Currently experiencing a whining type noise (98 5.4 w/ 76k), which I hear from the driver seat, but my wife can't hear from the passenger seat. It starts about 2200 rpm and goes away above 2500 rpm. I think I can hear some whine below these speeds, but I can't be certain. I do NOT have a CEL on. I have done the following...

-Verified noise is not from a belt-driven accessory.
-"Listened" using a long screwdriver to various engine components.
-Checked for vacuum leaks/unplugged vacuum lines. None found.

During my listening to the engine components, I hear a similar noise when probing the DPFE sensor. I don't remember hearing this from the EGR valve. I've done research on here, and the DPFE seems like a common failure. However, most everyone reports a CEL with P0401 code. I've never seen my CEL on, nor pulled any codes. I understand the DPFE sensor controls the operation of the EGR valve, but I don't understand how. Could this part cause my noise, or am I likely hearing the noise through the lines to the EGR valve?

I am about to the point of replacing parts, and think the DPFE is the place to start. Should I get this part at the dealer, AutoZone, NAPA, ???. Should I start with another part, or just replace everything... I also plan to clean any carbon buildup on whatever I can get to.

Thanks in advance! I really want to resolve this without going to the dealer.

Jim

 

Does the sound come from the middle of the dash?
If so, it's the heater core whistling.
We've been putting restrictors in the heater core coolant supply hose to correct the concern.

To test if it's the heater core, have someone pinch the heater core hose off with some needle nose pliers and verify that the noise goes away.

 

What would cause the heater core to start doing this al of the sudden? I will definately try this to see if it fixes the problem...

BTW, I did replace the DPFE last night, and it made no difference...

 

THANKS for the tip. I did as you said and the noise goes away! You don't know how long I have been trying to figure this out.

Questions:
- What would make the heater core start to whistle all of the sudden?
- Is this an indication that the heater core is going bad? Is it full of deposits? I did a coolant flush/fill with regular Prestone at 50k. I am not at 76k and had planned to do it again at 80k.
- If these are deposits, do I need to run a chemical flush through it, or does the heater core need to be replaced?
- If I go the restrictor route, is there a part number I need? Are there any negative effects of this route?

Thanks in advance!

Jim

 

I did some searching and found the following part number, listed as a restrictor...

F1UZ18D406A

This was listed under TSB#01156 which talks about electrolysis in the heater core.

?? If I need this restrictor to fix a noise issue in the heater core, do I have the electrolysis problem also?

Thanks,
Jim