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Just how important are head bolt washers?


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Ok, so after a wonderfully enjoyable essex 12 car navigation rally a few weekends ago I discovered that I had blown my head gasket. Oil in the water and definite cylinder gas leakage into the cooling system. I have taken the whole thing apart and one thing I noticed was that the head nuts seemed not to be as tight is I would have thought. When I fitted the reconned head they were torqued down using. A new torque wrench and checked using a digital torque wrench and retorqued after 500 miles.

I also noticed that the washers seem to be soft and have signs of distortion from compression. This isn't normal? Is it possible that these are too soft and have distorted reducing the clamping force of the head nuts? I have bought some new ones from Moss and they look a lot thicker and sturdier.

Cheers

Tim

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Soft metal washers when fitted on 4 pot engines is a horror show too due to the even higher nut torque. The washers just ooze out and split.

Washers are there for a reason - to spread and transmit the torque load etc.

So fit the right ones. - just hope the specialists have sourced the correct grade of hardened washers - or they will be wearing them.....

 

Austin Morris went over to flange faced nuts for the cylinder heads of A series Mini quite late in its production. (No washers required) The same nuts are rather nice for retaining the rocket gear if a 3/8 unf nut is used (4pot again)

 

Peter W

Edited by BlueTR3A-5EKT
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Think you've answered your own question Tim, where washers are specified and fitted by the manufacturer they are of the utmost importance.

Lets get this clear NO manufacturer fits ANYTHING they can get away from fitting if they safely can, even the lowly profit from the non supply of washers would go into the pot.

The washers are very important to apply and keep maintained the torque applied to the cylinder head, any warping or "gouging" of the nuts under torque will screw up the "stiction" (sticking friction) forces allowed for, this would compromise the torque applied (lessening it) because as we know Triumph specifications are for dry fitted fastenings throughout the engine. Also any warping or squashing out of washers after fitment would again compromise the torque, hopefully your timely action in discovering and retorquing the head will preserve the gasket seal.

 

Mick Richards

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You need the proper, hardened washers. While some signs of scuffing is normal, deep gouging or outright distortion shows that the washers are not correct and this causes stud tension to be lost - and HGF.

 

You need to source the correct washers or flanged nuts. The smaller 3/8" flanged nuts are available easily and cheaply from Mini spares suppliers (and work really well on the small Triumph 4 cylinder or Mk1 6 cylinder engines) but I've never found a source for 7/16" without coughing up for the full ARP kit. $$$$$!

 

Nick

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Ok this sounds good.. Was surprised that the head gasket failed as the head was newly reconned and skimmed and I spent an age prepping the top of the block so nothing was left of any old head gasket. My only other concern was whether the surface of the block had been pulled up around the studs.. guess I can check that with a decent straight edge?

 

Cheers

tim

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Tim,

 

You didn't mention the height of the liners above the block.

I assume you did this ? It's not just a matter of cleaning.

 

AlnR

Are you confusing a 6 cyl engine with a 4cyl engine Alan ?

 

Mick Richards

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No Liners here.. just beautiful (ish) cylinders cut into traditional cast iron..

Cheers

Tim

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Ok this sounds good.. Was surprised that the head gasket failed as the head was newly reconned and skimmed and I spent an age prepping the top of the block so nothing was left of any old head gasket. My only other concern was whether the surface of the block had been pulled up around the studs.. guess I can check that with a decent straight edge?

 

Cheers

tim

Hi Tim! Was your head gasket a J. Payen one? There are some really el-cheapo ones on the market which I would not use! Lastly if you have a recessed block did you use the right head gasket?

Bruce.

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Yes correct gasket for the recessed block. Gasket was payen. How do you tell the bad ones?

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Yes and the tab was in the right place..

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Ok so had a look at the washers. All bar 4 look the same and are very close to he new high tensile ones I have from Moss. The other 4 are a motely crew all different and with different thicknesses. 3 have clearly been compressed.

 

I have also gone back to look at the head and block. On the block that are two patches of black residue around 8mm in diameter circular in shape that look like the size of waterways. They match with water ways in the head although they are just solid bits of the block surface. They felt slightly raised but when rubbed VERY carefully with fine wet and dry they seem to come off. It looks like corrosion caused by water from the water jacket in the head? Anyone seen these before?

My original gasket had holes that matched but the new payen one that blew didn't. Strange.

Cheers

Tim

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Interestingly I forgot that i noticed this mismatched in 2015 when the car was in prices.

http://72tr6.blogspot.co.uk/2015/01/the-cylinder-heads-return.html?m=1

Cheers

Tim

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Not in the garage at the mo but the word TOP was on the top of the the tab..

Cheers

Tim

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Interestingly I forgot that i noticed this mismatched in 2015 when the car was in prices.

http://72tr6.blogspot.co.uk/2015/01/the-cylinder-heads-return.html?m=1

Cheers

Tim

BL did a lot of mods to the cylinder head wall thickness of casting in the early 1970's to cure valve seat distortion and cracking in order to stop loss of compression and warranty claims.Remember BL did not stress relief their castings, customers did that by driving their cars? This also included strengthening the block as well, hence the redesign of the head gasket with reinforced fire rings and counter bored rings around the bores. Make sure that the top face of your block is flat as early blocks warp! Later blocks have a strengthening web along the bottom of the block, on the outside, to stop this.

 

Bruce.

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Ok so replaced the head gasket complete with new (correct) head washers. Started the car with the rad cap off and the radiator full... after about 3-4 mins of running I had a small fountain from the rad.. Bu$%er!

Replaced the lost water and ran again... little bit of overflow and then stable.. Is this just the system burping? Was quite spectacular as the water hit the mechanical fan giving me an antifreeze shower!

Cheers

Tim

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The burping was probably just an airlock clearing. Make sure that you have the heater valve fully open when you filled the radiator. If you can race the engine without bubbles appearing in the coolant at the filler neck then the head gasket is almost certainly sealing correctly.

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  • 2 years later...

resurrecting this topic; recognising the importance of decent head stud washers, where do people recommend to purchase from, or what is to be avoided?

Many thanks

David

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