How do you determine RMS or VC leak? -
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post #1 of 4 Old 08-11-2011, 07:22 AM Thread Starter
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1979 CJ7 
Join Date: Dec 2003
Location: Schenectady
Posts: 1,462
How do you determine RMS or VC leak?

This might be a little lengthy and I know the VC and RMS topics have been beaten to death, but bear with me.

The CJ has been leaking for a while. Some time after doing what I thought was a good job replaceing the VC gasket the leak came back, so I assumed it was the RMS - which I am DREADING doing.

I just crawled under it to start the RMS repair I got to thinking maybe the oil pattern on the motor was questionable.

So far I have cleaned the outside of the motor/ trans in the area of the RMS, tightened the pan nuts (which were a little loose) removed the 2 inspection covers and cleaned behind them.
Started the CJ and let it run for a good 20-30, through the rpm range - no leaks. I even crawled under it while running to look for leaks.
Drove it 2 miles and let it sit for 10 minutes - small puddle had formed.
Drove it .5 mile to gas station. Fueled up and found 1 drop on the ground.
Drove 1.5 miles home, half hour later I have a decent puddle.

Now, the oil pattern on the motor is as follows:
Motor IS wet below passenger side of VC, but doesn't appear to be enough to cause this much of a leak.
Oil pan is wet from top to bottom on passenger's side.
Motor side of starter is wet.
I notice there is oil on the 'rim' of the transmission dipstick tube flange.
The torque converter inspection cover is wet from top to bottom, passengers side only.
The oil seems to be dripping off of the bottom passenger side bolt on the torque converter inspection cover.

My VC is definitely beat up from who knows how many PO's, so now I am thinking I might need to redo my VC gasket and not the RMS.

IF anyone has any thoughts on this, or a method to determine exactly which it is, I would GREATLY appreciate the heads-up. I'd hate to spend 3+ hours covered in oil, only to have the leak remain. I'd like to actually drive this thing some time this summer.....

Thanks in advance.


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post #2 of 4 Old 08-11-2011, 07:53 AM
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1979 CJ7 
Join Date: May 2011
Location: clinton
Posts: 487
A leaking VC is one of the most common mis-diagnosis events related to Jeeps. Most folks automatically think rear main seal.

In general, gravity works, so if oil is above the area of concern, it is not the likely culprit.

If the the oil is below the VC and above the head, then replace the VC gasket.

If it is below the head and above the various oil things such as sending unit, the CONSIDER the head gasket (but this is probably not the case).

If it is below the oil sender, oil filter, and above the pan, it is possible that they may need some attention.

If it is below the pan only, then it is the pan or RMS.

To partially validate the RMS thing, bring it to running temp, then park it on a hill facing nose down (or jack up the rear) sufficient to get the oil in the pan away from the RMS, and see if it still leaks. If it drips on a flat surface, and not on a hill, then it may be the RMS.
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post #3 of 4 Old 09-12-2011, 04:22 PM
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1978 CJ5 
Join Date: Apr 2011
Location: Gilbert
Posts: 426
I'm having a similar problem. Oil forms on the bottom of the bell housing. Seems as though it's coming down the drivers side of the bell housing from where the clutch linkage attaches. I'll attach some pics. Maybe your having a similar problem?
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post #4 of 4 Old 09-12-2011, 04:40 PM
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1986 CJ7 
Join Date: Jun 2008
Location: The otherside of your monitor...
Posts: 5,656
Smell the oil and make sure it is engine oil not gear oil. If the front seal on the tranny starts to leak you will sometimes see it at the bottom of the bellhouse like that. Once you have determined that it is engine oil get a shop towel and spray it with brake cleaner. Reach between the head and the fire wall and wipe the area clean below the valve cover. Go burn some gas on the highway. When you get back wipe you hand between the firewall area again. If you have oil on it theres you leak.

Only you can really determine where the leak is. Could be from blow by out the dizzy or breather. If is also possible that the oil pan is leaking and not the RMS but IMO if you pull the pan you should replace the RMS as well.

Look here for RMS info.

good luck

Under A Sun Thats See It All Before...
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