My 2002 Dodge caravan makes squeaking noise underhood. It occurs when I am in "Drive" gear mode. It makes squeaking noise when engine heats up and when something turns on, near the belt / pully system - underhood passenger side. After some time the squeaking noise stops and re-starts along with some other system that turn on and off frequently and repeatedly. Is this other unknow-system, water pump ?

My question is, does the water pump bearing make this noise when it is engaged ? and noise goes away when water pump idles? Noise occurs when something is running and then stop and then restarts again and then stops and restarts (frequently in rhythm). This is observed when the car is idling in "Drive" gear mode as well. Does the water pump start and stop frequently, even when car is ideling but engine is hot? Since the noise seems to be associated with something that start & stops frequently, but engine is hot and idling as well as running.

Any help in diagonising this will be very much appreciated!!!

Thanks

 

Greetings,

The water pump is directly driven and does not engage or disengage.

Any noise from the water pump may fade in and out mostly due to engine RPM.

The water pump noise will be most pronounced at particular engine RPMs, however, there will not be an abrupt on and off behavior of water pump noise.

The air conditioning compressor does engage and disengage automatically when the air conditioning is set to on.

Any heater or temperature control setting that includes window defrost will also activate the air conditioning compressor.

Try running the engine with all heater or temperature controls off and any window defrost settings off to see if the on and off squeak behavior is still present.

If the on and off squeak behavior is still present then it is the result of the smog control system, however, the actual squeaking may come from elsewhere.

If the on and off squeak behavior appears to be associated with the air conditioning compressor then the squeak may be comingdirectly from the air conditioning compressor or from the serpentine belt tensioner due to the loading of the air conditioning compressor.

 

This sounds very similer to symptoms i've had before. In my case it was the alternator.

As the alternator wears you can almost diagnose it if you have the premium gages, with the battery voltage gage. idle the engine with no systems on, then turn on the blower full blast, head lights, wipers, defrost, operate your power windows, and essentially draw on the electrical system.
A strong alternator should produce enough power that this shouldn't draw to much. if the battery voltage gage drops significantly then you can guess that the alternator might need to be replaced.

If you have the basic gages, you can do the same thing with a voltmeter attached to the battery terminals, but that ussually means someone has to hold it there for you.


And one final thing to note, while my alternator was on its way out, i just left it without repair for a while. this put some stress on the belt. a few weeks after i changed out the alternator, the idler pully went and i threw the belt on my way into work. not an expensive repair, but definitely an inconveniance.

 

Thank you caravan77 & Calmec87 for your prompt replies and detailed insight !!! Both your answers were very very helpful in taking my diagonisis a step further. I got my Alternator and battery tested and it is not the case of the squeak. The cause is due to explaination provided by caravan77 !!!

I tried running the engine with all temperature controls off, and window defrost settings off, and obsereved that on and off squeak behavior was gone. When the A/C was turned on, I again started observing on and off squeak behavior. When the a/c was turned off, the on and off squeak behavior still persisted. So the conclusion was that if the A/C - Heater is not engaged, then is no squeak, but once I turn them ON and later OFF, the on and off squeak behavior is experienced.

My question is with this further detailing of my problem can someone help me in narrowing down the root cause?
Could this be from air conditioning compressor or from the serpentine belt tensioner due to the loading of the air conditioning compressor?
Should I have this fixed immediately, since this can cause irrevocable damage to my dodge caravan? How much time can I use my car without getting this fixed ?

All your help & insight so far has been fantastic and any futher help will be greatly appreciated!!!

 

sounds like the clutch is going bad on the a/c compressor if it dosen't drive you crazy then drive on.if you just can't take it then change the a/c compressor and recharge the system.

 

I not only have a noise (mine goes away after several minutes of driving) but my air conditiong has been out. The guy at the shop told me it was something under the dashboard and had to have the dashboard taken out to get to it. I am skeptical of this as the AC holds about a day of freon, then gets hot with no air. This guy said it had to do with something connected to a vent but that doesn't make sense either as, with heat or just air flow, my vents are fine. Help please!!!

 

Another option I don't see listed and I'm not sure it applies to the 2002's but the 2001's (3.3L) have a de-clutching mechanism on the altertnator that either squeaks when it engages or makes the belt belt squeak when it engages (not sure which). If the AC is cycling on and off which is normal, then the alternator may be the problem, or maybe not LOL

 

Here is some information on a TSB for belt squeak.

SUBJECT:
Belt-Like Squeal Sound at High Engine RPM
OVERVIEW:
This bulletin involves replacing the heater core return hose and replacing
the variable restrictor with a fixed restrictor.
MODELS:
2001 - 2002 (RS) Town & Country/Caravan/Voyager
NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 3.3L
ENGINE AND WITHOUT REAR HVAC (SALES CODE HBB) AND WITHOUT
AN ENGINE OIL COOLER (SALES CODE NHA).
SYMPTOM/CONDITION:
With the engine at 3000 RPM or higher, a belt-like squeal sound may be heard
from the center of the dash area. This sound is similar to the sound produced
by a worn/loose accessory drive belt or faulty generator.
DIAGNOSIS:
Start engine and apply the parking brake. Open and support the hood. From the engine
compartment, accelerate the engine to produce the sound (3000 RPM or higher). Use
pliers to pinch off the heater core return hose (top hose) between the heater core outlet
tube and the in-line restrictor. If the noise is eliminated, perform the Repair Procedure.
PARTS REQUIRED:
Qty. Part No. Description
1 05005341AA Coolant Hose, Heater Core Return
1 05072197AA Restrictor
AR 05066386AA Coolant, Engine (MS9769)
07-001-02 -2-
REPAIR PROCEDURE:
WARNING: TO PREVENT INJURY, ALLOW THE ENGINE TO COOL BEFORE
PERFORMING THIS REPAIR. WHEN THE ENGINE IS AT OPERATING TEMPERATURE,
ENGINE COOLANT IS HOT AND UNDER PRESSURE.
1. Using pliers, remove both tension clamps from the heater core return
hose (top hose to heater core) (Fig. 1).
Fig. 1 HEATER RETURN LINE & RESTRICTOR
1 - HEATER CORE OUTLET TUBE
2 - HEATER CORE RETURN HOSE AND RESTRICTOR LOCATION
2. Remove and discard the heater core return hose and restrictor.
3. Install the new restrictor into the coolant tube as shown in (Fig. 2)
Fig. 2 RESTRICTOR LOCATION
1 - COOLANT TUBE
2 - RESTRICTOR
3 - HOSE TO HEATER CORE OUTLET TUBE
4. Install the tension clamps to the new heater core return hose.
5. Install and fully seat the heater core return hose onto the coolant tube and
the heater core outlet tube. Install the tension clamps.
6. Fill the coolant recovery/reserve container to the full level using a 50/50 mix
of Mopar coolant (p/n 05066386AA) and distilled water.
7. Start the engine and check for coolant leaks.
-3- 07-001-02