I went by the shop and my mechanic showed me the heads. Four of the six valve chambers are cracked! The job was supposed to be covered under warranty but not now! Plus, it’s $300 for a set of used heads! I looked at just replacing the engine but the cheapest one I could find was $2,999! What makes them so freakin’ expensive? If I wasn’t already building a 5.0 Ranger I’d drop one in this truck!

 

[RonD]

Heads crack between valves seats because head was over heated, metal is thinner at those spots so when the metal expands as it gets hotter it will crack

Blown head gaskets are usually caused by overheating, leak in cooling system that is not noticed or a hose failing and sudden loss of coolant.
All metal expands as it is heated up, overheating causes extra expansion
The head metal gets the hottest, so it expands the most, and when it expands downward it Crushes the head gasket between head and block, and this can cause weakened cylinder ring in that gasket at that time or it can just "blow" at that time

When head gasket blows it usually causes an overheating cycle AGAIN because coolant is forced out by the "air" being pushed in, and the heads end up with just "air" and no coolant so get super HOT, same as running low on coolant
So heads may have already been cracked from first overheating but not as noticeable, or weakened from the overheating from what caused blown head gaskets to begin with

Blown heads gaskets are 99% from overheating, 1% from pinging/knocking, incorrect replacement, or bad gasket from maker
Cracked head is 100% from overheating

The 4.0l SOHC was used in several popular Ford models, and earlier years did have the failing timing chain tensioners so used replacement 4.0l SOHC often have several buyers, so wrecking yards do price them higher
4.0l SOHC didn't have the "cracked head" issues that the 4.0l OHV did, so yours is not a known issue like the 4.0l OHV, but can happen on any engine

On any engine, never try to "make it home" when temp gauge starts to climb, pull over, and wait for engine to cool down
Limp home in short trips or get towed, it will save you at least $1,000, and if it takes you 10 hours to get home you were making $100/hour, lol, not a bad payday

 

[Broosedamoose]

Good news and bad news. The bad news is, it cost me $450 to get my truck fixed. But, the good news is, he still covered it under warranty! All I had to pay for was the cost of the heads and having them machined! When I got my truck back after doing the head gaskets it never idled or ran right. He even took it back in and used the tool from Ford to set the timing but it didn't change anything. Well I guess he said it was because there must have been cracks (or at least one) and he didn't see it. I mean, I looked at the old heads on the floor for a couple minutes and it wasn't until he pointed them out that I saw them! My old truck is back! It runs SO much better than it has for the last six months! I'm so thankful he is covering the labor cost! It was around $800 to do the gaskets! One weird thing that happened though was that a weld holding the oil tube (running along the top of the cam) broke. It came loose from the tab right at the end. The first day I got it back it started "ticking" just like a bad lifer but there are none. I could hear something hitting the valve cover also. It was the oil tube. He just took the one from my old heads and swapped it out and everything is good. Just odd that the weld broke. I'm so happy to have my truck back!

 

[ekrampitzjr]

On other forums posters say if your 4.0 overheats, you will have a cracked head or cracked block. It won't be just a head gasket replacement.

 

[RonD]

On other forums posters say if your 4.0 overheats, you will have a cracked head or cracked block. It won't be just a head gasket replacement.

That's the 4.0l OHV engines, 1990-2000 Rangers, even if overheated just once
4.0l SOHC(2001-2011 Rangers) didn't have that weak spot between valve seats

But ANY head can crack if over heated long enough, just the physics of metal expansion when heated

 

[FEandGoingBroke]

I replaced the head gaskets about six month ago and the other day the truck started “sputtering” and blowing white smoke out the exhaust. Seemed like the head gaskets were blown again. Well, today I went by the shop and my mechanic showed me the heads. Four of the six valve chambers are cracked! The job was supposed to be covered under warranty but not now! Plus, it’s $300 for a set of used heads! I looked at just replacing the engine but the cheapest one I could find was $2,999! What makes them so freakin’ expensive? If I wasn’t already building a 5.0 Ranger I’d drop one in this truck!
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The part that makes them expensive is because the water pumps fail and nobody notices and then they overheat and that causes the heads to crack when the water steams up and pushes coolant from the bottom of the motor up into the head that’s colder than the head and it causes them to crack. So there’s a lot of heads out there you cannot get a hold of him 300 bucks for a pair is a pretty damn good price

 

[Broosedamoose]

The part that makes them expensive is because the water pumps fail and nobody notices and then they overheat and that causes the heads to crack when the water steams up and pushes coolant from the bottom of the motor up into the head that’s colder than the head and it causes them to crack. So there’s a lot of heads out there you cannot get a hold of him 300 bucks for a pair is a pretty damn good price

Yes, the $300 heads were a great deal! I was questioning why the 4.0 SOHC engines are so expensive. Not like they were limited or anything! As for the engine overheating, it never has since doing the head gaskets 6 months ago. Back then it overheated but it was because the head gasket blew. Not the other way around. It had never overheated before then. I got the truck with 240K miles on it but my mechanic said the heads had never been off before. It may have overheated at some point prior to me buying it which weakened the head gasket. The day the head gasket blew, it overheated! It overheated before I had a chance to pull over to the breakdown lane! That's when the heads must have cracked. I don't know why my mechanic didn't notice it when he machined them though. But like I said, I looked at the heads for at least two minutes while waiting for him to finish with a customer and I never saw the cracks! It wasn't until he pointed them out to me that I saw them. But, he's covering it under warranty because even he said he should have seen it when he machined them, so I'm happy about that. Now, why are these engines so expensive?