Sudden onset--truck sitting only a few days, weather here foggy but around 50F 98 12v 4x4 4.10

Just now
Started truck, died first time but restarted immediately next time I turned the key
There's a loud humming noise, my brake pedal is super stiff
When I'm sitting, the hum gets really loud and I feel a vibration?
Hum sounds like something metal? Not a grinding, or chatter, a continuous
medium tone loud kind of a steady ringing
When I move forward, the hum is still there but alot quieter, but the truck feels like? brakes on?
I put it into 4wd, again I feel a lot of vibration, it doesn't seem to shift easily and makes a lot of noise but it does go into 4wd (I used low, didn't try high)
I moved a little forward and little backward to see if I could know something loose but it didn't change so I stopped, worried I'd do damage (or more damage)
I wasn't the last one to drive the truck...

What should I start looking for? thanks

 

OK, I checked all my fluids--everything normal.

Truck is parked (ignition off) in 4wd Low--the brake pedal feels incredibly stiff, thats whether the emergency brake is on or off.

I use 4WD low to back slowly when towing or just in tight spaces, instead of riding my clutch. I have POSI_LOK so that I'm actually in 2WD low, not 4WD low, I just thought that adding that would be better for the truck since I use the low gear alot

It isn't possible that the last driver drove very far in low gear, since it drives so slow its obvcious, but she might not have shifted the transfer case to regular 2wd correctly...its not likely but she could have driven in 4WD high, but if so it was only for less than 2 miles, more like a mile. (The shift stick positioning for 4WD high and 2WD are deceptive)

I'm afraid to start it and run it, Please give advice.

 

Do you use your park brake? If not the last person may have used it and it's seized on. The pedal may be up but the cables seize internally. Does your truck have 4 wheel ABS? If so is it the ABS motor? Power steering fluid OK?

 

Power steering fluid is full...I have had, however, a chronic leak and shamefully, I used some Lucas leak stopper, which I'm told will cause a worse leak...
I have the repair kit from Geno's, but it seems like time intensive job, so haven't gotten around to it...I"m inspired now to do it sooner

I do use the parking brake regularly, and since the light on the dash never goes off, occassionally I start down the road with it on, but never for very long...

Last time it was driven was to pick up a one ton pallet in the bed,
when they load it in we always have to stand on the brakes as they slide it in.
That was the last trip it made, but driver says it drove home no problems like usual and she says it was in 2WD when she got in, she didn't change anything with the transfer case.

If the emergency brake was seized, it would make the regular brakes stiff?

 

Not sure about the ABS... I think it does have it..and the ABS pump uses the powersteering fluid? But the steering fluid is definitely full, and since I put in the leakstop, it actually hasn't required adding any fluid at all. The fluid looks clean too...
How would I check the ABS pump?

And how do I check if the emergency brake cable is seized?

I have to head out the door for now (I'll drive the MINI), but I'll be checking back here soon as I get home again...thanks for the help!

 

The 4 wheel ABS tests itself on each start up. The amber ABS lite comes on then goes off if the test is good. The red "parking brake lite" is also used to warn of a hydraulic fault. If this lite is on all the time it may not be because of the parking brake. The red PB lite will also lite up if the amber ABS lite is burnt out and there is an ABS fault.

One way to see if the brakes are dragging is to just jack up one axle at a time and rotate each wheel.

 

Did you ever think the booster may be hung up. Stiff pedal, brakes applied with no push of pedal. Internal hydro boost failure. Still have normal steering??? PS pumg groaning noise??????

 

Dozer, the brakes are acting just like you said, and yes, I think turning the steering wheel was making a lot of noise, and it turned hard, as a matter of fact I think I turned it off when I was turning because the noise was scary and it felt stiff, tight, vibrating. The brakes are definitely applied, I can't even push the pedal.

Yeah, I think the noise could be a groaning noise...the power steering fluid was normal...and the brake fluid level looked normal too...
So if my booster is hung up or failed, how much damage can I do moving the truck? Can i "unhang" it?
To prevent any further damage, should I leave it right where it is, can I drive it into the garage?

I have a ton of horse food to pack to the barn now...bummer...


Busboy, now I remember I normally do have an orange ABS light check on startup, I'll recheck now. The red parking brake light has been on since I got the truck, I had new rear brakes and my shop said they thought the problem was in the dash since there was no problem in the brake system and they couldn't find anything to fix to turn it off.

 

Power steering pump. You might try replacing what's in there with Valvoline synthetic power steering fluid. Brake booster is a 'Hydroboost' unit.

 

If its power steering pump,
will I break something driving it 100 feet or so to the garage?

 

check out the power steerting pressure switch

 

Hmmm....is this a secret switch only you know about ?
tell me more...

 

Maybe your arms or leg
Think the damage is done, you may need to replace the power steering pump but first check if the screen is clogged up. The Lucas could have clogged it.

 

Maybe a vaccum leak in your booster if it or the wheels aren't hung up. All it takes is a little leak in the diaphragm, which can also cause a buzzing noise (how loud or how much depends on the size of the leak).

Just a foolish question, but if the wheels are hanging up, could you have missed fully disengaging the parking brake when your booster or PS failed?

Let us know when you get it fixed. I'm curious.

BTW: If it is JUST a leak in your booster diaphragm, you will cause no harm in driving your truck, you'll just have to get out your Adonis leg. I drove for six months in my car with no booster help, had to get a bigger pair of jeans for my right leg though.

 

OK. To move vehicle (limited distance), loosen the two brake line fittings at Master cylinder. You will have fluid escape under pressure so be carefull. That should release the brakes so can be moved. Now you will only have the park brake so no fancy driving. I believe it has hydroboost and not vacaum booster. That is why PS pump noise and lack of steering assist.