4wd hubs won't engage

riata_ag · 03-27-2007, 08:17 PM

I have a 1990 3500 4X4 with an auto tranny. The transfer case works and the front driveshaft turns, but the front hubs won't engage.

Can someone give me some suggestions of what to do and where to look first.

Thanks,
riata

junior3382 · 03-27-2007, 08:19 PM

Bearings.... are they manual locking? If so, do they turn to lock? Does it wistle at all when you drive it, thinking its engaged? If so, i would definitely check the bearings on both ends.

riata_ag · 03-27-2007, 08:41 PM

Its a dually with the big steel dually wheels on the front.

The center of them is hollow with only an axle nut showing back in the hole in the wheel. So I assume they are auto locking, but I wasn't sure if they were like the mid-90's Ford hubs, or if they worked off of vacum or electric, etc..

Realizing that they are 17 years old maybe I need to buy new hubs?

Thanks in advance for your suggestions.

riata

junior3382 · 03-27-2007, 08:50 PM

Okay, you need to determine for sure if they are auto or manual locking. and no, you may not need whole new hubs, depends on why they are not engageing. Once you determine wich hub you have, the diagnosis can continue....

Did you buy it used? I am assuming you did since it is rare people keep vehicles for that long, but I ask because when you bought it, did the 4x4 work? Did you check? usually a good item to check.

still sounds like a lube problem to me though... Depends on how long it has been since the system was used. Do you know how long it has been?

riata_ag · 03-27-2007, 09:01 PM

I assume they are not MANUAL since there is not a a dial or switch to turn, right?

Yes, I did recently purchase the truck to use as a feed truck and I did try out the 4WD as far as the transfer case working, but I had to wait for rain so I could spin the tires a little in the mud to see if the front tires were spinning, and they weren't. I think it has been about 8-10 years since the 4wd was last used.

junior3382 · 03-27-2007, 09:10 PM

Okay, you are right about the hubs. And with it being that long of not being used, either the mechanical actuator is rotted or yes, may need new hubs. So it doesn't grind at all? Or make any strange noise when you try to activate it? Usually the auto ones will continue to try, and end up either grinding, whistling or making a strange noise of some sort. Does the truck have a solid axle fron or an IFS?

riata_ag · 03-27-2007, 09:25 PM

its not a solid front axle.

It has small CV axles connected from the diff. to the hubs.

junior3382 · 03-27-2007, 09:31 PM

Okay, check those, if it hasn't been driven in that long, then that could be your problem. So I take it there are no noises, so check for tears and leaks of fluid in the boots. At least those are a little less expensive then whole new hubs. however, if they are broken or at least breaking, there would be a clicking when you turn wile driving..... but this is proof that just like men with sex, your truck needs the 4x4 engaged and used at least once a year, wether you need it or not....lol. Let us know.

436'd skylark · 03-28-2007, 09:24 AM

The front of your truck doesn't have hubs, The CV shafts is directly splined to the wheels. the engagement and disengagement is done in the differential. There is a thermal actuator that switches on when the lever is pulled via a switch in the transfer case. The actuator heats up and expands and pushes something in the front diff to engage. This system is notoriously slow and crappy. It normally takes 10 or 15 seconds to engage, which seems like a lifetime to wait, every time.

There a few things to check. First, you might not have waited long enough, like I said it takes along time.
There is a fuse for the actuator in the fuse box, labeled "4x4" it might be popped. If it is, replace it. Pull it in 4x4, and if it instantly pops again, the actuator is likely shot. its a dealer only item around 75-100 bucks. very easy to replace

The connector is under teh truck and could be corroded. If the fuse is good, un plug the connector while the truck is in 4x4 and make sure you have power at the connector.

more than likely the actuator is toast. common on those.

riata_ag · 03-28-2007, 02:00 PM

Thanks alot

I finally realized today after thinking about it that those CV axles do turn all of the time.

I will check out that fuse and electrical switch tonight.

03-27-2007, 08:17 PM	#1
riata_ag Junior Member Join Date: Mar 2007 Posts: 7	4wd hubs won't engage I have a 1990 3500 4X4 with an auto tranny. The transfer case works and the front driveshaft turns, but the front hubs won't engage. Can someone give me some suggestions of what to do and where to look first. Thanks, riata

03-27-2007, 08:19 PM	#2
junior3382 Senior Member Join Date: Mar 2007 Location: Currently, I live in Lancaster county, Pennsylvania. Posts: 3,040	Bearings.... are they manual locking? If so, do they turn to lock? Does it wistle at all when you drive it, thinking its engaged? If so, i would definitely check the bearings on both ends. __________________ *Parts have been found, tools are collecting, tensions are rising, the weather is changing...look out.... the SAS is comming!*

03-27-2007, 08:50 PM	#4
junior3382 Senior Member Join Date: Mar 2007 Location: Currently, I live in Lancaster county, Pennsylvania. Posts: 3,040	Okay, you need to determine for sure if they are auto or manual locking. and no, you may not need whole new hubs, depends on why they are not engageing. Once you determine wich hub you have, the diagnosis can continue.... Did you buy it used? I am assuming you did since it is rare people keep vehicles for that long, but I ask because when you bought it, did the 4x4 work? Did you check? usually a good item to check. still sounds like a lube problem to me though... Depends on how long it has been since the system was used. Do you know how long it has been? __________________ *Parts have been found, tools are collecting, tensions are rising, the weather is changing...look out.... the SAS is comming!*

03-27-2007, 09:10 PM	#6
junior3382 Senior Member Join Date: Mar 2007 Location: Currently, I live in Lancaster county, Pennsylvania. Posts: 3,040	Okay, you are right about the hubs. And with it being that long of not being used, either the mechanical actuator is rotted or yes, may need new hubs. So it doesn't grind at all? Or make any strange noise when you try to activate it? Usually the auto ones will continue to try, and end up either grinding, whistling or making a strange noise of some sort. Does the truck have a solid axle fron or an IFS? __________________ *Parts have been found, tools are collecting, tensions are rising, the weather is changing...look out.... the SAS is comming!*

03-27-2007, 09:31 PM	#8
junior3382 Senior Member Join Date: Mar 2007 Location: Currently, I live in Lancaster county, Pennsylvania. Posts: 3,040	Okay, check those, if it hasn't been driven in that long, then that could be your problem. So I take it there are no noises, so check for tears and leaks of fluid in the boots. At least those are a little less expensive then whole new hubs. however, if they are broken or at least breaking, there would be a clicking when you turn wile driving..... but this is proof that just like men with sex, your truck needs the 4x4 engaged and used at least once a year, wether you need it or not....lol. Let us know. __________________ *Parts have been found, tools are collecting, tensions are rising, the weather is changing...look out.... the SAS is comming!*

03-27-2007, 08:41 PM	#3
riata_ag Junior Member Join Date: Mar 2007 Posts: 7	Its a dually with the big steel dually wheels on the front. The center of them is hollow with only an axle nut showing back in the hole in the wheel. So I assume they are auto locking, but I wasn't sure if they were like the mid-90's Ford hubs, or if they worked off of vacum or electric, etc.. Realizing that they are 17 years old maybe I need to buy new hubs? Thanks in advance for your suggestions. riata

03-27-2007, 09:01 PM	#5
riata_ag Junior Member Join Date: Mar 2007 Posts: 7	I assume they are not MANUAL since there is not a a dial or switch to turn, right? Yes, I did recently purchase the truck to use as a feed truck and I did try out the 4WD as far as the transfer case working, but I had to wait for rain so I could spin the tires a little in the mud to see if the front tires were spinning, and they weren't. I think it has been about 8-10 years since the 4wd was last used.

03-27-2007, 09:25 PM	#7
riata_ag Junior Member Join Date: Mar 2007 Posts: 7	its not a solid front axle. It has small CV axles connected from the diff. to the hubs.

03-28-2007, 09:24 AM	#9
436'd skylark Senior Member Join Date: Mar 2007 Location: Buffalo Ny Posts: 627	The front of your truck doesn't have hubs, The CV shafts is directly splined to the wheels. the engagement and disengagement is done in the differential. There is a thermal actuator that switches on when the lever is pulled via a switch in the transfer case. The actuator heats up and expands and pushes something in the front diff to engage. This system is notoriously slow and crappy. It normally takes 10 or 15 seconds to engage, which seems like a lifetime to wait, every time. There a few things to check. First, you might not have waited long enough, like I said it takes along time. There is a fuse for the actuator in the fuse box, labeled "4x4" it might be popped. If it is, replace it. Pull it in 4x4, and if it instantly pops again, the actuator is likely shot. its a dealer only item around 75-100 bucks. very easy to replace The connector is under teh truck and could be corroded. If the fuse is good, un plug the connector while the truck is in 4x4 and make sure you have power at the connector. more than likely the actuator is toast. common on those. __________________ Joe 89 K2500 Chevy, Wee-Oh-five 285K miles, completly rebuilt needs a motor, bad 1962 IHC Scout All Wheel Drive (Scout speak for locking axles) 152 ci, dana everything else

03-28-2007, 02:00 PM	#10
riata_ag Junior Member Join Date: Mar 2007 Posts: 7	Thanks alot I finally realized today after thinking about it that those CV axles do turn all of the time. I will check out that fuse and electrical switch tonight.

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