Cylinder liners - how easy to displace?

S

Stuey

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Hi all,

How easy are wet cylinder liners to accidentally displace once you've got the head off? We all know the requirement to clamp them when the head's off if you're not doing bottom end work and intend to remove them anyway. I've made a clamp from angle iron bolted between two of the head bolts that spans all of the liners, but I need to clean up the tops of the pistons. If I'm careful, is it safe to work on the piston tops without the liners clamped? As it is, the angle iron's in the way - otherwise I'll have to use big washers and bolts. Comments, please...

Thanks,

Stuey.
 
I've removed a couple of cylinder heads in the past and replaced them successfully without removing the liners, using washers and bolts to retain the liners once the head is off. Probably just the usual instructions, turn the head sideways pivoting it on a single bolt to dislodge it rather than pulling it straight up off the head.
 
Cleaning up the tops of the pistons - that sounds messy without removing them - how do you stop particles slipping down the sides of the pistons and scoring the bore?

I've changed a couple of heads over now without clamping - all OK as long as the pistons don't move (probably best to keep the car out of gear!)
 
Usually grease is applied to fill the gap between the piston and cylinder wall, that way the carbon laden grease is scraped off leaving clean grease in the gap.

Likely after starting the motor the clean grease burns off leaving more carbon on the pistons than was removed :)
 
I've always just cleaned the pistons by careful scraping and a green kitchen scourer with a bit of petrol (use gloves) to polish it. I always have liners clamped - easy to do and leave access to the whole piston top.
Upon reassembly, I put an capful of clean engine oil onto the piston and smear it over the bores. This replaces lube taken off by the cleaning with petrol and will pick up any stray bits of carbon and toss them out the exhaust port upon start up. Had engines apart again after this method, and no bore scoring ever.
 
Normally you wouldn’t need to. The old old days of regular decarbonising are thankfully over. Nowadays if the rings are good , it is only likely required if the motor has poor valve guides causing oil burning and excessive deposits on the piston (which I think is Stuey’s problem). Renault motors seem to have an original factory lifespan where the valve guides wearing out coincides with the piston/liner set requiring replacement. I suppose if a PO has just replaced the rings or piston liner set only, without doing the head, that is where the head needs to come off between overhauls and when decarbonising caused by excessive oil burning needs to take place.
 
Valve guide clearance (was cylinder liners)

Absolutely, Simon. The guy that rebuilt the motor didn't do the head, and I've been burning a bit of oil, hence the carbon. The grease-in-the-piston-gap method was what I was going to do, by the way...

I got the head back from the head shop today, looked at the receipt...and they only did the exhaust guides!!! Arrrrrrgggghhhh! I'd inspected the inlet valves before taking it in, and they had oil on their heads, so I'm pretty sure this was the problem. I spoke to the boss of the head shop who reckons they would definitely have inspected all of the guides, stating that they would rather have done all of them because they'd have made more money - fair enough. But there is definitely some lateral play in the valve (i took one off again) and I'm pretty sure there shouldn't be...

Whatdya reckon?

Stuey
 
Stuey said:
Absolutely, Simon. The guy that rebuilt the motor didn't do the head, and I've been burning a bit of oil, hence the carbon. The grease-in-the-piston-gap method was what I was going to do, by the way...

I got the head back from the head shop today, looked at the receipt...and they only did the exhaust guides!!! Arrrrrrgggghhhh! I'd inspected the inlet valves before taking it in, and they had oil on their heads, so I'm pretty sure this was the problem. I spoke to the boss of the head shop who reckons they would definitely have inspected all of the guides, stating that they would rather have done all of them because they'd have made more money - fair enough. But there is definitely some lateral play in the valve (i took one off again) and I'm pretty sure there shouldn't be...

Whatdya reckon?

Stuey
Click to expand...

Sigh. There's no choice. Back again!! Last time I had valve guide work done, most were perfect but a couple needed changing. The workshop guy said even worn, the Renault clearances were better than some new cars he dealt with. I remember replacing 3 exhaust guides and no inlets. But there wasn't sideways movement in the inlets. Sigh again.

You can email me where not to go!!!

Cheers

John
 
Stuey (second reply),

The sleeves won't move in my experience unless you turn the crankshaft but I'd not chance it. If you push too hard on one piston it might rotate, and it doesnt' take much!

I'd use the bolts and washers approach, as it leaves more room to get at the pistons. Maybe some woollen yarn around the top of the piston at the base of the grease, then pull it out afterwards?

Good luck.

Then it's not that hard to replace the sleeves at the same time.......

Cheers

John
 
Hmm,

I've haven't removed a lot of sleaves, however you will probably find in order to remove them you'll have to:

--Turn the block upside down and suppport it using two peices of wood at the ends.
--Using a peice of redgum against the base of the liners, and a sledge hammer belt the liners out ....

Yep, you've gotta be **really** careful not to displace them with the head off :roflmao: :roflmao: :roflmao:

Then again it'd but just my luck one of the buggers would move if I didn't retain them :mad: Just bolt somthing across the liners using a couple of head bolts.

seeya,
Shane L.
 
They don't exactly sit there loosely do they!

My V6 motor had them well and truly stuck in place, so much so I'm wondering if they used some "goo" on the seals at the factory. I'm still trying to remove the residue from the block.

I had one come loose in a spare R16 block on the weekend - I was moving the block and the flywheel turned - and one liner moved up - no problem as it was just an old spare engine, would need to replace them anyway - but shows it can also happen easily sometimes...
 
The 10/12 1300/15/16/17 liner seals are made from "Excelnyl", I reckon it is some form of plasto-paper co-production, so under heat it may actually set like glue, and consequently be as difficult to remove. Curiously, they don't mention in the manual to use the "Magstrip" gasket stripper on the liner seals like they do to remove cylinder head gasket residue.

Also the V6 block being alloy it may just react more than the seals than on an iron block which seem simple to clean up. Probably another reason I'm a fan of the Sierra motor :)
 
Postscript: I spoke to the head shop and they were quite adamant that the inlet guides were within tolerance, the biggest clearance measured being 1.8 thou. interference using a small hole guage and micrometer. The guy was quite sure that I wouldn't want them much tighter than that otherwise they might sieze. In fact, even with me paying more, they didn't want to do the job because they thought it was the wrong thing to do. Does anyone have a factory manual that describes the inlet valve tolerances (John W, I don't doubt you, as my Haynes says the same, but you know, if I can give factory specs to the shop...).

Stuey
 
can't you just use a vacuum in conjuction with cleaning the carbon off the pistons ????
i have remove broken windscreens whilst useing a vacuum and with the amount of glass there is in a screen i have harldy left a piece of glass behind
just a thought anyway
then you can just leave the bolts in there with the washers under them to hold the liners and you may not even have to move the crank
only thing that would stop you is the size of your hand to get it in the bore with the vacuum unless you sucked it all out after the job is done
something like what the dentists use would be ideal and you could probably rig something up on the vaccy
 
Rambo, already done it the same way you've described! I use the vaccy on a lot of car stuff. Like the others, though, I just though it was unlikely that the liners would move. Not worth the risk, though, as I haven't got five minutes spare to replace the buggers.

Stuey
 
DoubleChevron said:
Hmm,

I've haven't removed a lot of sleaves, however you will probably find in order to remove them you'll have to:

--Turn the block upside down and suppport it using two peices of wood at the ends.
--Using a peice of redgum against the base of the liners, and a sledge hammer belt the liners out ....

seeya,
Shane L.
Click to expand...

Great stuff - red gum eh? Just the timber. For Stuey, I'd suggest jarrah. Both work really well in my experience!

No need to remove the block from the car, provided you are careful to cover the crankshaft journals when belting them up from underneath.

JohnW
 
Stuey said:
Postscript: I spoke to the head shop and they were quite adamant that the inlet guides were within tolerance, the biggest clearance measured being 1.8 thou. interference using a small hole guage and micrometer.

(John W, I don't doubt you, as my Haynes says the same, but you know, if I can give factory specs to the shop...).

Stuey
Click to expand...

Stuey,

I've checked every factory and non-factory manual in my collection and, as you've no doubt discovered, there aren't any specs.

Useful phrases like "a very small amount of movement" are there but nothing quantitative.

I'd have thought that 1.8 thou would be OK myself. What was the final outcome?

JohnW
 
Hi John,

Thanks for that. Outcome..? I can't see the oil smoke on startup being exhaust valve guides, so I went to another head shop recommended to me because they have a load of loose valve guide seals in small containers lying around. Well blow me down, there was a top quality BMW guide seal (positive type) that was PERFECT for the job - designed for a 7mm stem and an 11mm guide, the type with the steel outside band around the base, like a can. These press onto the guide using a 13mm socket and copper hammer (tight) and seat right down on the deck. They have the spring around the sealing lip, and really look made for the job. Worst thing is that the guy didn't know WHICH BMW they were off, but I know they're a German brand (Sabo). I asked about lubrication and he reckons they're designed to let a small amount of oil through. I've only put these on the inlets. Must push him to find out, though, which model. The only BMW I know with 7mm stems is the 12V 325i, but that has 14mm OD guides. The 16V Golf also has 7mm stems... As it is, I've run out of time to do the porting now, except for matching the inlet manifold to the ports (done), so it's going back on stock standard...probably wouldn't have noticed the difference anyway!

Smokin'..!

Stuey
 
Stuey said:
Hi John,

Thanks for that. Outcome..? I can't see the oil smoke on startup being exhaust valve guides, so I went to another head shop recommended to me because they have a load of loose valve guide seals in small containers lying around. Well blow me down, there was a top quality BMW guide seal (positive type) that was PERFECT for the job - designed for a 7mm stem and an 11mm guide, the type with the steel outside band around the base, like a can.
Stuey
Click to expand...

Where did you find them???

Sound wonderful. I should buy 8 for the future.

JohnW
 
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