Diff fluid sprayed on underbody…..

[duece71]

All,
I just got back from KY and TN, drove I-75 all the way. Cruised at 110kms/hr (70-ish mph) and really nice and hot outside. About 10 mins from home on an outer belt highway at 65-70mph, I heard what I thought was a bump from the road and then a sudden intense petroleum burning smell entered the cabin. The AC was on, windows up and there were several large trucks ahead of me hauling equipment. The smell eventually went away and thought the trucks must have been the culprit. No other issues and made it home no problem. While off loading my bike rack, it felt greasy which I thought was strange. I decided to change my clothes and have a peek underneath just to make sure. Here is what I found…..
The pink fluid is diff fluid (Redline Hi-shok 75W90) and it sprayed upwards from the area around the rear diff lock. It was on the exhaust, the coil spring, some on the shock, around the diff lock, some on the wiring going to the diff lock and some residual that had dripped down to the bottom by the diff drain plug. There wasn’t any diff fluid anywhere else or on the left side of the vehicle. I wiped everything down, started the truck and checked to see if the diff lock would engage. The indicator light flashed for a while, I moved the truck forwards and backwards in the driveway and the light stopped flashing and was illuminated solid. I shut the truck down and checked if there were any more leaks, none found. There was NO diff fluid coming out of the drive shaft connection at the front of the diff. The burning petroleum smell was clearly the sprayed diff fluid on the exhaust. I took the diff lock protector shield off and didn’t find any fluid on the locker assembly itself.
The FSM shows a gasket between the indicator switch and the cover that the diff lock attaches to. The FSM also shows a seal (FPIG or “seal packing”?) on the cover itself that is attached to the differential. Any ideas? Did the indicator switch gasket blow or maybe the cover seal? What would cause this? I checked the diff breather hose and didn’t find any tears, kinks or leakage.
1990 HDJ81, triple factory differential lockers, all 3 were used this past weekend and last week, all lockers engaged and disengaged with switch actuation and transfer shifter.
It doesn’t look like I lost very much fluid but I am not 100% sure. Not driving it until I find out what happened.
Thank you for any input.

 

[NeverFinis]

That is very odd.

The front of the diff lock protector is covered with it, meaning it probably came from something forward of it.

I would say you hit a bottle of diff fluid on the road.

 

[Mark W]

deleted. never mind

 

[Kernal]

First thing is to clean that area off and take another photo or three including around where the diff carrier
is bolted to the axle housing looking for leaks and another showing the pinion seal area (where the driveshaft/U-joint/Pinion flange goes into the front of the rear Diff)

Have you checked the fluid level in the Rear Differential?

Have you checked your rear axle breather and pipe to see if anything is blocked? The breather, located on the left top of the axle housing running up a foot or so just under the floor, can be reached via the left rear wheel well, easier IME if the wheel/tire are removed.

You could wash off the mess and take it for a short drive (assuming the Diff fluid is not low), maybe slowly at first while listening for any odd noises,
then come back and check for leaks.

 

[robnicko]

That is very odd.

The front of the diff lock protector is covered with it, meaning it probably came from something forward of it.

I would say you hit a bottle of diff fluid on the road.

thats what I was thinking having driven over a 1Lt oil bottle one night in the dark and it made one hell of a mess underneath the car. I think the bottle had its lid pointed towards the diff centre so when the tyre went over it the lid popped off and sprayed under my car. Stunk like hell so off to the 24hr car wash I went.....

 

[NeverFinis]

I think something hit this spot

 

[mudgudgeon]

What's the odds of someone who's using pink diff oil hitting a bottle of pink diff oil randomly on the motorway?


Degrease the whole area and then look for sign off a leak

 

[duece71]

First thing is to clean that area off and take another photo or three including around where the diff carrier
is bolted to the axle housing looking for leaks and another showing the pinion seal area (where the driveshaft/U-joint/Pinion flange goes into the front of the rear Diff)

Have you checked the fluid level in the Rear Differential?

Have you checked your rear axle breather and pipe to see if anything is blocked? The breather, located on the left top of the axle housing running up a foot or so just under the floor, can be reached via the left rear wheel well, easier IME if the wheel/tire are removed.

You could wash off the mess and take it for a short drive (assuming the Diff fluid is not low), maybe slowly at first while listening for any odd noises,
then come back and check for leaks.

Ok, yes, I checked the diff breather tube, no signs of stress and the top cap moved up and down. Maybe I will take the tube off of the diff and stick a small straw or something down just to make sure there are no blockages. Yes, next step is to check the level of the diff fluid.

 

[duece71]

What's the odds of someone who's using pink diff oil hitting a bottle of pink diff oil randomly on the motorway?


Degrease the whole area and then look for sign off a leak

IMO, the odds are a real long shot. Traffic was quite dense as it was close to 5pm, maybe a bottle of pink lube fell off of one of the trucks carrying equipment that was ahead of me in traffic. I will post up what I find.

 

[western flyer]

Any chance you had a high speed run during this trip? I had a diff spurt oil out of the diff breather during a somewhat fast run leaving a similar (but smaller) mess. Long shot, but more likely than pink bottle of oil falling off the truck in front of a rig that uses pink lube. I had a pinon seal fail following rock damage that spurted oil like that.

Probably good to drain the diff and measure what was in it to see how much oil is left (to determine if you lost any oil), then clean and search for problems like others above noted.

 

[mudgudgeon]

Any chance you had a high speed run during this trip? I had a diff spurt oil out of the diff breather during a somewhat fast run leaving a similar (but smaller) mess. Long shot, but more likely than pink bottle of oil falling off the truck in front of a rig that uses pink lube. I had a pinon seal fail following rock damage that spurted oil like that.

Probably good to drain the diff and measure what was in it to see how much oil is left (to determine if you lost any oil), then clean and search for problems like others above noted.

Even just a long distance run on motorways, gets everything heat soaked, more so than normal driving. I'll smell gear oil from my manual trans 80 after a few hours motorway time, otherwise, i don't.
If the breather hose is blocked, could have puked oil somewhere else.
Common for the breather hose barb in the housing to clog up

 

[Shipwreck]

Common for the breather hose barb in the housing to clog up

I agree with @mudgudgeon .
I would take some time to remove, clean and clear your axle housing breather. If it is partially clogged it can allow pressure to build up in the housing, especially during the heat of highway driving.
Also look carefully at the diff-locker breather tube. Make sure it is attached and not split or cracked.

This breather tube exits the diff-lock actuator and enters the wiring loom that travels up the rear control arm. The end of the tube is just open, with no valve on the end.

If pressure has built up in the axle housing due to the other axle breather being clogged, it is possible that the pressure will force diff fluid out this diff-lock breather. It will spill out forward, and above the differential near the control arm. Your pictures indicate this might be happening.

That's my theory, anyway.

 

[DIRTBIKEUSA]

I think you got a combo going on here.

Possible issue with your rig.
Possible you ran over a jug of oil as well.
Running over the jug brought your attention to the issues with your rig..

 

[BucketEighty]

I think @Shipwreck has it right, your main breather hose is clogged and a bunch of gear oil puked out of the locker assembly breather hose because of it.

 

[duece71]

Alright,
I got the cruiser into my garage and removed the drain plug. NO diff fluid dripped out. I stuck my pinky finger in and it came out covered in diff fluid. I put some diff fluid (redline hi shok 75w90) into a hand pump and pumped it in. It took about 30-35 pumps before I saw the level of the fluid up to the fill hole. I gave it one more pump and fluid started to drip down below the fill hole. It looks like I definitely lost some fluid. I reinstalled the fill plug with a new metal gasket and tightened it but not to torque spec. I took the diff breather line off and blasted some brake and parts cleaner through it from both ends. I checked it carefully and didn’t see any damage/cracks. It’s probably the original rubber tube. I took a thin straw and carefully poked it down into the breather plug on top. There was some resistance but not much. I moved it up and down a couple of times and and all clear. Maybe it was partially blocked? I resecured the breather tube and cleaned everything up. I took a short drive around the neighborhood and returned to my driveway. When I looked under and around the diff……nothing, no pink fluid anywhere. I drove a bit further to fill up on diesel and checked again…..nothing. I decided I would take it up to highway speed for 1 exit. I got the cruiser up to 70 mph, no weird noises, no loud grinding, everything sounded normal. In the driveway at home….nothing, no pink fluid anywhere. I probed all over the diff lock assembly and on top of the diff with my fingers….nothing at all. I think what mudgudgeon and shipwreck suggested might have happened. I did wheel through some 2-3 ft deep muddy water last week and last weekend. Could something have gotten into the diff breather and plugged it? Wouldn’t I have had this happen much sooner? It was almost a 7 hour drive (baaad traffic, Bucees stop in KY, road construction etc….) from TN back to Columbus. My speed was 70-75mph most of the time when not stoppped in traffic. No idea about this except that I think the diff breather got plugged and diff fluid had to come out from somewhere. But where??? I didn’t even know the diff lock had a breather line and yes, that line is attached and doesn’t seem damaged at all.

 

[duece71]

Sorry, pictures are reverse order.

 

[Shipwreck]

I did wheel through some 2-3 ft deep muddy water last week and last weekend.

Ahh, the plot thickens...
It looks like you didn't lose enough 90 weight to cause gear damage and you are probably good to go. However, you are not done yet. Did you drain any of the old gear oil out before refilling? If not, here is what I would recommend: Open the drain plug and drain a portion of the oil into a clear jar. Let it stand and look for water settling to the bottom.
Water in the axle housing exacerbates the pressurization of the housing if the breather becomes clogged. Remember, water expands and vaporizes as it heats up, oil, not so much. It's a classic scenario. As you drive, the axle housing heats up. When you submerge the warm axle housing into water, it cools rapidly, sucking water into the housing as the pressure changes from positive to negative. That little one-way valve on the breather is supposed to prevent this, but if it is not in perfect working order, or your axle seals are worn, water can get in. The muddy, gritty, dirty water can also cause the breather to clog. Then you hit the interstate, heat up the water and puke oil out the actuator.
For peace of mind, I would want to make sure there is no residual water in your diff.

 

[duece71]

Ahh, the plot thickens...
It looks like you didn't lose enough 90 weight to cause gear damage and you are probably good to go. However, you are not done yet. Did you drain any of the old gear oil out before refilling? If not, here is what I would recommend: Open the drain plug and drain a portion of the oil into a clear jar. Let it stand and look for water settling to the bottom.
Water in the axle housing exacerbates the pressurization of the housing if the breather becomes clogged. Remember, water expands and vaporizes as it heats up, oil, not so much. It's a classic scenario. As you drive, the axle housing heats up. When you submerge the warm axle housing into water, it cools rapidly, sucking water into the housing as the pressure changes from positive to negative. That little one-way valve on the breather is supposed to prevent this, but if it is not in perfect working order, or your axle seals are worn, water can get in. The muddy, gritty, dirty water can also cause the breather to clog. Then you hit the interstate, heat up the water and puke oil out the actuator.
For peace of mind, I would want to make sure there is no residual water in your diff.

Sounds great, I will drain it and see what I can see. Do you think the axle seals are worn? I don’t see any fluid leaking out on to the rear tires. I want to get the extended breather lines and route them up to a high spot in the engine bay. I think Terrain Tamer sells a 2 breather kit and a 3 breather kit. Looking for them now.

 

[Kernal]

Another option is to route the rear axle breather up into the left rear quarter panel. There is a factory hole and grommet on the inner aspect of the quarter panel cavity ie: looking from the spare tire to the backside (at least in US FZJ80's as most had a tow harness installed which came out via that grommet/hole).

 

[Shipwreck]

And you don't need a fancy expensive extension kit. Just go to the local auto parts store and buy some bulk fuel hose. Some guys put an in-line fuel filter at the end, I just put the stock one way valve back on.