How do I tell if it's the valve cover or RMS leaking?

thomat65

thomat65

TJ Enthusiast
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Nov 9, 2019
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351
Location
Southwest MI
2004 4.0L auto. 190-something thousand miles.

There's a drip coming from the RMS area down the transmission.
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Sorry, I don't know what my camera was focusing on.

The bottom of my oil pan is dry.
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...in spite of some missing bolts. I need to fix that...

And as far as I can see it's dryish around the valve cover.
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Plus, that valve cover gasket was replaced about a year/6k miles ago.

If I swipe my finger behind the block below the valve cover then it's definitely greasy, but not super wet where I can reach. And it's not like it's ever been cleaned back there.

So what's the verdict? RMS? Replace the valve cover gasket again?
 
Maybe this is why the bottom of my oil pan is dry.
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I'm the worst owner this Jeep has ever had.

I tossed a quart of oil in. I do like how easy it is to access the oil hole. Much easier than my car.
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It is possible that the back of your valve cover gasket is weeping very slightly. This and a buildup of dirt/ crud could result in the greasy condition. I'd recommend cleaning the back of the cylinder head as much as you can reach. Use a good degreaser and get it as clean as you can, then monitor it for a few days. If it's still weeping you'll be able to tell by wiping the area with a clean rag or paper towel.
 
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Ohh my efing Lord, this gets better and better and I am only on my 3rd round of limonchello
 
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If your RMS is leaking and if you're running a synthetic engine oil there's a better than good chance simply changing to a High Mileage CONVENTIONAL engine oil will cure it. Not just plug it up but cure it. Synthetic engine oils are known to be able to cause RMS leaks.
 
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SvtLdr said:
Please don't tell us you poured oil in the radiator?
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Haha no. That was a joke.

SvtLdr said:
It is possible that the back of your valve cover gasket is weeping very slightly. This and a buildup of dirt/ crud could result in the greasy condition. I'd recommend cleaning the back of the cylinder head as much as you can reach. Use a good degreaser and get it as clean as you can, then monitor it for a few days. If it's still weeping you'll be able to tell by wiping the area with a clean rag or paper towel.
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Good idea. I'll do this.

Jerry Bransford said:
If your RMS is leaking and if you're running a synthetic engine oil there's a better than good chance simply changing to a High Mileage CONVENTIONAL engine oil will cure it. Not just plug it up but cure it. Synthetic engine oils are known to be able to cause RMS leaks.
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Another good idea. You guys are great. Keep it up!
 
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Go to your local car wash and use the engine degreaser and clean your engine as much as possible.
Then get a bottle of UV dye and UV light and glasses.

https://www.amazon.com/dp/B008PKV07O/?tag=wranglerorg-20
Example of dye. They sell kits with everything you need. Put dye in the engine and drive around for 30 minutes. Then check for leaks. The dye will help identify where the leak is at.
 
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Wildman said:
Go to your local car wash and use the engine degreaser and clean your engine as much as possible.
Then get a bottle of UV dye and UV light and glasses.

https://www.amazon.com/dp/B008PKV07O/?tag=wranglerorg-20
Example of dye. They sell kits with everything you need. Put dye in the engine and drive around for 30 minutes. Then check for leaks. The dye will help identify where the leak is at.
Click to expand...
Is the dye hard to spot under UV light with the naked eye?
 
Definitely looks like a RMS leak to me. The bottom of the oil pan doesn't necessarily accumulate oil with a RMS leak. Mine mainly comes through and down the bellhousing.
 
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thomat65 said:
Is the dye hard to spot under UV light with the naked eye?
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Like Jerry said no not when doing it in darker conditions.
I like using the UV flashlight and found that I didn't need the glasses about half the time.

But it sure makes it easier to find out where the leak is.
 
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Tob said:
Definitely looks like a RMS leak to me. The bottom of the oil pan doesn't necessarily accumulate oil with a RMS leak. Mine mainly comes through and down the bellhousing.
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True, oil pan does not accumulate oil leak, but it is not necessarily rms only. Rear of valve cover is a fairly common leak spot, and it also leaks down back of engine to bellhousing.

Both, RMS and rear of valve cover, are common leak spots. Valve cover should not be leaking, it is simply a hard spot to get to and apply proper torque, even on new seals. And RMS is inherently prone to leaks.

I had a good success with applying Permatex Super 300 on new valve cover to spot a leak. It has been over a year and not even a wet spot around it.
RMS on other hand, changed mine 3 times in a row, still leaks, and oil type makes no difference to it.

Valve cover goes one step further and spreads leak through intake manifold on later models, which result in oil dropping on O2 sensors, and as a result destroys them.

I had to change my O2 sensors 3 times in a row till I finally figured out what caused them to fail one after another.
 
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