Re-use head gasket?

So I've come full circle...

A few weeks ago I found a leaking freeze plug on the side of the block. Pulled the manifolds, replaced all 5 plugs on the side of the block. I used some Dorman 2" steel plugs I got from O'Reillys, with black RTV around the edge for good measure.

While reinstalling the manifolds, I snapped the rear stud off. Pulled the head so I could drill it out and replace with a stainless stud. Spent a couple of weeks (off and on between work and stuff, bumming rides) cleaning out the sludge and carbon from the head and from the block, and replacing the freeze plug at the back of the head (since I was there...).

Finally got it all back together today, pour 70 bucks worth of coolant and oil in it, and do one final check before I crank it over. I notice a wet spot on the bellhousing. Get out the inspection mirror and discover that the new freeze plug on the cylinder head is leaking. Great. Take a look at the side of the block under the manifolds...and all 5 of those new plugs are leaking too! A steady drip on all of them.

So I've already got the head pulled again. I have two questions, really:

-Do I need to get another head gasket when I reinstall the head? I am leaning towards yes, but... I had replaced the old one with a nice Victor-Reinz from rock auto, and all I could get locally tomorrow would be a Felpro. The VR has only been torqued down, it hasn't been run at all. What do you all think?

-What the heck am I doing wrong to have 6 out of 6 new freeze plugs end up leaking? They are chinese Dorman plugs, but that was all I could find. They seemed to fit pretty well, I installed them while cold, straight out of the freezer, with some black RTV smeared around the lip of the plug. Tapped them in with a big socket, they seemed to seat well. I also had cleaned up the bores in the block pretty well before I installed them. I thought I had done a pretty through, by-the-book job.

I sort of enjoyed pulling the head the first time (my first time pulling a cylinder head), but I might take a sledgehammer to something valuable if I have to pull it a third time.

Any advice/suggestions would be appreciated.

4.0L/AW4/NP231

-Rob

http://www.permatex.com/documents/tds/automotive/80008.pdf

Old school but it works, Indian Head is also supposed to be good you'll have to ask OldMan about it though, I haven't seen any around here for years. There are likely newer gasket Cements that work as well or better, but the old tried and proven stuff is known to work as advertised. Henkel (Loc Tite) makes stuff that works as advertised, I've never gone wrong with any of their products.

Head gaskets often come with a coating, the coating gets damaged and it may not seal. I've had good luck with Fel Pro blue which comes with a silicon (I think) coating. I've also used Mr. Gasket with Mercedes head gasket glue. But in my opinion it is likely to be a one time deal, it is unlikely to ever come off again without screwing something up..

absolutley do not reuse the head gasket, once it is torqued down it will not seal correctly again. The felpro gaskets are great, that is the only ones I use.

In a hurry, I'd reuse the gasket. But why take the risk?

The right thing would be to get another gasket but I dout you would have any issues with the one you have.

Not worth taking the chance after it has been torqued down. Get another one; they aren't that expensive in the big scheme of things for this repair.

Yeah, I figured that would be the consensus. So I'll get a Felpro today. I just hate throwing away what still looks like a new gasket.

But the bigger issue here, really, is the freeze plugs. Hopefully I can find enough today to do the replacement. When I do, I think I'll try the Permatex No. 1. I'm also going to apply the sealant to the bore in the block/head, in addition to the freeze plug lip. Last time, I only put the RTV on the plugs. My thinking was that they should be able to seal without any sealant at all, so I wouldn't need much at all. One thing is that they were at freezer temps when I applied the RTV - between the temps and condensation that may have screwed up the RTV. I think I'll tap them in at room temperature this time.

Any other freeze plug tips/advice?

Thanks for the responses so far, guys.

-Rob

i would not use rtv or any other type of silicon there.

the stuff only cures with air exposure, which will never not ever happen in between the freeze plug and the block or head.

use something else, or go dry. probably use new plugs, too.

New head gasket and new head bolts torqued in the FSM order and spec.

The head bolts can be re-used "once" but unless you are the original owner of the XJ I wouldn't chance it. If the head has been removed then a qualified tech would have paint marked the head of the bolts to signify that they have been re-used once and are now "torque to yield". Being a tech myself and working around some of the grease monkeys that I do, the chances are that a tech would have marked those bolt heads is slim and none.

For $40 bucks I'd get new head bolts too, I hate having to do the same job over again just because I didn't want to spend money.

HeadBolts.com, 89-96 Jeep 4.0 head bolts

I have never put anything on the freeze plugs or ever had one leak.

Well, thankfully I ordered new head bolts and used them when I installed the head. So these current bolts should be good for one more torque cycle, and I'll paint the tops before I install them.

The only plugs I was able to find in town today were at NAPA, but the lips on these are about 1/8" deeper than the other ones I used. They may even be too deep to drive in all the way, but if not, the extra lip might help the sealing. I'm about to pop out the currently installed plugs, and see if the new ones will hit the cylinder walls. I also bought some permatex #1, which lists freeze plugs as one of its uses, so hopefully it will be able to cure.

I wish there was some way to test them before I put everything back together. I guess I can fill up the block to just underneath the deck, and test the block plugs that way, but that won't tell me if they'll hold under pressure. I don't see any way to test the head plug without putting it all back together.

Guess its off to the garage. Thanks for all the replies so far.

Robs92XJ said:

I'm also going to apply the sealant to the bore in the block/head, in addition to the freeze plug lip. Last time, I only put the RTV on the plugs.
-Rob

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Good plan, always apply non-hardening sealant to inside of bore. Make sure to get it good and clean first.

Interesting that you say non-hardening. 8Mud's reply referred to Permatex #1, which is a hard-setting sealant. It lists freeze plugs as one of its uses. I also have some Permatex #2 on hand, which is non-hardening. I would think that the hardening sealer would be good at preventing the entire plug from blowing out under pressure. Might make it harder to remove in the future, but that is not my primary concern right now. Is there another reason you recommend the non-hardening?

Anyways, I think the plugs I bought today are too deep. They could be installed in the block without hitting anything inside, but the face of the plugs would be sitting inside the water jacket a bit far (about 1/8"). The one in the head could not be driven in all the way, due to a small lip on the back side of the bore that would serve as a stop.

I think I will order some brass ones from rockauto, and bum rides for another week.

I like rockauto but you can usually get Dorman parts faster from Autozone et al if you have the part number. If the local stores don't have it they might have it at a distribution center. Last resort they can usually order stuff straight from Dorman, but (1) usually not any faster than rockauto, and (2) the counter jockeys aren't real skilled at the catalog stuff.

I use #2 non-hardening. One place I recall seeing non-hardening sealer recommended for plugs was the boxwrench engine rebuilding video. I guess it makes sense when you consider the thermal expansion cycle that will be repeated (we hope) many times.

ehall said:

the counter jockeys aren't real skilled at the catalog stuff.

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That must be the case. In my original quest for freeze plugs, one of the places I went by was Autozone. They found some kind of plugs that were $20 a peice they could special order for me (picture looked like an ordinary freeze plug), and told me that was my only option. The O'Reilly's across the street had Dorman's for 99 cents a peice. The NAPA ones are made by Sealed Power/Federal-Mogul, and would seem to be higher quality than the Dorman's (it's probably just that they don't have a big "CHINA" stamped on the exposed face), but are deeper for some reason. Anyways I doubt it was the plugs themselves that are responsible for the leaks.

Like the man said, Indian Head for the win. Otherwise use #1. I always take some sand paper to the head and plugs to get things good and clean prior to pressing them in.

As far as head gaskets, I still spray mine with CopperCoat. I also use it on the intake/exhaust gaskets on the 4.0L. I have seen CopperCoat used on freeze plugs as well.

x 2 on Indian head. Just replaced most of the freeze plugs in mine while it was out. Ordered the Dorman brass ones from rock auto, the set came with one steel and was missing a few, pissed, but what can ya do for such a cheap price. Head gasket was replaced also due to high mileage, 175k. The old one looked fine, but was weeping a bit on the pass side. Indian head used on gasket and freeze plugs. Not a ton, just enough. If your not sure, just install them dry, no harm from that. The Dorman plugs were kinda cheap, the outer wall was real narrow. I'd rather have plenty of extra wall.

Well, yesterday I installed the five plugs on the side of the block. I used the deep cup sealed power ones I got from NAPA, with permatex #1 on the block bores and on the plug walls. Didn't bother freezing them beforehand. Today I filled the block with coolant up to the deck (head is off) to test them. 2 leakers out of 5, so I'm improving I guess. The leaks were not heavy, just a little bead of wetness between the cup and bore...of course there is essentially no pressure on them right now. I didn't trust the installation so I've popped them out.

I did discover that I did not quite follow the instructions on the permatex. It says you are supposed to let it dry "for a few minutes" until tacky (which isn't very helpful since its pretty tacky when it comes out) before assembling parts. I popped the plugs in right after applying the sealant. About how long do y'all let it sit before installing?

I will follow the instructions when I do this again, but I have another question: how deep do you want to seat the plug? I have read various opinions on this. Some say to knock it in flush with the block. I have also read to drive it in so the edge of the plug lip sits just inside the bore. I followed the latter advice and drove them in about 1/16" past the bore edge. Since there is a chamfer around the bore edge, if you drove it in flush with block the plug lip would actually extend out of the bore slightly. The other obvious option is to drive the plug in so the lip is flush with the bore edge. What do y'all think?

I'd put them in slightly recessed. Didn't see, what are you using to push them in? Not something that fits the OD, right? You should be using a socket or something that drops down in the middle, probably 3/4 of the OD.