Felt knuckle seals caught fire (1 Viewer)

[bullsheadcruiser]

Recently riving my 1989 FJ62 it felt sluggish as if the parking brake was on or something was holding it back. We ended up pulling off the highway and the front end was smoking. Turns out the inside of both front wheels was on fire. We got the fires out by chucking water from bottles on it but I am still not sure what caused it. My sense is either the front calipers were frozen which would explain the resistance while driving, or that the grease had seeped out of the knuckles.I have had very seepy knuckles since I bought it 8/9 years ago and they've been looked at and I've been advised to have them rebuilt but it was never urgent. I haven't yet been able to get underneath and see if there is any grease left. Has anyone got any ideas as to what I should look at/for? The parking brake light is always on even when the handle is all the way down. It used to be that it would go out after while but for the past several months it has stayed on all the time. I suppose that could have caused the friction that caused the fire.

 

[franklin40]

park brake only is on the rear drums so shouldn’t be part of this problem (though it is one that should be addressed). you can take out the large square plug on top of the knuckle to see if you have grease in there. either way sounds like it’s time for a rebuild. if you’re out of grease there’s a brass bushing inside that may also have seized up and come loose from the spindle. you should be ready to get a new one of those too if it has. ask me how i know. then get new calipers and while the rotors are off go get them turned (or at least checked). brakes are a system you need to make sure are working properly. don’t put them off. while your checking them make sure your rears are adjusted and the cylinders aren’t leaking.

these jobs aren’t too hard. you’ll learn a ton about your truck if you haven’t done this job before. it takes a while the first time (like most of a weekend) but with pretty basic tools it’s not hard.

@cruiseroutfit (cruiser outfitters) for parts for sure

 

[Spook50]

I'm guessing your wheel bearings finally lost enough lubrication to heat up enough for the felt seals to combust. The real problem is that if things get hot enough for the felt seals to go up, the steel of the knuckle balls (where the birfield joints ride inside), and the birfields themselves have been annealed and lost strength; possibly the knuckles themselves too. I hate to be the bearer of bad news, but at this point I suspect (could be wrong; hope I'm wrong) you're into it for an entire new axle, housing included.

How much did the water sizzle when you splooged it onto the axle?

 

[bullsheadcruiser]

park brake only is on the rear drums so shouldn’t be part of this problem (though it is one that should be addressed). you can take out the large square plug on top of the knuckle to see if you have grease in there. either way sounds like it’s time for a rebuild. if you’re out of grease there’s a brass bushing inside that may also have seized up and come loose from the spindle. you should be ready to get a new one of those too if it has. ask me how i know. then get new calipers and while the rotors are off go get them turned (or at least checked). brakes are a system you need to make sure are working properly. don’t put them off. while your checking them make sure your rears are adjusted and the cylinders aren’t leaking.

these jobs aren’t too hard. you’ll learn a ton about your truck if you haven’t done this job before. it takes a while the first time (like most of a weekend) but with pretty basic tools it’s not hard.

@cruiseroutfit (cruiser outfitters) for parts for sure

Thanks very much. I'll dig around to see how I access the plug on top of the knuckle. I watched a video about front knuckle, hub and brake service overhaul and there are some tools that I definitely don't have such as the c clip spreader, the huge socket to remove the locking washer and inner nut behind the manual hub. How much do I have to remove to find the "large square plug on top of the knuckle"?

 

[bullsheadcruiser]

I'm guessing your wheel bearings finally lost enough lubrication to heat up enough for the felt seals to combust. The real problem is that if things get hot enough for the felt seals to go up, the steel of the knuckle balls (where the birfield joints ride inside), and the birfields themselves have been annealed and lost strength; possibly the knuckles themselves too. I hate to be the bearer of bad news, but at this point I suspect (could be wrong; hope I'm wrong) you're into it for an entire new axle, housing included.

How much did the water sizzle when you splooged it onto the axle?

It was a fairly short sizzle. It did alarm me though as I wondered if I had helped anything warp.

 

[OSS]

My guess is that the front pads were dragging due to binding calipers. And if there's a lot of grease & oil grime coating the knuckle assembly - I suppose it could heat up high enough to catch fire.

 

[Spook50]

My guess is that the front pads were dragging due to binding calipers. And if there's a lot of grease & oil grime coating the knuckle assembly - I suppose it could heat up high enough to catch fire.

Also very possible. My concern is the amount of heating it takes for the steel to light up the materials on it. That's enough to affect its strength.

 

[gbogh]

Post up some pictures of the carnage when you get a chance, it might help us help you.

 

[franklin40]

shouldn’t have to take anything off to get at the bolt to check grease. it’s right on top of the knuckle and it square. not a typical hex

 

[RredFJ40]

Your parking brake light could either be a bad switch or wiring, or low fluid level in the Master Cylinder.

 

[cps432]

Were you running with the front hubs locked going faster than 45mph? Cuz running your axle locked at highway speeds will toast some things.

 

[BILT4ME]

Were you running with the front hubs locked going faster than 45mph? Cuz running your axle locked at highway speeds will toast some things.

Ummm.......No, it won't.

 

[cps432]

Ummm.......No, it won't.

I toasted a brand new set of inner axle seals doing it. Ran 65mph on the highway for about two hours a day for a week after a snow storm and forgot to unlock my hubs. The seals were melted. Doing it once or twice by mistake probably won’t damage things, but the owners manual clearly states not to run over 50 mph. I’ve done it and dealt with the damage. If I had continued without repairing it I would have dumped all the oil out of my axle through the seals and metal would have begun to heat up. Luckily I caught it before anything really catastrophic happened.

 

[Spook50]

Were you running with the front hubs locked going faster than 45mph? Cuz running your axle locked at highway speeds will toast some things.

Nah, nothing to worry about with that. It'll put extra wear on the front driveline components and reduce your fuel economy, but won't on its own cause any damage. I've driven highway speeds many times with my hubs locked. Louder and vibrates a lot more, but that's all.

 

[BILT4ME]

I toasted a brand new set of inner axle seals doing it. Ran 65mph on the highway for about two hours a day for a week after a snow storm and forgot to unlock my hubs. The seals were melted. Doing it once or twice by mistake probably won’t damage things, but the owners manual clearly states not to run over 50 mph. I’ve done it and dealt with the damage. If I had continued without repairing it I would have dumped all the oil out of my axle through the seals and metal would have begun to heat up. Luckily I caught it before anything really catastrophic happened.

I have driven many makes and models over the years and have driven MUCH faster than 45 MPH on every one of them and have yet to toast a set of seals sue to anything other than having installed a piece backwards inside a set of locking hubs, which, in turn, started my hub grease on fire and smoking the wheel bearings.

I have driven NAPCO 4WD trucks, 1960 Chevrolet K10 4WD, 1968 Chev K20, 1978 K20, 96 LC. Open knuckle, closed knuckle, disc and drum brake versions.

The only one that wouldn't have been an issue was the NAPCO truck, as it would barely make 45 MPH anyway.

I would guess that there was an alignment issue with the hubs or a bent axle on there that exacerbated the problem if you smoked inner seals.
Did you have a hard time engaging and disengaging your hubs?

 

[ntdb]

Buy a fire extinguisher!

 

[bullsheadcruiser]

Were you running with the front hubs locked going faster than 45mph? Cuz running your axle locked at highway speeds will toast some things.

The hubs weren't locked. I haven't yet looked at the grease level nor the brakes to see if they were frozen, but will be able to do so next weekend. Someone who is rebuilding an '88 with a 2F engine is going to get it up on a lift and have a good look at everything. His first reaction was that the axle is probably going to need to be replaced though.

 

[cps432]

I have driven many makes and models over the years and have driven MUCH faster than 45 MPH on every one of them and have yet to toast a set of seals sue to anything other than having installed a piece backwards inside a set of locking hubs, which, in turn, started my hub grease on fire and smoking the wheel bearings.

I have driven NAPCO 4WD trucks, 1960 Chevrolet K10 4WD, 1968 Chev K20, 1978 K20, 96 LC. Open knuckle, closed knuckle, disc and drum brake versions.

The only one that wouldn't have been an issue was the NAPCO truck, as it would barely make 45 MPH anyway.

I would guess that there was an alignment issue with the hubs or a bent axle on there that exacerbated the problem if you smoked inner seals.
Did you have a hard time engaging and disengaging your hubs?

No, the hubs worked fine and still do. It was the first time I did the knuckle job and admittedly I may have done something wrong but everything functioned fine and was almost spot on with the alignment. No hang ups anywhere. I’m not sure what happened, now that we’re having this conversation... I just assumed I toasted them because I drove faster than what the owners manual suggests for an extended period of time for days and days on end. Who knows. I don’t have any pictures from back then... I used Marlin seals last time I was in there and I have zero fluid migration issues now.

 

[Randy88FJ62]

@bullsheadcruiser
Your knuckle seals have been leaking for far too long and the thick grease that used to be in the knuckles is a slushy mix with your differential fluid. You need to do a full knuckle rebuild with new bearings and the bronze bushings. You may get lucky and not need new spindles but that's in question given how you've abused it and lack of maintenance.

Just opening up the grease fitting on the knuckle and putting more grease in will not solve your problem. Address the front end before you blow the front differential. I bet you're low on diff fluid too.

Regarding annealing. You gotta get up to 500°F and hold that for awhile or up to 1400°F for a short period. I doubt you annealed the knuckles. The front birfields and spindles may be upset given the lack of lubrication.

If you can catch the front felt on fire then we can only guess what kind of condition your front end is in....

 

[DEADSALT]

and both sides on fire at the same time? ..... absolutely amazing!

“it was acting a bit sluggish like something was holding it back”