2008 3.7L Questions Jeep Newbie Daughter's truck down.....!

[fastmerc]

Greetings!

Trying to get some help here with the 3.7 engine. Paint it ugly. This is first foray into land of new-ish Jeeps.... I've tons of experience in old and some 90's SOHC Fords, but not the SOHC 3.7 Dodge/Chrysler mill.

Truck is stuck in Colorado Springs near where she lives and this is a reeeeemote diagnosis by a fairly known shop...to someone else. I'm stuck further west.......no idea how good these guys are but they seem to have the correct gear...!
Daughter just bought the truck about a year ago at the most....ran great....and never really put that many miles on it due to her location and working from home.
She started truck one morning about 6-8weeks back during the BIG cold spell many days under zero.....and it started having problems. Noisy engine clatter......(as it was told to me...)

Fast forward to finally getting the truck to a shop with actual competent mechanic(s). Compression test (dry???) shows even across the board 90's one 100 (#4) and one 45 on #5.

ECM code shows a fault of P0304....???

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They also sent back a running video of #4 on a compression tester gauge and it is very rough......not holding up.....but I would think any cylinder would show that if you took the valve out of the gauge!!!??? See my NOTE: at bottom of post.....needed to rethink this!

1) I don't know, I've never tried to rely on a running compression test......is that even real? Yes bubba, it IS real! (See below note!)
2) Would like to see the compression test results on a "wet" test. (Spec for 2008 3.7 shows 170-225??? Sea level?)
3) This is high altitude..... can one expect to see results in the 90-100 instead of higher? (140-160 SOHC Static- Seal Level?)
4) What sort of wear can one expect on the Dodge 3.7 engines for cylinders and rings if not running synthetic oils?
4.5) Are valve springs a common issue with these engines?
5) Based on results of #4, two rebuilt heads in order......or get pulled into long block?????

Uugh!

After re-reading the tech comments below, and watching a couple of good u-tube videos, it would sound like potentially two bad cylinder heads.....but that all depends on how Dodge 3.7's react to mileage, ie see my question #4 above. Rings will likely wear fairly uniform in my experience....outer cylinders more than inners.... (outers are cooled more....metal wears less at elevated temps on the inner cylinders!)

The last 5L Ford I tore down several years back, from a 95-sh T-Bird, had over 250K on it and the cylinder walls still had cross hatch markings! My bore wear tool hardly registered .002-,003" of wear!

I was thinking this looked a lot like a bad valve spring.....and the bouncy running test is suspect.......never done that. Would have been nice to see a running test on say....#1, or 2, or 3........

Here is the tech's write up:
For noise concern and compression test on Cyl #4, I started by removing all ignition coils and spark plugs on all 6 cylinders. See photo #3 for compression test results. Cylinder #4 actually tested okay for static compression at about 100 psi. 100 psi is lower than we want, but I was surprised to see it as high as it was. The weak cylinder ended up being Cyl #5 at 45psi. Specification for static engine compression is 170-225psi, but that will not happen with our conditions in Colorado. I would expect to see about 120-160 psi with a good running engine. 45psi on Cyl #5 indicates cylinder damage or leakage in the cylinder. I then installed 5 of the 6 spark plugs and ignition coils, leaving out Cyl #4, then running the engine to check a running compression test. See video #2 for running compression test results. You can see that while running that cylinder does not hold pressure well and also is only producing about 45 psi. This tells me that two cylinders are damaged, not just the one. At this time, due to excessive engine wear and lack of compression on multiple cylinders, we recommend engine replacement. I do not believe that it is worth the cost to repair cylinder heads or head gaskets due to lack of compression on Cyl #5.

Note: After looking up "how to conduct a running compression test" I found it can be done both ways, with Schroeder valve in and out...... It is possible that a loose valve seat could be at fault, or perhaps a valve spring...... Most interesting!

THANKS FOR LOOKING!!! Intelligent and informed comments are most welcome here in this ugly situation!
Cheers!
Steve

 

[KJowner]

You said it was running well up until the problem. Was it burning oil and breathing? Has it done many miles and got a regular service history?
Remote diagnosis is always a nightmare, the compression readings are low but how good is the gauge that took them?
I'd like to get the valve covers off and see what's happening around 4 & 5 and then do a leak down test if nothing is obvious.
Unfortunately unless you are going to drag it home you are in the hands of the garage & everything they do is going on the bill.

 

[DadOSix]

Depending on where the ‘rattle’ sound is coming from, I am going to suggest, up high? She threw a lash adjuster (known to the rest of the world as a lifter). If an intake rocker/lifter, the cyl will not build as much compression since it can’t breathe in. If an exhaust side, again low pressures, backfiring thru the intake, and possibly dropped valve seat.

I would request her shop / mechanic to poke a borescope into #4 and #5 and see if any damage is present.

Easy to tell if a rocker situation by popping the valve covers off. Very obvious.

Down low? Anything at this point.

 

[Hec In Omaha]

Since the the problems arised during the cold snap, I would suspect the wrong oil grade is in the engine and not 5W-20 as specified and therefore doesn’t have the cold temperature flow properties of 5W-20 oil. If the oil thickened up perhaps it could not flow properly to the hydraulic lifters and pump them up. Sludge in the engine will prohibit proper oil flow too complicating things. Hopefully no damage was done during operation in the cold temps!
Now that’s its warmed up outside, I would run a bottle of ATS brand 505 CRO oil treatment and change the oil with 5W-20 full synthetic oil. It’s pricey but it works great and worth a shot. I have used it on my daughter’s 2009 KK’s first oil change and I was surprised how black the oil color changed to when I changed the oil. It also quieted down a noisy lifter! No more tapping after start up! Order directly from ATS and get the fuel and oil treatment package. The company recommends the oil treatment every other oil change. I am ready for the second treatment this month when I change the oil.

Good luck

Hec

 

[fastmerc]

Thanks for the replies!!!

This truck was an "unknown"...... Daughter and care of vehicles (how much she actually retained from dad is an unknown.......!

The rattling was more like popping in the intake from what the tech wrote.

Oil type and prior care....unknown. I would have gone with a 10-30 synthetic on higher mileage....... I do that with all the other vehicles I own and am very pleased with how clean they stay!!!

The varying compression on #4 has be buggered, symptomatic of perhaps a loose valve seat....

I would also like to see what the bores look like.....as the compression numbers are not that low if you factor in a "dry" run...... Not sure if they warmed it up.... And also the probability of a failed spring.... will be calling in a few minutes to get the ugly....

Thanks again!!!!!
Steve

 

[AFT2008KK]

Best of luck! Keep us updated. As a parent 4.5hrs away from kid in college, car issues are stressful. I feel your pain.

 

[fastmerc]

Waiting at the station here folks........... I'm thinking perhaps a valve train failure in #5 as compression is low.....but not recording any faults. 4 & 5 are next to each other in firing order so 4 may be getting blamed for #5 low operations.... But the varying dynamic compression is the most goofy.....wild pumping yet static test is the highest of all 6 at 100!?

Thus far the guestimate of working on two heads is around $2K I know valve jobs can be expensive but not quite this high for only 6 cylinders..... OHC may be partially to fault.....

For kicks I looked up a long block on O'Reilly's website and got a $4200 figure....UGH! However, not knowing the whole history behind this engine and such (it seemed very quiet and strong when we got it....) I'm guessing that bottom end bearings are likely needing replacing as a standard thing to do for 180Kish miles..... If I had my engine apart at that point I would do bearings just because. Not going to worry about rings and cylinders as that technology has improved dramatically since the 80's. As long as you are running a good thermostat, cylinder wear is WAY down....... and synthetic oils.

At this point, it would seem a matter of trade off between labor hours and cost of hardware. Pay a little more for the hardware and utilize the a similar amount of labor......sort of. Old engine out, swap pieces to new engine, drop it back in. Ba da boom!

Thanks for asking!
Steve

 

[KJowner]

If you do go down the full engine or service exhange heads route there are several reviews on here for companies, might be worth a look before you deal with any companies.