Cylinder Liner Protrusion & other issues

[Ian Vincent]

Some of you may remember that a couple of weeks ago I posted a query regarding whether or not I had blown the head gasket on my TR3a.

 

There were various suggestions on how to check but in the end I decided to bite the bullet and pull the head anyway.

 

There were a couple of reasons for doing this:

 

1. The head is aluminium and I have always been slightly nervous about its durability before the engine has fully warmed up, and
2. I have a spare rebuilt cast iron head.

The aluminium head is an ex racing one with big valves and is used with a solid copper gasket - partly to accommodate where the ali head has been opened out around the inlet valves and the corresponding part of the liners has been opened out, and partly to reduce the compression ratio as the head had been skimmed quite a lot.

 

Anyway, having removed the head there is no clear evidence of a 'blow' but there was quite lot of 'gel type material, (which I assume is a corrosion product) around some of the waterways and particularly in the heater outlet and bypass hose, both of which were virtually blocked so this could have been the reason for the issues I was having with cooling. Incidentally I have been using what I thought was the right antifreeze with the correct corrosion inhibitors.

 

The next thing I checked was the protrusion of the liners (using a length of 1/2 round silver steel) and there is a problem.

• Liner #1 - varies between .004 and .002
• Liner #2 - varies between .003 and .001
• Liner #3 - varies between .003 and .001
• Liner #4 - varies between .004 and .005

All of the above depend on whereabouts around the circumference you measure the protrusion and are with the liners firmly clamped in the recommended fashion (on the higher side).

 

The top of the block is flat - I have checked it and it was refaced when I rebuilt the engine.

 

Clearly, I have an issue but is it one that will be solved by fitting new FO8 gaskets? Any thoughts gratefully received.

 

Rgds Ian

 

PS as and when I put the engine back together I am planning to anneal and re-use the solid copper gasket with something like Blue Hylomar to give it a helping hand - does anyone have any views on that as well pls?

Edited April 14, 2016 by Ian Vincent

[Motorsport Mickey]

Ian,

 

From your comment regarding 1/2" round silver steel I presume you are using that across liners or block surface and then measuring with feeler gauges underneath ? If so it gives an overall view in a single plane, but to help establish where the problem lies if you have a depth micrometer or the loan of one you'll find it a much easier to use tool which helps give repeatable measuring.

You'll find depth mics available on e bay or other sites for fairly low amounts of money, you can mic from the top of the liner in a spoke fashion onto the cylinder block deck The information you currently give on the liner heights are too generalised to be able to make an accurate prognosis. What you need to give an idea of what's happening through the liner planes, log the information along the lines of 2o4 3o1 1o3 4o5 on the passenger side for example, and then measure the liner height on the other drivers side recording the liner heights in the same manner. I expect that the measuring on the other side will be different, that should then give you an idea on whether the liners have twisted or settled. You say the engine block has been skimmed and is flat, if so when you rebuilt the engine and the liners went in square and even, you had equalised liner heights in the two planes ? If you can establish how the liners are now tilted you may be able to achieve a more uniform liner height by swapping propitiously the liners around, mark the liners first 1 2 3 4 etc with a permanent marker and their orientation ( I mark the liner heights around the liner top surface). Failing that and if the decision is the liner shoulders in the block have moved the shoulders can be machined flat and square an even amount down from the block surface and then the liners machined accordingly. Really try for the liner height to be a uniform set of 5555s or 4444s having liners showing low amounts in the centre of the block will likely cause a future failure point .

Mick Richards

*and I've buggered my line spacing up now, you may have noticed !

Edited April 14, 2016 by Motorsport Mickey

[Ian Vincent]

Thks for that Mick.

 

Rgds Ian

[Geko]

Ian, I've had the same type of result after measuring the protrusion following a blown head gasket (fogging the entire hill around my house - so the real thing) a couple years ago.

Findings:

1/ uneven protrusion around each liner

2/ no obvious signs of blown head gasket

3/ a mild crack on the head at cyl 1

4/ a strange bump on the side and I could insert a 0.5 mm feeler gauge between the head and the table

 

What did I do about it ?

1/ nothing

2/ replaced the gasket and applied red sealant liberally which i had not done 5 years earlier

3/ and 4/ skimmed the head by 15 thou after which the crack disapeared and the face of the head was nicely flat

and 5/....torqued the head properly which I had not done earlier either

 

 

 

 

[RogerH]

Hi Stef,

looking at your liner protrusion slant ( 0.003 on one side and 0.005 on the other) is quite common I have found.

If the top of the liner and its lower shoulder is square then it should sit equally flat.

So either the block or the liner seat in the block is on the slant.

 

The only way to overcome this is to have the block acid cleaned and the the block top face and liner seats measured and machine if required.

 

The Fo8 gaskets have a uniform thickness so they are ruled out.

 

I noticed during my rebuild that what I believed were Ali Fo8 gaskets were in fact steel - they look, feel and smell like Ali but are magnetic.

 

Roger

[Andy Moltu]

You appear to have the middle two cylinder liners protruding less than 1 and 4. Lows between highs is not a good thing as far as sealing and gasket life is concerned on the 4 cylinder engines and to be avoided.

 

I recall a conversation with Stanpartmanpartwolf a while back where he mentioned that the alloy heads had problems with gasket life unless modified head studs were used that could cope with the different expansion of the studs and head with heat. Apparently this is why stretch bolts are used on modern ali engines to maintain the force holding the head at different temps.

[Stanpartmanpartwolf]

The alloy heads tend to be happier with a composite gasket using compressible fire rings; these also allow considerable variation in liner protrusion to be accommodated, rather like the original Coopers ribbed hard steel gaskets did.

AFAIK the tooling for those went in the 90s Moss crash- the recent efforts are next to useless for various reasons.

Johnson Gaskets near Bradford will hand-make you a crushable compo gasket at a sensible price, matched to your chamber & liner shapes.

It is also essential to use a non-setting sealant on it, Wellseal has yet to be bettered IMO.

You will get away with regular size head studs for a road engine, torqued to ca. 85ft/lb with lube; but do not use ARP studs.

Keeping an alloy head on a competition engine is another matter entirely.

Please also remember to set valve clearances at full running temperature; they can increase by as much as 0.010" from cold as the head grows.

Good luck!

& hello Andy M €;0}