Expansion plug sizes 4.2 6 cylinder

[Curly]

I am replacing a bad freeze plug in the block, while I'm at it, I want to do the 3 small ones in the cylinder head. Can anyone tell me the size of the ones in the block and in the head? Searching Autozone, O'reillys and Napa, I am not finding the info. 1981 4.2 6 Cyl. Thanks.

[tgreese]

How to do this.

The obvious way to me - go to the parts book and look up the Jeep Corp part numbers for the parts you want. Then search the internet for the parts that match "Jeep <the part number>".

There are parts books on the Tom Collins site that should cover these parts. They are probably the same as what I show in the '74-80 parts book. Note that the 258 engines were revised for 1981, so the parts may not be the same. Up to you to check.

My book shows one 2" plug in the cylinder head, and three 7/8". These are 3105394 and 3172319 resp. The 2" plug is the same PN as the four plugs in the side of the block. There is also a cam plug at the back, 3172313.

The alternative is to wait until you take the engine apart, and measure them or match them at your parts store.

[Curly]

Thanks Tim. I'm not rebuilding the engine, just replacing one bad plug on the side of the block. Thought I should do all the ones I can reach while I'm at it. A mirror and a flashlight shows the one on the back of the head is ok, I'm going to gamble the one on the back of the block is ok too.