Poor Dauntless Performance

I hope it's okay to resurrect this thread. I attempted to drive the Jeep down to Moab yesterday (about 240 miles from my house). We did not make it. I am experiencing similar problems to when I had the distributor installed 180 degrees out. Drive-ability is much improved, but from what I have read about how you all speak of these Dauntless V6 motors I am not getting anywhere near the performance I expect. On this trip the major symptoms were overheating, loss of power (big time), lack of power overall (inability to maintain 55 mph up the slightest incline), and backfiring? out the carburetor. At one stop while the Jeep was cooling down, I pulled the thermostat completely and that did not solve the heating up or losing power when hot especially problem. What do you guys think? Could it have been sitting so long the water passages are all gunked up? How can it overheat with no thermostat? Is backfiring out the carburetor the correct term? Where do I start? I am thinking a compression test right now?

 

Wow............I thought this was fixed...........OK so One thing at a time:

First , is this Jeep new to you? and is this lack of power something that just started?
What gear ratio do you have and what tire size?
Do you have Overdrive? And are you using the OD when you feel there is a lack of power?

Overheating would cause a lack of power...........Did this just start to overheat? What was the ambient outside temperature? What elevation? Do you have a winch in front of the grill? How close is your fan blade to the radiator and do you have a shroud between the Fan blade and the radiator?

Did you ever run a Leak down or compression test?

Answer all of these questions first.................and there may be more.

 

I thought so too....
Answers:
It's new to being on the road. It's got less than 300 miles on it during my ownership. So yes. New to me.
The lack of power has been evident during all the miles I have driven it.
3.73 gear ratios
235/75/15 tires
No overdrive
I took it on the freeway the first time yesterday, it's never overheated around town before.
It was close to 80 degrees when we left and down in the high 50's on the ride home.
Elevation is about 4700'
No winch
4" of clearance fan to radiator. Stock fan, stock radiator

I started a cold compression test just now and the numbers are alarmingly low so it's idling next to me and warming up as I type this.

 

3.73 gears are the first thing that sticks out.............Lot's of folks like them but a little lower like the 4.27 gears help the little motor out especially at 4700 ft elevation..........which on any given day the adjusted altitude at 80 degrees could be several thousand feet higher.............which equals no power!

4" of clearance between the fan and radiator without a shroud is probably at least one of the problems for overheating.........it needs a shroud.
Warm the motor up , pull the plugs , Do a compression test.........if you find some weak cylinders follow that up with a leak down test.............But with the backfiring through the carb I think a leak down test is a good Idea either way.

 

The compression test results are in:
1: 70
2: 75
3: 80
4: 75
5: 65
6: 80
I don't have the equipment to do a leak down test but these results are pretty damning aren't they?

 

Have you checked the exhaust manifold temperatures at each cylinder with an infrared thermometer to find out if all cylinders are burning about the same?

 

On the surface they look low............did you have all the plugs pulled out? .............engine warmed up and consistent amount of revolutions in all cylinders at a constant speed?

You could go back now and squirt a little oil in each cylinder and then perform the test again.....

 

Yes, all plugs out.

Engine warm, and I held the key in the cranking position for a count of 8 mississippi on each cylinder

Aren't these readings barely half of what a healthy engine should be putting out?

What does squirting oil into the cylinders do? I am game to try anything.

Thanks for your help!

 

I don't have an infrared thermometer but I can tell that the exhaust is relatiely the same temp out both tailpipes and if I put my hand around the manifolds, it SEEMS to be consistently hot at each cylinder.

 

Putting a little oil in each hole prior to the test will temporarily seal the rings.......and give you a higher reading...........just a quick way to see if the leakage is from the piston rings...........A leak down test will better tell you if it's a head gasket, rings, or valve leakage...........

 

I would think they should be around 120 even at 4700 ft..............if the motor is in good condition...........and I'm assuming this is a 9.0 :1 Oddfire motor is it not?

One last thing, did you have the throttle blade open all of the way during the test? It will make a difference.

 

It's a 9.0:1 oddfire yes,
I didn't have the throttle blade all the way open, it had been idling to warm up before the compression test was run so it was probably mostly closed. I will squirt some oil, open the throttle blade and try again.

Thanks again!

 

There could be something else going on but it does point to low compression being the problem. Next step for me would be to determine if it's the rings or valves. As others have mentioned put a little oil down the plug hole and recheck. If compression comes right up that would indicate rings.

As far as counting 8 Mississippi - usually I just watch the needle on the gauge. It generally goes up a bit on the first few strokes and then you can stop cranking when the needle stops going up. Prop the throttle plate open on the carb also.

 

How often/regular is the backfire through the carb? And is it only under acceleration, or any time while running? This might point to a valve sealing or ignition timing issue.

Are you certain the timing chain is in good shape and hasn't skipped a tooth, or had been installed improperly?

Does it smoke or consume any oil? How do the plugs look?

 

It only backfires through the carb under a load, only seems to in 3rd gear at highway speeds and only when it's super hot. I don't have first hand knowledge of the timing light but the mark holds steady with a timing light on it.
It doesn't smoke or consume oil, the plugs look good.

 

Without smoke or oil consumption, and with the compression readings that consistently low across the board, combined with the backfiring, I'd really be interested to see if the valve timing is off. If you run out of things to check, you might want to pull the front cover off the engine to see if the marks align and everything looks to be in good shape. I know it's a PITA, but it's a good last ditch effort if all else fails.

 

Warmed up motor. All plugs out. Throttle all the way open. Squirt of oil in each cylinder. Compression results: 1. 80 3. 90 5. 90 2. 90 4. 90 6. 90

 

And the plugs looked pretty black. I dont know if that was because it hadn't run very long warming up.

 

Well looking at the numbers from before and then after w/ oil there is at least a 10% plus gain in compression.........which as I mentioned before points to Rings and cylinder wear.
There could also be a leaking valve or two which could get you that backfiring. The Black Plugs is a sure sign of it burning oil..........do a leak down if you want to further confirm what seems to be a worn motor.

Looks like it's time for a rebuild...........(Blueprint 225)
or you could limp it around the way it is until it expires.........

 

You should try another compression test with the oil in the cylinders and with the carb closed, just to see which made more of a difference last time... opening the carb or adding the oil. Doing both at once makes it hard to pinpoint it as the rings for sure.