Cat 988B heating issue

[kshansen]

The solenoid should be part number 4V1222. Circled in red below"


I always found it easier to remove and install by removing the nut that is in the center of that tag with the numbers on it and slide the coil with the two wire terminals off then use a large socket to unscrew the part from the valve body. As I recall that 45º elbow just above it in picture is in the way of the wire terminals. Plus the hex at the bottom of the valve is so thin it's hard to get a wrench on good.

Also right where the "F" is located in that picture would be where the control cable from the cab control lever would come out of the top of the valve. The small red arrow points to the bolt you need to remove to get the cable to slide out of the valve body.

 

[kshansen]

Here's another view of the same valve, it's a bit grainy but best I can do from SIS. From this angle you can see the hole the control cable goes in and a different view of the solenoid valve. Cat refers to this complete valve as the:
Sequence And Pressure Control Valve

 

[ajginger]

I installed this electronic temp reader into the cab so I can see exactly what the engine and Torque converter temps are doing as I work the 988b.

The device has an early warning alarm that can be set to go off at a pre-selected temp before things get too hot. I currently Have the alarm set as follows.

Engine early warning Alarm : 95° Cels

Transmission early warning : 98° Cels.

Yesterday I was working the machine with 5 hours of hard digging and the weather warmed up quiet a bit in the afternoon so the temps climbed along with it and the torque converter 98° cel ' early warning temp ' alarm on the new device kept going off.
The torque converter sat almost exactly 20° cels warmer than the engine temp.

According to Cat, the correct working temp range for the torque converter is between 33° - 129 ° Cel .....( green color on dash guage )

What is your recommendation at a good ' early warning temp ' to set the new device at so It doesnt go off when unless things are starting to get too warm ?

 

[Nige]

Personally I'd set it at somewhere around 115 DegC and see how it goes. You might have to go to 120.
A Level 3 warning on an electronic (modern) machine generally goes off around 125+ DegC. Your old girl probably needs a little bit more babying than that.

 

[ajginger]

Personally I'd set it at somewhere around 115 DegC and see how it goes. You might have to go to 120.
A Level 3 warning on an electronic (modern) machine generally goes off around 125+ DegC. Your old girl probably needs a little bit more babying than that.

Thanks for that advise Nige.
I set the transmission alarm at 105° C today but being a slightly cooler day it never climbed higher than 98 °C.

 

[Nige]

What to watch is how fast the converter outlet temperature drops once you take the converter out of stall after filling the bucket. The way it falls is an indication how well the cooling sysytem (especially the transmission oil cooler) is working. the TC out temp will never go down to the same temp as the coolant but it should get within maybe around 5 degrees of it at best.

 

[ajginger]

What to watch is how fast the converter outlet temperature drops once you take the converter out of stall after filling the bucket. The way it falls is an indication how well the cooling sysytem (especially the transmission oil cooler) is working. the TC out temp will never go down to the same temp as the coolant but it should get within maybe around 5 degrees of it at best.

I have the new electronic Transmission temp sensor placed on a bolt where the oil leaves the converter to be directed to the oil cooler. With the work it is being asked to do, the loader is pushing in 1st gear into unbroken hard rock/dirt till the bucket is filled, then straight into reverse up out of the excavation hole to run a short distance to dump onto the dam wall then back into the hole to hard digging again.
So far the converter temp doesnt seem drop as soon as the bucket is filled & the pressure comes off the torque converter a short moment to go into reverse.......both the coolant & converter temps drop a few deg while I am spreading the dirt/rock along the dam wall ( not hard pushing ).

The temps seem to be consistantly about 20 deg C apart while working hard with the engine temp being the lower of the two.
For example if the engine temp is 78 °C... the torque converter will be 98°C.
The converter seems to go between 93°C - 100°C depending on how hard it is being pushed once it has warmed up properly .
95°-98°C is where it seems to spend most of the time once it has done an hour of work to warm up properly.

Is the oil outlet on the converter the best place to have the temp sensor for best temp readings ?

 

[kshansen]

Apologize for the grainy picture but it's the best I could fine fast on SIS. This is the valve on the back of the converter that Cat installs their temp sender in, see the red arrow there should be a steel line going to the converter from the port on the left side of the valve as it is positioned in the picture. PS:When I say "back" of converter I do mean the side facing the cab, I think of front and back and right and left of engine as somewhat separate from those terms relating to the machine itself. Front of engine being the end the fan is on and the left is as determined while standing at the flywheel end looking over engine towards the fan end!

One thought I might have is if your temp gauge is using one of the bolts as a point to read the temperature as opposed to having a probe right in the flow of the fluid there could be a bit of a delay in reaction to the temperature of the oil as the casting of the housing would need to cool down before your sensor could read it.

Maybe Nige or someone else could word that better or expand on the thought!

 

[ajginger]

View attachment 222802

Apologize for the grainy picture but it's the best I could fine fast on SIS. This is the valve on the back of the converter that Cat installs their temp sender in, see the red arrow there should be a steel line going to the converter from the port on the left side of the valve as it is positioned in the picture. PS:When I say "back" of converter I do mean the side facing the cab, I think of front and back and right and left of engine as somewhat separate from those terms relating to the machine itself. Front of engine being the end the fan is on and the left is as determined while standing at the flywheel end looking over engine towards the fan end!

One thought I might have is if your temp gauge is using one of the bolts as a point to read the temperature as opposed to having a probe right in the flow of the fluid there could be a bit of a delay in reaction to the temperature of the oil as the casting of the housing would need to cool down before your sensor could read it.

Maybe Nige or someone else could word that better or expand on the thought!

Yes I think you would be right about the sensor only picking up the housing temp and not the oil temp directly. I have finally located the temp sender for the TC dash guage but unfortuninatly the wiring loom that goes to it & the vctc solenoid is missing.
I might try relocating the NEW electronic sensor onto the original TC temp sender and see if it picks up more of a direct oil temp seeing as how the TC sender has the end in oil flo.

The white arrow on this pic shows where I currently have the sender.

 

[ajginger]

View attachment 222827 View attachment 222827 I think I finally located the wiring loom that goes to the vctc solenoid and Converter oil temp sender......it was wrapped around up against the chassis on the right side of the engine ( facing the bucket from cab seat ) .
After investigation I found out that the previous owners cows got to it and ate some of the wiring while it was parked in a cow paddock.

I repaired the ends with some new eyes and hooked up the correct wires to the new solenoid to se if it would engage ( click ) with the swith on the lift lever being activated. I couldnt get the switch to cause the solenoid to activate or make the green light on the dash come on.

Whith the wires hooked up, if I pressed the solenoid terminal with the red wire attached against the engine exhaust manifold, it would click and activate the green dash light..... it wouldn't do this while pressing the solenoid body against the manifold and activating the lift lever switch.

I then pulled the lift lever apart to look at the vctc switch. There is a red and black wire that goes to the switch with no other wires visible.

Does the switch not activating the solenoid mean it is dead ?

 

[kshansen]

I circled the fitting the temperature gauge would go in if you had a mechanical gauge, if an electric gauge then the sender would be in that location.

 

[kshansen]

Just to refresh my memory, do you have an actual wiring schematic? Not just the one in the parts book?

It's been many years since I worked on one of these but there are diodes in the wiring of this machine and I see at least one in the wiring for the solenoid, not saying that's the problem but it does add a level of complication! Right now I'm having trouble following the wires on computer screen and may at some point have to print it out to be able to follow the wiring on paper!

 

[ajginger]

Just to refresh my memory, do you have an actual wiring schematic? Not just the one in the parts book?

It's been many years since I worked on one of these but there are diodes in the wiring of this machine and I see at least one in the wiring for the solenoid, not saying that's the problem but it does add a level of complication! Right now I'm having trouble following the wires on computer screen and may at some point have to print it out to be able to follow the wiring on paper!

Yes Nige sent me a wiring schematic for the 988b.
According to the sis parts documents, the lift lever handle vctc switch has a wire that runs to earth.......I will need to check that hss a good earth. I will take a test light to see if the switch is recieving and allowing power through.

By the way........there is a Cat electrical engineer somewhere who deserves the
Caterpiller Award for : ' Best invention to cause total frustration to anyone who pulls this apart and tries to re-assemble '.
That spring idea listed #2 is a proper pain in the ---- to get to stay in position while trying to get the handle back together.

 

[ajginger]

Just an update on the vctc switch and solenoid :

After pulling panels, pulling apart the lift lever handle again, pulling the instrument panel, running external wiring to do tests ect.....turns out that the switch in the lever is faulty.

I got another switch from the vehicle, hooked it up to the original switch wires and the green dash light came on and solenoid clicked when I flicked the switch.
I then set about the unpleasent task of removing a 2 inch steel oil pipe thatruns from the pump in the center of the engine to the screen housing on the transmission. Cat run the oil line right in front of where the vctc solenoid has to be threaded into the housing just close enough so you cant get a socket onto the solenoid to tighten it up.

After hours of struggling to get my hand/tools in past the other hoses ect... to get whats left of the old solenoid out, new one in and wires hooked up
( including the torque converter temp wire ), I now have the vctc solenoid and green dash light going on and off at the flick of a switch. ( non-Cat switch till I can get the real thing )

Thanks to you guys for sharing the needed info so I could find the parts and locations of the needed repairs.

 

[kshansen]

I always liked the dash panels on those 988B's take out a couple screws and loosen a couple others and you could unplug the harness and take down on to bench to clean up and work on them. Much better that trying to stand on head under dash of a loader!

Also nice that someone thought enough to color code the plugs!

Looks like yours needs a little patching with some fiberglass cloth and epoxy! And a couple wires look to be cobbled up might want to keep an eye on those!

 

[Nige]

Always nbice to hear a success story.

 

[ajginger]

I just noticed that 2 injector lines have started weeping a little down the outside of the rocker covers on the 3408 engine. The two injecter lines have a little movement at the rocker cover when I push/pull them. ( no movement in the others )
I put a spanner on them but they are tight.

Question : Is there a seal between the inner & outer fuel lines or would this be a cracked injector line causing the fuel leak ?
( Pic is not my engine but its one I found on the internet to show where the leak is.)

Also I have to pull one of the steering cylinders to put a seal kit in.
2 Questions :

1. Can I articulate the machine, ( chocking the wheels ) pull the front pin and pull the rod/piston out of the cylinder without removing the whole cylinder ?

2. Which direction will the pins come out .... up or down ?
The pins are very tight. ( I imagine the pin should be forced upwards direction )

 

[Cmark]

1. The leak is engine oil I presume? There is a seal on the adapter that goes through the rocker box.
This point may or may not be related to your leak, but it's important to keep all the injection line clamps present and in the correct place.

2. The steering cylinder pins are tapered and come out from the top. My preferred quick-and-dirty method for removal is to put a jack under the bottom of the pin then hit the clevis with a sledge hammer, much the same as releasing a steering ball joint in a car.
Can you get enough clearance to get the rod out by articulating the machine? I'm going to say a cautious yes. It's been a long time since I worked on a B series but I seem to remember that perhaps one side will and one side has the hydraulic tank in the way???

 

[ajginger]

1. The leak is engine oil I presume? There is a seal on the adapter that goes through the rocker box.
This point may or may not be related to your leak, but it's important to keep all the injection line clamps present and in the correct place.

2. The steering cylinder pins are tapered and come out from the top. My preferred quick-and-dirty method for removal is to put a jack under the bottom of the pin then hit the clevis with a sledge hammer, much the same as releasing a steering ball joint in a car.
Can you get enough clearance to get the rod out by articulating the machine? I'm going to say a cautious yes. It's been a long time since I worked on a B series but I seem to remember that perhaps one side will and one side has the hydraulic tank in the way???

Thanks for that info Cmark

1. Now that you mention it I didn't actually check if the weep is engine oil or diesel. I saw it and assumed it was diesel so will check to make sure. The engine runs fine so it might be engine oil getting through the rocker cover seals.
By " injection line clamps " do you mean the clamps back near the governer area ?

2. I thought the pins might have been a tapered pin. I have a 15 ton puller that I can also use as a press to have a go at them. I might try you method first as well. It is the cylinder on the fuel tank side. ( left side if you are sitting in the drivers seat )

 

[Cmark]

By clamps I mean the clamps on the lines between the injection pump and rocker boxes. They appear to be in random places but are actually carefully placed to eliminate harmonic vibrations. Without them, leaks and broken injection lines are guaranteed.

By all means have a go with your puller but I usually find that a 50T bottle jack pushing hard enough to take the weight off the tyres is necessary.