Bruce has to enroll at MJ academy

[brucecooner]

My first ever compression check was uneventful but interesting.

I started by looking up where the fuel pump relay was (second from the rear), and pulling that relay and the coil wire.

THEN I remembered you're supposed to let the engine warm up first.

I took the chance to scrub and OxGard the relay contacts, plugged things back up and started it up to let it warm.

 

The check itself is straightforward enough. Take out a plug, screw in the tester, push the gas all the way down and turn it over a few times.

The videos I watched to study conflicted with each other whether to take all the plugs out or leave them in.

I split the difference and left one of the next plugs out as I went down the line.

 

But I got some numbers (took three readings on each cylinder), and the numbers I got were consistent on each cylinder, and they look pretty good.

It showed in the middle 130's on 3 through 6.

Daylight ran out before I was done, and I couldn't even think about doing whatever it takes to get #2 out. That thing is BURIED.

 

Number one was a steady 118, but that one is pretty well guarded behind the AC compressor and I know I didn't have the fitting snugged in there.

I got out my extended needle nose and grabbed it best I could to tighten it down a wee bit.

Then #1 read a steady 128.  I feel like if I had been able to properly tighten the fitting it would have gone up a bit.

 

So I guess that's that.

I've heard you're looking for 130 or better so If I did it right, it shows readings right around where they should be.

I feel like parts are pretty well snuggled together inside, and the head gasket is in decent shape.

 

Plugged everything back together and it was a rough-ish start but it settled right in to idle.

Strangely enough the weird surging-suring-surging idle was considerably reduced this evening.

It does have a distinctly rough moment that reoccurs every few seconds. The engine shakes just a little when it happens.

It's making some concerning noises now though, and now sounds like it has an exhaust leak? 

Could swear that's new, so I'm wondering now if the exhaust manifold has cracked...

Old jeep ownership is certainly an adventure, whether you take them offroad or not.

 

 

 

[Pete M]

the key is similar pressures across the cylinders.  but anything 120+ is pretty good for an old Jeep engine.  

[brucecooner]

On 6/1/2022 at 9:29 PM, Pete M said:

the key is similar pressures across the cylinders.  but anything 120+ is pretty good for an old Jeep engine.  

I've heard that about consistent pressure too, but it wasn't on my mind. 

All the numbers were within about 10 PSI low to high (assuming #2 gives a similar reading).

Now to try and answer the question of how oil is getting into the breather if compression is not getting past the valves.

[Pete M]

7 hours ago, brucecooner said:

I've heard that about consistent pressure too, but it wasn't on my mind. 

All the numbers were within about 10 PSI low to high (assuming #2 gives a similar reading).

Now to try and answer the question of how oil is getting into the breather if compression is not getting past the valves.

 

super common.  gotta do the valve cover mods.