Rear Main Engine Seal

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Michael Murphy 2

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Hello,
Thanks for viewing my post.
The rear main engine seal on my 2010 ST xlt 4.0 has been leaking now for more than a few months.
I am planning on getting it replaced shortly by a local mechanic...not the dealer.
I am making this post to check whether there is something else that should be checked or replaced at the same time to save me money and future aggravation.
I have already added the oil pan gasket to the project.
Anything else?
Thank you,
Murph
 
Rear of the valve covers can leak down and look like a RMS leaking. Rear of the intake as well.
 
Hi Dave,
I have a 2010 ST xlt 4.0 2WD.
Should I still have him replace the valve cover gaskets?
And, pardon the ignorance, but what is the rear of the intake?? Is that a replaceable gasket also?
One other thing...what is the approximate cost of replacing the RMS?
And how much to replace both valve cover gaskets?
And how much to replace the rear intake gasket...if that is what it is?
Thank you once again,
Murph
 
I'm not real technician, just a backyard one. If it were me, I would have the shop diagnose the leak. Preferably with dye, this way you can drive around another week and find out where any oil leak is, how bad it is, and give you a quote. A quality shop will charge for the dye and diagnose the 1st time around. 2nd time they should inspect it for free and give quote(s) on the leak(s).

https://www.google.com/search?q=201...BBAhGAriAwQYACBBiAYBkAYI&sclient=gws-wiz-serp
https://www.google.com/search?q=201...CsICBBAhGAriAwQYACBBiAYB&sclient=gws-wiz-serp
I believe the RMS would be more because most engines you have to pull the transmission. If you have a 2 piece RMS then I could see the price.

https://www.google.com/search?q=201...WGB4YHeIDBBgAIEGIBgGQBgI&sclient=gws-wiz-serp
IMO, these prices are low and a quality shop will explain all that is done.
 
Yes, I already did that, but it was in the darn Pandemic and I simply thought I could get it done a bit later. At that point it wasn't leaking that much...maybe a drop every two days or so.
But now it's like three drops and I don't like the spot in my driveway.
Again...about how much to get the above issues, fixed?
Thanks
Murph
 
I would start over then. Because an oil leak can be a lot of little things or just one. Don't go in telling a shop what to fix because there may be nothing wrong with it and you'd be throwing money out.
 
Other possibilities?
* An OilLeak at RearMainSeal can result from PositiveCaseVent system not working as it should,
slightly increasing CrankCase pressure, forcing Oil around Seals that otherwise dont leak;
a Plugged\Bad PCVValve or Leaking\Diconnected PCVHoses may be the culprit.
PCVValve at rear of LeftValveCover needs renewal or cleaning with Carb\ThrottleSpray every 33kMiles\4Yrs,
along with inspecting associated RubberHoses+Elbows & PlasticTubes on both Left+RightValveCovers.
* An OilLeak at rearend of RightValveCover can result from the enclosed TimingChain being loose,
slapping the inside of the Cover, damaging the CoverSeal &\or cracking that end of the Cover itself.
Closely inspect rear ends of both ValveCovers for leaks\cracks.
Is there any rattle noise from that area, either briefly during cold starts, or after engin warms up?
Root cause of this TimingChain getting loose, is typically the associated OilPressurized TimingTensioner at the RightRear, wearing out or getting clogged with OilSludge.
Both RightRear+LeftFront OilPressurized TimingTensioners need renewal every 100kMiles\12Yrs,
along with Oil+Filter changes every 4kMiles\6Mths.
* Have you tried any LeakStopAdditive in your Oil?
Ive had some luck stopping small OilLeaks using ATP#AT-205 or LubeGard#SealFixx

Hope this helps.
 
Last edited:
Thank you for your time and responses. I have already changed the PCV valve. The mechanic who tears down and rebuilds motors every day, got under the vehicle and confirmed the RMS was leaking. Can I have confidence in his evaluation, or should I ask him to degrease the area and add the dye?
If so, how long should I drive it after the dye is added before having it rechecked?
Murph
 
Michael Murphy 2 said:
Thank you for your time and responses. I have already changed the PCV valve. The mechanic who tears down and rebuilds motors every day, got under the vehicle and confirmed the RMS was leaking. Can I have confidence in his evaluation, or should I ask him to degrease the area and add the dye?
If so, how long should I drive it after the dye is added before having it rechecked?
Murph
Click to expand...
Your mechanic will know, read the label on the dye bottle.
 
Michael Murphy 2 said:
Thank you....I will inform the mechanic that if he is not absolutely certain it is the RMS, that he should clean the undercarriage and put the dye in the oil.
Otherwise, he is responsible for additional oil leak issues.
Murph
Click to expand...
Old engines can have death of a thousand cuts. I would power wash the complete engine first. Take care of covering up the alternator and coil. It's hard to track an oil leak if the engine has leaks all over. Even with dye it is not a 100% call. Keep in mind that your RMS will leak down and not up. So after the engine is cleaned look for leaks after a few days of driving. If the top of the bell housing is wet with oil, you need to start up top. You could have more then a few leaks. There is no guarantee that replacing one gasket or seal solves the problem.

Check behind the passenger side wheel well. The timing chain tensioner is there. It can also leak oil.
 
My 2005 4.0L has a similar RMS engine leak @ 89,000 miles. Loses less than one half pint (8 ounces) in between twelve month oil changes. Reason I don't change oil at the recommended 6 month or 3000 mile whichever comes first interval is because I sent a 12 month old, 4000 mile oil sample to Blackstone Labs for analysis and EVERYTHING checked out OK with several months of oil life remaining. I only use time proven Motorcraft FL-820S filters. The positive Blackstone Labs results may have something to do with our usually mild climate and humidity in Hawaii. I've been living with a small rear main seal oil leak over three years with an occasional drip on the front cat that stinks but quickly burns off. My dilemma is a $20 rear main seal replacement + over $1000 in shop labor cost or continue with this annoyance until it becomes a fire hazard. I have tried Bars Leak and Blue Devil RMS liquid seal repair that both sealed well initially, but the drips reappeared on the bottom of the bell housing after less than one month.
 
Preference here is to continue 4kMile 6mth Oil+Filter changes, considering the OilPressurized TimingTensioners tendency to become sludged and stop working over time. Personal practice is to first spray a little carb cleaner down the OilDipTube and OilFill, idle the engine for 10-15min, then change the Oil+Filter. No doubt full syn oil will last 10k miles plus, but I want to keep those tensioners clean.
 
Nick Mann said:
I would never go 10,000 miles on any oil.
Click to expand...
Yep, certainly not advisable with a V6~4.0L~SOHC Engin, considering the notorious TimingTensioners.
Unfortunately it seems the typical vehicle owner neglects\delays\avoids routine maintenance, even
basic Oil+Filter changes, waiting\driving until something breaks & repairs are much costlier.
Many new vehicle buyers, spend that big money or at least have never-ending ever-larger payments,
then just don't do maintenance; they simply buy a new vehicle every 2~4yrs, leaving used buyers to
suffer with consequences of their neglect & deal with the lowly task of repairs+maintenance.
 
Hi folks,
Well, you all really helped with my leaking oil issue.
And yes, many said there could be more than one leak.
And yes, there were three of them....one on the back of the valve covers...so new gaskets there.
Then there was the Rear Main Seal.....so new seal.
And finally we found that the upper oil pan (i guess it is called the oil pan frame or something like that).....so all new gaskets and sealant. They also had to replace the engine balance tensioner as they found pieces of it in the oil pan.
Again, thank you all for your help....I love my 2010 Sport Trac and am a happy man knowing it is no longer dripping oil on my driveway. But it was not cheap!!
Oh, well.
Murphy
 

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