Here's the deal guys. My car is located in CA and I'm in Utah, so I really can't describe the exact problem in great detail, but here goes.

I got a call from my younger bro this morning (he drives the car occasionally) that theres some "oil" (fluid) dripping from the rear of my car. First thing that comes to my mind is the differential, so I told him to go underneath and try to locate the leak.

He calls me back and says its dripping some fluid (brownish similiar to clean oil) around the pumpkin, but he can't seem to locate the exact area. Also said most of it is hitting the rear tie bar and thats pretty much all he knows, so I told him to take my keys into my room and put them away because NO ONE is allowed to drive my car anymore.

Here's some history on the car. I'm running a CTSC w/ about 10lbs of boost with an AP2 Comptech Reinforced diff. After the diff. was installed I had the fluid changed w/in 1KMI and changed again after 3KMI, so 2 changes w/in 4K total miles. I did the 2nd change because my installer said he noticed some metallic residue during the intial change which he said might be common because it was the 1st flush since the car was new. During the 2nd fluid change he said everything looked normal.

Also, I drove the car about 3 weeks ago when I was down in CA and noticed a weird whirling noise coming from the rear of the car during acceleration, but there are some many noises coming from the rear (fuel pump, exhaust, and all plastic panels in the rear removed) that I didn't really pay much attention to it.

No finally the questions:

1. what color is REDLINE diff. fluid? I originally hoped the fluid drip was from the diff. mount but found out the fluid from the mounts are redish.

2. how do you know if your diff. is going bad? any signs before it actually breaks?

3. and will it cost the same to repair the diff. now (if it is the diff.) or after it actually breaks.

Any input would be helpful and if theres something I should tell my bro to look for then please let me know. I won't be back to CA until early May, so this issue is going to be on my mind until I find out what the problem is.

 

Have him look at the output shafts. They go into the diff on each side and connect to the drive shafts that connect to each wheel. If it is leaking from there, there will be a thin film of oil on the pan above the diff, under the trunk pan. That would mean you have an output oil seal that has failed. They are cheap and not that hard to replace. However you have to pull the diff to do them right.

If that is not it, have him look at the input flange. This is where the prop shaft connects to the diff. If that is leaking, there should be oil on the tip of the diff. That again would require the diff to be pulled and a skilled tech to do the work. You have to remove the flange and that releases the preload on the pinion. So reinstallation is critical. That is why a skilled diff tech woould be needed.

There are now only three other places that oil can leak out left. The drain bolt, the fill bolt and the cover seal. Since your list of mods includes a CT reinforced housing, it could be the case seal. That would leave the oil around that seal.

Since you say he saw oil on the rear tie bar, that leads me to think that it might be an output seal. The oil whould be only on one side of the other (right or left) unless they both failed. But the odds are slim on them both failing. You would know better since your installer did the rebuild as to if he replaced all the seals or not.

Sorry I can't help anymore. But without some pictures, it is going to be hard.

 

yeah, I kind of expected this would be a hard issue to resolve online w/o some pictures or better describtion of where the oil is actually coming from. I'm going to tell him to lift the car up soon and clean the entire area and wait to see where the fluid is coming from. pictures will be posted shortly.

Thanks again

 

what about the mounts?

 

well I was hoping it was the mounts, but from searching previous thread the mount fluid is redish not brownish, so I ruled that out. let me know if I shouldn't have.

Thanks

 

The problem you describe is very similar to what i experienced when my diff mounts went out, and i remember that the fluid was a dark red, but looked brown under the car. Good luck

 

And what color do you think redline diff fluid is?


We're getting this from someone (you) who is getting this from someone else (your bro). Now, we're sitting here asking you to ask your bro to check this and that and get back to you to get back to us. You see where I'm having a problem with all of this?
You're starting to get all worried about a "thing" that may or may not be the diff, may or may not be the diff mounts and you are asking yet another level of spectator (us) to diagnose that "thing" that may or may not be. Would you like to borrow my crystal ball?

 

i just talked to my lil bro again and ran some of this info by him. he thinks the drip is coming from top of the diff somewhere and will lift the car up tommorrow and clean the area out to get a better idea locating the drip. concerning the mounts, when they crack/break, how much fluid is actually in them that can be released and what are some of the signs other than just drips on the floor?

Thanks

 

xviper: yeah i kind of figured that i wouldn't get a good precise answer to problem with the current situation, but didn't know what else to do to help the issue other then blow some steam here. i will post more info or ask my bro to when i get something more precise.

thanks again for the heads up and more info will be posted once I get something to work with like pictures and such

 

There is only the diff vent at the top where fluid can possibly come out and this is HIGHLY unlikely as it would take an IMMENSE overfill to cause this to happen. A diff mount leak generally looks like a stream of reddish goo. It's quite thick and is not a fast leak. Over time, it gets covered with dirt and crap and looks like reddish/brown crap. It takes a while for it to actually form a drop that will find itself to the floor. By this time, the mount is pretty much gonzo.