2000 F-150, 4.6, 103G MILES.
Parked it on Wednesday morning, Started it Wednesday afternoon and heard this weird clunking noise from the front of the engine, but only every 15 seconds or so, like a resonance. Oil was down, added two quarts, thought it might be a lfter, but noise is not constant, and can't be heard while driving. Engine starts right up and runs good, sounds solid, no loss of power, everything seems normal except for this clunking while at rest. Thought it might be the water pump? Any of you guys got an idea of what it could be?

 

The 15 or so seconds sounds like AC related. Turn off AC and recheck. Another idea is the belt tensioner. Look and see if it bounces when you hear the noise. Good luck and keep us posted as to outcome.

 

Looked around under the truck good while changing the oil. Nothing unusual.
On start up, had the same noise after about a minute of running, but seemed louder. Then I decided to remove the surpentine belt, ran the engine for a couple of minutes, no noise. Put it back on, noise was back. With a long extention, I listen to the water pump, altenator, steering pump, and a/c compressor. The noise was most prevalent in the a/c compressor. When I turn on the a/c it almost disappears, then comes back when the compressor is turned off. Sounds like a piston slap in the compressor. A buddy says I'm not suppose to try and change it out, have to take it to a shop, what do you think?

 

If I understand you correctly, the noise is present when the AC clutch is NOT engaged or locked in. If this is correct than its the clutch brearing making the noise. This bearing can be changed with out any freon loss. Check with your local auto parts store as to what is available. Bearing only or do you have to change the whole clutch assy. Also ask about the puller necessary to remove the clutch assy. If the noise is present when the compressor is turning, this is an involved job and better left to the AC people. Hope this helps. Good luck and enjoy!

 

Bill, you might have hit it right on the head. I was having this same discussion with my know it all buddy, and questioned the fact if the noise was present with the ac off, how could it be the compression? I'm going to check with auto zone for parts and tools and see if the cost is low enough to make the change without knowing for sure if this is the problem. I'll let you know. Ed

 

If you replace the bearings or the whole clutch assm., be sure to not loose the shim that is on the shaft after you remove the clutch plate and to reinstall it when reassmbling,it gives you your gap between the plate and clutch.

 

i dont know about todays prices but about 3 years ago on MOST applications it was cheaper to buy a new compressor than to change the clutch assembly. It does vary by vehicle though.

 

Auto zone has the bearing, about $35, the whole clutch assembly, about $95, and the whole compressor is about $300. They also rent the tools necessary to pull the bearing.... now I need to make sure it's the bearing, cause the auto zone guy said it could be tricky to pull the bearing.

 

sounds like a spectator sport to me...lol

 

So its the clutch... How can the bearing be replaced without losing any freon??