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3.0L Heavy Oil Leak at Rear of Engine


Rangstang

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Hello everyone!

I'm a long time Ranger owner, so I recently added a 2003 Edge 5 speed for my son to drive. Noticed it had a pretty serious leak coming off the bottom of the bell housing when I bought it, but figured a quick rear main seal replacement would take care of it.

When I got the flywheel off, I noticed it had been recently changed to a "FelPro" orange rubber seal just like what I was about to install, which concerned me a bit. Although, the installer had dented the seal in 3 places trying to install, so I figured that was it.

I noticed that the seal lip was riding in a different place on the crank than the original Ford seal was riding, so there were two clean paths on the crank surface. Needless to say, I spent a little time cleaning the crank with 320 grit and then followed up with 600 grit and 1000 grit before installing the new seal as I wanted to keep from damaging the seal on the carbon build up that was on the surface.

I also replaced the oil pressure switch/sending unit while the trans was out since it was easy to get to. During a visual inspection, the whole back of the block was dry inside the mounting area, so it didn't look to be leaking from something else. The only leak I could even see appears to be a minor one from the passenger valve cover.

Put it all back together and it leaks just as bad as it did before. I watched and determined it drips every 10 seconds.

This is not my first rear main seal replacement. I've done Mustang 5.0s at least 20 times and I replaced one on my 2000 Ranger 3.0 back in 2008. Any ideas? Thanks in advance for reading this long post...
 


Rangstang

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Did a little searching online last night and was reminded of the possibility of crankcase pressure causing the heavy leaking. This morning, I inspected the PCV hose and found it to be normal. I started it up and removed the dipstick to see if there was any pressure, positive or negative and found it to be neutral. I even put a plastic sandwich bag over it and used a twisty-tie to "seal" it around the tube, but never saw any change in the bag inflating or deflating.

I also jacked up the back of the truck to try and level out the transmission as these manuals are at quite an angle and it takes 20 minutes for the bell housing to fill up with oil enough to where it will drip out the front. After that, it seems to provide a drip about every 25 seconds or so.

Feeling like my only option is to assume that the rear main just isn't sealing to the crank and that I need to either go with a teflon seal, an OEM Ford seal, or a repair sleeve for the crank with a new seal.

Hoping someone will chime in with some thoughts.
 

Craig0320

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Yep most likely a rear main seal. I have changed them before and was able to drive them in a little deeper into the block and pass the old wear mark from the factory seal and did not have to use a repair sleeve. I have never had one leak. Be sure if you pull it down that you have enough room to drive it in further before you decide to go that route.
 

Rangstang

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Yep most likely a rear main seal. I have changed them before and was able to drive them in a little deeper into the block and pass the old wear mark from the factory seal and did not have to use a repair sleeve.
Would you recommend trying the PTFE seal? I don't want to do this 3 times.
 

Craig0320

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You could use a ptfe seal. Just be careful installing it. Do not lube the seal lip and make sure the crankshaft is completely dry when you install it. The ptfe seal is a synthetic polymer and it has a chemical in it that transfers to the crankshaft sealing journal creating a leak free surface. They have a really good reputation of not leaking if the crank surface is not worn away. If you lube the crankshaft and install it it is most likely going to leak.Or you could just buy a ford oem rubber seal lube the sealing lip and install it. I usually always use oem parts. But that is just me.
 
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Rangstang

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I usually always use oem parts. But that is just me.
I was on the fence whether to go with OEM or the PTFE. I bought the PTFE FelPro seal tonight, but the orientation of the plastic sleeve that is inside the seal would require it to be installed backward of traditional. It was an opened box, so most likely it was removed and replaced backwards. Did a quick search about this and found that even on the FelPro forum, the answer is "typically", not specific to the BS40646 seal.

Anyone know for sure if it's installed like the traditional seal orientation (closed end out)?
 

Craig0320

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I just thought about something. The oil sending unit for the 3.0 is on the top back passenger side of the block. If it is leaking really bad it could run down the transmission housing. It might even seep into the transmission bell housing. Give it a check to see if it is leaking first before you pull the transmission.
 

Rangstang

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I just thought about something. The oil sending unit for the 3.0 is on the top back passenger side of the block. If it is leaking really bad it could run down the transmission housing. It might even seep into the transmission bell housing. Give it a check to see if it is leaking first before you pull the transmission.
You probably missed it on my loooonnnnggg post, but I changed it just in case and it was dry anyway. Thanks though.
 

Craig0320

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Ah. Funny thing is I reread your op lol.
 

Rangstang

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Okay, pulled the trans again and polished the crank with 1500 grit. Installed the FelPro PTFE rear main seal using a 4" drain cleanout cap with a very small amount of black RTV around the outside of the seal. Only took like 6 taps with a rubber mallet to install.

Let it run for around 5 minutes in the driveway downhill (leaks out quicker that way) and no drips. Took it for a 10 minute drive and parked it for 5 minutes on a loading ramp downhill and not one drop.

Looks like it's taken care of. Thanks guys!
 

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