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kovic 07-10-2013 03:49 PM

Block Pressure Issue?
31 Attachment(s)
Hey guys,

I had just made a trip across the state in my CJ 5, it was 3 hours on the highway at 70 + mph. Fastest and farthest Ive ever driven it.

As in my other Thead "I made it" there were no major issues.

When I got there I noticed oil has came out a little around the rubber oil fill plug, possibly around the valve cover, the face plate for old fuel pump, where dizzy goes into the block, and possibly around the oil pan a little bit.

Keep in mind, this engine was rebuilt about 5000 miles ago, and the compression ratings are good so its not the rings.

The fuel pump face plate was homemade and seemed a bit warped so I ordered one from summit.

I was going to replace the dizzy gasket but then I read about the PCV system so I want to make sure its working properly before replacing other stuff.

The front hole on the valve cover has a pcv valve that goes right to manifold vac, and the back hole goes to the air filter. Thats it, nothing goes to the purge canister(ive seen it both ways). I shake the valve and I can here it opening and closing, its fairly new, its one of the single nozzel valves, not the two.

I guess I expected this a little bit with that much speed and distance, and I didnt lose anyoil according to my dipstick but it made a little mess of things.

Any suggestions? Should I just start replacing gaskets or is this a block pressure issue?

Thanks guys.


Balvar24 07-10-2013 03:50 PM

3 hours at 3-3.5k rpm would make mine leak. I just hit 3000 miles on a rebuild.

How much of a leak are we talking about?

kovic 07-10-2013 04:21 PM

31 Attachment(s)
Well, When I stopped for gas I noticed 2 drops on the cement before I left.
- Valve cover, seems a little wet around the cork gasket.
- oil fill plug, some I believe worked its way out and started to drift back along the top of the valve cover.
- mech fuel pump cover, wet to touch,
- where dizzy enters block, wet seems to carry down towards the oil pan, that is why im not sure if the oil pan is wet from that or has a leak of its own.

But it was not enough of a leak to read on the dipstick.

Hope that helps.



Chuckles0227 07-10-2013 05:46 PM

You are lucky id be down half a quart after that.

My advice would be just to leave it alone. If it ain't broke dont fix it

Balvar24 07-11-2013 07:29 AM

I wouldn't worry about it.

2Xtreme 07-11-2013 07:39 AM


Originally Posted by Chuckles0227 (Post 15663517)
....My advice would be just to leave it alone. If it ain't broke dont fix it

CJ's are like old Harley's....

If they ain't leakin', they ain't runnin'.

kovic 07-13-2013 07:40 PM

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Yea I know it is fairly normal for the 258 to leak. This jeep will be seeing highway speeds almost everyday now and I don't want to have to wipe the engine clean after every run.
Was just hoping there is a way to figure this out or is this engine just not meant for a lot of high rpm running.

I figured out the face plate for the mech fuel pump, I purchased the one from summit, it leaked like crazy, took it off and it was bent. I figured out that you have to barely tighten it, if you righted it a lot is will bend and leak.

There is still a slight leak around the dizzy.

My main worry is the oil that makes its way out around the rubber oil fill plug on the aluminum valve cover, it leaves a little puddle on the top.
I was told getting a vented plug may help the issue, but has anyone else had this. Any ideas?



Spieg8 07-13-2013 08:09 PM

Your profile has zero details about your drive train. I'd hesitate to make any suggestions without more information. What gear ratio axles, what transmission, etc..

kovic 07-13-2013 08:41 PM

31 Attachment(s)
I filled out what I could, Please either way, you can always give suggestions. Thanks


RWise 07-14-2013 04:17 AM

My dizy leaked until I tightend it down good.
PCV, is it working?
New does not mean good, new rings will have blow by until they seat. With the engine warmed up and at an idle remove the oil fill cap, anything coming out? (safety note, dont stick hand/s in moving parts like fan blades/belts/etc)
What flavor oil?
But if you are running high rpms (for this engine) it could well be normal,,,,

kovic 07-14-2013 09:27 AM

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Rwise, thanks for the response. Ill take it for another spin and then I'll take the cap off and see if anything is coming out. I have my dizzy down pretty tight, to the point where I dont want to tighten much more in fears of stripping the bolt.
Are there any sure ways of checking the function of the pcv?

I use shell rotella 15/40 oil.


kovic 07-14-2013 01:41 PM

31 Attachment(s)
Ok I took it for a spin, got it warm and then took off the oil fill cap. Nothing was coming out, and I even put a piece of paper over it to see if there was air being pushed out(blow-by) there was nothing, if anything the paper was getting sucked to the hole. It is just a rubber cap the sticks into the hole, maybe its just not sealing enough....


Balvar24 07-15-2013 08:07 AM

Sounds like it's not a block pressure issue, if air is being pulled into the valve cover.

How many RPM's at 70 MPH? 55 MPH?

kovic 07-15-2013 10:30 AM

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I have no Tach but am going to purchase one today, I will have to answer that exact question later after its installed and after a few runs.


Spieg8 07-15-2013 11:56 AM

If we knew your gear ratio and tire size, we could ball-park your RPM

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