The great leak hunt

[Yogi123]

I would imagine that this is a sticky somewhere, and if so please forgive me. My 84CJ leaks, imagine that, I think there may be more than one source (front and rear dif, valve cover, MS, etc...) I have placed cardboard on the ground and think I may know the answer, but I want to be sure. For instance if it is the front dif is it the seal or the pinion. In order to decide/know I think I need to clean all the grunge from the underside. My current plan is to go to the open bay at the local car wash and use degreaser on the underside and under the hood (w/o actually pulling the trigger on the sprayer, just let it go on "free flow") Hoping that will clean things up to give me a better idea on where to focus my efforts. What have you all done to clean the underside and engine compartment? Any painful lessons learned or tips?

 

[mriplaybass]

All CJ's "mark their territory"
Differentials are usually cover gasket or pinion seal. Rarely is it the pinion yoke itself.
Lots of places for the engine to leak. Front or rear main seal, pan gasket, rocker cover gasket, timing cover gasket. Sometimes you can just tighten the bolts on the valve cover, oil pan, and timing cover, but usually a new gasket is in order.
Depending on what Transmission you have, there are several gaskets and seals that commonly leak.
Transfer Case is usually yoke seals or pan gasket.
I would try to scrape as much gunk off as you can first before going to DIY car wash. Most car washes around here won't let you wash extremely greasy or muddy vehicles.

 

[Lumpy Grits]

I have a pressure washer.
My front and rear main seals leak, and has done so for 25+ yrs.
If I lose 1/2 cup of oil a yr, I'd be surprised.
Very common leak, is the back of the valve cover and folks think it's the rear main.
Make sure you have the correct PCV valve for your engine. AMC used several different ones, over the years.
LG

 

[Torxhead]

Check around the car wash and look for any signage indicating it is o.k. to spray off grease. Sometimes the owners of those places don't fancy grease in their filters.

 

[hole]

Buy yourself a cheap electric pressure washer and a gallon of Simple Green, put it up on jack stands/ramps in your yard/street and have at it. Valve cover gasket is it the top of the list usually, then the mains. If you have diff leaks, check that the vents are clear first.

 

[Yogi123]

Is it possible for a vent line to be to long? I found the front diff vent line. The line ran from the diff all the way up in the engine compartment and was mounted almost right behind the right headlight. It had an old plastic cap on it that rotated freely. Is that normal? Sorry maybe a noob question, new to all this.

 

[mtnwhlr]

That is the normal place for it. They are mounted high to keep water out of it when doing water crossings.

 

[Lumpy Grits]

Mine was at the top of the D/S radiator mount.
Still is

LG

 

[Yogi123]

If it's that long of a hose how does one ensure that it is clear of any blockage? If our CJ7 is a fair weather non off road jeep (I know that may anger a few, but we do have an "endangered species" sticker on the hard top) does it even need to be that long? Can I get away with a vent that is an inch or two above the diff?

 

[Yogi123]

Also checked with the car wash attendant (happens to be the owners son/partner) who looked at the grim and said "eh that should be alright". Followed by "so how much do you want for it" Haha. Didn't wash then as I was still in my work clothes, but hoping to be able to get it cleaned up soon.

 

[hole]

I wouldnt shorten the hose, regardless of its use.The shorter it is the more will get into it. Check to see if its clear

 

[Lumpy Grits]

LG

 

[slomo]

So where does you Jeep NOT leak? LOL That's the question.

slomo

 

[Belizean]

So where does you Jeep NOT leak? LOL That's the question.

slomo

Right there at the top of the valve cover where you pour the oil in

 

[Hedgehog]

Most differentials seep through the gasket more than leak. Sure some leak, but when you look under most old and used work vehicles there is a bunch of oily dirt around the differential with very little in the way of a true leak.

Just fixed a troublesome leak on the CJ. It ended up being a leaky oil sending unit and a need to put some thread seal on the threads of some support hardware. Easy enough, but several parts needed to be removed to get at the problem.