Hissing cylinder head!

[RogerH]

Isn't this fun, are you getting excited

 

I have found on two engines that the front exhaust manifold stud was screwed in so far it was locking the head stud - remove/slacken this manifold stud first.

 

The head is quite heavy and you are leaning over a long way. If you have a hoist it may be a good idea to spend a few minutes rigging this up to lift the head.

If you feel the urge to jam a lever between the head and block to help raise it be very careful not to damage the surfaces.

as the head is going up you could insert blocks of wood in the gap. It is surprising how easy it is for the head to fall all the way back down in the blink of an eye.

 

DO NOT rotate the crank when the head has been move (even a llittle bit) this may nessesitate and engine rebuilt, body repaint, chassis replacement and probably more.

 

Roger

[Revolution]

Roger

 

At the moment my wife is the hoist......I'll ask her she would mind if I rigg her up a bit!

 

Think I might get a rude and rather direct response!!

 

Roll on saturday

 

Nick

[Revolution]

Morning Everyone

 

Well......some progress!

 

I thought it would be a good idea to run the car up on the ramps and loosen the 4 "manifold to downpipe" brass nuts from underneath the car before embarking on removing the carbs etc., as the exhaust system has been in place for 10+ years and some of the nuts may be tricky to release from the top of the engine bay

 

Ok apart from the nut to the rear and nearest to the engine block. Not only is It unaccessible from underneath but it had a locking nut on it (non standard)

 

Managed to free the locking nut, but could I shift the brass nut.....no leverage space and anxious about stripping the thread

 

I'm wondering why it had a locking nut on it.......oh no not another stripped stud!!!!

 

Well after an hour I couldn't shift the nut so I've gone over to "the dark side" and enlisted the help of a neighbour who has recently completely restored his MGA

 

He reckons he can shift the offending bolt so finger's crossed for wednesday morning

 

I'm hoping he will be free when I get to the part when we're ready to lift the head too!!

 

Will keep you updated

 

Nick

[stuartmac]

Ive found it easiest / quickest to remove the carbs from the inlet manifold, with cables etc still attached, keep them together with spidles etc in place, and prop them up on the scuttle somewhere, This gives easy access to the lower retainers for the manifolds, remove these, remove the inlet manifold and pull the exhaust system clear, tying it back to the inner wing to stop waving about. I appreciate that depending on how the carbs are connected this may not necessarily work for you.

[Ashley James]

Very carefully examine the face of the block where the front RH head stud screws in because it can be cracked. Also the two front and rear on the left where cracks into the water jacket are not uncommon.

[Revolution]

Hello Everyone

 

Thought it was time to update you!

 

We couldn't get enough clearance to free up the exhaust system as per Stuart's suggestion above and had to undo the lower steering column where it joins the top flexible coupling to gain some extra room..........manifold all clear of its studs now!

 

Right, make sure we undo the cylinder head nuts in the correct order..........OMG who did these up........no choice but to use the leverage of two of us and a lengthy piece of scaffold tube.........each nut became free.....just and two studs came out too!

 

Started to jiggle, rock and tap the head and the head gasket was freed up and a gap of a few mm appeared

 

Can't raise it anymore so decided to see if the studs would come free using the locking nut method. All but three came out nicely and look in good condition BUT the RH front stud where my "hiss" started, came out all too easily!

 

I had to sit down and think positively because the stud in question has completely broken half way down the length of it and I have a horrible feeling the bottom half is left behind in the block

 

Well, I'm staying positive until the head is off but I fear some drilling may be needed to remove the broken part of the stud.......or will it come out freely?

 

To be continued.............Nick

[Motorsport Mickey]

Give us a clue,... " the stud has-broken half way down the length of it...the bottom half is left behind in the block" does that mean the stud broken in about half, or do you mean the threaded portion at the end which screws in the block ?

 

Reason I'm asking is " I have a horrible feeling the bottom half is left behind in the block " where else do you think it's likely to be ? If the stud has broken midway down it's total length there should be a good shank length to attack to remove. If the stud broke midway down it's threaded portion all is not lost, it should be a candidate for drilling and removing via stud removal tools. NOTE ! Do not go near it with an "Easy out" (left hand threaded tapered tool).

 

Mick Richards

[AlanT]

Just so we dont have to go through all this again, FIND THE TOPIC where we had to overcome this exact problem recently.

 

This is a nuisance rather than a disaster but can get worse if you don't do it right.

[RogerH]

Hi Nick,

'if' you have to drill into the remains of the stud, you need to ensure it is down the middle.

Get yourself a round bar of the diameter of the stud hole in the block (minus a couple of thou for a nice easy sliding fit) using a lathe if possible drill a hole down the centre of this rod.

This will now guarantee that you drill dead centre into the stud remains.

 

Roger

[Lebro]

Surely the head will come off now, with only half a stud holding it + sticktion of the head gasket.

Once off you will see the stud. If "half of it left" means a short section protruding from the block, then you could try heat cycles on the stud, combined with a stud extractor (external type) or mole grips etc. If the threaded part is half remaining, then you will have to drill it out, following Roger's guide lines.

 

Bob.

[Revolution]

Guys

 

The head is off and the thread of the RH front stud had broken where it screws into the engine block (no idea how or why)....hence the reason why it couldn't be torqued down and I guess the reason why the head gasket blew

 

Will need to be drilled out as threaded part id half remaining

 

Getting there!

 

Cheers, Nick

[Motorsport Mickey]

Check out the earlier thread with regard to stripped/broken threads and studs, all the info needed is there for you to remove it, normal engineering practice will sort it.

 

Mick Richards

[AlanT]

I had two exactly like this. Broken about 1/8in below the surface of the block.

 

I used a jig to get an exact centre drill and took them out to 3/8in to a depth of about 1in.

 

I used a parallel-fluted extractor from Rigid. These are quite cheap to buy.

 

This removed the end of the old stud and left a perfect original thread in the block.

[Motorsport Mickey]

What Alan said

 

Mick Richards

[RogerH]

Hi Nick,

if the stud has sheared off flush with the top of the block then you can't centre drill (using a round bar with drilled centre hole) using the block stud hole.

 

You will need to make up a plate that attaches to two other stud holes plus the hole you are concerned with.

Once you have a centre for the stud then you can drill into it - 1/8" is a good starting point thewn open up to your extractor size.

 

If you have problems drilling square to the stud then you may need to attach a long guide to the centring plate.

 

DO NOT ROTATE THE CRANK UNLESS YOU HAVE CLAMPED DOWN THE LINERS

 

Roger

[AlanT]

Post a picture so we can see what you are up against.

[Revolution]

Hi Alan

 

Photo of the offending stud!

 

Nick

[Lebro]

Looks like that's been broken for some time

 

Bob.

[AlanT]

See Roger, its not flush at all. It's about 2-3mm below the surface. Just like mine were.

 

Are we all sure these are "short-studs" here?

 

You might get a good centre on this with a 1/2in transfer-punch.

http://www.chronos.ltd.uk/acatalog/info_TPS1.html

[Motorsport Mickey]

As Bob says, broken for some time, the top block surface will need cleaning to check whether there is a crack into the water jacket but attend to that after removing the stud.

Looks quite heavily corroded so I should wipe the top surfaces of the block and liner with thinners and tape over the orifices at the rear of the engine you don't want debris down.

 

Wire brush the stud area INSIDE the circumference of the broken stud and especially scratch around the outer dia with a sharp scraper, you need to try and find the edge of the block thread and then flood the area up to the edge of the block with WD/Plus gas or your choice of penetrant to try and give it a chance of being wound out. Leave overnight and see if the penetrant soaks into the threads, it will pay to persevere with this trying various things, if you can get penetrant into the threads I will give a better chance of winding out. If after trying this there is no absorption of the penetrant into the threads because of the heavy corrosion you have to decide whether to try a fluted extractor into the centre or the best removal method may be drilling out rather than risking breaking a stud extractor in the remains of it.

 

Definite candidate for drilling out down the centre, as Roger suggested make up a plate picking up off two of the other studs to ensure the centre of the stud is fixed by measurement with a suitable hole to start it with a centre drill if you have one, if not use a 1/8th drill carefully so as not to snap it and then open up to a suitable size.

 

Mick Richards

[Motorsport Mickey]

Hi Alan,

 

Yes these studs at the front and rear are short studs.

 

Mick Richards

[AlanT]

Do these threads run right to the block surface?

 

I think they stop about 2mm below the surface.

 

The stud breaks where there is a sharp corner at the end of the thread.

This is exactly what I would expect if they were over-torqued.

 

I had two like this and the engine had run many thousands of miles like this and the gasket was holding.

You can be sure somebody else broke this in the past and probably used some "glue" to make it seem tight.

 

I'll say this AGAIN. 110 lbft is a bit TOO MUCH if the threads are lubricated.

 

This is happening because its a UNC thread to suit the cast block.

UNC threads cut deeper into the stud than the UNF threads.

[Motorsport Mickey]

Hi Alan,

 

I agree about lubing the threads being a mistake, it increases the actual torqueing force applied to the stud by removing the thread stiction which part of the torqueing effort normally has to overcome. Therefore 110lb ft multiplies up to higher figures when lubed.

 

Mick Richards

[Revolution]

Thanks to Alan T for making a drill template for me which enabled me to drill straight through the broken bolt

 

Thought I'd try a stud extractor although not feeling too confident

 

A little pressure and bingo! with a little squeek out came the broken piece of the stud without any problem

 

Can't believe it and it appears No rust

 

Checking for damaged threads and cleaning everything thoroughly before reassembly starts

 

Have found an engineering "one man band" near Bicester, recommnended by the local TR group who is converting the head to unleaded....will keep you posted of progress

 

Nick

[AlanT]

Here is the little part I made to centre the stud drill-out operation.

 

https://www.flickr.com/photos/90670218@N04/13666421304/

 

The minor diameter is 0.490in and it carries a 3mm pilot hole.

Edited April 11, 2014 by AlanT