4wd Newbie - Need help with a possible leak

Just bought my 98 tacoma 4x4 DLX and when I went to take the skid plate off to get powder coated, I noticed some red oil residue. At first I assumed it was my steering rack but when I looked closer, it looks to be coming from the passenger side front axle. Any ideas what this leak is and if it is an at home job?

 

CV axle seal if anything is leaking from there, but it wouldn't be red.

Red would depict coolant (factory stuff), power steering fluid (transmission fluid basically).

 

Ok that would make sense being it’s right there by the axel seal. I cleaned it off and the rag was black but when I touched the skid plate, it kinda looked red. I’ll see if it pools up again overnight and check the color again tomorrow.

thank you

 

Could have multiple fluids leaking.

But a build-up of fluid right there is a cv axle seal; part numbers in my signature.

Since you'll be adding new fluid, just drain the old stuff and put completely new stuff in it;

$29 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90.

Replace the plugs too; part numbers in my signature.

When you remove the fill plug, make sure to use a pick to clean any and all dirt and grime out as the plug is pretty shallow. When you put your allen socket in, hit the rear of it with a hammer a few times to "break" it loose before removing it.

 

Another thing you could do "while you're there" is replace the o-ring, gaskets, and lube used in your manual hubs.

They're really easy to remove, disassemble, and reassemble. The only part that catches some people off guard is when they're attempting to remove the hub assembly only to get stuck trying to remove the cone washers.

Loosen the nuts until they sit flush with the stud. Take a brass drift, rest it on the nut/stud surface, and wack the top with a hammer or sledge maybe 2 or 3 times. That'll knock the cone washers right up and you'll be able to remove the entire assembly.

Don't have the part numbers off hand but they're easy to find online.

 

Before you go all in on this being the axle seal- I'd get in there with some foaming engine degreaser or simple green and spray everything in that area from the top down. Agitate everything you can touch with brush something like this:

And then rinse it really well. Once it's all clean you have to watch from the top down if any leaks re appear.

The issue with looking at leaks like this from the bottom is that they could originate from anywhere above. You need to identify the source before you throw parts at it. And given that the fluid color doesn't match the gear oil you'd expect to see from the diff, it's unlikely to be the source.

 

Thank you for all the info! I am going to give the undercarriage a thorough cleaning and see if the fluid re appears. Didn't see any this morning. I took the truck to a reputable toyota shop for a once over and they said everything looked good. Didn't really expect them to take the skid plate off but for $45, I'm sure they didn't. There was a ton of oil residue from when the valve cover gasket was leaking a while back and the previous owner never cleaned up the residual mess. Since the CV axle was hidden by the skid plate, I'm sure thats how they missed it.

I am not opposed to doing a front end overhaul as i plan on keeping this truck forever, but will wait and see if i truly need to replace these items first before i go out and spend a few hundred on parts.

I could be totally off on the red fluid too which is why I am going to wait and see what pools up again, if anything.

Again, really appreciate all the info!

 

Totally, was planning on renting/buying a pressure washer so I can't really clean the undercarriage. The truck has been all over the world, so it could use a thorough cleaning under there.

Like i said above, i am not opposed to starting fresh with all new suspension components, but will def wait until something goes out instead of replacing already good parts.

Appreciate the info! cheers

 

Update: so the leak is still there after degreasing and pressure washing the undercarriage and engine bay. Most of the fluid is on the bottom of where the CV axle goes into the carrier housing, probably due to gravity, but nothing in the engine bay is leaking, so i think its safe to say its coming from the carrier housing.

The fluid is red, and smells like gear oil (sulfur). Never seen red gear oil before, but I am not really an expert in gear oil colors. I do think the output shaft seal is my culprit but please correct me if you think I am off base.

 

Hows the coolant? Might be trans? I use mobil1 front diff oil and its yellow not red. Idk. Congratz on the truck I have one aswell but its a auto which i prefer. Uhm offtopic but i would change balljoints asap aswell.

 

May as well open up the filler on the front diff and stick your finger in there. If it’s red fluid, then you’ve found your leak.

 

Haha no worries. Coolant looks good and know what that smells and looks like from experience. As for the ball joints, I will def be replacing those lower ones if i have to pull the axles out. Currently they feel good, but they def look like they are as old as the control arms.

 

Haha Dur dur durrr .... should have thought of that myself. Thank you

 

Yepp, its the fluid from the diff... thanks for the blatantly obvious advice lol

 

It's April, you haven't fixed it yet?

Half hour job per side, which includes replacing the lower ball joints and bolts.

 

I started off initially saying you should change your diff fluid asap- and I don't think that's wrong. BUT... I did a due diligence google, and apparently there is one company that actually dies their gear oil red. Otherwise, if it's red in color, then it's almost certainly transmission or power steering fluid.

If you, yourself, did not put red gear oil in there, I would err on the side of the unknown, and replace that immediately with gear oil (twice- once to get the potential ATF out, and another (100 miles later) to make sure . Those seals don't tend to fail easily, and maybe ATF would explain why you're seeing a leak here.

I'd suggest at least a drain and fill on the diff, and see if the color of the leak changes. If it follows the color of the new gear oil you put in, you're 100% confident that it's an axle seal. If it's still red... then you're looking at PS or ATF.

 

I have had other priorities but this is now top of my list.

 

Thank you for the info! I did some gooogling and it is not a common color but I saw it pop up a few times in various forums. I don’t recall ATF fluid smelling like anything, but distinctly remember gear oil smelling like sulfur which is what that red fluid smells like. When I pulled the fill plug the fluid looked really clear, hinting to me it is relatively new. I will probably change though since now you put a tiny bit of doubt in my head lol.

Good thing I haven’t put it in 4wd yet (was waiting to fix this leak) so I know that front carrier hasn’t been spinning with possible ATF in there. Previous owner took good care of the truck so I doubt it’s ATF but better to be safe than sorry.