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  Topic Review (Newest First)
06-30-2021 10:53 AM
222Doc short block would be the way since the heads are ready. where you are and how to get one might be the question. Here in the USA could have in a few days.

the heads the main issue would be the seats and how tight they fit. generally its a over heat that takes a seat or wall out. must of got hot?

basically you are at the new bock point so some ancillary parts might be replaced if still stock. water pump, all hoses to any cooling system and most any other perhaps hard to get at stuff. check the harness in the back will be easy right now too.
06-30-2021 10:22 AM
firebirder Hi all,
here is my feedback. Both heads have been shaved at the machine shop. They pressure tested the heads before in water. No leaks found at the heads. With a self-made leak down tester for the cylinders without the head, I made the leak down test for every single cylinder. Results were 5-7% per cylinder. So all in green range.

After heads were finished, we put all back together and fired the car yesterday up. A lot of white smoke (burned water) from the right exhaust and a the check engine light came up immediately.

What shout I say: in Germany we say "a hit to the water" :-/

Check videos from endoskope camera (crack in cylinder 2 wall) Engine cold with 7 psi pressure on coolant system.

So this horse is dead I think. Or is there a good source for a base engine without all the things like alternator and others?

Kind regards,

06-30-2021 07:35 AM
HurriJeff Daniel, "shaving" or surfacing of the head is a common practice for warped heads. You will not need a thicker head gasket to offset the material removed from the head. That tiny amount removed is highly unlikely to increase your compression enough to measure. By now Im sure you have completed the repairs... how did it go ?
06-09-2021 10:52 PM
firebirder Hi all,
yesterday I took the head off, but could not see any cracks in head or block. Also the head gasket looks fine. For a first test, I gave the head to a machine shop for a leak test in water. Afterwards the head will be measured and maybe 0.10mm will be "shaped". (I hope this is the correct wording).
I could not find 0.10mm thicker head gaskets yet, to have the same compression on both heads after installation. Do you have a source or an idea where to get one thicker head gasket?
Kind regards,
06-07-2021 09:27 PM
firebirder Thank you a 1000 times. Will do the job and replay when it has done.
06-07-2021 04:48 PM
ColdCase When you remove the rocker arms and push rods. Note their location to ensure installation in their original locations as removed.

Clean all sealing surfaces of the cylinder block and cylinder heads using Brake Parts Cleaner (or equivalent).

Inspect the cylinder head for out-of-flatness using a straightedge and a feeler gauge. If tolerances exceed 0.0508 mm (0.002 in.) replace the cylinder head

Inspect the valve seats for damage. Service the valve seats as necessary.

Inspect the valve guides for wear, cracks or looseness. If either condition exist, replace the cylinder head.

Inspect the pushrods. Replace worn or bent pushrods. You may need a pushrod retainer (9070) to install the rocker shaft.

Use a new cylinder head gasket

FSM does not note that new cylinder head bolts, or any of the other bolts are required.

Inspect the cylinder head cover gasket and replace if necessary. Do not use harsh cleaners. The cylinder head cover gasket may be used again, provided no cuts, tears, or deformation have occurred.

Use Mopar® Lock & Seal Adhesive on the cylinder head cover and intake manifold bolts.

Inspect the intake manifold seals and replace as necessary. The intake manifold seals may be used again, provided no cuts, tears, or deformation have occurred.

Change the oil and filter

The #2 spark plug may be fouled, so you you may want to replace it.
06-07-2021 02:26 PM
firebirder Hi ColdCase,
thank you for your great answer. Today I did a cylinder leak down test and the cylinder with the problems blast compressed air to the cooling water (coolant). So maybe the headgasket, broken head, or broken engine block. I will disassemble the head in the next days.
What needs to be renewd in case of the headgasket?
- new original headgasket for sure
- new bolts for head for sure
- new gaskets for valve cover and manifold also ok
- need to get new bolds for the lifter "linkage"?
(Oil, coolant and spark plugs are already on the way.)
Other parts?
06-06-2021 04:54 PM
ColdCase Anything that affects the speed of the crankshaft can cause a misfire DTC. The PCM uses the Crankshaft (CKP) and Camshaft (CMP) sensors to determine when an engine misfire event is occurring and determine individual misfire events by monitoring the crankshaft rotational speed. A sudden different in speed is interpreted as a misfire.

When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinder's Injector Control circuit.

Misfires detected during a deceleration are indicators of mechanical concerns.

These are usually a bad spark plug or bad lifter/cam but it sounds like you checked everything but the PCM. This code may not be reset right away, so make sure to routinely clear the codes manually. Did you do a cylinder leak down test while you were checking compression to completely rule out a burned valve? Most of the other things, like an intermittent CKP or CMP, would probably cause multiple misfires.

Anyway I've heard of a couple stories where a misfire cause could not be found. When they swapped the PCM and crank sensor it finally fixed it. There have been stories of a coolant leak shorting out the ignition to one cylinder.
06-06-2021 01:59 PM
6.4 Hemi misfires 2015 GC SRT

Hi all,
my name is Daniel. I'm from Hamburg (Germany).
At the moment my 2015 Jeep Grand Cherokee SRT 6.4 Hemi drives me crazy. The car has done about 63tmls. I got the OBD code P0302 (cylinder 2 misfire) from my JScan. Until January the car was always at the official dealer for inspection. Correct oil 0W40 has always been changed and the car has not been driven hard.

The problem: from my point of view it takes gas, air, compression and a good spark for a nice combustion/explosion in the cylinder.

Compression: I checked all cylinders with a compression tester and all are in good identical shape (far in green range of the scale).

Ignition: I cross swapped the coils from cylinder 2 and 4. Misfires stay at cylinder 2. The two spark plugs from cylinder 2 has then been cross swapped with the spark plugs from cylinder 4. Misfires stay at cylinder 2. Spark plugs from cylinder 2 are wet and smell for gas. (seems there is no ignition/explosion). I grouded the spark plugs with its coil from cylinder 2 and there is a very good spark to see at starting/idling.

Gas: Next was the check of the injectors. I took out the rail with the 4 injectors and the spay pattern of all 4 injectors looks simular and the amount of gas is the same. As a second test I cross swapped the injectors from cylinder 2 and cylinder 4. Misfires stay with cylinder 2.

Air: I connected a smoke generator to the manifold with unconnected rail/injectors. (Injector holes are open). From all injector holes came the same amount of smoke. So there should not be an air problem. How can air really be excluded as a factor of the problem? Could an torque runner trap/door (Hope this is the correct name) in the manifold be broken or its axle and block the needed amount of air? Otherwise there is smoke with the smoke test...

At least I checked for the "typical" Hemi Gen. 3 problem with bad lifters and a bad camshaft. First test: took my endoscope and checked the input valve of cylinder 2 via the hole of the injector and a friend turn the engine by hand. Valve is opening and closing normally all the "way" as usual. Valve is really closing, a few drops of oil could not pass the closed valve. When the engine turned by hand they went to the cylinder normally. Second test to be sure, was to remove the valve cover, but all rocker arms move normally and full way up and down. I can not hear any ticking from the engine. So I think the mechanically part is fine.

Now I'm stuck. Could it be a bad PCM module that send the igniotion signal to early/late to the coil only of one cylinder?

Hopefully here are some Hemi specialists. They are less than rare in Germany.

Kind regards,


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