Hole behind exhaust manifold stud...what the hell??

[tsi1991awd]

OK, so I have read that there is an oil galley that runs behind the BOTTOM MIDDLE exhaust manifold stud. Well the idiots that I bought my car from did some shit and when I was taking the nuts off of the studs, the whole stud came out from the very top left hole.

Now, that wasn't a big deal BUT the hole had been tapped and helicoiled...the helicoil was sticking out AND it was a size M10!! They stuck a goddamn M8 stud in the M10 thread! So I took the helicoil out and noticed there was some soft shit at the back of the hole and when I drilled into it, it came out powdery and chalky. I looked behind THAT and noticed a hole that was drilled into the head farther.

Is this hole supposed to be there or did they use that "sealer" to cover up their ####up?? As I said, it was an M10 hole, M10 x 1.5 thread pitch with the M8 stud just stuck in there barely hanging. Now inside the big gaping hole there, there is a smaller hole drilled and their "sealer" is out because I just scraped it all out with a screwdriver.

What is this hole and what was that sealer? Is it supposed to be there or is it something they did?

 

[dented_coffee]

Pictures would be nice and helpful. Is the powder black? Sounds like its exhaust residue or old fryed jb weld.

 

[tsi1991awd]

No, it's a grayish white looking...it was real soft, I could poke it with a screw driver and if I stuck a drill bit in there, I could scoop it right out by twisting the bit. It COULD be JB Weld...since it's not meant to handle that high of heat in that area, it might've lost some of its properties.

Don't have pictures because I rethreaded the hole, put in an M10 helicoil and then threaded an M8 x 1.25 helicoil into that and put the stud in. Surprisingly the M8 x 1.25 helicoil fits perfectly into the M10 x 1.5...I am assuming the M10 thread pitch is what would have been made originally if you were tapping a real M8 x 1.25 hole with a helicoil.

I am just wanting to know if the damn hole was drilled by them or what the #### it is.

 

[crashman1972]

I would assume it is anti-seize without seeing a picture.

 

[tsi1991awd]

No way it is antiseize...it came out powdery and part of it came out as a chunk. Hard but soft at the same time (like you can run your fingernail through it) As I said, it was only at the back of the hole where the stud goes....behind the "sealer" crap, there is a hole drilled farther back, but it is smaller than the hole for the stud.

It just looks like what sealer I broke up and vacuumed out of there was just covering the hole that is drilled in there. I dont care so much about the sealer...I just want to know if that hole is supposed to be there or if they ####ed up and drilled into the head.

The reason being,this hole doesnt go anywhere....it just goes straight back to....who knows where. So that means wherever it starts, it just ends right at the manifold stud. Seems odd.

 

[68442]

They probably just drilled too far when removing a broken stud. The goop might be teflon thread sealing paste or plumbers sealant. Both stay pliable. Pretty sure thats a dry stud hole.

 

[tsi1991awd]

I am wondering if I should take the stud back out that I put in and then stick JB Weld in there and put the stud back....if it is supposed to be a dry hole and only as deep as the stud....?

 

[floader]

I would not worry to much about it, if they had drilled into a water jacket or another oil galley it would have leaked. The chalky stuff is probably some sort of sealer they used.

 

[tsi1991awd]

So my question is, should I put some type of sealer or JB Weld in there then put the stud in?

I want to stress that it was completely blocking that small hole to begin with...it wasn't until after I took it out that it was chalky (from the small pieces being scraped away and such) I did not see any oil or anything behind there. BUT the car HAS been sitting for over a month and the coolant has been drained. Sooo....could've had time to escape that area.

So should I take the stud out and put JB Weld or something back there and then put the stud back in or??

 

[and1chewy]

sounds like it could have been some sort of 5 min apoxy to hold in to small of a stud

 

[MidShipCivic]

I'm pretty sure one of the exhaust studs open to one of the drain back oil holes in the head.

 

[dented_coffee]

I have a spare head here at my house that came off my 6-bolt out of my 1990 GS-t. It has no studs at all from beeing surfaced from porting. I will reply back with whats behind the bolt hole on the upper left corner.

How deep does the hole that they drilled go in the head? I will post the OEM depth and whats behind the backing of the hole.

 

[2GbTalonGuy]

I would say stick some jb in there, it couldnt hurt. Or you could get a new head if it really bothers you knowing that hole is there.

 

[tsi1991awd]

I have a spare head here at my house that came off my 6-bolt out of my 1990 GS-t. It has no studs at all from beeing surfaced from porting. I will reply back with whats behind the bolt hole on the upper left corner.

How deep does the hole that they drilled go in the head? I will post the OEM depth and whats behind the backing of the hole.

Mine is a 6 bolt, 1990 as well, so it should be identical. Hopefully that hole is completely solid behind where the stud is supposed to go. I don't know how deep the hole is. There's nothing I can stick in there that is small enough to measure. I can't even see far back enough with a flashlight. I think I may stick a ziptie in there and see how far it goes or if it hits oil or coolant.

Also, MidShipCivic, as I threw in on my quick diagram, the bottom middle hole has the oil galley behind the stud.

And BlackWidow, it doesn't bother me knowing it is there...it bothers me NOT knowing if it's going to puke oil all over the place and require me to take the manifold off yet again.

 

[dented_coffee]

Here are the measurements of depth that I got on the factory hole depth on that stud hole that your dealing with specifically. Behind that hole your right between 2 valve springs. If you are deeper than that you might be in a coolant or oil jacket. Not sure and don't quote me on it because I could be wrong. I hope any of this information helps you out on figuring out what they did to the head on your DSM.

MY SPECS ON MEASUREMENTS:
.872 inches
22.15 mm

I would go to auto-zone or some place like that and buy a digital caliper. You will use it more than you think. I know I was thinking " oh great buy it and use it once and let it sit and never be used again ". I was wrong. I have used it so much now that I'm on my 5th battery replacement on it. I use energizer button cell battery's. I don't leave it on all the time. I use it get the measurements and shut it off. Trust me you will be happy to have it.

 

[turboglenn]

I'm pretty sure one of the exhaust studs open to one of the drain back oil holes in the head.

The "galley" is a feed, in the top left stud it passes through to the "drain passage" area under the valve cover in the head

yes, that one particular one does for sure and i think it's just into the draining area and not the pressure feed IIRC ( with my spare heads and engines in storage now i can't just run and look for you ) but it's nothing to be worried about. You may need to use some ultra-grey silicone to seal the threads (or even thread tape) But i'm betting what you doug out of there was them putting JB weld on the stud either to A.) fix the threads redneck style (or) B.) seal oil from leaking out around those threads at the stud as they sometimes do.

you will be fine as long as you are not finding big chuncks of the threads or gobs of JB weld and heli-coil pieces in the oil. You did change it when you bought it ...right?.... good rule of thumb ona turbo car -

if i'm seriousely looking into a used car purchase, i am leary if the oil is "too new/clean" and if it's nice and dirty i always offer to do an oil change so i can see how the car is as far as engine health, and they get a free oil change if i don't buy the thing so they usually don't refuse when you make that point. Then when i'm doing it if i can get a compression test in too i will. Most people selling a car will let you do these things at your own expense if you can show or they belive you are in fact a mechanic, and if they won't let you check or do those things..Don't Buy IT, cause they're hiding something


but don't worry about that hole, besids some one trashing the threads in it, then utilizing a major "FAIL" in the repair, it's normal for that one to have oil drain out of it if the stud comes out. But that type of "repair" if done by the previouse owner would have me worried untill i checked out the rest ofthe car top to bottom... if you start seeing "wire nuts" on sensor leads and sch just put it back in the paper and sell it...that's a BAD sign of idiot owners who thought they were mechanics

 

[tsi1991awd]

I took my VC off since I am having it coated....managed to snap ONE picture before the rain started pouring down on my ass. It was not of the stud area though.

ALSO, I had to use TWO helicoils, and LUCKILY the outter threads of the M8x1.25 are M10x1.5 and it screwed into that M10 helicoil. I may put a bit of JB or ultra black sealant on there or something since there are two helicoils and then the stud. I don't know. I'll get more pics in a minute when it stops raining.

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I took the stud out and the M8 helicoil came out with it. It's garbage.

I jimmy rigged it back like it was, gooped JB weld all over the end of the stud and stuck it in and then screwed the bastard in. It holds on its own so it must catch the M10 helicoil just right.

You can't see the hole in the back very well at all...it is in the lower portion of that hole so....

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You can see it in the last picture the best...you can see the very top of the smaller hole in the bottom...