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Discussion Starter #1 (Edited)
Hi I just joined the group try to get some help diagnosing my issue with my nitro that I just recently purchased.It’s an 2008 dodge nitro with a 3.7l engine.

seem like these nitro are notorious for these type of issues. The car will crank but won’t start unless pressing the gas pedal and won’t stay on unless pressing the gas pedal, it will misfire lower rpm but will smooth out if keeping it around 2-3k rpm and seem like a random misfire but no codes are stored. Since it seem to be effecting the engine as a whole and not a particular cylinder or bank, I’m assumed it has a vacuum leak and tried spraying carb starting fluid which didnt reveal any leaks, my next guess is throttle body or idle are control, also I like to state I did a fuel pressure test and while with the key on it primed 60lb and while starting it maintained at 60lb of pressure

also I read as well that the crank sensor and or cam sensor can be bad but I’m trying to get some feedback who had the same issue
 

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Discussion Starter #2
I just did a compression test on all cylinders and 2,3,5,6 all gave me 120 psi with 3 engine turn, cylinder 4 gave me 90 psi but with more engine turns it went up to 120 psi, pull some oil in it and went above 120 psi with 3 engine turns. Now cylinder 1 has no compression what so ever. I blew some air into the quick disconnect of the compression tester and I heard the air come out of the air intake. I’m going to turn the engine manually to tdc and see if anything changes. And if not I guess I will be tearing down bank 1 valve cover off and inspecting the camshaft and valve stems
 

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Khaki Nitro Nut
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Welcome to the forum @Rambo. When you have a chance, head over to the Newbie Section (<click this) and say "Hi".
Tell us a little about yourself and your ride.
That way we can welcome you all proper like.

Sounds like you are on the right track. Probably a rocker arm fell off and is keeping a valve open on # 1. At least that would be best case...
The 3.7 Specs are: Compression should be no less than 100 psi, and not have more than 25 percent variation from cylinder to cylinder.
Cylinder 1 & 4 concerns me.
Fuel pressure, 58 psi ± 5 psi.
 

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Discussion Starter #4
Welcome to the forum @Rambo. When you have a chance, head over to the Newbie Section (<click this) and say "Hi".
Tell us a little about yourself and your ride.
That way we can welcome you all proper like.

Sounds like you are on the right track. Probably a rocker arm fell off and is keeping a valve open on # 1. At least that would be best case...
The 3.7 Specs are: Compression should be no less than 100 psi, and not have more than 25 percent variation from cylinder to cylinder.
Cylinder 1 & 4 concerns me.
Fuel pressure, 58 psi ± 5 psi.
Im going to do A wet compression test and leak down test, I’m sure cylinder is all good, but I think valve are bad. I wouldn’t mind rebuilding both banks, but once I access what’s going on I may swap engines. Still being that 4 out of the 6 cylinder are reading good, the misfire and rough start got me stump. I would of assumed it will still idle rough with misfire with little power. Maybe cam phaser or timing issues
 

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Discussion Starter #5
Ok seem like the hydraulic lifter failed and the rocker arm fell off but it seem to have bent the intake valve. So seem like I’ll be taking it apart and replacing the exhaust valve and or cylinder head depending on the damage
 

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Khaki Nitro Nut
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Hopefully it did not pop a hole in the top of the piston.
 

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Discussion Starter #7
Got the engine pretty much disassembled, all I need to do now is take the pulley out, timing cover and timing chain assembly along with the cylinder head.

I will be buying new head bolts, hydraulic lifter, coil packs, fuel injector, thermostat, timing chain assembly, water pump and all new gaskets all for $320, now once I seen the valves I may either repair the head or pull some out the junk yard for $70 per head with camshaft
38591
 

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Discussion Starter #8
Hopefully it did not pop a hole in the top of the piston.
I wouldn’t worry about that, the valve seem like it just bent enough to not seat, I actually had valve break off in my Volvo s40 and just made some dent on the piston head,

38592
rods were still good.

I replace the cylinder head when I bought the volvo and then again the following year because belt snapped, then again because I left the pulley bolt was loose, then repaired it for a final time then I went into a ditch in a huge flood we had and had electrical issue and just junk the car. Only reason I kept reaping it is because I done up the whole car for car audio.

but I bought the dodge nitro for my next car audio project. I didn’t think bent valves but hey once I’m done I won’t really have to worry about water pump and timing chain etc
 

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Discussion Starter #9
Got both cylinder off, valve seat popped off, but the seat is too damaged in my opinion to fix. Made a scratch on the top of the piston l, nothing major.
Going to the junk yard this weekend to pull out passenger side head, waiting for parts now
38593
38594
38595
 

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Khaki Nitro Nut
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You work quick! LOL
You also got lucky. These pistons are not the strongest around. 90% of the time a dropped valve = a piston hole.
Your on the home stretch now...
 

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Discussion Starter #11
yea trying to do the job quick, usually teardown is quick, I say 7hrs in total, rebuilding maybe 13hr or so.

It helps renting a friend garage and not some parking lot in the weather and limited sunlight. I work every other weekend but took off Saturday to work on the car and yesterday I got to the timing chain/heads before work. But once I get all the parts I will be working on the car after work until it’s done

And there totally a difference between these valve on the Volvo I had, if these were to drop in the block it would of cause Huge problems, I’m actually surprised with 183k miles there no carbon build up on the piston just valve
You work quick! LOL
You also got lucky. These pistons are not the strongest around. 90% of the time a dropped valve = a piston hole.
Your on the home stretch now...
 

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Khaki Nitro Nut
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Ya the 3.7 is known for carbon buildup. Check the EGR, I'm sure it is packed.
To keep things clean I use seafoam 1-2 times a year, induced into the brake Vac line, then sprayed into the TB throat, and a can in the tank.
 

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Discussion Starter #13
Ya the 3.7 is known for carbon buildup. Check the EGR, I'm sure it is packed.
To keep things clean I use seafoam 1-2 times a year, induced into the brake Vac line, then sprayed into the TB throat, and a can in the tank.
Hey had a questioned for you, do you know of any revision to the nitro cylinder head? The rocker arm didn’t fail it was the valve seat that failed and cause the rocker arm to fall. Wondering before I rebuild this engine if there any newer heads so it’s doesn’t happen again
 

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Discussion Starter #15
Only engine is back up and running but still have a hard time starting at times and seem to have a random misfire while idling. Read the codes and came back with bank 1 too rich. New coil pack and injector are replaced as well with spark plugs too. Also did another compression test and with 3 engine turn all cylinder did 120psi

I think idle air control? I need help and suggestions. I may replace cam, crank, iac sensor and see what happens
 

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Khaki Nitro Nut
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Could be a leaking injector.
No IAC in the Nitro. It uses a MAP (Manifold Absolute Pressure) sensor, and IAT intake air temp. If they were faulty you should be getting to rich/lean on both banks.
What was the code#?

The MAP sensor on the 3.7 is located on the front bottom of the intake manifold.
 
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