4x4 info

ktm-wes

New member
Hello

I am new to this forum, have been browsing for a while as I have a year 2000 312D MWB 4x4 sprinter which I plan to convert into a weekend camper / motocross van to take 2 bikes. I bought a 4x4 because I have been stuck afew times in muddy fields at enduro events, not fun!

I am going to install a 3 way fridge, leisure battery, caravan zig unit, gas hob and grill and arrange the back so a bed can be made up when the bikes are out the way.

Does anyone have any manuals for the 4x4 sprinters? I would like to check front and back diff, transfer box, gearbox etc but I have no details of what type of oil or volumes? or what the service intervals for these are?
I am assuming that they need doing as although the van is in good condition there is no recorded service history!

Many Thanks
 

Eric Experience

Well-known member
Wes.
The gear box and diff are the same as a 4x2 so the info in the manual is still relavant. unless it has done extra large miles the transfer case oil will not need changing. If it has a diff lock it is a good idea to open the bleed valve and drain out about half a cup full of brake fluid being sure to keep the master cylinder toped up. this is done because the diff lock is not used enough to keep the fliud moving. The only extra job is cleaning the vaccum lines to the transfer case, the mechanism that moves the gears is in the oil so a small leak into the vaccum line allows oil to get into the soleniod valve under the seat, if that happens the valve will stick and you lose control of the shift. So just make a drawing of the hose set up and then pull it out and clean the tubing. I have found it pays to use the MB oils and fluids they do cost more but you will not have any problems. My 3 4x4 have done a total of 500 thousand with no problems. Eric.
 

ktm-wes

New member
Yep it has rear diff lock, I thought it was operated by vacuum! So when I bleed fresh fluid through where is the master cylinder in the engine bay for diff lock? is it normal dot4 fluid? to engage the diff lock most of the time I need to roll back slow in reverse, and do the same to dis-engage, but this isnt a problem.

4x4 selects fine, but seems tempermental sometimes to dis-engage? I will do what you reccomended. Do your vans make more of a whine noise when 4x4 selected? and what speed do you drive when 4x4 selected, around 15mph ok?

Many Thanks for the info
 

Eric Experience

Well-known member
Wes.
The diff lock has a unit like a small brake booster, the fluid is taken from the brake master cylinder reserve. I recomend using the fluid supplied by MB. The transmission noise increases if you are driving in 4x4 on a hard surface. The reluctance to disengage is normaly caused by the oil in tube problem. Eric.
 

emlclcy

Member
Wes.
The diff lock has a unit like a small brake booster, the fluid is taken from the brake master cylinder reserve. I recomend using the fluid supplied by MB. The transmission noise increases if you are driving in 4x4 on a hard surface. The reluctance to disengage is normaly caused by the oil in tube problem. Eric.
hi eric, i've a problem with the diff lock on my 316 sprinter, it does not operate no more (after jamming on!) so i undid the bleed screw and with the engine running, operated the diff lock switch. a small amount of oil squirted out then nothing and it does not engage any more.
I thought it was fed from the gearbox oil!
How do you bleed it? where is the solenoid that switches the fluid?
Do you have to pump the brake pedal?
thanks
carl
 

Eric Experience

Well-known member
Carl.
The diff lock uses brake fluid. the fluid is taken from a tube comming out the side of the reservior, the vaccum to pressure transducer is mounted behind the left front wheel about level with the starter motor. Make sure your brake reservior is full of MB brake fluid and just leave it for a day to allow the air to rise then operate the lock with the bleed open. If that does not fix it you may have to clean out the slave cylinder, this is the very reason I was recomending changing the fliud. Eric.
 

emlclcy

Member
Carl.
The diff lock uses brake fluid. the fluid is taken from a tube comming out the side of the reservior, the vaccum to pressure transducer is mounted behind the left front wheel about level with the starter motor. Make sure your brake reservior is full of MB brake fluid and just leave it for a day to allow the air to rise then operate the lock with the bleed open. If that does not fix it you may have to clean out the slave cylinder, this is the very reason I was recomending changing the fliud. Eric.
Hi Eric, I had a look last night, there is a pipe from the brake fluid reservior that goes to 'something' above the gearbox(sprintshift) and following the pipe from the diff lock actuator to somewhere near the same place but you cant get to it! a pipe from the brake vacuum seems to go the same place. The oil in the slave cylinder doesn't look to fresh so i need to drain it somehow without pumping it through the calipers (syphon it out maybe??)

what wheels and tyres do you run on your 4x4? I'd like to put landrover tyres on, something with a larger rolling diameter as she changes to third at 15mph and i'll never carry a full load as it's a camper conversion
carl
 

Eric Experience

Well-known member
Carl.
The fluid change is important, the critical component is the antilock brake unit,it has very small valves in it so pumping the fluid through if should be avoided. One posibility is to use a bicycle tyre pump. Take the pump apart and reverse the washer to convert it into a sucker and then suck out the fluid from the reservior.
The wheels I use are standard most of the time but when I go into challenging areas I use a set of 16 inch with 235/85/16 tyres they are the same as the old 750/16. You have to do a major cut and weld job to get clearance for them and the snow chains I carry. The 10% speedo error makes it worth reverting to standard as soon as I get home. Eric.
 

emlclcy

Member
Carl.
The diff lock uses brake fluid. the fluid is taken from a tube comming out the side of the reservior, the vaccum to pressure transducer is mounted behind the left front wheel about level with the starter motor. Make sure your brake reservior is full of MB brake fluid and just leave it for a day to allow the air to rise then operate the lock with the bleed open. If that does not fix it you may have to clean out the slave cylinder, this is the very reason I was recomending changing the fliud. Eric.
Hi Eric, I had a look last night, there is a pipe from the brake fluid reservior that goes to 'something' above the gearbox(sprintshift) and following the pipe from the diff lock actuator to somewhere near the same place but you cant get to it! a pipe from the brake vacuum seems to go the same place. The oil in the slave cylinder doesn't look to fresh so i need to drain it somehow without pumping it through the calipers (syphon it out maybe??)

what wheels and tyres do you run on your 4x4? I'd like to put landrover tyres on, something with a larger rolling diameter as she changes to third at 15mph and i'll never carry a full load as it's a camper conversion
carl
 

emlclcy

Member
cheers eric, like the bike pump idea!
is bleeding the system easy?
is it the usual 'press letgo' or do you need the engine running?
there seems to be heaps of wheel arch clearance, didn't think large diameter tyres would be an issue
cheers
carl
 

Eric Experience

Well-known member
Carl.
The most reliable way to bleed is to get someone to press the pedal while you open the bleed, then close the bleed before the pedal is returned. It is not necessary to have the motor running.
If you turn your front wheel to about half lock you will have very little clearance at th back of the wheel, imagine the wheel raised up about 4 inches. At the back when a wheel is raised it also moves back very close to the mud flap. Eric
 

emlclcy

Member
Carl.
If you turn your front wheel to about half lock you will have very little clearance at th back of the wheel, imagine the wheel raised up about 4 inches. At the back when a wheel is raised it also moves back very close to the mud flap. Eric
Eric. does your 316 4x4 ride real hight? there must be a good foot of clearance from the top of the front wheel to the wheel arch. you can easily work under the van without jacking it up as the clearance is so great. that lead me to think about larger diameter wheels. Will have a look at the stock clearances with the wheels on half / full lock.
thanks for your input
carl
 

emlclcy

Member
Carl.
The diff lock uses brake fluid. the fluid is taken from a tube comming out the side of the reservior, the vaccum to pressure transducer is mounted behind the left front wheel about level with the starter motor. Make sure your brake reservior is full of MB brake fluid and just leave it for a day to allow the air to rise then operate the lock with the bleed open. If that does not fix it you may have to clean out the slave cylinder, this is the very reason I was recomending changing the fliud. Eric.
Eric, i've just been under my van and ,found the diff lock veservior, has a hand sizes plastic ball next to it. where do you start to diagnose the diff lock problem?
I've booked the van in for tuesday for a brake fluid change, they do it with pressure some how, do you think they pump the fluid out via the master cylinder veservior?
I'm pretty practically minded but with no service manual i'm lost.

cheers
carl
 

emlclcy

Member
Carl.

The wheels I use are standard most of the time but when I go into challenging areas I use a set of 16 inch with 235/85/16 tyres they are the same as the old 750/16. You have to do a major cut and weld job to get clearance for them and the snow chains I carry. The 10% speedo error makes it worth reverting to standard as soon as I get home. Eric.
i went to the type shop today and offered up a 235/85/16 tyre to my van wheels (landrover defender size). they are 4" larger in diameter and look like they will catch the body front and back, up seems ok.
Have you a close up of the wheels on your van to see what i'm up against?
cheers
carl
 

Eric Experience

Well-known member
Carl.
The hard plastic ball is the device that converts the vaccumm to fliud pressure. When you get the fluid changed I hope the mechanic is smart enough to change the diff lock fluid as well.
The big wheels you describe will require you to cut the body and reweld both front and back of the rear wheels and just the back of the front wheels. If you are planning to go off road you will have to cut about 2 inchs at the bottom tapering to 0 about 6 inchs up. Sorry I don't have pictures to post. What I did was to make a bracket to hold the grinder bolted the the wheel hub, that way the cut was even and curved to the wheel radius. You will also have to make a new spare tyre holder. Eric
 

emlclcy

Member
Carl.
The hard plastic ball is the device that converts the vaccumm to fliud pressure. When you get the fluid changed I hope the mechanic is smart enough to change the diff lock fluid as well.
The big wheels you describe will require you to cut the body and reweld both front and back of the rear wheels and just the back of the front wheels. If you are planning to go off road you will have to cut about 2 inchs at the bottom tapering to 0 about 6 inchs up. Sorry I don't have pictures to post. What I did was to make a bracket to hold the grinder bolted the the wheel hub, that way the cut was even and curved to the wheel radius. You will also have to make a new spare tyre holder. Eric
with an unloaded van do you think it improves mpg?
the merc dealer didn't do my brake fluid change, there vacuum oil pump didn't work so i've ebayed my own and will change it myself with merc oil!
you must have a picture of your 316!!
carl
 

Eric Experience

Well-known member
Carl
The large wheels increase vehicle profile and rolling resistance so the fuel use increases.
I will get a picture next time I run the 16 inch wheels. Eric.
 

emlclcy

Member
Carl
The large wheels increase vehicle profile and rolling resistance so the fuel use increases.
I will get a picture next time I run the 16 inch wheels. Eric.
i thought as i'm not loading the van up, taller gears would improve fuel ecomomy

after bleeding the brakes i tried to bleed the diff lock actuator. Put quite i high vacuum on the bleed nipple but only a few drops of oil. I undid the banjo and the actuator is clear (pumping the vacuum through it), i reassembled started the engine, operated the diff lock switch and tried again to bleed it with the engine on, still the same.
I took of the drivers seat an had a look for vacuum pipes but couldn't see anything, maybe the layout in my van is different as it has a sprintshift box.

carl
 

emlclcy

Member
diff lock actuator problem - i also tried to back flush the oil from the master cylinder, i removed the pipe that feeds the diff lock unit from the master cylinder and tried to pull the brake fluid back (with the diff lock bleed nipple loose) nothing, even with a high vacuum.
I need to track down a manual i think
 

Eric Experience

Well-known member
Carl.
Because the transducer is not used much it most likely got a bit of sludge in the valve inside it. Picture how it works, when the diaphram starts to move it must shut of the line back to the resorvoir otherwise the the fluid would flow back. this valve must close with very little movement so by definition it must be small. What I would do is to remove the unit after blocking the hose with a pair of vise grips. make a drawing of the conections and just pull them of and unscrew the metal line. With the unit on the bench blow out the oil line with air or soak it in metho then blow it out. obvously you would dry it out before refitting it. Very easy job as the threads in the unit are brass. Eric
 

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