Head gasket failure-3rd in 2½ years

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oliver90owner
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Re: Head gasket failure-3rd in 2½ years

Post by oliver90owner »

Two torque wrenches? It is simple enough to compare them, shirley?

They can be calibrated, at some cost, or checked by yourself (with some ingenuity of arranging suitable forces).

Personally, I would not rely on a deflection type. All mine are Britool, bar one - and that one agrees well with the relevant sized Britools. It is my ‘go to’ wrench simply because it is easier to operate.
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Re: Head gasket failure-3rd in 2½ years

Post by jagnut66 »

Reading through all this again, my money is still on you needing your head skimmed, whilst the torque wrenches could be mis-calibrated, I feel it's a distraction here.
But an engineers straight edge would settle it.
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
Mark Wilson
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Re: Head gasket failure-3rd in 2½ years

Post by Mark Wilson »

oliver90owner wrote: Sat Jun 12, 2021 8:13 pm
They can be calibrated, at some cost, or checked by yourself (with some ingenuity of arranging suitable forces).
I did have cause to doubt mine a few years ago, even though it's a Norbar, one of the better makes. I followed an online guide to home calibration, similar to this, and found that it was working fine.
https://www.equipmentworld.com/maintena ... stepbystep
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ndevans
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Re: Head gasket failure-3rd in 2½ years

Post by ndevans »

Well, I am at the point of getting the engine out to have the block skimmed now. The machine shop have quoted much the same as for the head skim, so cost wise, it's not a big deal, it's just the general pita of getting the engine out and stripping it. I might get away with a head skim, but if I don't, then I'm back to square one, still have to get the whole lot out, strip it, skim the block & reassemble. And next time the head gasket goes, I might not be as close to home as Exmoor. Anyway, I need to look at the clutch, so it's not a total waste of time.
As for torque wrenches, well a quick and dirty test of the deflection unit suggests it's not far out, but I've only managed to hang 10kg on it so far, which only equates to a 10th of it's rating. I was thinking I'll do a little comparison between the two, using a bit of angle and some nuts & bolts. Not scientific, but if both agree then they probably aren't far out.
However, one possiblity that has occurred to me, is that up until the last time I had the head off, I was doing the nuts up to 45lb-ft. I have a Marina 1275, with big valve head, which should be 50lb-ft (see one of my other long running sagas on here). Maybe the lower torque setting has caused, or contributed to, some head warping?
cheers N

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Re: Head gasket failure-3rd in 2½ years

Post by philthehill »

Only set the nuts to 50lbf ft if you have the correct studs which can be identified by a pointed top, a dimple in the top or a Y on the top.
High tensile flanged steel nuts should be used with the marked studs.

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ndevans
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Re: Head gasket failure-3rd in 2½ years

Post by ndevans »

Hi Phil,

I've got A+ studs & nuts now. I was just speculating whether the lower torque on the big valve head might have caused the head to warp with the higher compression and combustion pressures, from the HC pistons?

Cheers N
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
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philthehill
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Re: Head gasket failure-3rd in 2½ years

Post by philthehill »

I doubt that the head has warped but having a lower torque setting for the head studs would not help the sealing.
I would suggest that you still investigate the flatness of the block. Lightly countersink the head stud holes to get rid of any pull up of the block face.

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Re: Head gasket failure-3rd in 2½ years

Post by Bowie69 »

If you can feel any lip around the bores, and I reckon you probably can, then the block definitely needs a skim.

Fingers crossed all goes back together well, very soon :)
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ndevans
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Re: Head gasket failure-3rd in 2½ years

Post by ndevans »

Bowie69 wrote: Mon Jun 14, 2021 9:03 am If you can feel any lip around the bores, and I reckon you probably can, then the block definitely needs a skim.

Fingers crossed all goes back together well, very soon :)
I can, but mainly carbon deposits around the top of the bores.

If the block is skimmed, is there a problem with the pistons clearing the block? Mine are HC pistons, and are very close to the face of the block, but not actually proud. (I think..... But difficult to measure!)
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
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Re: Head gasket failure-3rd in 2½ years

Post by philthehill »

A lip around the top of the bores will not effect the flatness of the top of the block.
If you have a lip around the top of the bore that is a good indicator that the bore need to be re-bored.
A light skimming of the top of the block should not impact on the height of the pistons relative to the top of the block/head.
If you are concerned - when you come to put it all back together place a piece of plasticine on top of the piston and with a pre used head gasket turn the engine over. Take off the head and see how much the plasticine has deflected. That will give you a good idea of clearances.

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Re: Head gasket failure-3rd in 2½ years

Post by paul 300358 »

Before doing anything else, I would check the block to ensure its flat with a decent straight edge and a 0.002" feeler gauge. If its flat, its flat.
oliver90owner
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Re: Head gasket failure-3rd in 2½ years

Post by oliver90owner »

But difficult to measure!)

Straight edge and feeler gauges?

I faced a block recently. The surface grinder took off less than enough to remove the stains of some water gallery apertures, but all the rest of the deck was shiny and flat. I doubt I took off more than a couple of thou at the most - possibly less than one.

Re the lip in the bore - if it is easily/quickly removed by a hone, it was carbon and no problem. A stepped top ring was always the ‘work-around precaution’, if fitting new rings or a new piston in possibly part-worn bores where the risk of broken rings was otherwise a reality. The wear, just below the lip, can easily be checked, even by a shade tree mechanic.

Re Paul’s post - you don’t even need the feeler gauge unless there is evidence of non-compliance.
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Re: Head gasket failure-3rd in 2½ years

Post by paul 300358 »

I wouldn't be in a hurry to take the engine out and strip it down if theirs nothing wrong with it.
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Re: Head gasket failure-3rd in 2½ years

Post by Bowie69 »

ndevans wrote: Mon Jun 14, 2021 9:10 am
Bowie69 wrote: Mon Jun 14, 2021 9:03 am If you can feel any lip around the bores, and I reckon you probably can, then the block definitely needs a skim.

Fingers crossed all goes back together well, very soon :)
I can, but mainly carbon deposits around the top of the bores.

If the block is skimmed, is there a problem with the pistons clearing the block? Mine are HC pistons, and are very close to the face of the block, but not actually proud. (I think..... But difficult to measure!)

Sorry but you misunderstood me, (and phil too), a lip on the top surface of the head around the bores, there is significant marking, and this it the combustion sealing surface, which appears to be where you are suffering all your problems.
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ndevans
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Re: Head gasket failure-3rd in 2½ years

Post by ndevans »

Yes, I meant around the top of the bores, on the block surface, not inside the bores. The inside of the bores looks clean and in good nick-which I'd hope it would be, 2 years & less than 3000 miles since reboring.
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
'69 Traveller, 1275, discs.
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ndevans
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Re: Head gasket failure-3rd in 2½ years

Post by ndevans »

jagnut66 wrote: Sun Jun 06, 2021 7:14 pm Hi,
Whilst the quality of some head gaskets, copper or otherwise can be questionable I would get hold of an engineers straight edge (if you don't already have one) and check both your head and block, it may be that one or both do need skimming.

Also do you have an oil cooler fitted?
Best wishes,
Mike.

NB: I have one of these, a worthwhile investment:

https://www.ebay.co.uk/itm/362316396414 ... Swj2Ra9Uj8
Is this just a plain straight edge, or does it have a laser, or a light, built into it? I've been looking at getting one, and most seem to be a bit like a ruler with a bevelled edge. I would like one that has a straight edge that is wide enough for it to stand up on, leaving me both hands free to manipulate feeler gauges.
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
'69 Traveller, 1275, discs.
oliver90owner
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Re: Head gasket failure-3rd in 2½ years

Post by oliver90owner »

Firstly you don’t necessarily need feeler gauges - they are only needed to assess/measure any gap observed.

Secondly a straight edge can be supported to free up a spare hand. A couple of hefty steel blocks comes to mind, possibly some magnets or engineering clamps. Imagination required.

Thirdly, an assistant could provide a whole pair of extra hands - possibly at zero cost.

Personally, I’ve never ever needed two hands, to insert one little feeler gauge, for an exercise like this.
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Re: Head gasket failure-3rd in 2½ years

Post by geoberni »

ndevans wrote: Tue Jun 22, 2021 7:37 am

Is this just a plain straight edge, or does it have a laser, or a light, built into it? I've been looking at getting one, and most seem to be a bit like a ruler with a bevelled edge. I would like one that has a straight edge that is wide enough for it to stand up on, leaving me both hands free to manipulate feeler gauges.
It's just a quality straight edge, made by Laser Tools, who supply/manufacture all manner of automotive tooling, multi-use and task specific for particular motors.
Basil the 1955 series II

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jagnut66
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Re: Head gasket failure-3rd in 2½ years

Post by jagnut66 »

Is this just a plain straight edge, or does it have a laser,
It's just a quality straight edge, made by Laser Tools, who supply/manufacture all manner of automotive tooling, multi-use and task specific for particular motors.
As above.
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
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ndevans
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Re: Head gasket failure-3rd in 2½ years

Post by ndevans »

jagnut66 wrote: Wed Jun 23, 2021 8:07 pm
Is this just a plain straight edge, or does it have a laser,
It's just a quality straight edge, made by Laser Tools, who supply/manufacture all manner of automotive tooling, multi-use and task specific for particular motors.
As above.
Best wishes,
Mike.
Thanks. eBay not playing nicely with me this evening, I'll try again tomorrow.

Cheers N
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
'69 Traveller, 1275, discs.
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