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Garchar1988 · 11-17-2020, 06:35 PM

I am new to this site. My 1998 Newmar Dutch star Freightliner chassis with cat 3126b diesel engine's side radiator Hydraulic fan is not working. Does anyone have knowledge of how to test the system. I contacted Cat and they want $400 just to plug it in for eval. I am 72 but able to do a most of my own mechanical work. Any help would be appreciated. Thank Gar

Skip426 · 11-17-2020, 06:40 PM

Welcome to iRV2 and the Newmar family .

I'll have to ask what chassis your coach is built on ?
Freightliner or Spartan .
I have info on the Freightliner system after two failures.

Garchar1988 · 11-17-2020, 06:58 PM

Freightliner

Skip426 · 11-17-2020, 07:24 PM

Ok , your F/L chassis may not have all the same systems as mine , because on Jan 4 , 1999 a new wiring harness was introduced on the assembly line . My chassis was built in Feb. 1999 and that's the wiring info I have , other info I've collected for a 96 F/L chassis , doesn't include info on side rad chassis .
All that being said we'll try and get to the bottom of your problem .
The 99 side rad set up has a rad fan control module ( first picture ) located to the left of the modules on the passenger side of the engine compartment under the bed ( yellow arrow in second picture) .
I couldn't find a picture of the rad fan control solenoid ; I'll take one tomorrow ; but it's on the lower left of the opening when the engine access is open ( Yellow arrow third picture) . There are two wires on the solenoid , and when the wires are disconnected the rad fan should go to full RPM.
If you can confirm you have the module , tomorrow I'll get back with more info and a picture of the fan speed hydraulic control solenoid . My rad fan wouldn't go to full RPM, just it's lowest constant speed , if yours doesn't turn at all then there could be a different problem.

Garchar1988 · 11-18-2020, 12:19 PM

Thanks for the info. What is currently occurring is upon start up of the 3126b the oil pressure is 50lbs and then 5 miles down the road the oil pressure drops to about 20 lbs with 5 to 10lbs at idle. this something new and all fluids oil and coolant were changed with no changes. As noted in last post the hydralic fan stopped working. Garchar1998.

wolfe10 · 11-18-2020, 12:29 PM

Quite likely you have a sender/box/gauge problem.

A 1999 Caterpillar 3126 uses oil pressure to activate the injectors. Low/no oil pressure= engine will not run.

Sorry, no first hand experience with your particular chassis, so don't know if the oil pressure reading is related to the fan issue.

But with two issues that could potentially be caused by electrical problems, sure wouldn't hurt to clean battery terminals/connections and recheck voltage.

Skip426 · 11-18-2020, 02:36 PM

Ok, the info in my first post is not correct for you chassis .

After going through the 1996 F/L wiring schematics, I got from another member , I found reference to the side rad hydraulic control solenoid .
Hopefully the solenoid and control solenoid are the same , just a different control . Picture #1. Hydraulic flow block just inside the engine access door in the rear cap ( on my 99 ) like I said ; hopefully this portion is the same .
On to the control electrical circuit . pdf ( attached )is a wiring schematic for a 96 chassis , this requires Adobe Acrobat Reader DC to view , if you can't open it , I'll print the pages and scan to a regular pdf file.

Lower left of the second page of the document ( with dashed lines indicating an optional circuit ) is the control sensors and solenoid , with a description of their operation . What is the same as my 99 chassis , is the solenoid is powered to turn the hydraulic fan off ; or in my case low speed ; removal of power by disconnecting at the solenoid should give full fan speed .
There are coolant and air sensors in the supply circuit either one can turn the fan on , by cutting power to the solenoid.
The actual location of the sensors is not given so it's a matter of following wires .
For testing , wear safety glasses

because once the rad fan goes high speed any debris on the engine flies in your face ( don't ask ).
With the engine running , disconnect power wire from the solenoid , if the fan goes to high speed , then the problem is electrical and you'll have to track down the sensors . If the fan doesn't go to speed then the problem is more than likely the control solenoid ; best guess would be stuck ; and you'll need a replacement .
Let us know how the test goes .

OK , wiring schematics won't load to iRV2 ; " invalid file "
I'll try and figure away around that and repost with the info.

Skip426 · 11-18-2020, 02:49 PM

Just noticed your oil pressure issue , your readings are within specs as per the chart below.
Did the reading change after the oil change , or did you change oil hoping to deal with the change ?
There is an issue with these engine needing the dipstick calibrated , to indicate full with the spec . 19 quarts with filter .
Overfilling leads to the crankshaft dipping into the oil causing froth , that can give low pressure and more slobber out the road vent tube.
My dipstick was off by 2 1/2 quarts ; way overfull.
Did you do your own change ?
15/40 oil?

Skip426 · 11-18-2020, 03:27 PM

Well I tried to print the document and re scan to a regular pdf , unfortunately there is so much clarity lost the text on the page is unreadable . As example below.
My computer skills aren't up to being comfortable trying to convert the document; and I really don't want to risk loosing it , so I'll look for other avenues .

Garchar1988 · 11-19-2020, 07:05 PM

The oil pressure was the same before the oil change. I was able to download and read the 1996 schematic you sent. Thanks a lot. Waiting for rain to stop so I can check and disconnect the solenoid on pic you sent. Not sure on the dipstick it has two markings with one stamped and one etched on it right above the stamped one..Garchar1998.

Skip426 · 11-19-2020, 07:17 PM

As per my message to your e mail , here's the file that I got back from my God son , re-formatted to better ( acceptable ) posting here .

NOTE : to others who may want to use this for wiring on their Freightliner chassis coaches ; now that Freightliner sees fit to no longer supply info for our older chassis .
There was a MAJOR change in wiring harnesses on Jan , 4,1999 , there may have been other changes between the date in this file and 01/04/99 , if this info doesn't match your wiring harness , all I can say is , sorry .

Garchar1988 · 11-29-2020, 03:12 PM

Skip426. Finally disconnected the solenoid wires inside left of engine compartment. With motor running the fan came on high immediately. Went to low when reconnected and completely off when motor turned off. Repeated process three times. So must be electrical as you noted. Any suggestions where to start and a systematic process of elimination. Thanks for the help and any other help is very much appreciated. Garchr1998

Skip426 · 11-29-2020, 03:30 PM

As indicated in the wiring schematics ( that hopefully cover your year of chassis) there are redundant sensors , coolant and air temp.
Because the schematic gives no clue as to actual sensor location , I'm afraid your down to following the wire , with 185 F listed as the coolant temp sensor opening , I'd think that sensor would be in the cylinder head in the area around the upper rad hose housing . The air temp sensor at 150 opening could be in the rad fan shroud .
Here's hoping the wire colors are correct ; as per the schematic ; and that having the side rad makes for a quick find.

slddnmatt · 12-27-2020, 04:45 PM

Hey skip I’m experiencing the same problem with my 99 Ultimate Freedom. I started having issues after I power washed my engine. I took apart the module that looks identical to your pic but with a part # 1539-10052-06 G1000. I took it apart and it looked to have a little corrosion around a piece and a diode of some sort looks to have maybe cooked a little bit by the looks of it. Fan will kick on but never the top speed. Trying to find a source for a new one. Thanks!