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Head Gasket - WATCH OUT!


herald65

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Hello all,

At Christmas I finished my Herald 1500 conversion! I'm only 20 so it was a pretty big deal. Anyway being at uni I've only clocked up 217 miles since. I had been noticing coolant disappearing slowly but only after driving, so I checked all the coolant pipes and saw one in the heating matrix that had a little water around it. So I thought I'd solved it.
However today I had a massive and sudden overheat, turns out the metal 'O' ring must have cracked shortly after installation and was the cause of the leak. Then it properly went... I'm sure you know the rest.

Anyway just thought I'd post this as a warning to people, got it from Canleys. However I don't want to point the finger before I ring them (It could have been a 1 off).








The head and block both look okay and before taking the head off I topped up the coolant and ran it and there were no nasty sounds. (Lucky it went 20 seconds from my drive)

Cheers

Andy

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Quoted from Velocita Rosso


Looks as you say, to me, the wrong gasket for that head


Cheers for the responses!

What makes you think that its the wrong gasket? I don't think I knew there was more than 1 type for a 1500.

I checked the head number before overhaul and it confirmed as a 1500 head, but when ordering the gaskets I don't remember there being more than one option.

Andy

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Around the top of the bore there should be a lip.....recessed bore.
Yours doesn't appear to have it yet your gasket has the rings that fit into the recess.
Hence its blown.....unless we can't see the recesses?
Buy a payen gasket and try again

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It is a recessed block - you can just see it on the last pic where it breaks into the waterway.  Nearly all 1500 engines are I think.  Also the gasket has a tab indicating recessed block type so there seems to be a match.  You can also see that the gasket material has compressed a fair bit (near the head stud) which doesn't tend to happen if using a recessed gasket on flat block - they usually pee water out the side as soon as you tip it in.

Need to remove the old gasket and clean the head and block surfaces really thoroughly, including the recesses around the bores.  I'd then use a steel rules and a torch to check that the head and block are flat especially in the area of the failure and between the bores.

If all good, reassemble using a good quality gasket (I like the black Payen ones best) and a decent torque wrench.  You need to use the proper nuts and the proper hardened washers too or you won't get/hold the right torques.  Re-torque (observing correct tightening sequence) after a couple of heat cycles and then again after 500 miles.

Good luck

Nick

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Quoted from Nick Jones
It is a recessed block - you can just see it on the last pic where it breaks into the waterway.  Nearly all 1500 engines are I think.  Also the gasket has a tab indicating recessed block type so there seems to be a match.  You can also see that the gasket material has compressed a fair bit (near the head stud) which doesn't tend to happen if using a recessed gasket on flat block - they usually pee water out the side as soon as you tip it in.

Need to remove the old gasket and clean the head and block surfaces really thoroughly, including the recesses around the bores.  I'd then use a steel rules and a torch to check that the head and block are flat especially in the area of the failure and between the bores.

If all good, reassemble using a good quality gasket (I like the black Payen ones best) and a decent torque wrench.  You need to use the proper nuts and the proper hardened washers too or you won't get/hold the right torques.  Re-torque (observing correct tightening sequence) after a couple of heat cycles and then again after 500 miles.

Good luck

Nick


Yes the head is recessed. So it was the right gasket for the head.

Before the head was fitted I sent it off to be skimmed and have unleaded seats put in, so it should be flat and I think I remember either me or my father checking with a rule but I'm not to sure. I will check again tho.

All correct torques were used when assembling which makes me think the gasket was to blame.

Who sells the Payen gaskets?

Cheers

Andy

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Just done a similar failed 1300 had weeny nuts that would not torque to 46lbft
its a common finding , the HD nuts from eg canley are much deeper than std nut makes it a reliable clamp
make sure the washers are as said you dont want any deformation.

run die nut down the  stud threads to clear any tightening obstruction crud

bear in mind std nuts strip will above 31 lbft  optimum   upside down wheel nuts make good option with decent area, but not next to the pedestals  
pete

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Just to clarify, it is the block that has the recesses around the bores. Post a pic of the block once the gasket is off and it is clean.

It is not unknown for blocks to be skimmed (decked) but the engine number disappears at the same time!

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Quoted from Pete Lewis
the HD nuts from eg canley are much deeper than std nut makes it a reliable clamp
make sure the washers are as said you dont want any deformation.


Definitely.

Unless the nuts are OE (dull black and heavy) then use new Heavy Duty nuts, as normal 8.8 nuts will not torque up to 46lb/ft (and hold)

nb the HD (3/8" UNF) nuts sold by Canleys etc are 14mm AF not 9/16" AF, but that is a useful way to check they are the right type. They are also a stronger grade of steel.


This is a problem on 1300's, 1500's and 2 Litre Mk1 engines. (oh and 1600 Vitesse). Most of the OE nuts have been lost

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If you have any problems getting decent head nuts then buy Mini A Series ones from MiniSpares or Mini Sport. http://www.minispares.com/prod.....4;Back%20to%20search

They fit perfectly and are of the correct hard steel. They have a built in flanged bottom face which gives it a large surface to spread the load.

I've used them for quite a while now and they work very well at the specified torque.

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  • 8 months later...

Looking at the pictures the gasket has blown initially into the blind 1/2" hole adjacent to the fire rim where it breaks into the recess. From there it then spread to the water hole. Why BL put these 1/2" goodness knows why BL put these blind holes there but it means there is no support for the fire ring at that point. A quick (fuzzy) photo of my own 1500 block:-
http://i1057.photobucket.com/albums/t386/Vulp53/PC272794_zpsghmaejbi.jpg

My own head gasket blew between pots 1 and 2 which are very close together. Whether after market gaskets can accommodate the recess is a debatable point .
Triumph / British Leyland did not (as far as I am aware) have any serious head gasket issues prior to the Spitfire 1500, so why they decided to recess the bores is an anathema to me.
I currently have both my Spitfire 1500 engines (prefix FM) completely stripped, just had one block re-bored +20 and the other will follow. If you compare the two pictures at:

http://i1057.photobucket.com/albums/t386/Vulp53/PC242792_zpsyfgzkftn.jpg
and
http://i1057.photobucket.com/albums/t386/Vulp53/PC242793_zpsyyqyevkg.jpg

As the clock drops into the recess the needle goes anti- clockwise. You will see on my newly re-bored block that the recess is 27 thou (0.027") deep (difference in clock readings).
Looking at the two new gaskets (correct type by the way), measuring with a 0 -1" mic (Mamas calibrated):

Gasket 'A': Basic material thickness = 56 thou, at reinforcement between pots = 65 thou, at fire ring = 85 thou.
Gasket 'B': Basic material thickness = 56 thou, at reinforcement between pots = 63 thou, at fire ring = 80 to 83 thou.
These are average figures as the gasket materials vary by up to 15 thou.

Using gasket 'A' as an example, subtracting the basic thickness from the fire ring leaves (85 - 56) = 29 thou, giving an interference of only 2 thou before tightening.

Given that gasket crush is say 5 to 10 thou (I didn't measure the old gaskets) this 7 to 10 thou crush at the fire ring - the fire rings need to be compressed (in my opinion) at least fifteen thou in order to do their job.
There is evidence of burning across pots 1 and 2 on my original block, so although the engine ran fine for 6000 miles it still clearly was never right (torqued to 46lb ft and re-torqued after 1000 miles) - then after the head gasket blew between pots 1 and 2 (where it had been burning) I went through four head gaskets just trying to get some compression. I did a (cold) leak-down test and it was blowing a gale between pots1 & 2 and 3 & 4 just at the head joint.

Decking the block to any degree will make no difference to compression ratio as the pistons will need to be decked by the same amount. And whilst decking the block completely is a bad idea it definitely looks

as though removing five or ten thou will aid gasket compression between the pots, in fact it would seem ludicrous not to do it given the mathematics .

Dave S

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Mine went the same after 500 miles.
It was a thin silver gasket as supplied by the reconditioners that honed the bores, fitted new rings and reground the crank.

I then bought a decent Payen gasket from Paddocks and a set of ARP studs and nuts (as I figured that in 30 odd years they had been used a few times 3 by me alone!)
All back together and well over 500 miles on all seems fine.

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Quoted from Brit car fan
Looking at the pictures the gasket has blown initially into the blind 1/2" hole adjacent to the fire rim where it breaks into the recess. From there it then spread to the water hole. Why BL put these 1/2" goodness knows why BL put these blind holes there but it means there is no support for the fire ring at that point. A quick (fuzzy) photo of my own 1500 block:-
http://i1057.photobucket.com/albums/t386/Vulp53/PC272794_zpsghmaejbi.jpg

My own head gasket blew between pots 1 and 2 which are very close together. Whether after market gaskets can accommodate the recess is a debatable point .
Triumph / British Leyland did not (as far as I am aware) have any serious head gasket issues prior to the Spitfire 1500, so why they decided to recess the bores is an anathema to me.
I currently have both my Spitfire 1500 engines (prefix FM) completely stripped, just had one block re-bored +20 and the other will follow. If you compare the two pictures at:

http://i1057.photobucket.com/albums/t386/Vulp53/PC242792_zpsyfgzkftn.jpg
and
http://i1057.photobucket.com/albums/t386/Vulp53/PC242793_zpsyyqyevkg.jpg

As the clock drops into the recess the needle goes anti- clockwise. You will see on my newly re-bored block that the recess is 27 thou (0.027") deep (difference in clock readings).
Looking at the two new gaskets (correct type by the way), measuring with a 0 -1" mic (Mamas calibrated):

Gasket 'A': Basic material thickness = 56 thou, at reinforcement between pots = 65 thou, at fire ring = 85 thou.
Gasket 'B': Basic material thickness = 56 thou, at reinforcement between pots = 63 thou, at fire ring = 80 to 83 thou.
These are average figures as the gasket materials vary by up to 15 thou.

Using gasket 'A' as an example, subtracting the basic thickness from the fire ring leaves (85 - 56) = 29 thou, giving an interference of only 2 thou before tightening.

Given that gasket crush is say 5 to 10 thou (I didn't measure the old gaskets) this 7 to 10 thou crush at the fire ring - the fire rings need to be compressed (in my opinion) at least fifteen thou in order to do their job.
There is evidence of burning across pots 1 and 2 on my original block, so although the engine ran fine for 6000 miles it still clearly was never right (torqued to 46lb ft and re-torqued after 1000 miles) - then after the head gasket blew between pots 1 and 2 (where it had been burning) I went through four head gaskets just trying to get some compression. I did a (cold) leak-down test and it was blowing a gale between pots1 & 2 and 3 & 4 just at the head joint.

Decking the block to any degree will make no difference to compression ratio as the pistons will need to be decked by the same amount. And whilst decking the block completely is a bad idea it definitely looks

as though removing five or ten thou will aid gasket compression between the pots, in fact it would seem ludicrous not to do it given the mathematics .

Dave S




Head gaskets blowing is almost certainly down to using an inferior quality gasket and not correctly torquing - and retorqueing the head.

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