Land Rover series 3, intermittent 4x4 issue

Hi there, I have a 1975 short wheel base series 3 and recently have experienced some intermittent 4x4 issues.

4x4 works when initially engaged, then shortly after I will find just my rear wheels spinning and I will get stuck. (I frequently drive in muddy fields where it’s very easy to test which wheels have drive!) This is the only indication that 4x4 has disengaged as the yellow lever will remain compressed. I will then re engage 4x4 and it will work, I can then drive straight out of where I was stuck. I have to keep repeating the process.

Perhaps worth mentioning… when reversing I noticed a clunking noise, I thought it was the drum brakes binding as these have all been replaced recently, however I am now starting to think it may be related to this issue? I also have free wheeling hubs.

Any pointers would be much appreciated! Thanks in advance for your help.

James

Does the 4wd work ok in low box?

4x4 works in low, however I have not driven around with it in long enough to see if it pops out. I only ever use it briefly when it comes out of 4x4 high

The shafts that control in/out of the 4wd protrude from front of transfer box and can become corroded limiting movement. There is a cover. Try driving more in low box to see if it stays in 4wd.

Thank you I’ll give it a go!

Clunking in reverse - any idea where from? It's not likely to be a connected problem.

I second Tottot's suggestion as it has happened to me before.
There is a thin steel cover at the front end of the transfer casing, just above the front prop flange. This protects the 4wd selector rods as they move back and forth as and when 4wd is needed. Either the cover's front face has collected mud inside it or more probably the rods have corrosion on them. Some emery paper and a dose of workshop spray will polish them up nicely. The transfer case uses spring pressure to select 4WD High (via yellow knob) but 4WD Low is manually selected with the red knob lever.
There is also a detent on the top of the casing, from memory its a brass hex nut approx 9/16''. This holds the spring/ball for the 4wd detent mechanism. The spring might have broken, albeit unlikely.

Thank you everyone for your help. I will remove the cover and clean up the 4wd selector rods over the weekend. Fingers crossed that does the job!

Thanks again for your help, it’s much appreciated!
James

I removed the selector rod cover to find that the bottom rod was well and truly seized and the cover was full of mud etc. I cleaned them up and covered in grease/oil and I am still having to free it up with mole grips to engage 4x4 high as it won’t pop out when I press the yellow lever down. I will try some emory paper tomorrow and see if that solves it.

Thanks again
James

Hi and happy new year. So I cleaned all the selector rods up, covered them in grease/oil and got them looking like new. They were covered in rust and the selector rod cover was full of rusty gunk.
However now, I cannot engage 2wd!! The low range lever will only engage in either direction when the yellow lever is fully compressed! I.e. to get low range I have to compress the yellow lever and to get into high range I have to have the yellow lever compressed too! This means that the 4wd is still engaged somehow (I unlock my freewheeling hubs and the prop is still spinning)

I also checked the spring/ball for the 4wd detent mechanism under the brass hex nut on top of the casing and that was all fine.

It’s really stumped me! Any ideas or help is much appreciated

Thanks again,
James

Are the shafts moving freely that you cleaned up , one maybe seized

It does seem like there is an issue with the mechanism in the front output, yellow should want to pop up on its spring when pulled into low.

steve2286w said:

Are the shafts moving freely that you cleaned up , one maybe seized

Click to expand...

Or too much grease giving a hydraulic lock? Just guessing because it's four years since I last built one and I didn't press save.

The little pin that the yellow knob operate is should be free and the shaft it secures should move under spring pressure when yellow knob pressed down

Grumpy Talks on the Youtube gives good explanation/demonstration on how the series 4wd system works.

Never seen them before looks good