Author Topic: Blown head gasket  (Read 2441 times)

Online bsa-bill

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Re: Blown head gasket
« Reply #15 on: 06.07. 2014 09:30 »
Good call Colin and fits in with Vic's problems

(Bodgers - I wouldn't dream of suggesting it takes one to know one *shh*)
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Online bikerboy

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Re: Blown head gasket
« Reply #16 on: 07.07. 2014 01:40 »
I will confess to having used 2 head gaskets on an A10 more than once  *sad2*
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Offline BSA_54A10

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Re: Blown head gasket
« Reply #17 on: 07.07. 2014 09:28 »
having to wait for valve guides and springs I had a closer look at the head gasket

In fact two were fitted(laminate type)

http://www.vicsjavascripts.org/BSA/HeadGaskets.jpg

any reason why two should be fitted.

The new gasket appears to be solid

annealing has been metioned, what temperature and how long?

I only have a domestic oven available.

Thanks Vic

Bright red,
No need to hold it there .
Oven will be too cold.
propane torch will be good enough.
start at one end when it gets to red then move the torch slowly taking the red with you as you traverse all of the gasket face.
A light rub with steel wool to clean off the oxide.
Roll your thumbnail on the gasket it should leave an indent if the gasket is full soft.
25 ft/lbs should be more than enough tension for all but 10:1 compression ratios.
Thick washers are essential for alloy heads to spread the load and prevent the head collapsing back into the stud hole.
If you buy them go to a car parts shop and ask for some thigh tensile head bolt washers.

Run the engine for an hour or so , let it cool then retension.
After that every couple of runs check that the bolts are still tensioned fully. Repeat till none are found loose.
Sometimes only 1 retension is needed some times it may tack 4 or more nip ups till they are stable.
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Offline charles whitfield

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Re: Blown head gasket
« Reply #18 on: 07.07. 2014 18:24 »
Or.... If you want to mix leisure with pleasure, when the barbecue coals are red hot - shove it in till it glows, toss it in the pool and treat yourself to a swim to fish it out.
Actually I use a primus stove which works really well, but doesn't sound so attractive


 
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Offline charles whitfield

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Re: Blown head gasket
« Reply #19 on: 07.07. 2014 20:35 »
and I don't have a pool  *sad2*
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Offline WozzA

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Re: Blown head gasket
« Reply #20 on: 08.07. 2014 04:47 »
After you anneal & clean the gasket I suggest you spray it with a good quality copper spray..
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Offline BSA_54A10

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Re: Blown head gasket
« Reply #21 on: 08.07. 2014 11:51 »
Or.... If you want to mix leisure with pleasure, when the barbecue coals are red hot - shove it in till it glows, toss it in the pool and treat yourself to a swim to fish it out.
Actually I use a primus stove which works really well, but doesn't sound so attractive

Go to the bathroom, remove your cloths and flail yourself with a stretched greasy timing chain.

Copper will adsorb both carbon and oxygen if heated in coals.
This will leave it tough with britle spots, not really what you want from a head gasket
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Offline cyclobutch

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Re: Blown head gasket
« Reply #22 on: 08.07. 2014 12:58 »
I can't imagine bothering removing the rocker box some 3 or 4 times for head re-tensioning. Surely just the once after a few hot cold cycles should suffice.
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Offline charles whitfield

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Re: Blown head gasket
« Reply #23 on: 08.07. 2014 17:50 »
Oh no - another daydream shot through  *sad2*
Back to my humdrum thoughts

 
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Online Greybeard

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Re: Blown head gasket
« Reply #24 on: 08.07. 2014 22:02 »
Quote
Bright red,
No need to hold it there .
Oven will be too cold.
propane torch will be good enough.
start at one end when it gets to red then move the torch slowly taking the red with you as you traverse all of the gasket face.

Quench
 
Quote

A light rub with steel wool to clean off the oxide.
Roll your thumbnail on the gasket it should leave an indent if the gasket is full soft.
25 ft/lbs should be more than enough tension for all but 10:1 compression ratios.
Thick washers are essential for alloy heads to spread the load and prevent the head  collapsing back into the stud hole.
If you buy them go to a car parts shop and ask for some thigh tensile head bolt washers.

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Offline BSA_54A10

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Re: Blown head gasket
« Reply #25 on: 10.07. 2014 03:37 »
No need to quench you are not trying to trap a high temperatiure phase at a low temperature.
However it does knock off heavy scale.
A light rub with white vinegar while warm ( cool enough to hold in your hand ) wil clean it off as well.
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Offline vwphillips

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Re: Blown head gasket
« Reply #26 on: 14.07. 2014 14:27 »
I have started to reassemble

I have noticed that the studs at the back/bottom going through the fins appear quite short as they can only be screwed into the rocker box by 1 turn to get a nut on underneth the fins

they appear to be the correct length for the front/bottom.

what length should they be?
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Online chaterlea25

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Re: Blown head gasket
« Reply #27 on: 14.07. 2014 18:26 »
Hi VW,
I'm presuming you are talking about the 4 outer studs on the rockerbox ?
I'm just about to refit one on a customer engine and have measured them 36/37mm
The rear have long sleeve nuts and spacers, do you have these?
There was a thread about these in the last week or two

HTH
John
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Offline vwphillips

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Re: Blown head gasket
« Reply #28 on: 14.07. 2014 22:46 »
Thanks chaterlea25

yes I found the sleeved nuts, I'm such a dummy

onward to the next disaster
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Offline vwphillips

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Re: Blown head gasket
« Reply #29 on: 21.07. 2014 14:14 »
I have got the bike back together again

I used the push rod comb tool as I cound not see enough to see the wires to align the pushrods
It took about 6 attempts but it is done now.

The engine sounds ok but I have a problem fitting the tank so have not been out on the road yet(subject of another thread).

thank you all for your information and suggestions.
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