Head replacement. Engine in or out?

andrew_donaldson1

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Hi experts!

Long story short, exhaust stud stuck in engine and drilling out process went a bit off and now a small amount of coolant is leaking out of the freshly drilled hole.

1st question: Im assuming the head now needs replacing?

2nd question: can the head be removed and a new one replaced with engine still in the frame?

Or, is it easier to remove the whole engine and do it on the bench?

2015 S10 for reference.

Thanks in advance everyone

Andy
 

Tenman

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If you got the hole threaded. I've used those epoxy sticks to fix engine cases a few times. 2 part jb weld is some good stuff too. Maybe get it clean and put a little in there and hope you don't have to ever remove it.
 

andrew_donaldson1

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Thanks. If i went down the jb weld route, guess id have to redrill and tap the hole? Or are you saying just pack the hole and wind in the stud and let it seal and set itself?
 

andrew_donaldson1

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I would take the head off and have a good machine shop weld it up and tap the hole back out. If a DIY fix fails, you'll have a big mess.
I can see a tiny pin hole right at the bottom of the freshly drilled and tapped hole. Might try a bit of JB weld first as head off is a big job for someone who hasnt done it before.

Do you think that would be an engine out job?

Appreciate your help.
 

andrew_donaldson1

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If it's just a tiny pin hole and your rethread job is good I'd just use some silicone sealer on the stud and put it back together.
You mean like a high temp gssket sealant? Would that survive the heat cycles at the exhaust manifold do you think? Guess it would if engine sealant does the same job...
 

andrew_donaldson1

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Btw ive fitted the new stud and managed to torque it down to the requirement 20nm and its holds fine...so im guessing my drilling and tapping is sufficient....just the leak to fix i guess...
 

RCinNC

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Extreme Heat JB Weld can withstand temperatures up to 1000 degrees F, so the heat itself in the cylinder head shouldn't present any problems.

The biggest problem with using JB Weld in that area is gravity and cleanliness. The base of the stud hole is probably roughly perpendicular to the ground. JB Weld is thick, but it will move with gravity until it stiffens up. It takes about a day to completely cure, and it'll stay viscous for at least an hour. If you apply it to a vertical surface, it might not stay exactly in that same place, which might uncover the hole you're patching.

The bigger problem is cleanliness. If you have coolant leaking out of that hole, you're going to have to stop the leak before you apply the JB Weld. JB Weld is amazing stuff, and I use it a lot, but it's not tolerant of things like oil or coolant. It won't stick properly to surfaces contaminated with things like that, and it won't cure properly. You'd probably have to drain the coolant out of the engine so it's at least below the level of that hole. Then you need to clean out that area thoroughly using something like acetone. You can't use any alcohol or petroleum based solvents (like WD40 or PB Blaster).

I can't offer a recommendation whether to use it or not. I know lots of riders have used it to patch holes in cases, oil pans, etc with much success.
 

Tenforeplay

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You mean like a high temp gssket sealant? Would that survive the heat cycles at the exhaust manifold do you think? Guess it would if engine sealant does the same job...
Oh yeah. If you have a tube of silicone sealer in a tube for household jobs sitting around that works. You want the 100% silicone stuff. I've used it between header flanges and the head on automobile engines. Or any high temp rtv silicone gasket sealer. Yamaha doesn't put anything on the nuts to keep them from loosening so I guess that is not a problem but I put some anti seize on my nuts on the header install, you can use a dab of rtv sealer on the threads also if you think the nuts might back off. Don't use so much on the studs you can't thread them all the way on, but enough to plug the hole and seal the threads I don't think would be a problem.

If you go another route like jb weld you want something that will move with the aluminum which expands quite a bit. I'd use the silicone, it is pretty flexible and will keep you from leaking. With the silicone sealer you can remove the stud later also.
 

andrew_donaldson1

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Extreme Heat JB Weld can withstand temperatures up to 1000 degrees F, so the heat itself in the cylinder head shouldn't present any problems.

The biggest problem with using JB Weld in that area is gravity and cleanliness. The base of the stud hole is probably roughly perpendicular to the ground. JB Weld is thick, but it will move with gravity until it stiffens up. It takes about a day to completely cure, and it'll stay viscous for at least an hour. If you apply it to a vertical surface, it might not stay exactly in that same place, which might uncover the hole you're patching.

The bigger problem is cleanliness. If you have coolant leaking out of that hole, you're going to have to stop the leak before you apply the JB Weld. JB Weld is amazing stuff, and I use it a lot, but it's not tolerant of things like oil or coolant. It won't stick properly to surfaces contaminated with things like that, and it won't cure properly. You'd probably have to drain the coolant out of the engine so it's at least below the level of that hole. Then you need to clean out that area thoroughly using something like acetone. You can't use any alcohol or petroleum based solvents (like WD40 or PB Blaster).

I can't offer a recommendation whether to use it or not. I know lots of riders have used it to patch holes in cases, oil pans, etc with much success.
Thanks for that. Makes sense.

Yeah ive drained the coolant and used brake cleaner to clean it thoroughly.

Maybe a good approach taking gravity into consideration would be to layer up gradually? So dot the tiniest bit in the whole then buld out a few hrs later?
 

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Ive not read every reply.... Ive pulled the head several times... You can do it with the engine in the bike. I dont know the exact bolt your referencing. If the bolt that has been drilled is located in the head, I would pull the head and after evaluating the situation, I would install a Time-Sert or probably replace. The cost for a machine shop to do this work is ""probably"" more expensive than a second hand head....... Obviously there are several directions you can go with this depending on time and money... It also really depends on YOU...... do you want a band-aid ? Or do you want it 100% fixed ? No one can answer that but you.......

IMOP, and for ME..... I would NOT use any type of JB-weld or any similar product to fix this type of issue... I have 40 years experience and have seen a lot. IMOP, I would suggest not going down this road, but this is me........

Like I mentioned, your can slide the head off on the bike, that is all pretty simple. You will have to replace all studs, they are one use only stretch bolts. Don't forget that (dont remember exactly this second) 3 of the 6 botls need an extra 30* past the max TQ the factory says.. Very important to fallow this 100%...... Last time I checked, the bolts have come down in price, but only came from Japan... 'Was' a long lead time.......

Depending on the bolt location and what it "does", I might feel "OK" installing a Time-Sert...... Not another brand- not a knock off- not something like a Time-Sert........ but the actual brand and product from Time-Sert..... Ive had extremely good luck fixing some 'special' parts with these kits over the years...... (this depends on where and how this original bolt is used)

Ive done all this job before......... If you need more suggestions or would like my opinion, hit me up......................... Thanks
 

RCinNC

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Am I correct that the hole is due to drilling too far into the stud hole, and that it's at the very bottom of the stud hole?

If so, and I'm just spitballing here, but you could try cutting out a small circle of thin sheet plastic (maybe about .020" thick), just slightly smaller than diameter of the stud hole, so the plastic disc fits inside. You could even glue a small plastic rod to the face of the disc, so you could evenly push the disc all the way into the stud hole. Apply a layer of JB Weld to the damaged area, put some on the side of the plastic disc that's going first into the stud hole, then push the small circle of plastic into the stud hole. Push it all the way down so it's in contact with the layer of JB Weld. Since the disc is kind of an interference fit, it should fit snugly in the hole and act as a dam to keep the JB Weld in place until it cures. It might even act like a plunger to help to force the JB Weld into the hole in the stud hole. Once it cures, you can break off the plastic rod you glued to the disc, and use needlenose pliers to pull out any bits of the rod that remain stuck to the plastic disc. You won't need to worry about the plastic disc; it'll melt the first time you run the bike, but the JB Weld will already be cured and stuck in place.

I don't think you'd have to worry about expansion and contraction of the Extreme Heat JB Weld. It's engineered to make repairs on things like exhaust manifolds, which definitely have a broad heating/cooling cycle.

You could probably use the same technique for high temperature RTV silicone sealer, if you decided to try that substance instead of the JB Weld.

Full disclaimer, I can't say this would work, as I've never done it.
 

andrew_donaldson1

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Ive not read every reply.... Ive pulled the head several times... You can do it with the engine in the bike. I dont know the exact bolt your referencing. If the bolt that has been drilled is located in the head, I would pull the head and after evaluating the situation, I would install a Time-Sert or probably replace. The cost for a machine shop to do this work is ""probably"" more expensive than a second hand head....... Obviously there are several directions you can go with this depending on time and money... It also really depends on YOU...... do you want a band-aid ? Or do you want it 100% fixed ? No one can answer that but you.......

IMOP, and for ME..... I would NOT use any type of JB-weld or any similar product to fix this type of issue... I have 40 years experience and have seen a lot. IMOP, I would suggest not going down this road, but this is me........

Like I mentioned, your can slide the head off on the bike, that is all pretty simple. You will have to replace all studs, they are one use only stretch bolts. Don't forget that (dont remember exactly this second) 3 of the 6 botls need an extra 30* past the max TQ the factory says.. Very important to fallow this 100%...... Last time I checked, the bolts have come down in price, but only came from Japan... 'Was' a long lead time.......

Depending on the bolt location and what it "does", I might feel "OK" installing a Time-Sert...... Not another brand- not a knock off- not something like a Time-Sert........ but the actual brand and product from Time-Sert..... Ive had extremely good luck fixing some 'special' parts with these kits over the years...... (this depends on where and how this original bolt is used)

Ive done all this job before......... If you need more suggestions or would like my opinion, hit me up......................... Thanks
Appreciate the detailed response.

It's actually one of the exhaust studs on the front of the engine.

After a lot of drilling i got the old stud out and re tapped the hole and the new stud fits a treat...but i noticed a tiny trickle of coolant coming out. When inspected closely, where the drill has bottomed out at the very bottom of the hole, there is a tiny hole. I must of drilled a few mm too long.

So ive drained the coolant and i think im going to at least try the jb weld angle and bulld up the layers bit by bit and see if that holds after a few engine heat cycles. If not, then can always take the head out

But trying to avoid buying a replacement as it seems they are over £500...
 

andrew_donaldson1

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Am I correct that the hole is due to drilling too far into the stud hole, and that it's at the very bottom of the stud hole?

If so, and I'm just spitballing here, but you could try cutting out a small circle of thin sheet plastic (maybe about .020" thick), just slightly smaller than diameter of the stud hole, so the plastic disc fits inside. You could even glue a small plastic rod to the face of the disc, so you could evenly push the disc all the way into the stud hole. Apply a layer of JB Weld to the damaged area, put some on the side of the plastic disc that's going first into the stud hole, then push the small circle of plastic into the stud hole. Push it all the way down so it's in contact with the layer of JB Weld. Since the disc is kind of an interference fit, it should fit snugly in the hole and act as a dam to keep the JB Weld in place until it cures. It might even act like a plunger to help to force the JB Weld into the hole in the stud hole. Once it cures, you can break off the plastic rod you glued to the disc, and use needlenose pliers to pull out any bits of the rod that remain stuck to the plastic disc. You won't need to worry about the plastic disc; it'll melt the first time you run the bike, but the JB Weld will already be cured and stuck in place.

I don't think you'd have to worry about expansion and contraction of the Extreme Heat JB Weld. It's engineered to make repairs on things like exhaust manifolds, which definitely have a broad heating/cooling cycle.

You could probably use the same technique for high temperature RTV silicone sealer, if you decided to try that substance instead of the JB Weld.

Full disclaimer, I can't say this would work, as I've never done it.
Thanks for your response.
 

andrew_donaldson1

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Lots of automotive engines have through holes from the factory, that if you don't install the bolt with sealant it goes into an oil or coolant passage and you will get leakage. The just use sealant on the threads of the bolt. I would do something like that first, least intrusive.
Ok thanks for the info.
 

Jlq1969

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Maybe you could make a Threaded Plug (about 5mm long), and insert it with a flat or Alem screwdriver and glue and then insert the stud (a little shorter now)……if you weakened the bottom of the hole (where the water comes out), You run the risk of breaking it even more when you adjust the stud...but if there is already a threaded plug on the bottom, the stud will stop on it...and you can adjust the stud to the corresponding tightening torque...(without a plug on the bottom , “maybe” the stud ends up breaking the hole even more when tightened
IMG_8762.jpeg
something like this

IMG_8764.jpeg
 
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