Cylinder Head Rear Freeze Plug

Eric M · Jul 20, 2021

So I'm in the middle of replacing the clutch, clutch components, and RMS on my '98 SE (2.5L / AX-5). As I was cleaning the oil pan and back of the block, I noticed this "thing" on the back of the cylinder head was semi-popped out. I asked my coworkers what this was and they said it was one of those rubber expandable freeze plugs and they are usually a temporary fix. I guess previous owner tried really hard to make it permanent with all that sealant around the plug.

Anyways my coworkers were saying I'll probably need to take out the engine to replace it with a proper freeze plug. Luckily my coworker has an engine hoist and stand, but I'd like to see if there's an option to not pull the engine if I don't have to. Does anyone have any experience installing this freeze plug while the engine is still in?

Rec_Rider · Jul 20, 2021

You don't need to pull the engine to get to it. Pulling the head will allow you to get to the freeze plug. Your coworkers are correct, those types of plugs are a temporary fix and shouldn't be used for too long.

Eric M · Jul 20, 2021

Oh that's an idea. I can replace the head gasket while I'm at it too. Thank you!

SkylinesSuck · Jul 20, 2021

If the tranny is already off, I think I'd be inclined to pull the motor to replace that vs. pulling the head. Probably easier.

JEEPCJTJ · Jul 20, 2021

My "Plan A" version of what SkylinesSuck just said:

If the tranny is still off, I think I'd be inclined to lean the motor back to see if I had enough room replace that vs. pulling motor or the head. Maybe even easier.

I'll call SkylinesSuck's version "Plan B" because you never know when "Plan A" will fall through.

SkylinesSuck · Jul 20, 2021

I didn't consider the fact that it's 4 angry squirrels living under the hood. No way you'd have enough room with a 6 popper, but if you could just loosen the mounts and lean it forward enough, that would be ideal. No need to pull the head and bring with it all the potential things that could go wrong if you don't have to.

Irun · Jul 20, 2021

I've changed them by removing the motor mounts and carefully lowering and tilting the engine far enough to get access to the freeze/expansion plug on the back of the head

Irun · Jul 20, 2021

SkylinesSuck said:
if you could just loosen the mounts and lean it forward enough, that would be ideal. No need to pull the head and bring with it all the potential things that could go wrong if you don't have to.

Been there done that!

Eric M · Jul 21, 2021

I think my coworker just really wants me to pull the engine lol. That way it "makes it easier" to change intake and exhaust manifold gaskets, clean the damn thing, and search for the source of a high idle I'm also experiencing. Yeah it might be easier but I've never pulled an engine before! But hell if @Irun was able to change the rear freeze plug with the 4.0 while still in, I assume I'll have plenty of room with mine. Thanks all and I'll update when I get around to doing this.

Irun · Jul 21, 2021

Eric M said:
I think my coworker just really wants me to pull the engine lol. That way it "makes it easier" to change intake and exhaust manifold gaskets, clean the damn thing, and search for the source of a high idle I'm also experiencing. Yeah it might be easier but I've never pulled an engine before! But hell if @Irun was able to change the rear freeze plug with the 4.0 while still in, I assume I'll have plenty of room with mine. Thanks all and I'll update when I get around to doing this.

I, and others, have done everything you mentioned with the engine still in the Jeep. Pulling it out is more complicated than you think!

Eric M · Oct 2, 2023

After 2 years, I finally drove the Jeep into work today! Lowering the engine worked like a charm and I was able to get a new freeze plug installed easily. Really, it was trying to reinstall the engine onto the mounts that put my project on hiatus for over 1.5 years, coupled with general life.

I guess when I lowered the engine, the engine shifted slightly, so I couldn't get it realigned properly. I was thinking I would need an engine hoist, and that stalled my progress for a long time. Eventually, one day I just decided to "manhandle" it and I got it aligned!

So really my only advice if any others need to do this repair is to be careful when lowering the engine, because realigning it was a pain!

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Cylinder Head Rear Freeze Plug

Eric M

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