Cylinder liners - how easy to displace?

John, it's the place that Mark Dyson uses, CGC Head Engineering, which is just up the road from Euromotive. I got in touch with them today to ask if they could be more specific about which model BMW they fit - they couldn't. (I just gave them the OD for the valve stem and guide, and the first one the guy picked was perfect.)

Stuey
 
Stuey said:
John, it's the place that Mark Dyson uses, CGC Head Engineering, which is just up the road from Euromotive. I got in touch with them today to ask if they could be more specific about which model BMW they fit - they couldn't. (I just gave them the OD for the valve stem and guide, and the first one the guy picked was perfect.)

Stuey
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Thanks Stuey. I must get to know them!

Cheers

JohnW
 
Finished the job today with a huge hangover. Advice: don't do it. I made loads of mistakes that needed redoing. Like putting the fan on without the pulley, and thinking while doing it, "hmmmmm, what's missing?", then only realising when I went to put the belt around...something...

One thing I was pleased about was that the Bretille liners used in the bottom end rebuild 80,000km ago have absolutely no wear - not only is there no wear ridge, but the hone cross hatching is clearly visible all round the bore. I know it's not a great mileage, but still, they must be pretty good quality.

Stuey
 
I hadn't seen this thread... but I would like to add a little...

Past experience has shown me it's very important to avoid liner movement. Both in the 16TS engine and in a 504 engine, I have seen a liner that got tilted, and they both caused problems.

The liners are definitely not tight in the block. They can and do move.

I have made up some special triangular washers that I use in conjunction with bits of tube over main bearing cap bolts to retain the liners when I dismantle an engine.

Also, to the suggestions about taking the liners out anyway... you simply don't know how much extra work this is!

Just getting the sump off is a problem, much less putting it back on and not kinking or losing the gasket in some way... and if you do disturb the liners, you really need to seat them again... I do this using valve grinding paste. You also have to go through the rigmarole of setting the liner heights, finding the thickness of seals to get these right... it's a lot of work in the car.

In fact, to do it on a 504 I would undo the bellhousing bolts, move the engine forward just enough to clear the dowels in the back of the block and turn the engine upright to make it easier. I retain it in that position by using a piece of timber across the bottom rails and under the front main bearing area. You have to remove the bracket for the passenger's side engine mount to do this, and also fold up the base of the battery carrier.

But if you're going so far as to remove the liners, it's worth the trouble to do this, it certainly makes it a lot easier to set up the liner heights and check for parallel with the block face.
 
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Ray Bell said:
Also, to the suggestions about taking the liners out anyway... you simply don't know how much extra work this is!

Just getting the sump off is a problem, much less putting it back on and not kinking or losing the gasket in some way... and if you do disturb the liners, you really need to seat them again... I do this using valve grinding paste. You also have to go through the rigmarole of setting the liner heights, finding the thickness of seals to get these right... it's a lot of work in the car.
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It really isn't a lot of work in an Renault 12 which is the actual subject of this thread, if just the head is being removed and care is taken to retain the liners properly. A Renault 12 does not have an obstructive crossmember under the car, just the roll bar and a bolt on crossmember which are easily removed. Also if the sump is removed a new gasket should be used, as the old one will be compressed, especially if it is old.

The liners don't need to be seated with valve grinding paste, unless it is an air cooled Volkswagen we are talking about! The liner seats on a 12 are pretty tough, and just need the old liner seals removing on the base of the liner and seat, if proper coolant has been used and the seats are uncorroded there should not be any problems. Setting the liner heights is easy, there are only three sizes of liner seals to choose from.

If the liners and valve guides are all done at the same time, and given normal maintenance of changing fluids etc. the time between overhauls can be quite significant in a Renault 12.
 
In any case, there was no question of me unseating the liners - I'd have to be bonkers given that they're so new and in good condition.

Incidentally, a major annoyance (given my hangover...) was that I'd prepared a different inlet manifold some weeks ago (same type) as I knew that the small coolant pipes on mine were a bit corroded. On this 'new' manifold, I'd re-tapped these and screwed in some new brass fittings, and generally tidied the manifold up. Well...the bloody thing didn't fit! When I offered it up to the exhaust manifold and head, the flanges (where it meets the head) were angled so that the bottom had about a 4mm gap when the top was in contact. Arrrggghh! All that work wasted, I had to use the original, hastily cleaned up. I assume the two manifolds must be matched? I hadn't even thought about it...

Stuey
 
I'd say in the factory there would have been a final machining process where the two manifolds are bolted together, then given a final machining where the faces mate up to the head. That way it would save the factory having the same problem you found.
 
Yes, I'd guessed that, too, Simon. I was just surprised by the size of the gap - so much so that I put them side by side because I figured someone must've milled the bad one for some reason. If you think about it, this'd put the exhaust flange(where it meets the downpipe) in towards the motor by about 15-20mm, a fair bit of manufacturing tolerance!

Stuey
 
Stuey said:
UPDATE: Smoking on startup cured...definitely was the valve guides, then.
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Excellent outcome. I'm puzzled by the manifold business. Sounds like there are more types than we realise - maybe some slightly different head side profiles??

I've never heard of such a thing though.

If ever you get to the bottom of it.....

JohnW
 
Arrrrrrrrrrrrrgggggh! Well, I spoke too soon. I took the old girl for a thrash yesterday and got it very warm so the oil was thin. Then I left it half an hour or so, the circumstances where before, the smoke would be at its worst. Result: a cloud of smoke. Bugger!

The head's coming off and going back. As for the guide seals...? :confused:

I have to get some hard data on the proper clearance between valve and guide so I can tell the guy exactly what I want, no guessing. I'm sure he won't do it unless I write it on the work order, as he reckoned he was worried about valves siezing. Does anyone have any leads; maybe contacts in the business?

Not happy...excess work and cost for nothing...

Stuey
 
Stuey said:
Arrrrrrrrrrrrrgggggh! Well, I spoke too soon. I took the old girl for a thrash yesterday and got it very warm so the oil was thin. Then I left it half an hour or so, the circumstances where before, the smoke would be at its worst. Result: a cloud of smoke. Bugger!

Stuey
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Stuey,

Hmm. Two things come to mind.

1. I'd have a chat with Mark Dyson and maybe (RACWA member?) Mark Bird, who is in charge of vehicle inspections at their Head Office and knows these engines well.

2. I remember years ago when I put the last sleeve kit in the R8 (1988!) that I bought the less expensive, non-genuine one in Adelaide, and my guru mechanic there commented that they looked the same but the non-genuine ones were a little prone to puffs of smoke on startup.

Do the plugs hint at one particular cylinder and if so, does it correspond with a looser valve to guide clearance?

Sympathy and good luck. I'll be interested to hear how this progresses - not as interested as you I imagine.....

Cheers

JohnW
 
John, thanks for that. I've actually spoken to Mark Dyson, but he didn't really know. I'm no longer an RAC member, but I'll try Mark Bird anyway.

Interesting comment about the sleeves - I assume you mean the cylinder liners, and not guide sleeves - I wonder if this is the case with mine? I know the liners are Bretille brand, because when they were done, Euromotive stuck the "Bretille Pistons" sticker on the car window. And these are the cheaper of the two brands that Caravelle stock. I wonder why this happens, if it is the case?

Other than that, the car runs really well. It has a bit more torque (I assume this is from better compression and the 9.75:1 CR resulting from the head skim) and there is no noticable smoke on the overrun, at least from the drivers seat looking in the mirror. But then, there wasn't before - my diagnosis of bad guides was purely because of the startup smoke. Maybe it was always the liners?

And no, the plugs don't suggest one cylinder. I might pull the inlet manifold today and have a feel of the valve stems to see if they're oily...

I say again...aaaaaarrrrrggghhh!

Stuey
 
Stuey said:
John, thanks for that. I've actually spoken to Mark Dyson, but he didn't really know. I'm no longer an RAC member, but I'll try Mark Bird anyway.

Interesting comment about the sleeves - I assume you mean the cylinder liners, and not guide sleeves - I wonder if this is the case with mine? ...

I say again...aaaaaarrrrrggghhh!

Stuey
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I did indeed mean pistons and liners. I don't know what brand mine are, but they aren't Renault.

Mark Bird is a good guy and very knowledgeable - you could mention my name.

My man in Adelaide was Ron Borholm, and he was heavily involved with Renault Australia back in R8 Gordini times. He said he had no idea what the problem was, as they looked much the same but oil control wasn't as good. I wonder if a bit of oil somehow gets up past the oil ring and sat behind the compression ring to be released on initial startup. God knows how.

Cheers

JohnW
 
Is it worth just leaving the car to settle back down again? Just wondering if the piston tops have been cleaned, there is no where for the oil to be absorbed. Once they get a bit of carbon on the pistons the (hopefully) small amounts of oil will be absorbed by the carbon.

Or is the car really imitating a James Bond Special on startup??
 
Simon said:
Is it worth just leaving the car to settle back down again? Just wondering if the piston tops have been cleaned, there is no where for the oil to be absorbed. Once they get a bit of carbon on the pistons the (hopefully) small amounts of oil will be absorbed by the carbon.

Or is the car really imitating a James Bond Special on startup??
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I guess it wouldn't take much oil to do this. Therefore not much carbon needed to absorb a bit and release it slowly.

I suspect it may improve a bit in this way but doubt a full smoke-free outcome.

Also, given that those stem seals were fitted and the clearance valve to guide isn't huge, I just wonder if something else is going on.

JohnW
 
Well, John, I spoke to Mark Bird who I must say was interested and helpful. He's had a similar problem with his R10, but in his case the head shop were reluctant to change the guides as they said it was a risky business and could cause damage (hmmmm...I'd have walked away - this is bread and butter stuff for them). Anyway, his cure was to replace the valves - the fraction that the stems had worn down made the difference. A complete cure, apparently. I suppose $40 for new guides and the hassle of taking the head back, versus $80 for new valves and the convenience of same day replacement is an important point to consider. Incidentally, his daughter's R12 does the same as mine.

After driving mine a bit more, I've realised the smoking is not as bad as it was, and it's only after the oil's very warm and it's been left a specific time (1/2 hour/1 hour) that it happens. Most of the time, there's none. At this stage I'll leave it as Simon's suggested - who knows, the seals might also wear in a bit.

Thanks for the comments and help.

Stuey
 
Stuey said:
Well, John, I spoke to Mark Bird who I must say was interested and helpful. After driving mine a bit more, I've realised the smoking is not as bad as it was, and it's only after the oil's very warm and it's been left a specific time (1/2 hour/1 hour) that it happens. Most of the time, there's none. At this stage I'll leave it as Simon's suggested - who knows, the seals might also wear in a bit.

Thanks for the comments and help.

Stuey
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Stuey,

He's very good. I'm glad you feel able to leave it at this stage. As long as it doesn't smoke when taking off after waiting for a green light, doesn't smoke on steady running and doesn't use much oil, I'd be inclined to leave it now if it were mine! Our Virage does it a tiny bit (190,000 km, original pistons and sleeves) too.

Incidentally, Mark's properly restored R10 is quite sensational. If there's a better one absolutely anywhere, it would be very surprising. Come to this year's French Car Day (Oct 10th I think) and have a look. It might be at the Classic Car Day in March (21st?) at the SIVA area too.

Cheers

JohnW
 
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