engine cycling at idle

bronco9588 · **Joined:** Sat Oct 29, 2011 8:17 pm **Posts:** 69

Hi All,

I just changed my driving style as I have just changed jobs and moved. Much more city driving. Drove my car with 3k lbs tow a 600 miles. Anyways I am noticing a couple weird things. The serpentine belt is really squeaking at idle (just changed my power steering pump and did 100k service). As soon as you accelerate, good to go. I just changed the idler pulley and belt (but before the power steering pump went.) Oil consumption as been about a half liter for the past 1k miles and the engine sounds like the AC clutch is turning on and off every 5 seconds. Any thoughts? I have gde ft eco tune.

papaindigo · **Posted:** Sun Oct 28, 2012 2:29 pm

Sounds, sorry, like several things:
1. serp belt squeal - at idle take a look "down" the belt from the alternator pulley to the serp belt tensioner; if the tensioner is not essentially rock steady (eg. is noticably bouncing) you likely have a bad alternator pulley which can damage tensioner. If tensioner leans toward PS pump then the tensioner is bad.
2. AC fast cycling is likely low coolant although one of the AC pressure sensors could be bad - need gauges to check. May also relate to your serp belt squeal. Keep in mind AC compressor runs in several modes (ex. defrost) to dry out air even if AC switch is "off"
3. oil consumption is high. Degrease top and bottom of engine (don't use high pressure water) and look for leak. May need compatable UV dye to help find.

bronco9588 · **Joined:** Sat Oct 29, 2011 8:17 pm **Posts:** 69

Would the AC compressor cycle even with the air system in the off position? Anything else with a electric clutch?

MRausch82 · **Posted:** Sun Oct 28, 2012 5:32 pm

bronco9588 wrote:

Would the AC compressor cycle even with the air system in the off position? Anything else with a electric clutch?

It should not, however, the viscous heater would if the temps are cold enough out and you have a bad thermostat. Where is your temp gauge needle when it is fully warmed up? As for the oil loss, check for leaks, but also make sure it is not the beginnings of a failing turbo.

ChooChooman74 · **Posted:** Sun Oct 28, 2012 5:37 pm

MRausch82 wrote:

bronco9588 wrote:

Would the AC compressor cycle even with the air system in the off position? Anything else with a electric clutch?

It should not, however, the viscous heater would if the temps are cold enough out and you have a bad thermostat. Where is your temp gauge needle when it is fully warmed up? As for the oil loss, check for leaks, but also make sure it is not the beginnings of a failing turbo.

He has the GDE tune. Viscous heater should not be in the equation.

Sent from my Nexus 7 using Tapatalk 2

MRausch82 · **Posted:** Sun Oct 28, 2012 6:27 pm

ChooChooman74 wrote:

MRausch82 wrote:

bronco9588 wrote:

Would the AC compressor cycle even with the air system in the off position? Anything else with a electric clutch?

It should not, however, the viscous heater would if the temps are cold enough out and you have a bad thermostat. Where is your temp gauge needle when it is fully warmed up? As for the oil loss, check for leaks, but also make sure it is not the beginnings of a failing turbo.

He has the GDE tune. Viscous heater should not be in the equation.
Well then, sounds like there is an issue. Make sure the AC is off, it is not on defrost or floor only (it will run if it is in the floor only selection, even with the AC off). Otherwise, I am out of ideas in that department.

Sent from my Nexus 7 using Tapatalk 2

bronco9588 · **Joined:** Sat Oct 29, 2011 8:17 pm **Posts:** 69

Well I owe you a big thank you... I guess I assumed the AC was always off when the yellow light was off. If you asked me if cars use AC to dehumidify when the ac is "off" I would have told you yes. That puts two and two together. I have a vacuum pump and the manifold thingy. I guess I will read up on how to charge an AC system.

I actually bought a alternator decoupler a while back but it was the last think on my 100K to do list and I ran out of daylight. I can hear a lot of noise coming from the alternator shaft. I pulled the serpentine bet to try to remove the decoupler. I couldn't do it! Maybe it is a reverse thread or something. I figure I might call a local shop and see if they will do an alternator rebuild and swap the decoupler. I did give it a good shake/ tug and she still feels tight. I do plan to replace her as I have the part, and I just replaced the tensoner and idlers.

I don't really understand how this thing works, why it isn't solid, and why it has such an influence on all the other pulleys.

As far as the oil leak, could I be burning oil? I had the car up on the dealership lift a while back trying to convince them to replace my Torque Converter (it didn't work). Me and the mechanic did take a good looksey underneath and he and I both agreed the jeep looked very good and that it hardly had any corrosion. He would have said something if there was an engine leak or something. I do notice a big black cloud when i floor it even with the ECO FT tune. Turbo whine seems to have increased, but maybe my ears are a little more cautious. I am curious if the turbo is burning oil? Also, should I consider EHM with GDE Eco tune?

Billwill · **Posted:** Mon Oct 29, 2012 5:18 am

bronco9588 wrote:

Well I owe you a big thank you... I guess I assumed the AC was always off when the yellow light was off. If you asked me if cars use AC to dehumidify when the ac is "off" I would have told you yes. That puts two and two together. I have a vacuum pump and the manifold thingy. I guess I will read up on how to charge an AC system.

I actually bought a alternator decoupler a while back but it was the last think on my 100K to do list and I ran out of daylight. I can hear a lot of noise coming from the alternator shaft. I pulled the serpentine bet to try to remove the decoupler. I couldn't do it! Maybe it is a reverse thread or something. I figure I might call a local shop and see if they will do an alternator rebuild and swap the decoupler. I did give it a good shake/ tug and she still feels tight. I do plan to replace her as I have the part, and I just replaced the tensoner and idlers.

I don't really understand how this thing works, why it isn't solid, and why it has such an influence on all the other pulleys.

As far as the oil leak, could I be burning oil? I had the car up on the dealership lift a while back trying to convince them to replace my Torque Converter (it didn't work). Me and the mechanic did take a good looksey underneath and he and I both agreed the jeep looked very good and that it hardly had any corrosion. He would have said something if there was an engine leak or something. I do notice a big black cloud when i floor it even with the ECO FT tune. Turbo whine seems to have increased, but maybe my ears are a little more cautious. I am curious if the turbo is burning oil? Also, should I consider EHM with GDE Eco tune?

The alternator needs the de-coupler on the CRD to cancel out the engine actions...it is essentially a one-way clutch.

It is a very complicated procedure to replace it....do a search here on this forum to see how to do it and maybe look in the "CRD Tech" forum.

papaindigo · **Posted:** Mon Oct 29, 2012 9:05 am

I'll try to touch on several points:
1. Yes the AC will cycle in certain vent setting modes (ex. defrost) even if the yellow AC button is off. The only way to prevent it from cycling is to turn the Mode Selector (center) switch to full off.
2. there are 3 clutched things driven by the serpentine belt - AC, alternator, and viscous heater.
3. I don't know how to test an AC clutch.
4. Alternator clutch/decoupler can be visually tested per my initial post. If it's bad there is a special Miller tool to remove it or some folks have had success with an impact wrench and appropriate size allen head (I don't recall thread direction). Virtually all of today's vehicles have clutched alternators but in diesels the clutch is beefed up to deal with diesel power. Translation a cheap clutch replacement won't hold up. Autozone can often supply a lifetime warranty rebuild with the proper clutch at a good prices.
5. Viscous heater does run with the GDE tune although the tune does lower the temperature at which it stops running. Pulling the viscous heater relay in the power distribution center is the only way to completely shut off the viscous heater.
6. Yes you could be burning oil or you could have a minor leak (ages ago on a gasser I was losing about that amount thru a very minor valve cover gasket leak) that could be almost invisible if oil drips on your engine skid or onto the exhaust manifold where it immediately burns off. That said it's worth checking you turbo shaft for excess play (tiny bit for/aft ok; barely felt side to side ok; more not ok) by pulling the airbox to turbo hose (check for tear on bottom and be sure on reinstall to get the upper end touching the MAF sensor before tightening the clamp)

engine cycling at idle

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