1.4 TU engine - Head Gasket?

[uncle buck]

Hi all,

Ok, I now have the head off the car, I have checked it with a straight edge & I'm happy to tell you its as flat as a very flat thing so no problems there.

However the piston liner protrusion above the block is way over specification The Haynes manual say the spec should be between 0.03 - 0.10mm)

Using feeler gauges & a straight edge I can get a 0.25mm gauge under the straight edge…but I would estimate the gap to be a smidge bigger than this

The head came off the block with no struggle at all so I doubt this could have disturbed the liners & the engine certainly hasn’t been turned over since the head was removed (Flywheel locking pin still in position)

I have tried tapping the liners down to see if they would move with a block over them & a few swift blows but there is no movement at all.


Can anyone advise on this problem as the Haynes doesn’t really explain what you should do if the liners aren’t within spec?

Regards.

[Gammy leg]

Buck,

If the water surrounding the liners hasn't dropped you have probably not done any damage and the seal is still intact. There is a a lot of hysteria surrounding these things. Once an engine has heated and cooled a number of times the seal is unlikely to break unless forced. Careful removal of the head will not cause any damage, whereas rapping it with a hammer to try to reseat it might.
As for the tolerances given in Haynes, I have successfully ignored them for 25 years with no ill effect.

Gammy

[uncle buck]

Yeah the water around the liners is staying there & not dropping despite my attempt at adjustment with the hammer

Whilst I would love to ignore the tolerance issue of the liners I can't help wondering if that's why the car had an oil leak!

If the liners are sticking up more than they should this will obviously stop the head compressing the gasket to the mating face of the block as much as it should.... this will give rise to leaks.... I can't help wondering if this is why so many of the TU engines suffer from oil leaks!

The engine has only done 48.000 miles & I'm pretty sure the engine hasn't been down before so it looks like its been like this from new!

Regards.

[citronut]

if the linners were stopping the head seatting properly you would have oil and water mixed and squirting out of the gap in a big way,

what did you use for a straight edge
regards malcolm

[uncle buck]

if the linners were stopping the head seatting properly you would have oil and water mixed and squirting out of the gap in a big way,

what did you use for a straight edge
regards malcolm

Yeah I see your point....obviously the oil or water wasn't squirting out so the gasket was doing it's job to an extent, but it can't be doing it 100% if the liners are protruding more more than they should be.

I used the blade of a set square for a straight edge to check across the width of the head & block & the back edge of a hand saw to check over the length.
Both of these were checked on glass for straightness before I started.

[citronut]

the engine was only leaking oil wasnt it and the coolant was ok, in which case this is the usual fault on the TU lump,

what happens is the bondded triangular section in the head gasket which seals the main block to head oil way becomes unbondded so it leaks oil,

i dont belive this is any thing to do with the linners maybe beeing to proud of the block,

these heads are wound down under an aufull lot of torque, if there was the prob you are sudgesting your oil and water would have been mixing in the sump and rad
regards malcolm

[uncle buck]

Yeah the engine had an oil leak , the coolant appeared to be fine with no oil contamination & the oil had no water in it, the only real symptom was the oil leak.

I'm not looking to make work for myself....but 0.15mm (at least) extra protrusion is a mile when we’re talking engine tolerances.

I would hate to put the engine back together only to find it leaking oil again in a few weeks time.

Considering that I'm this far into the job I don't know if I should remove the liners to check that they are seating 100% properly.
As I have never worked on the TU engine before I’m not exactly sure of how the liners are seated & sealed to the block...if the head had been off before is there a posibility that the liners could have been diturbed & lifted slightly off their seat to their current position without causing the coolant to leak into the sump?

I imagine that it would just be a case of dropping the sump & that I would be able to remove the liners with the crank in situ?

Regards.

[Gammy leg]

Buck,

The liners are extracted from above and there is no need to remove the sump to do this. They are a push fit with the seal approx 1/2" above the bottom of the liner. The seal is maintained by the pressure of cylinder head when bolted down & torqued-up.
Obviously once you remove the liners you then have the problem of refitting them. This is the point where you would need to remove the sump, big end caps and bearings, and withdraw pistons.

Gammy

[citronut]

the correct way to remove the linners is to drop the sump, disconect the big ends and pull the linner out with the piston and con rod complete,

but i strongly advise you leave them where they are, as the seal between the block and linner is very very fine and once you have disturbed them you will have your work cut out to re/seal them,

regards malcolm

[uncle buck]

They are a push fit with the seal approx 1/2" above the bottom of the liner. The seal is maintained by the pressure of cylinder head when bolted down & torqued-up.

Yeah there is a picture (quite poor) in the Haynes of a liner with the O ring....so I sort of know what it looks like , but it would be nice to be able to see a liner close up & more so how it fits & seals into the block.

If the O ring seal is maintained under pressure....pressure from the head being in place, then I assume that the liner will actually move down a little when the head is fitted & bolted down!
If that's the case it's also possible that the liners will also give a little upward movement when the clamping force of the head is removed?

I would imagine that the liners would be made to be a fraction higher than the block when the head is fitted & bolted down so they are exerting a positive sealing pressure onto the head!

I wonder if the Haynes actually has the facts right.....maybe the measurements that the Haynes quote should actually be made with a certain force applied to the liners!

I have in the past noticed discrepancies in Haynes manuals of this nature...when they have omitted to mention that a certain measurement has to be taken with a load present!

I apologize if I seem to be "reading into" the subject of liner protrusion a lot but I just like to understand things thoroughly....especially as the measurements I got from the engine were way over spec.

I think I'll just go with your advice Malcolm!

Regards.

[uncle buck]

So there I was with my home made liner clamp....
(a length of wood with a hole in each end that can be bolted over the liners to keep them pressed down while the engine is turned)

I cleaned the carbon off piston 1 & 4 then fitted the liner clamp & turned the engine to bring piston 2 & 3 to TDC to clean them.
Once done I turned the engine to get back to the timing pin position, but I had forgot to put the liner clamp back on....

The result was that liner 1 & 4 had lifted up as the pistons had came up Doh!
So it looks like I will be replacing the liner seals after all

I dropped the sump & removed all the big ends & removed the pistons with the liners.

Just out of interest & inspired by something I read on the net I temporary re-fitted the liners with NO seals fitted to check the liner protrusion & would you know it the protrusion was 0.08mm (the spec is 0.03 - 0.10mm)

So I would say that the liner protrusion above the block has to be checked with NO seal fitted....a fact that the Haynes manual neglects to mention!

Then came the shock of all shocks....the liner seals are £5.97 each (£23.87 for 4) for the thinest O ring ....you would expect them to be a few pence each......the robbing *#:~+^*$

At least Dick Turpin wore a mask....

[uncle buck]

Hi....I forgot all about this thread of mine....so not one to leave a story with out an ending here’s the epilogue

Ok...so I paid the ridiculous price they wanted for the new liner seals & fitted them....fitted the liners, big ends back on, oil pump....you have to remove it to gain access to No 4 (camshaft end) big end cap.... sump re fitted....all went well.

New head gasket in place....head on & bolted down.

I resisted the temptation of having the “As a matter of course” head skim as I could find no distortion at all when I checked it with a straight edge (I checked the flatness of the straight edge on a piece of plate glass first) so I decided skimming the head wasn’t necessary in this case.

A new cambelt & aux belt were fitted & all other bits that been removed replaced along with new coolant & oil filter.

Initial start up....the engine sprang into life at the first turn of the key....the cooling system was bled & ran up to temperature....all ok.

So here we are now 3 weeks or so later & the engine is running fine with no leaks & all is well…..so I think I can call a result.

Many thanks to all who offered advice.


Regards.