Faulty Fan Clutch Hack

[RandyA]

2004 Volvo VNL670 with D12D engine.

We left Richmond Tuesday morning heading north to IN.  On I-81 just south of Winchester the cooling fan turned on.  When it does that it will normally run for maybe a minute and then cut off.  But this time it did not cut off.  With the fan locked on my mileage dropped like a rock and I could feel a loss of power, not to mention the noise.  We drove another 250 miles to Pittsburgh with the fan locked on.

Once parked overnight in the campground I went online to the Volvo eMediaCenter to try and find out how the fan clutch worked.  Everything I found was for an electronic viscous fan – but mine had an air line not a wiring harness.  Finally I found some info on a mechanical viscous fan.  After reading how it was suppose to work it appeared that the solenoid valve for the air line to the fan wasn’t opening to supply pressure to the fan clutch.  I went to sleep that night trying to figure out how I was going to fix the thing in the campground before heading out the next morning.  Crazy as it sounds I woke up this morning with a solution.  Apparently my brain was working on the problem while I slept (it does that often).  I cut the green 1/4" air line going to the fan and capped off the supply end.  I then put a coupler in the line from the fan and inserted some spare 1/4" air line.  I cut another constant pressure air line in two that I had added for a second set of air horns under the hood.  I inserted a “T” with a connection to the new line going to the fan clutch.  I still needed a way to turn on the fan if the coolant temp went up.  Well, several years back I added two solenoid valves to the water lines going to the heater core with a switch on the dash to open or close them (helped the AC to be colder).  I had a spare air line solenoid in my parts bag with 1/4" connectors.  I put the solenoid in the new fan clutch supply line and moved the wires from the water solenoid valves for the heater to the added air solenoid.  This way I figured I could turn on the fan at any time by flipping the dash switch to close off air pressure to the fan clutch.  It worked!  Back on I-70 and rolling along at 65 mph the fan stayed off, my mileage went back up from the 5.9 mpg with the fan locked on to my normal 8.4 mpg and all was quiet in the cab. I set the dash DID to show the coolant temperature so I could be sure all was well under the hood. When we stopped to take a break at a Service Center in Ohio I left the engine running so the dog and DW would have AC while I walked around to exercise my legs.  I flipped the re-purposed dash switch to off which closed  the air supply to the fan clutch while parked and the fan cut on keeping the coolant temperature to about 185 F. 

When the opportunity arises I will have to roll the front wheels up on boards so I can crawl under the truck and find the OEM solenoid and valve for the air line to the fan clutch.  I do not know where it is - I will have to trace the supply line on the left side of the frame to find it.  The solenoid could be faulty, the wires to the solenoid could be open or the temperature sensor could be bad.  There could even be an ECM issue (yes, the fuse is good).  But, until I find the problem I have my “hack” that is working!  I also now have first hand experience on how much engine power it takes to run the fan at highway speed and what it can do to fuel mileage.  I am also thankful for carrying all the needed spare parts.  I have no way of knowing but maybe this will help someone else one of these days.  I hope the Photobucket image files below come through.

 

[dblr]

Glad to hear you figured out a fix, now come on into the FROG Rally I have a spot personally picked out with your name on it.

[SuiteSuccess]

Randy,

My solenoid was on the frame rail on the drivers side near the front air bag.  When I had my fan clutch replaced they moved it to a bracket below the air governor and airline pass thru on the drivers side firewall.  Told me that is its normal location.

[GeorgiaHybrid]

If you have the room on your dash, a spare electric over air solenoid switch on the dash and solenoid on the frame can come in handy. I have two plumbed in and they can be used for ANY airline that needs to be switched in an emergency. Both of mine are non latching but a latching solenoid can be used also.

[RandyA]

Carl - excellent idea.  Once I find it I will move it where it is accessible and cleaner to get to.  I imagine you have the electro-viscous clutch rather than mechanical.  Your truck is newer and it appears that the mechanical viscous was replaced during the model year my truck was built (?).  Do you have the air line on the right side going into the engine?  But, either way there are solenoid(s) and sensors that work with the ECM to turn the fan on or off.  The main difference from what I can gather is with the mechanical viscous fan you only have an on or off function.  With the electro-viscous the fan can run at different speeds between on and off thus saving fuel.  I am glad the fan clutch is OK - I remember what you shared on the cost to replace yours. OUCH!

GeorgiaHybrid - another excellent suggestion.  I do have two spare switches on the dash and the spare solenoid I used.  I may need to use the solenoid I have to replace the OEM unit on the truck if it is bad.  I will need to run new wires for just the solenoid but that is no problem.  I am going to follow your advice and copy your idea.

A lesson to be learned?  Well, spare parts, tools and access to service literature are the Creator's gift to those of us that choose to drive these behemoths.  Without those you had best have a grocery sack full of hundred dollar bills and be willing to wait for service.   Gads, what I have learned in the past 8 years of ownership of this truck is more than I ever learned in college - and I am still learning!  But there are still things that go wrong I can't fix and have to empty out the grocery sack.

 

[SuiteSuccess]

Randy,

Not as smart as you guys so can't say what I have. Mine is not variable speed just on/off. Single green 1/4" air line from drivers side into clutch on right side. 

[Brad & Jacolyn]

Randy, mine is under the truck approximately in the middle of the truck in a bank of 5 solenoids. I have had to change mine.

 

Brad 

[sclord2002]

Randy, Carl and I have the pneumatic/mechanical fan clutch. just as you have.

Charlie

[JPL]

Randy    This just goes to show how you can diagnose a problem and solve it. I hope my ECM repair fixes my clutch fan issue. Should know this weekend. Have a great trip ands be safe!   Pat

 

 

The Old Sailor 

[RandyA]

Soon after we arrived at the Elkhart County Fairgrounds a really bad storm rolled in.  Rain flooding our campsite, wind blowing away signs and awnings, small hail, etc.  Rain again last night and a storm brewing right now.  There will be no crawling under the truck today for sure. 

Brad, is the bank of five solenoids independent or is it a solenoid pack where they are all in one block?

[Scrap]

The book on it (I think):

http://graphicvillage.org/meritor/tp0223.pdf

[Brad & Jacolyn]

50 minutes ago, RandyA said:

 

Brad, is the bank of five solenoids independent or is it a solenoid pack where they are all in one block?

Randy the 5 solenoids are all independent. They are just all mounted together in a group. When you remove the bolts (2 I think) to pull down the entire group be sure to not lose the bushings in the mounting holes. I have no idea why they are there except maybe to reduce a big hole to a small one. After you are sitting under the truck it is not a real bad job to remove and replace.

Since you have made the fan work with your work around I would be fairly sure it is the solenoid in the bank that is bad. As I recall, all the solenoids have a different color air line and the one you want is green. A quick check to test the line from the solenoid to the fan is to apply air pressure and see if the clutch disengages. This is easiest to do with 2 people unless you are REALLY REALLY fast.

 

Brad 

[RandyA]

Scrap - as always, thank you for the .pdf

Brad - I found the solenoid but it was not in the pack.  It was a single solenoid slightly behind the pack.  I did disconnect the air line and wiring from the solenoid and ran a new wire to a new solenoid valve I placed on the firewall below the air governor.  Cut the green fan clutch line and tapped in before the new solenoid on an available 1/4" line.

The fan remained engaged - meaning the problem was not the solenoid but rather the link from the ECM to the solenoid or sensor for the ECM.  I then wired in a key-on DPDT switch on the dash giving me ready access to solenoid off, solenoid on or ECM supply.  I am currently running in solenoid on position (fan off) until I stop or when traffic slows.  I think I am going to simply forget the Volvo fan engagement system and add an adjustable water temperature sensor to close the solenoid (fan on) at about 190F and keep the dash switch.  I will investigate more when we get back to the stick and bricks facility next month.  For now, all is working well.

[JPL]

Randy     I got the ECM back today and installed it. Checked on the alternator and it seemed to have issues so I replaced it. Fired the truck up this afternoon and it worked like it was suppose to. The fan clutch engages when the FCM tells it to and Disengages  when the ECM tells it to. Did a 20 min road test. Seems to be fine. I just wish I had the knowledge you have. I would feel more comfortable on the road. But what I do have is friends like you and if I have problems I'll just get on the Forum and ask for help. How has the trip been going? Take care and be safe.   Pat

 

 

The Old Sailor 

[JPL]

i should have mentioned that I got my ECM Recalibrated at DSO Industrial in Dassel Mn 320 275 9760.They just have the billing office there. The repair shop is in Westcliffe Co. My sending it out there proved 2 things to me. The shop that told me the ECM was the issue with the clutch fan was correct. That was found when DSO checked the ECM. Sending it out to them cost $1200 instead of $3400 for a new one from Cummins. The second thing was that DSO did what they said they could do. Granted I only gave it a 20 min road test but I feel comfortable. We plan on a short trip for Labor Day in preparation for our western run. They also say if it test out good no Charge. If you have a cummins this might be a good number to keep handy and/or put in the Resource Guide.     Pat

 

 

The Old Sailor

[Chad Heiser]

 

32 minutes ago, JPL said:

i should have mentioned that I got my ECM Recalibrated at DSO Industrial in Dassel Mn 320 275 9760.They just have the billing office there. The repair shop is in Westcliffe Co. My sending it out there proved 2 things to me. The shop that told me the ECM was the issue with the clutch fan was correct. That was found when DSO checked the ECM. Sending it out to them cost $1200 instead of $3400 for a new one from Cummins. The second thing was that DSO did what they said they could do. Granted I only gave it a 20 min road test but I feel comfortable. We plan on a short trip for Labor Day in preparation for our western run. They also say if it test out good no Charge. If you have a cummins this might be a good number to keep handy and/or put in the Resource Guide.     Pat

 

 

The Old Sailor

That is good information I will have to squirrel away.  I have family in Westcliffe, CO also so an added bonus.

[HERO Maker]

Just in Westcliff the other day!  Nice drive in the smart from Rye, CO.

[Scrap]

Be sure to lock fan on when going backwards and/or going slower than your tailwind.  It'll save you from a cracked CAC.  I guess same applies to the condenser & AC clutch in those situations if the AC is on.  Charge air temps and AC head pressure are part of fan programming so you got to compensate for that too.

Grumps always made me lock fan at the low RPM right before changing a gear to save the belts, so it kinda becomes habit after awhile.  If I close my eyes I can still hear all the Goddamits from the riders seat.....