4WD Actuator or Transfer Case (or something else ?) - freewheeling?

Hello all, I have read a bunch of threads about the 4WD actuator but am thinking that is not my problem.

I have a 2006 4cyl 4WD with standard shift... about 125K miles. New clutch this year. Toyota frame recall/replacement this year. 300 pounds of sand bags in the back for snow plowing - upstate NY.

Neighbor borrowed my truck to do some plowing. I think he kept it in 4LO for most or all of the job. He used it to plow a grassy field that he needed for some parking for people coming to an event at his place. Heavy work, I know, for my 4cyl. But it has managed 4 winters or my 0.3 mile driveway with no problems.

He returned the truck worried about "clunking noises". There was more...

(a) In forward or reverse gears, low speed, in 4HI the "clunk" sound that it has sometimes made when switching from 2WD to 4WD is now repeating every 10-20 feet.

(b) If I switch to 2WD the 4WD indicator goes off but then the transmission does not engage at all... basically as if I am in neutral.

(c) It was difficult to get it to switch to 4LO (just kept blinking) but after 6 or 7 tries with the switch (in neutral and unmoving as usual) I got it into 4LO but the periodic clunk was still there.

I think I would be up to the 4WD actuator replacement but another friend told me that the business of the transmission/clutch not engaging at all (he called it "freewheeling") while in 2WD meant it was the "transfer case actuator" that was stuck trying to get from 4HI to 4LO... (But I finally got it to switch to 4LO still had the "clunk" and when I switched back to 4HI then 2WD the same symptoms: no engagement of transmission.

I see recommendations to whack the transfer case with a hammer in case something is stuck/frozen ?

any thoughts ?
thanks
D>

 

Probably the rear diff. Have someone check the driveshaft while in gear in 2wd, just don't run over the person checking.

 

Ah. Duh.... that makes sense (tho it does not make me happy).

So:

In 2WD the rear differential problem means no engagement/pulling from the rear which explains the "freewheeling" symptom.
In 4WD the front wheels are engaged and pulling but the "clunk... clunk... " is the 4WD actuator fighting to get some response from the rear.

Makes sense: crikey... Well, it would be nice to have a warm, dry garage or barn with a lift, but since I have none of the three and instead 16 inches of snow, it is off to the local shop on the back of a tow hook.

thanks sandman for the fast brainstorming.
D.

 

My thought is the clunk clunk is the teeth of the ring and pinion in the rear diff jamming up. It would not move if the 4wd actuator was attempting to engage still. I've broken my rear driveshaft and driven 8hrs home at 75mph with no clunking noise.

 

Check this -

Start truck, put in 2WD, transmission in neutral.

Block the wheels.

Put trans in 1st gear, ease clutch out.

If truck isn't trying to move, look under and see if the rear driveshaft is spinning. If it is spinning, then the problem is in the rear end. If it's not spinning, problem is in the transfer case.

Since the truck moves in 4WD, you can rule out the transmission, but not necessarily the transfer case.

If it's the ass-end of the truck, the noise would probably be busted teeth on the ring gear, or maybe a snapped axle.

If the rear driveshaft shows no spin in 2WD, I'd probably pull the fill and drain plugs on the rear, pull the axles, and pull the 3rd member. You may want to have someone standing by with a bottle of good whisky, just in case it's bad news.

 

Rear end would be better news than transfer case. Opportunities to regear/lock.