Cracked 5.9L Heads
#1
11-01-2010 | 03:45 PM
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From: Chicago, IL
Cracked 5.9L Heads
Took one set of heads into the machine shop and was told they are both cracked. I have heard they are prone to cracking, anyone else have this happen? Did you have to replace with new or used?
I have one more set to take in and see if they are ok, which I am hoping they are.
I have one more set to take in and see if they are ok, which I am hoping they are.
#2
11-01-2010 | 05:07 PM
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From: NM
It happened to me. When I first got the 5.9 from the junkyard. I took it to get new valve seals, and one head had a crack in between the valves. The engine had a 1 week warranty. They tried to give me heads off of a 5.2 since they didn't have any more 5.9's. But I fought and made them buy me a re-manufactured one with the correct part number, it was still in the wrapping and box when I picked it up. $300 free to me. And I only had to pay for 1 head of valve work. I did get them machined down and matched.
#3
11-01-2010 | 07:28 PM
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From: Florida
Took one set of heads into the machine shop and was told they are both cracked. I have heard they are prone to cracking, anyone else have this happen? Did you have to replace with new or used?
I have one more set to take in and see if they are ok, which I am hoping they are.
I have one more set to take in and see if they are ok, which I am hoping they are.
It is common with these heads because the center between the inner two cylinders have the exhaust valve next to one another, and the casting is thin there. Most recommend upgrading the heads to at least "RT" heads (not from an RT mind you).
#6
11-10-2010 | 05:20 PM
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From: NM
The only difference is the Valve sizes and I believe the combustion chamber size. For exact details check out this site. http://dodgeram.org/tech/gas/specs/index.html
#7
11-10-2010 | 07:13 PM
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On the LA engine there were a couple of differences between the heads. But on the Magnum engines the 5.2 and the 5.9 used the same valve sizes and combustion chamber volume.
Intake: 1.92"
Exhaust: 1.625"
Combustion chamber: 60cc
The 5.9 has dished pistons to get a lower compression ratio.
Intake: 1.92"
Exhaust: 1.625"
Combustion chamber: 60cc
The 5.9 has dished pistons to get a lower compression ratio.
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#8
11-11-2010 | 03:04 AM
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From: NM
On the LA engine there were a couple of differences between the heads. But on the Magnum engines the 5.2 and the 5.9 used the same valve sizes and combustion chamber volume.
Intake: 1.92"
Exhaust: 1.625"
Combustion chamber: 60cc
The 5.9 has dished pistons to get a lower compression ratio.
Intake: 1.92"
Exhaust: 1.625"
Combustion chamber: 60cc
The 5.9 has dished pistons to get a lower compression ratio.
No the compression ratio is the same. And the Valves are different. The 5.2 are actually larger. Both engines use the same style of pistions.
If you would looked at the link I provided it has it listed. Also I double checked with the factory service manual for both engines.
If you wanted you can download the FSM for the 5.2 from here in the 1st Gen. For the 5.9 from the 2nd Gen.
Displacement 5.2L (318 c.i.)
Compression Ratio 9.1:1If you would looked at the link I provided it has it listed. Also I double checked with the factory service manual for both engines.
If you wanted you can download the FSM for the 5.2 from here in the 1st Gen. For the 5.9 from the 2nd Gen.
Displacement 5.2L (318 c.i.)
Valves
Head Diameter – Intake 1.916 inch (48.666mm)
Head Diameter –Exhaust 1.624 inch (41.250 mm)
Displacement 5.9L (360 c.i.)
Compression Ratio 9.1:1Head Diameter – Intake 1.916 inch (48.666mm)
Head Diameter –Exhaust 1.624 inch (41.250 mm)
Displacement 5.9L (360 c.i.)
Valves
Head Diameter – Intake 47.752 mm (1.88 in.)
Head Diameter –Exhaust 41.072 mm (1.617 in.)
Head Diameter – Intake 47.752 mm (1.88 in.)
Head Diameter –Exhaust 41.072 mm (1.617 in.)
#9
11-11-2010 | 11:55 AM
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I have 2 books that say the heads are the same, "How to build Big-Inch Mopar Small Blocks" and "how to Modify Your Mopar Magnum" The second one is supposedly written by a former engineer at Chrysler who worked on the Magnum engines.
When I tore down a 5.9 from a 1996 Ram for the 408 build in my Jeep, it had dished pistons. The 5.2 that came out of my 1995 Jeep had flat top pistons.
Stock 5.9 piston on the right:
So I don't know where all of the inconsistencies come from.
When I tore down a 5.9 from a 1996 Ram for the 408 build in my Jeep, it had dished pistons. The 5.2 that came out of my 1995 Jeep had flat top pistons.
Stock 5.9 piston on the right:
So I don't know where all of the inconsistencies come from.
Last edited by JGC403; 11-11-2010 at 11:58 AM.
#10
11-11-2010 | 12:42 PM
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From: NM
I have 2 books that say the heads are the same, "How to build Big-Inch Mopar Small Blocks" and "how to Modify Your Mopar Magnum" The second one is supposedly written by a former engineer at Chrysler who worked on the Magnum engines.
When I tore down a 5.9 from a 1996 Ram for the 408 build in my Jeep, it had dished pistons. The 5.2 that came out of my 1995 Jeep had flat top pistons.
Stock 5.9 piston on the right:
So I don't know where all of the inconsistencies come from.
When I tore down a 5.9 from a 1996 Ram for the 408 build in my Jeep, it had dished pistons. The 5.2 that came out of my 1995 Jeep had flat top pistons.
Stock 5.9 piston on the right:
So I don't know where all of the inconsistencies come from.
I would rather trust the Factory service manuals. Which was written by more than one active engineer, and all the stock replacement parts and manuals.
The heads are externally the same. And can be swapped over on each other. So they are almost the same. Maybe you just misinterpreted what he was talking about.