FJ62 A440F Transfer case has bum solenoid and sounds like a loose slinging saw blade?

[TheElegantFox]

Hey all, I've recently been chasing a rattle/resonance under load from 30-35mph and during my troubleshooting I found that the truck will enter 4WD but not shift out. I have to do the bush fix of swapping the hoses to disengage the front driveshaft. I did this fix a while back: Writeup: 1988 FJ62 4WD Solenoid fix for $17.77 - https://forum.ih8mud.com/threads/writeup-1988-fj62-4wd-solenoid-fix-for-17-77.224061/ but the solenoid must've burnt out early so I've ordered another one plus a full kit from Vintage TEQ.

Main question I have is would a failed (disengagement) solenoid cause partial engagement of the transfer case, leading to a metal rasp noise under load sounding like a loose saw blade? The trans was rebuilt 40k miles ago by the PO and it overall seems fine.

 

[TheElegantFox]

Is there a way I can disconnect the transfer case vacuum while I'm waiting for parts?

 

[cruisermatt]

Pressure the 4wd side of the diaphragm (the opposite of vacuum pulling on the 2wd side) with shop air to make sure it’s fully disengaged. yes it’s possible that is your noise, however you might have some permanent damage to front output shaft/collar/output hub if it is making noise.
You can run it with no vacuum hoses, but originally the 2wd side has constant vacuum on it, there is no detent for 2/4wd shifting on the vacuum setups. So keep that in mind.

 

[TheElegantFox]

Pressure the 4wd side of the diaphragm (the opposite of vacuum pulling on the 2wd side) with shop air to make sure it’s fully disengaged. yes it’s possible that is your noise, however you might have some permanent damage to front output shaft/collar/output hub if it is making noise.
You can run it with no vacuum hoses, but originally the 2wd side has constant vacuum on it, there is no detent for 2/4wd shifting on the vacuum setups. So keep that in mind.

Hmm, this transfer case has given me engagement issues in the past due to the PO never using it, leading it to get stuck often. Last time I was able to free the case with a vacuum hand pump. I'll dig through the FSM to see what the diagrams say.

What would be the plan for a trouble shooting tear down? Starting with the transfer case housing?

 

[TheElegantFox]

I found this to be really helpful:

 

[TheElegantFox]

Swapping in the original solenoid I kept on the shelf, will try some load testing to see if the transfer case rattle is still present.

 

[cruisermatt]

did you try doing what I recommended?

 

[TheElegantFox]

did you try doing what I recommended?

I don't have a compressor on hand, so I can't add air to the system. Could I try something similar with a vacuum pump?


Rereading this now, I can engage and disengage the diaphragm if I swap the hoses and it seems to stay closed if I leave it. It won’t disengage once it’s flipped on for 4WD. When I swap the in and out hoses at the diaphragm, a button press will disengage the front driveshaft.

 

[TheElegantFox]

Swapping in the old solenoid did not alter the behavior. I did get a video from acceleration up a gentle hill from 5mph up to 30-35mph where the noise starts. With the audio up, you can hear the noise.

This occurs under load and will disperse on coasting. I wonder if this transfer case is calling for a rebuild?

 

[TheElegantFox]

Well, after putting on my thinking brain, it seems like the noise is too far forward to be to the transfer case itself. The noise is present in the front of the truck. Kinda like something is trying to engage the front end.

The diaphragm is where my mind is placing the noise under load, but it could be along the front driveshaft.

Since the front driveshaft is having disengagement failure after being engaged, that might be a clue? I might need to start considering transmission issues as well. It was rebuilt in 2018 or so based on paperwork I have from to PO.

 

[TheElegantFox]

I'm thinking this problem isn't related to the vacuum issue, though I'll be fixing that once the part arrives. Any ideas for further troubleshooting based on the noise in the video and general front location?

Looking more into it and the sound might be the front driveshaft ringing/rattling even though it's set to 2WD. I've been de-greasing the undercarriage and I wonder if that's affected anything. I've also been hitting the grease zerks as maintenance.

May look into this :TRAIL TECH TIP: 62-SERIES Stuck In 4WD, 2WD Solenoid ByPass - https://redlinelandcruisers.com/trail-tech-tip-62-series-stuck-in-4wd-2wd-solenoid-bypass/

 

[TheElegantFox]

After months and 3 separate orders for a vacuum solenoid, I finally got the 4WD switch replaced so that’s that issue resolved. However, the intermittent ringing/grinding is still present. Is this a shot transfer case then?

I am seriously stumped here.

I have been degreasing and power-washing, including the knuckles: Driving and.... horrible grinding noise intermittent - https://forum.ih8mud.com/threads/driving-and-horrible-grinding-noise-intermittent.1025947/page-2 Maybe it's worth looking into the knuckles? They've been rebuilt twice in 5 years I believe.

———-
Did more troubleshooting and cleaning. Doesn’t seem to be an exhaust or cat rattle. I can get it pretty consistently in 2nd and 3rd at 2k RPM and it immediately goes away if I back off throttle to less than 2k. Is that something with the flywheel or trans?

 

[TheElegantFox]

Working on cleaning the area to better assess it. All the drive train zerks are recently topped off with the exception of the rear driveshaft where it meets the transfer case. I can’t fit the nozzle onto it there. That specific one is very dry and I don’t think these have been done in 5 years, but the front driveshaft is newer.

Will be re-coating the frame with fluid film shortly after the work is done in the area.

 

[TheElegantFox]

Yeah, I think I’ve confirmed this rattle is exactly around 2k RPM and that’s the main thing needed for it to rattle/grind.

 

[TheElegantFox]

May have a culprit, this heat shield for one of the chassis bushings is broken at one of two tack welds near the top of the cat

———-

Yep, just confirmed with a test drive that this was the rattle source. Bending it away from the frame mitigated it. Sorry I’ve been talking to myself this whole time, but hopefully this’ll be a good resource for future rattle chasers haha.

 

[BurntToast]

Congratz on finding it, that kind of issues are a nightmare to find sometimes