Well now that I got some time and my new to me LB7 I am going through it with a fine tooth comb. Last night I made sure everything was greased. I got fluid to change my front and rear diff also need to change the ally filters. Anything else I am forgetting??
While I was working underneath the truck tonight I took off the aluminum brush guard and the other side of the guard (the engine side) was an oily mess. I then looked further into it and noticed that the passenger side trans cooler line was all wet and slick with oil. Also noticed that there was a lot of oily mess between the oil pan and transmisson. Any ideas on what could be leaking? I was thinking of taking the truck over to the car wash and hosing off the underside of the engine to see if might just be some old oil from when the injectors were replaced.

Sometimes the cooler lines develope leaks at the "crimp" at the fitting. It could be a simple "O" ring replacement if it's like the fuel lines. I don't know for sure.

The tranny pan, I would just try to tweek the pan bolts a little tighter while you're under there replacing the Allison filter. Trans fluid tends to "clean" the area it's leaking at. That would be a good indicator if it's an active leak or leftover residue from the previous work done.

Well now that I got some time and my new to me LB7 I am going through it with a fine tooth comb. Last night I made sure everything was greased. I got fluid to change my front and rear diff also need to change the ally filters. Anything else I am forgetting??
While I was working underneath the truck tonight I took off the aluminum brush guard and the other side of the guard (the engine side) was an oily mess. I then looked further into it and noticed that the passenger side trans cooler line was all wet and slick with oil. Also noticed that there was a lot of oily mess between the oil pan and transmisson. Any ideas on what could be leaking? I was thinking of taking the truck over to the car wash and hosing off the underside of the engine to see if might just be some old oil from when the injectors were replaced.


Did you ever figure this out? I am having the same issue.

Well now that I got some time and my new to me LB7 I am going through it with a fine tooth comb. Last night I made sure everything was greased. I got fluid to change my front and rear diff also need to change the ally filters. Anything else I am forgetting??
While I was working underneath the truck tonight I took off the aluminum brush guard and the other side of the guard (the engine side) was an oily mess. I then looked further into it and noticed that the passenger side trans cooler line was all wet and slick with oil. Also noticed that there was a lot of oily mess between the oil pan and transmisson. Any ideas on what could be leaking? I was thinking of taking the truck over to the car wash and hosing off the underside of the engine to see if might just be some old oil from when the injectors were replaced.
The first time I changed my oil on my truck, the oil drained right onto that alum pan. It wasn't right away, but when it was almost out and just a weak stream when it did it. The oil all over everything else could just be that it is blowing out all over while driving.

Its red fluid. :)

Part of it could be the "puke tube" on the PCV. The PCV oil separator and return line vents right at the passenger side front of the engine and will leave a greasy mess in that area just inside the lower A-arm on an LB7.

The cooler lines do leak especially in cooler weather. Mine is doing the same thing just not all the time. I don't think it is something that will blow apart on you and cause a lot of trouble but if you want to be sure I'd replace the line. About a hundred bucks and a bit of time and cussing and its all done.

Its red fluid. :)


Check your transfer case!!! Look for a hole, I'm waiting on my new one to come in right now for the same reason. :mad:

When you buy your new Allison tranny filter and get ready to install it, put a clean plastic gal milk jug with the top cut off under the filter. Then take off the old filter, collecting the fluid that comes out and then pour the fluid from the filter into the milk jug.

Now pay attention, look at the old filter before tossing it. On top of the filter is a round doughnut magnet. Take it off, see what kind of stuff it collected, clean it and put it on the new filter and screw it in. Then add about the same amount of fluid that you have in the milk jug, plus just a little more.

Unless you know when it was replaced, I would also drain the old fluid out of the tranny at the same time, and replace it with Mobil 1 Synthetic ATF meeting Dexron III since you are doing the other fluids.

JMHO.

Check your transfer case!!! Look for a hole, I'm waiting on my new one to come in right now for the same reason. :mad:


YES!!! CHECK TRANSFER CASE!!!! I was staring to hear a horrific noise from my truck and noticed an oily mess underneath. -:tTransfer case lost all fluid and now Im getting a new one.:(

I think it was a combination of the tranny cooler line leaking, for a long time it was 1.5 quarts low. the PVC tube, and some loose bolts on the oil pan. I bought some teflon tape and fixed the leaking tranny cooler line, tightened the bolts and then took it to the 25 cent carwash with a jack and lifted up my truck and hosed everything off. It has been clean underneath since.
Kevin