Head Gasket blown twice

[AweMan]

Yea! What DrEntropy said Varoooooom pics. AND just to be sure, after you have put 3 or 4 hundres miles on that new headgasket go back and at least check the torque or re torque it. It may not need re tightening but I would hate to see you have more problems.
Kerry

 

[austin10_4]

Thanks, i been told 50 miles check, then 100 probaly tighten and then every 3/400 just check them.
Dont worry, Ill post the pictures!

 

[austin10_4]

first problem.

Just ran a nut down one of the studs to make sure the thread was good on it, but the nut has seized up on the end, so when i undid the nut, it undid the stud aswell. Not only did it pull the stud out, but the part inside that it screws into. Im not sire what it is called but it is silver and the part that the stud goes into, has come right out, leaving only a hole with a screw track that is too large for the stud. I cannot screw this "thing" back into its hole because it has bent and is stuck on the stud. I cannot remove it! Can anyone tell me what this is likely to be that i have pulled out, and are they easy to get hold of?

 

[DrEntropy]

The block has apparently been damaged in past. That's a "HeliCoil" or equivalent... and you may have just found what has caused your gasket failures. Can you get a machinist or engineer to have a look at it? May be a simple matter of reinserting a new HeliCoil, but p'raps the rest of the studs need checking too.

 

[austin10_4]

Ok, the other studs are sound it is just this one. Can you think of any way to remove the helicoil? The thread which the helicoil sits in still looks in good condition so i think it would be just a case of replacing it. How do i found out what size?

Heres the picture of the stud with seized nut and squashed helicoil

 

[Dave Russell]

A couple of thoughts. Your Austin 10 may use some non standard threads in certain places.

Helicoils require a special tap to cut threads that match the stud thread. They also require an insert that is matched to the intended thread form & an inserting tool that is matched to both. If the correct insert is used with the correct tap & inserting tool, the Helicoil is self locking in the tapped hole & will not come out with the stud.

Also, the Helicoil must be long enough to go full depth in it's intended hole.

If your 10 has a non standard thread such as French metric, which I believe it may have, I don't know if the correct Helicoil tap, insert, & inserting tool are even available.

You really should check this out with a qualified shop before something is bodged beyond repair.
Best of luck,
D

 

[eschneider]

Can you think of any way to remove the helicoil? The thread which the helicoil sits in still looks in good condition so i think it would be just a case of replacing it. How do i found out what size?

removal - you should just be able to "uncoil" or "unwrap" the helicoil from the bolt with pair of pliers.

correct size - dunno what the spec is for the engine, but it's possible that since a helicoil was used, this stud may be nonstandard anyway. If you don't have a thread guage, thread chart, and vernier caliper - I would take the stud to a machine shop who knows british engines.

 

[austin10_4]

i have found a BSF 3/8" helicoil equivilant if you think thats any good. 3/8 BSF is definitely the size of the stud because i used a die to clean them. But, even if it fits the stud, im not sure if it will fit in the stud hole.

bottom of page...
https://www.namrick.co.uk/browse.asp?PCID=28

 

[DrEntropy]

ahh... Also check with AR-Sheldon. https://www.ar-sheldon.com/acatalog/Whitworth_HeliCoil_Thread_Repair_Kits.html

Unfortunately, they're up in Manchester area.

It would be desirable to have the proper tap, insert and tool. Cleanliness is a MUST for a good permanent repair here. ~IF~ the old insert is a genuine HeliCoil and the tapped hole was done with the proper tap, you MAY get away with just winding another insert in... but I'd be looking to get the kit to be certain.

 

[austin10_4]

ahh... Also check with AR-Sheldon. https://www.ar-sheldon.com/acatalog/Whitworth_HeliCoil_Thread_Repair_Kits.html

Unfortunately, they're up in Manchester area.

It would be desirable to have the proper tap, insert and tool. Cleanliness is a MUST for a good permanent repair here. ~IF~ the old insert is a genuine HeliCoil and the tapped hole was done with the proper tap, you MAY get away with just winding another insert in... but I'd be looking to get the kit to be certain.

Thanks, i just found a table which tells about tapping, and the required hole for a 3/8" namrick imperial coil is 9.9mm, and i have measured the hole and i made it 10mm but im sure that is the right size. I think ill order a coil and see. If its right, should i use some sort of locktight sealant to stop it coming loose again?

 

[Sparkie]

Another thought regarding the head gasket itself.

Aluminum spray paint. Apply a good coat to both sides of the gasket before installing.

I had an MGA that I built to the hilt, including a used alloy cross flow head and twin DCOE's. The head had been raced and skimmed so many times that the compression ratio was over 12.5:1 - OK for the fuel we could get 35 years ago. Anyway, I constantly was replacing head gaskets and put the word out for a solution. After trying a couple of strange ideas, I tried the aluminum paint. The idea is that the paint uses actual aluminum particles and they move around to fill the voids. The paint base material likely serves as a gasket sealer too. The head also removes very nicely following this process - burned a valve some time following. I do this to all my head gaskets now.

 

[austin10_4]

NEWSFLASH-

I passed the stud onto an engineer who said a helicoil will not stay in place even with locktite as its on the dynamo. So, he is going to make a special stud for me. 10mm base with a 3/8 thread, and then make the rest of the stud as normal, to the same dimension. So, hopefully, as long as this works, things are looking up. Hopefully get her to roar once more! Now, next post should be VROOM if no more hiccups!

Once again, Thanks for the help guys. Brilliant forum!

/bcforum/images/%%GRAEMLIN_URL%%/thankyousign.gif

 

[DrEntropy]

Once again, Thanks for the help guys. Brilliant forum!

Innit?! /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

The fix sounds great, hope it goes smoothly from there. Locking compounds for HeliCoils are available, some of 'em even WORK. Usually it's more trouble than joy, tho.

If the thing has only to hold forty ft/lb, I very much doubt you'll strain anything the machinist makes up for ya beyond tensile limits. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

 

[austin10_4]

tomorrow sees the spanners out again! Lokced and replaced new studs in place, and replaced one other loose one. Brand new nuts and washers on everything aswell. The head came back after having 0.005 fowl removed and i cleaned the block up using fine glasspaper. The block's been checked for trueness, and passed! So, tomorrow, ill fire her up and see what happens!

 

[DrEntropy]

Most EXCELLENT! Be sure to let us know how you get on with it! /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif

 

[mikespain]

Hi just throw my pennath in,the bolt with the helicoil was it a head bolt or as appears -one for the dynamo?I had a case once where a head gasket kept blowing,I reclaimed against the manufacturer of the gasket,they analised the gasket and came back with the reason being that although the head had been tightened correctly there was pre-ignition due to too high compression (in this case the head had been skimmed too much or too many times)In your case if the gasket was half the thickness this would affect the compression.Using the gasket that you are now being supplied with (along with the new studs nuts etc)no doubt will cure your problem.good luck

 

[austin10_4]

Oh Dear, Oh dear, Oh dear! /bcforum/images/%%GRAEMLIN_URL%%/cry.gif

Just tightened the head up slowly to 28 on all the studs and pulling up to 30lb stripped number 5 dynamo stud /bcforum/images/%%GRAEMLIN_URL%%/frown.gif Top. Finally managed to remove the nut but it looks like the stud is unable to be re threaded. Tried to remove the stud aswell, but its stuck in fast to the block so no hope. The other problem is... i was advised to use hylomar to seal the gasket, so if i need to remove the head, ill also have to buy a new gasket seeing as its stuck down hard! All the other nuts are currently tightened to 30lb so, if i was to just relax those down to finger tight, once the stud is repaired, would i be able to then retighten all the studs as normal? Im thinking along the lines of drilling into the dynamo cradle, to take the nut far enough down as to bite on a good thread on the stud. Any thoughts, This has really defeated me, i cant believe what bad luck im having at the moment /bcforum/images/%%GRAEMLIN_URL%%/mad.gif so, any ideas please put them forwards!

Thanks guys

 

[DrEntropy]

That should not happen if the studs and nuts are new. 30 ft/lb shouldn't be enough to strip threads. If the new gasket hasn't been under load (engine run) or had any coolant in it then I'd say you need not undo the rest of the work, BUT: you really need to replace the stripped stud. Was the nut perhaps a different pitch? Did it go onto the stud smoothly to contact the washer/head? All very frustrating. Since the stud is already knacker'd, try finding a "sprag" style stud removing tool to get it out to replace it.

Truly sorry to learn of your difficulty with this!

 

[austin10_4]

Thats the annoying thing! the nut was going down so smoothly and well, and then it just went very soft and i knew what had happened! At least the gasket shouldnt need replacing. Itt have another go at removing the stud later.

 

[DrEntropy]

Gah. Sounds as if that stud was made from taffy!