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HI all, Iooks like I'm going to have to replace the head gasket on my 4 over the winter. I've got oil leaking out from behind the exhaust manifold and running down the block exactly between cylinders 2 and 3 (not rocker cover), well I'm hoping its the head gasket :unsure: and not a new head :o

 

So I'm looking to get a head set ready, now if I go to the Moss site, they'll happily take £108.00 off my hands, just for a copper gasket (43 thou thickness), but if I look on the web there are complete head sets inc all the ancillary gaskets for around £20.

So the questions, am I missing something? Do I really need the Moss item, or is this for special purposes, and can I just pick up a headset from a reputable supplier in the £20-£30 range which is more like what I was expecting to pay?

 

Any guidance gratefully received as always.

 

As far as I know the engine is very much standard and does not seem to have been modified, but you can never tell from the outside.

 

Mark

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Hi guys, thanks, yes I could only find the solid copper and shim gasket in the engine components on the Moss site, very difficult site to find things now. Took me 20 minutes to find the B post capping for a 4a this morning. Thanks for the help.

 

One last question, what is the likelihood of unseating a liner if it sticks to the head? Do I need to use the copper/hide to release the liners before lifting the head? Or is this unlikely?

 

Mark

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Never ever ever had a liner lift from the block without a lot of assistance from pullers etc. If the head and gasket has been fitted with Wellseal or even Hylomar or similar substance the gasket will likely remain in position on top of the block, lift with confidence.

 

If you do not wish to remove the liners, or don't know what's to be done yet, DON'T undo the nuts and then turn the engine over to break the cylinder head seal. The movement of the pistons in the bores without the cylinder head maintaining a downward pressure MAY unseat the liner from the Figure of 8 gaskets at the bottom and cause a leak if not then replaced.

Sidewards blows from copper mallet at strong points on the cylinder head will help break the gasket seal and then a vertical lift from a hoist (they're heavy to lift at a distance) lifting squarely and equally with many a wiggle will normally get the head up the studs.

 

Mick Richards

Edited by Motorsport Mickey
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Never ever ever had a liner lift from the block without a lot of assistance from pullers etc.

Mick Richards

Mick,

 

That has been my own experience, though far more limited

than your own.

 

But, equally, this inevitably means that the required/specified

6-8 thou liner height above the block is not achieved which

means you have to/should replace the Fig of 8 seals anyway

or the head gasket will not seal adequately against the liners.

Your take on that would be appreciated.

 

AlanR

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Hi Alan,

I follow your point on the liner height being reduced to its running height after a head torquing.

 

However as the Fo8 seals are now as flat as they are ever going to be, and sealed, simply replacing the head (without the liner protrusion for NEW Fo8's seals) shouldn't cause a problem.

 

Much the same as removing the head for any simple task and refitting.

 

Roger

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For what it's worth, when I remove a wet liner head, I always remove first all the studs.

 

This allow me to push the head laterally, breaking any sealant glue or equivalent who may have been applied on the head gasket.

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Mick,

 

That has been my own experience, though far more limited

than your own.

 

But, equally, this inevitably means that the required/specified

6-8 thou liner height above the block is not achieved which

means you have to/should replace the Fig of 8 seals anyway

or the head gasket will not seal adequately against the liners.

Your take on that would be appreciated.

 

AlanR

Hi Alan,

 

Well I've sat liners at a 6 thou protrusion before where I've thought that an exotic compression required it and the head sealed ok using the steel shim gasket with the pressed compression rings (but only using half of one ring width), but I'd be a little concerned with an 8 thou liner height with it being over 50% more than the recommended 3-5 thou range. Perhaps you just misquoted it ?.

As Roger says once the FO8 gaskets have been compressed (even the copper ones only compress a "smidgeon" less than a thou) and the sealing solution displaced and gone off the liner height should be fixed. That's why we fit the head and pull it down to about 40 lb ft first without a head gasket, making sure the liners and gaskets are seated correctly. Then remove the head and then measure the liner heights at 4 points around the circumference to confirm your liner heights.

Between 3 and 5 thou is good as long as consistent across the liners and even a slight 1 thou lean towards one end will be acceptable unless its on the inside liners, and once fitted and run for more than a couple of years the liners will need effort to move them.

 

Mick Richards

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A tip I got from the forum was, when you've renewed the FO8s, to torque the head down using the old (cleaned up) head gasket. Then remove the head and check liner heights before final head fitting.

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I only did two TR4s but I am wondering why

nobody of the specialists tells that guy

that at the manifold side between 2&3 there

is no oil to seal by the head gasket.

 

Did I miss something???

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Sorry Andreas don't understand.

 

Mick Richards

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Mick - I think Andeas was questioning an oil leak being on the manifold side of the engine as Mark describes, when there us no oilway there. If it is indeed an oil leak and is not leakage from the rocker cover, then somehow it must be getting past the cylinder bores from the other side of the engine, or else coming from the cylinders.

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Ahhh, no I wasn't answering that point, only the question raised regarding the liner securing and head removal process.

 

Depending upon how accurate the oil leak position is described there is no oilway or drilling on the exhaust side that would likely cause a leak. However, the dynamo positioning bracket is positioned on the exhaust side and the holes securing it do go through into the crankcase and are drenched in oil, in race cars we often drill the securing bolts and wire together to prevent a bolt vibrating loose or even out. My money (if the oil leak position is far enough forward) would be on the bolts leaking on the dynamo bracket.

 

If correct the oil leak can be sorted without removal of the cylinder head, remove the dynamo bracket bolts one at a time and clean the threads in the block and the bolts with thinners and screwing the bolts into the block, then remove and PTFE the bolts and rescrew back into the block one at a time. The drilled bolt heads and wiring together are a good process to prevent these bolts loosening in use.

 

Mick Richards

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Hi guys regarding where the oil is coming from.

I've attached two pictures, one shows the engine in the car with the line of oil down the block just behind the manifold and the other is a picture of a spare engine I have in my garage showing no obvious points for oil to leak from.

 

You are right all the oil galleries are on the otherside of the block and looking at pictures of head gaskets, I can't see where it can be coming from, if it is not the gasket. It could be coming from the inlet manifold, but there is no smoke either on full load or high speed over run, rough running or obvious leaks from the front carb. Plugs are clean and rocker cover gasket is totally sealed.

 

l'll have to remove both manifolds I think to see if there are any clues. Tried to see up behind the manifold with a small inspection mirror and a light, but all I can see is the line of oil disappearing out of sight to wards the gasget.

 

Markpost-12879-0-76133800-1443977617_thumb.jpgpost-12879-0-99356200-1443977635_thumb.jpg

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Hi Roger I had the generator off yesterday for other reasons (voltage regulator failed in dynamator - dynamo back on again), and there was no obvious oil around the rear bracket, the oil is coming down from somewhere behind the exhaust manifold inline with the manifold stud between no2 inlet port and no3 exhaust port.

 

Mark

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If the identification is correct then Mark an analytical stripdown is required taking care to examine as each component is removed (especially the manifolds) to help gain further details. As you can see from the oil transfer hole positioned in the gasket it is positioned at the rear and towards the passenger side so if oil is leaking from there it has to traverse the cylinders and find a way forward.

I should carry out a compression test before head removal to see if all is well, and conform the uniformity of the compressions. If the gasket has gone a favourite place is at the rear often caused by the liner subsiding into the block a couple of thou reducing the clamp pressure this would likely reduce the clamp around the oil hole sealing and allow some oil to escape spreading across the surface and maybe as far forward as the area shown in the photo, although I think that's a wild card and something I've not experienced.

Please report back as you progress, it will be interesting to bottom this.

 

Mick Richards

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If the identification is correct then Mark an analytical stripdown is required taking care to examine as each component is removed (especially the manifolds) to help gain further details. As you can see from the oil transfer hole positioned in the gasket it is positioned at the rear and towards the passenger side so if oil is leaking from there it has to traverse the cylinders and find a way forward.I should carry out a compression test before head removal to see if all is well, and conform the uniformity of the compressions. If the gasket has gone a favourite place is at the rear often caused by the liner subsiding into the block a couple of thou reducing the clamp pressure this would likely reduce the clamp around the oil hole sealing and allow some oil to escape spreading across the surface and maybe as far forward as the area shown in the photo, although I think that's a wild card and something I've not experienced.Please report back as you progress, it will be interesting to bottom this.Mick Richards

Hi Mick, yes I plan to remove inlet manifold and exhaust carefully to check what I can see, will also recheck the compressions. I'll report back once I can get time to do it.

 

 

Mark

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