Sludge on skid plate

So I just bought a 1996 SR5 Xtra cab a week ago from a fellow TW member and was looking over it. It's real clean and had been garage kept. When I bought it I went underneath and looked at the drive train and everything. It all looked fine, I pointed out some bolts that had a little bit of clean oil on them and he said he's never had a drip or he would've seen it on the floor. The bolts did have crush washers So i wasn't too worried.
Today I took the skid plates off and one was caked in sludge which could just be dirt and messy oil changes. I took some before and after pics of some sludge I took off the front diff and near the shaft for the front. Also a pic of the oil pan before I wiped it off.
Just wanted to know anyone's thoughts on what to look into cleaning and maintaining next.

 

How do the valve cover seals look?

 

Baseline the leaks: Hose leaks (oily areas), down with engine cleaner. Watch for new oil (leaks). Take appropriate actions.

You are trying to determine if all the oil under the truck is the result of sloppy oil changes or real leaks.

 

I concur. Clean everything up real good and monitor it

 

I would clean it up real good like suggested by the others, and also hit those drain/fill plug bolts with a torque wrench and make sure they're on there tight. Can't hurt to hit the bolts all around the diff too in case they might be loose and causing a slow leak. Then over the next few days watch to see where it's coming from. Right now it looks like a combination of possible leak(s), messy oil changes and excess grease flung around by the u-joints. Hard to tell what might be a problem and what just might be a messy spot.

 

Does it look like theres bolts missing?

 

I don't think so, I've noticed those same empty spots under my truck on the trans too. Not sure why they're there but I believe it's normal, maybe someone else can confirm

 

Oil pan doesn't look that bad. Mine weeps, but there's never been any drips. I've also never cleaned it. It couldn't hurt to put a new crush washer on the drain plug and retorque it.

 

Also, could the oil pan bolts maybe be over torqued? Looks like a rubber gasket is protruding out in the area I circled. Maybe I'm just trippin

 

Not sure about the oil around the back of the oil pan, but the oil on the front differential could be from oil changes. It's directly below the oil filter and there's no avoiding some drips when the old filter is removed. The skid plates can get caked in sludge if they aren't removed during an oil change.

I'd definitely clean the area around the back of the oil pan and see if it gets gunked up again.

 

Good stuff from everyone. Thank you guys. I can chock the differential and skid plate up to oil changes so that's cool. It is a 23 year old truck and I doubt anyone got under and cleaned it so for knowing all that it really is not bad at all.

I was wondering about the back of the pan and the front of the trans or flywheel. I'm gonna but a wrench on the oil pan bolts just to see how tight they are and maybe tighten if needed.

 

If you're right about the U-joints then I'm pretty sure the Ujoint probably threw oil on the trans/flywheel cover because they are right next to each other but I'm going to go cleaning and look around again right now

 

When greasing the ujoints the old grease gets pushed out of them and tends to get flung around everything that's around them when the driveshaft starts spinning, can make quite a mess

 

So it wasn't the U-joints that caused sludge in the flywheel cover/transmission. So I'll be watching that, it is right under that weird looking gasket that is squished between the trans and back of the oil pan.

I did see some oil/sludge residue on the back passenger side of the motor. Didn't look like alot but it did look a little more wet than the sludge underneath (more dirt underneath could mean less wet oil and more sludge). I checked all around the motor and it is only on the passenger side back corner, there is some kind of hole on a valve or something right there. First pic is looking down at it. Second pic is in line/plane with the valve and oil residue.

Right now I believe everything underneath is from oil changes and that weird gasket on the back of the oil pan.
This new oil I found on the motor is something I don't know so your help would be appreciated .

 

Based on those pictures, it looks like a valve cover gasket leak. You can try cleaning the area and carefully tightening those valve cover bolts about 1/4 to 1/2 turn, do not overtighten. If that doesn't work, the gaskets will need to be replaced. It's a fairly common maintenance item on older vehicles.

 

I believe I found the culprit gasket. The side my finger sits on is not attached and comes off while the right side is still attached
Also, checked the oil and the level was right at the top.

 

This due to:



Leaking rear cam plug. Change those too when you do the valve cover gaskets.

 

Just tightenend up the bolts for the valve cover and all of them on the passenger side needed about 1/4-1/2 turn to get them snug

 

for fluid identification I would rub it between my thumb and index finger and see what it leaves behind, clear, red or brown, then sniff it then taste it. Anti freeze will separate from oil, brake fluid and ATF will mix with engine oil. Anti freeze smells sweet, brake fluid with bite your tongue, 90wt smells of sulfur.

 

Thank you for the advice. I believe it's just oil, I don't believe any brake or Antifreeze components are around the back passenger corner of the engine and I could see it in the uncovered threaded hole in the picture I took yesterday. I tightened the bolts, am gonna clean it a bit better later, and once I get my new Spiral cable installed I'll be taking it for rides to check it out.