Grinding sound at low speed/idling (5R55E)

[FordExp98]

I have been silently reading the forums here for quite a while already and found a tremendous amount of very useful information here! So far I have done only maintenance work on cars, but this time I need some advice as I have no experience to work on transmissions.

I bought a used 98 Explorer Sport 4.0 OHV 2WD three years ago with 60k miles and it has worked flawlessly so far (100k miles now). Some months ago I noticed some vibrations and thought it might be the engine. After a thorough tune-up (all filters, spark plugs, wires, etc., but also removed and cleaned upper intake, fuel injectors...) it got a whole lot better and the engine felt almost like new - but the vibrations were not completely gone.

Some days ago I noticed a sudden grinding sound at a traffic light - I immediately thought of the transmission and shifted to N and the grinding sound went away. Switching back into D, I could drive the car some miles, but then the high pitch grinding came back, always a low speed or while idling at a traffic light. The car seemed to shift OK, perhaps a bit harder as normal. Accelerating was no problem, grinding stopped at higher speed. I drove home and parked the car.

Although I am not afraid of working on the engine, transmissions are new territory for me. For the last days I have read now the forum here back and forth, especially the VB/trans rebuilding diaries are fantastic and I also read the Haynes manual, Ford documentation, etc. After reading all this I am still unsure what to think of the grinding sound - I dropped the transmission pan just to see if there is an obvious problem, but everything looked OK, fluid level OK, red in color, no metal pieces or other obvious defects. Pulled the VB and it also looks fine to me. Trans is a 5R55E.
Could it be the torque converter? What would you recommend to check next? Thanks a lot, any help is greatly appreciated!!

 

[Blee1099]

It may be your front wheel bearings, luckily since you have a 2wd, its a cheap replacement..

 

[FordExp98]

It may be your front wheel bearings, luckily since you have a 2wd, its a cheap replacement..

It is a very high pitch sound and most of the time the truck actually stood still at a traffic light when it started. It stopped immediately when I changed into N, therefore I suspect the trans...

 

[BrooklynBay]

Remove the drive belt, and let the engine idle. If you don't hear the sound, then reinstall the belt, and check for the grinding noise again. If it comes back, it might be something that is driven by the belt, like the water pump, alternator, A/C, P/S pump, idler/tensioner.

 

[FordExp98]

Remove the drive belt, and let the engine idle. If you don't hear the sound, then reinstall the belt, and check for the grinding noise again. If it comes back, it might be something that is driven by the belt, like the water pump, alternator, A/C, P/S pump, idler/tensioner.

Within minutes there are replies, although I never posted here before - the forums are fantastic! But of course I have totally forgotten to mention that the OD light flashes! I know I should get the codes read somewhere, but I didn't want to drive the car any longer (I live in suburbia, the next dealership is quite far away). I have an ELM-based reader myself, but no OBD2 codes are set. It cannot read any of the special Ford codes though.
Thanks!

 

[BrooklynBay]

AutoZone reads codes for free, but I'm not sure if their code reader will read Ford specific codes. It doesn't hurt to ask them. By the way, welcome to this forum!

 

[FordExp98]

AutoZone reads codes for free, but I'm not sure if their code reader will read Ford specific codes. It doesn't hurt to ask them. By the way, welcome to this forum!

Thanks!! But do you think it would be safe to drive the car - the grinding does sound quite scary, I guess some gears are having a bad time...the next autozone is much closer than the next dealer but still some miles away. If you can think of anything I could check, I would feel better trying that first...

 

[BrooklynBay]

I'm thinking that the transmission is probably going into FMEM mode (limp mode). The banging is being caused by high pressure from the EPC solenoid in this setting. When the PCM detects some sort of electrical failure within the transmission (like the turbine speed sensor), it puts the vehicle into this default mode of operation. It is recommended not to drive too much, since the high pressure might do some damage. Drop the pan, and check for any metal parts that might have broken off. Retorque the valve body bolts, adjust the bands, and clean the electrical plugs outside of the transmission.

 

[FordExp98]

I'm thinking that the transmission is probably going into FMEM mode (limp mode). The banging is being caused by high pressure from the EPC solenoid in this setting. When the PCM detects some sort of electrical failure within the transmission (like the turbine speed sensor), it puts the vehicle into this default mode of operation. It is recommended not to drive too much, since the high pressure might do some damage. Drop the pan, and check for any metal parts that might have broken off. Retorque the valve body bolts, adjust the bands, and clean the electrical plugs outside of the transmission.

When in limp mode, does the OD light always flash? Or could it be that the car was in limp mode for a longer time without any lights telling the driver that something is wrong?
I pulled the pan and everything looks fine, no metal parts, fluid looks OK (red, not black), fluid level was perfect before dropping the pan.

I was looking at the VB and pulled out what I believe is the TCC solenoid. Is it normal that I can slightly move the tip in respect to the rest of the solenoid (with tip I mean the shiny part pointing left in the image)?

 

[BrooklynBay]

Most likely, it only went into limp mode when the OD light started to flash, and you had the hard banging. The solenoids are supposed to be solid. If the front seems like it is wobbly, then something might be wrong with it. The EPC, and TCC solenoids are modulated, and are among the high wear parts.

 

[FordExp98]

Most likely, it only went into limp mode when the OD light started to flash, and you had the hard banging. The solenoids are supposed to be solid. If the front seems like it is wobbly, then something might be wrong with it. The EPC, and TCC solenoids are modulated, and are among the high wear parts.

I checked the other solenoids and they are solid, but the TCC tip I can definately move/rotate a bit. I guess I better change all the solenoids while having the VB removed (at 100k miles they might be at the end of their lifetime anyway). Can you recommend a place where I can get a set for a reasonable price? Thanks!

 

[BrooklynBay]

It's not always necessary to replace all of them. If you get the code read, it might be related to some other problem. Some solenoids could even go until 150k miles. WWW.TransmissionPartsUSA.Com sells solenoids.