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Author Topic: Zero compression on #4 cyl  (Read 1181 times)

Offline aread4

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Zero compression on #4 cyl
« on: January 09, 2014, 04:02:01 am »
Hey folks, new to the forum.  I've got a big problem I'm hoping to get some help with on my truck.  Haven't had any degradation in performance lately but the other day I fired her up and she was making some loud sounds and stalling at low idle.  Had to keep engine rev'd high with the brake on to limp to the mechanic.  They replaced injector, but still couldn't fix it and referred me to the dealer who checked and said zero compression on #4 cyl.  They want $700 to take head apart and investigate, but also quoted me $5k for 90k used engine or $8k for long block.  I could spend the $700 and still need to fork over the cash for the engine, or just call it a loss, since KBB is only $7500.  Scrap...trade...fix??  Other ideas??  Any advice is much appreciated!

'04 Ram 1500 SLT Quad Cab
5.7L Hemi
K&N, brake/tow pkg
135,000 mi

Offline Drew

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Re: Zero compression on #4 cyl
« Reply #1 on: January 09, 2014, 05:03:29 am »
Quickest way to tell what is wrong is to put some oil into the cylinder and run the compression test again. If the compression comes up then the Rings are shot. That also means the cylinder wall is scored. If the compression does not come up then you have an issue with the valves, rockers,  push rods, or even the cam.

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Offline kenz

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Re: Zero compression on #4 cyl
« Reply #2 on: January 09, 2014, 02:08:03 pm »
Agree with Drew. But I got to ask, 5 grand for a used motor? Even for a dealer install that's extremely high! I would think a reputable shop could rebuild the original motor for less than that.


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Offline Cujo

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Re: Zero compression on #4 cyl
« Reply #3 on: January 09, 2014, 04:58:05 pm »
I agree with Ken on the cost of the motor, originally thought 5K wasn't bad for a 5.9 ISB, then noticed it was a HEMI.

Can't you pull the plug and stick a borescope in the cylinder to check for cylinder wall damage?

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Offline spencea15

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Re: Zero compression on #4 cyl
« Reply #4 on: January 10, 2014, 06:04:17 pm »
I would bet $100 it is a brooken exhaust spring.
2000 Dakota CC slt plus, v6 :( auto.

Offline aread4

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Re: Zero compression on #4 cyl
« Reply #5 on: January 11, 2014, 12:59:37 am »
Thanks for the feedback guys.  I had them pull the valve cover to check and they said the springs and those components look good, but said it's definitely something with the head.  So they are sending it to a machine shop.  If head's good or repairable, or just the valve, it's $1400 out the door.  If head needs replacement, looking like $2400.  Not cheap, but much better than long block replacement!  Thanks again!

 

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