Manifold alignment stud fell out

All,

I've been tracking down a coolant leak on my '82 4.2L CJ-8 for the past few months and have finally found it (after replacing every other component first, of course): one of the studs used for aligning the manifolds fell out. There's a fine mist of coolant that's coming out of the hole where the stud normally is, at least until the engine gets hot - usage is about a quart every 3000 miles. I can't find anything about removing or replacing this stud in the factory service manual, although I admit I haven't looked thoroughly. How is it "installed"? Is this something that's pressed in? Will I have to take the head off to fix this? If so, maybe it's to upgrade to the 4.0 head; the Mopar fuel injection kit's already on there.

Thanks, Michael

Reply to
Michael White
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Depends on if the rest of that stud is still in there. If it's an empty hole you could probably just chase it out with a bolt then put a new stud and sealant in there. If the stud broke off then "it depends" on if you have enough to get a grasp on it with vicegrips or if you have to work it out another way.

This shoud give you some ideas:

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If it were me, I'd pull the manifolds off and replace all the studs/bolts. If one is broken the others might not be far behind.

Reply to
DougW

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Reply to
DougW

DougW,

Thanks for the reply. It looks as if the stud just fell out (it's a remanufactured engine). If I use a mirror, I can see clear through into the head, i.e. there's nothing in the hole now. I'm not completely sure what's on the other side of there, and I don't -think- the stud was threaded in, but I won't know until I pull things apart. No problem if it's already threaded, or if the hole sits on one of the exhaust ports, or is between ports. If it's in the intake port, I'll have to figure out something. Maybe if I magnetize the tap... Hey - there's an idea for a product - magnetic taps! No dropped shavings! At least on steel or iron....

Thanks, Michael

Reply to
Michael White

You probably just need to chase the threads so most of the cuttings will be hardened gunk which is no real problem. I've never seen a pressed stud used in that application since the thermal cycling would work it out in no time.

There are some old tricks for capturing chips that might also work. One is to coat the tap - really gunk it up - with a thick grease like the fibrous wheel bearing grease then keep a good vacuum cleaner sucking the chips out. The grease keeps the chips from falling thru and makes them adhere to the threads as you back the tap out. Not perfect but it does a decent job if the grease is sticky enough. You might also be tapping into a blind galley, in which case there's no problem. A good magnetic drain plug will also get most of the pieces if you are careful to capture as much as you can while tapping. The other approach - which I like better - is to connect a compressor into the block and have that blow the chips out as you work. I've even used that on electrical boxes but be sure you wear safety glasses - them chips are SHARP!

I have also heard of a wax trick where you let the tap force a stick of wax ahead of it as a plug but those who told me about it weren't too fond of it - you have to be careful not to tap all the way to the bottom of the hole or you just push the plug - chips and all - on through into the cavity. I never did figure out how you would pull that plug back out when done, either.

Reply to
Will Honea

Since you are leaking coolant, it appears that it goes into a collant passage...

Sadly many taps are made of steels that don't magentize well... Do what I do, coat it with light grease, run in a few turns, remove clean and recoat, repeat until done. But... I suspect that it won't matter, it likely doesn't go anywhere. (BTW, use a bottoming tap, and be careful not to break it off in the head!)

Reply to
PeterD

DougW,

Thanks for the reply. It looks as if the stud just fell out (it's a remanufactured engine). If I use a mirror, I can see clear through into the head, i.e. there's nothing in the hole now. I'm not completely sure what's on the other side of there, and I don't -think- the stud was threaded in, but I won't know until I pull things apart. No problem if it's already threaded, or if the hole sits on one of the exhaust ports, or is between ports. If it's in the intake port, I'll have to figure out something. Maybe if I magnetize the tap... Hey - there's an idea for a product - magnetic taps! No dropped shavings! At least on steel or iron....

--- ---- --- It could be a steel dowel. Remanufacturers typically remove all fittings, bolts and plugs for cleaning the block, and sometimes they just forget to put them back in. If the hole is not threaded then you have to find a steel pin or dowel of the right size, coat it with a sealer compatible with coolant, and tap it into the hole, preferably with a soft hammer like brass. A manifold alignment dowel shouldn't contact coolant though. That seems strange to me.

Earle

Reply to
Earle Horton

Will,

I've pulled off the intake manifold and the hole is definitely -not- threaded. The diameter of the remaining pin is .425", which is just a hair under 7/16". The hole is tapered and is 5/8" deep. A 7/16" diameter rod will not fit into the hole. The back of the hold is covered by one of the bolts that holds the head in place. It looks like it is a steel dowel, as mentioned by Earle.

Tomorrow I'm going to call around to some local engine and machine shops asking for a steel dowel. If that fails, I'll try to find a "bottom tap", one that is used tapping threads that bottom out (as mentioned by PeterD). I've used them before when tapping the holes for the after market valve cover. It should allow me to put in a decent number of threads in a shallow hole.

Thanks, Michael

Reply to
Michael White

Earle,

You're right - there shouldn't be any coolant coming out. It may be an internal coolant leak. However, given the number of miles on the engine (about 70000) and that the engine remanufacturer is no longer in business, I'm not going to worry too much about it. Worst case, I'll pour some stop leak in there. I guess I'll see after I run it for a while.

Thanks, Michael

Reply to
Michael White

Will,

I've pulled off the intake manifold and the hole is definitely -not- threaded. The diameter of the remaining pin is .425", which is just a hair under 7/16". The hole is tapered and is 5/8" deep. A 7/16" diameter rod will not fit into the hole. The back of the hold is covered by one of the bolts that holds the head in place. It looks like it is a steel dowel, as mentioned by Earle.

Tomorrow I'm going to call around to some local engine and machine shops asking for a steel dowel. If that fails, I'll try to find a "bottom tap", one that is used tapping threads that bottom out (as mentioned by PeterD). I've used them before when tapping the holes for the after market valve cover. It should allow me to put in a decent number of threads in a shallow hole.

Thanks, Michael

--- --- --- --- I wonder if that head bolt goes into the water jacket? If you give a machine shop accurate dimensions, they should be able to make the pin you need.

Earle

Reply to
Earle Horton

you could just take a rod that is the size of the largest diameter and eyeball the taper. Put the rod in a drill then use crocus cloth (or a file) and spin the rod against the abrasive to form the taper. stop and tap it into the hole every so often to check the fit. If you "paint" the work area with a felt rip marker before inserting it, the tapping will remove the ink at the high spots so that you can see where to grind next. Cut the rod an inch or so longer than the finished pin to allow work room with the drill - and to get the !@#$% thing out when it gets stuck in the hole .

As a general suggestion, some people use J-B Weld to plug water jacket ports when doing the 4.2 - 4.0 head swap so that should also hold the pin for you.

Reply to
Will Honea

Or get a drill bit that is the right size, and cut the end off and use that? Numbered bits will probably work (big ones) or a lettered bit?

Reply to
PeterD

I think you want something rather soft so that it conforms to the hole when you tap it in. I doubt you can taper a drill bit or that it will seal properly. From the OP's previous description I am guessing a bad head gasket or an improperly sealed head bolt that communicates with the hole in question also.

Cheers,

Earle

Reply to
Earle Horton

Thanks for all the suggestions. I could not locate a proper steel dowel, so I bought one of those hollow, spring-loaded spacers; the ones that are split the length of the spacer so they will compress. I pounded this in and filled it with QuikSteel, a putty epoxy that is supposed to be good for up to 500 degrees. After re-installing the manifold, there was a very loud whistle, which I tracked down to the manifold not being aligned properly. So I elongated the hole on the manifold a bit and forced it to line up.

If this gives me problems in the future, I'll just switch to the 4.0 head.

Michael

Reply to
Michael White

A roll-pin. Good idea.

Looks like you fixed it, only worry I can think of is if the epoxy were to deteroriate.

Reply to
PeterD

Roll pin - thank you!

That brand of epoxy has done well for me in the past on a dishwasher tub repair very near the heating element. I know the stresses are quite different between the inside of a dishwasher versus an engine head, but the epoxy held up for more than five years inside the dishwasher (used nearly every other day) before I finally sold the house :).

Michael

Reply to
Michael White

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