Cleaning hubs and 4x4 problem

People have suggested that cleaning front autolocking hubs on my 98 Trooper may solve intermittent 4wd engagement problem. Is this complicated, and likely to solve 4wd issue? So far I've checked the actuator motor, and
vacuum - actuator works, and vacuum sucks... yet 4x4 light will often just keep blinking. The weird thing is - after it's been sitting in driveway overnight 4x4 will always come on no problem... drive it 5mins and no joy.
Any suggestions? Peter
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Peter wrote:

On the previous model cleaning and lubricating the auto hubs is not complicated althoug the manual suggests otherwise. It actually solves most engaging/disengaging problems. Don't know on the later model. Give it a try. Good luck, Erik-Jan. -- http://www.fotograaf.com/trooper
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It depends when in 98 your vehicle was made. If it is the late 98 new model trooper read on.
I don't think cleaning the hub bearings on this model will make any difference, anyone with more knowledge please correct.
I have a late 98 trooper which with 4WD activated by a push button on the dashboard. Having serviced the hubs on mine for similar reasons I believe the hub to be a simple splined stub axle and wheel bearing arrangement and that the front wheel engage/disengage mechanism is in the axle and solenoid operated. The solenoids control which side of a diaphram located on the axle vacuum is applied to. The diaphram engages and disengages the drive.
Originally my trooper was not engaging 4WD at all (I found out when I got stuck). I had thought that the 4WD light flashing slowly was an indication that the car was in 4WD this was not so. The front axle was not engaging, the engagment (on the front axle) is activated by two solenoid valves on the front axle, you may be able to check whether these appear to be working by having someone operate the switch whilst you listen carefully to them, they should make a very slight click and both the solenoids need to operate as it is a changeover. If this is inconclusive it is not a big job to remove the solenoids and bench test them. Label all the rubber pipes going to the solenoid clearly as to which pipe on the solenoid. remove all pipes, disconnect power plug and undo two nuts. With the solenoids off I used a 9Volt battery with flying leads inserted in the sol. plug to activate it. They were jammed due to corrosion inside, I bought new at 70 odd then found out it was possible to open and repair with persistence. Applying voltage activates a coil embedded in the case of sol. moves a plug in a bore. There is a common pipe into the sol. depending on where the plug is air will flow from one of the other two pipes. (simple pneumatic change over solenoid).
When I replaced the solenoid 4WD engaged OK initially dropped in and out of 4WD at random particularly in winter. Later investigattion showed a poor earth to be the problem. Prior to my ownership someone had disconnecte the earth which went from the control circuit direct to the solenoid plug and picked up a local earth on the axle which given the way axles are fitted with springs, rubbers etc. was unreliable . I reconnected the original wires and have not had a problem since.
The engagement of 4WD is complicated, there are solenoids and sensors on the transfer box as well. I would check electrical connections to all them. It may also be a sensor giving an erroneous reading, Your vehicle may be in 4WD but a faulty sensor is telling the control circuit it isn't.
I did write up what I did and found. If you need any more help please post and I will try to help.
David

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OK, I've located the fault to be in vacuum solenoid valve that engages 4wd (connects hubs to the front differential). Problem is - local (Opel) dealer wants hefty sum for both valves (these are sold as pair), and I can't locate these valves online. Plus, Alldata does not list OEM part number of these valves, and the workshop manual that I have does not have part numbers either. Can anybody tell me the part number(s), point to mail-order store, or tell me whether these are repairable?
Peter
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prices... This problem seems to occur regularly in Troopers with the push-button 4x4 system. Is there any way of preventing it from happening, eg regularly spray-washing the vehicle from below to get the dirt and salt off? We have a lot of snow & ice on austrian roads so I need to keep the 4X4-mechanism functional for as long as possible.
RL
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Peter wrote:

Why not just bolt it out. Take it apart, clean the parts, check the coil if applicable with a resistance meter. Put it all back together and see if it works. Nothing to lose i.m.o. Kind regards, Erik-Jan.
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It's put together pretty well, not easy to take it apart.
Anyway, I got replacement from a junkyard (cost me equivalent of ~30$). It engaged 4wd just fine but would not disengage. Removed vacuum hoses from the new valve, it would disengage now. Put the hoses back, everything works just fine. Hope it stays that way... ;)
Peter
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