Confirm this CDR?

[Zeus51]

Hey guys, I replaced my original rear main seal and vacuum lines back in April on my M1008 and until today I have not had any issues. But today I found a small amount of oil that was gathering on the backside of my oil pan which appears to be coming from or around the rear main. Last week, I noticed some oil in the air intake so I changed my CDR for the first time as well as a new air cleaner because it was time. I used a CDR that looks like and claims to be a replacement for the CV871 that I was taking off. It has MF986309284 stamped on the outside. Which brings me to my question:

Can anyone vouche that this is an actual replacement for the CV871? If it is the correct part, are there any other possible leaks locations besides the rear main that I'm not thinking about?

 

[Drock]

Can't confirm the CDR, but I doubt it's the problem. Leaks are just part of owning these old trucks. Their 30+ years old and every gasket & piece of rubber is dry rotted from sitting, and WILL fail one by one. I would check for leaks up top. Starting with the injection pump and move back from there. Seal around the vacuum pump, or the sensor on the rear drivers side of the block, oil cooler lines, valve covers, and so on.

 

[Zeus51]

That's a good idea Drock. I know the IP is good. I'll try to check the vacuum pump and sensor. Quick question though, if the vacuum pump seal wasn't sealing, wouldn't my vacuum pressures be off a bit? Also, what drivers side sensor are you talking about?

 

[corelokt]

It looks just like mine.By seal, I think he means the oil seals / gaskets, not a vacuum leak. Your vacuum pump is for the transmission.
Oil be blown all over by the fan. Try cleaning it off and with it well lifted up front on stands, and wheels blocked in back, lay under it and watch.
Mine is high enough to do this without jacking it. I found several coolant leaks and oil leaks this way.

 

[Drock]

The vacuum pump fits in the block the same way a distributor fits in a gasser. There's a rubber O-ring that seals it to the block. Also I wouldn't count out the injection pump leaking fuel. Most of them start leaking out around the throttle shaft. That little bit of fuel mixes with all the sins in the lifter valley. And buy the time it makes it down the back of the engine it looks & feels like oil.

 

[Zeus51]

Yeah, that makes sense. I've been under it and I don't see any oil being blown on the fan. Problem is, I don't see an active leak anywhere while the truck is running and I'm lying underneath it. What I do see is oil run off coming down the back of the oil pan just in front of the flywheel cover. I guess I'm just trying to head off any leaks before they get too bad. But..... there's always the chance that I am over thinking it and should just wait until it gets worse. Thanks for the help!

 

[Zeus51]

The vacuum pump fits in the block the same way a distributor fits in a gasser. There's a rubber O-ring that seals it to the block. Also I wouldn't count out the injection pump leaking fuel. Most of them start leaking out around the throttle shaft. That little bit of fuel mixes with all the sins in the lifter valley. And buy the time it makes it down the back of the engine it looks & feels like oil.

I think I will just replace the vacuum pump gasket since I know I have never done it. Besides, it's time for an oil change anyway. While I am back there, what sensor is on the back of the motor on the driver's side? I'll probably change it while I'm there. I just need to know so I can read through the TM's for the correct info. Thanks!

 

[Drock]

I think I will just replace the vacuum pump gasket since I know I have never done it. Besides, it's time for an oil change anyway. While I am back there, what sensor is on the back of the motor on the driver's side? I'll probably change it while I'm there. I just need to know so I can read through the TM's for the correct info. Thanks!

I wasn't sure either LOL! I had to look it up just now myself. I think it's the oil pressure sensor? I need to change mine as well LOL!