Just over a week ago I finally changed the gasket (and head) on my '93 CLX, and it's running really well at the moment - it also starts nicer than it's ever done in the 2 1/2 years I've owned it.

I swapped the head becuase I didn't like the look of the face that much, as it has obviously suffered some corrosion damage due to lack of fresh antifreeze, but the vital area immediately adjacent to the bores looks OK.


Early hours of sunday morning our youngest comes home in the '93 "Parade": "I'm freezing! - the heater doesn't work any more, and the temperature gauge went up to 110 on the way home".

No prizes for guessing what I was doing yesterday:
head off the "Parade".

Now the head face on that head is a lot cleaner, but number 3 cylinder looks like it's fresh off the assembly line - bright shiny piston top, I could even read the numbers and see the arrow. Whereas the others are the usual carbon deposits.

The edge of the cylinder head for number 3 cylinder has a small but significant "V" nick in the edge - I think I can guess where all the coolant went
It might respond to a skim, but the damage may be too deep.

Meanwhile - I put the old CLX head on.
Used a 8UKP head gasket set I got on Ebay a while ago, and so far so good - but it's a bit more "tappety" than the other head, but it has 40K more miles on it....


Will have to see how they both fare over the coming months (and see what can be done with the "newer" head.

As an aside, I think the answer to something which puzzled me a bit has come to light:
the exhaust on the "Parade" would sometimes look really clean, rather than the slightly sooty look which seems to be the norm for my Panda - I had thought it was a less worn engine just running that bit cleaner.
Perhaps it was a bit of coolant leakage before the total loss?


Regards


John H

Nice one, sounds like you've had your work cut out!

Regarding the head you took off your CLX, my head looked pretty dodgey when i took it off but decided it probably had enough meat around the bores for me to get away with re using it. 5000 miles later and it is still fine, with lots of inhibitor in the water!!

I was suprised about the amount of corrosion damage, it has taught me the value of changing your coolant regularly!

Hope both repairs are a success, i am sure they will be!

Phil

John - Sounds like it never rains but it pours

You know what, I envy you even knowing how to change that.. i wish i did

Jaff_Fox said:

You know what, I envy you even knowing how to change that.. i wish i did

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It's probably one of the easiest heads to change there is - detailed well enough in Haynes.

The longest job is cleaning everything up sufficiently.

About 6 months ago i changed the head gasket on my 1000cl. All going fine when on angle tightening the final and tenth bolt it suddenly clunked round about 20 degrees!! Gulp! Guess i stripped something is there any way of telling if just the bolt went or the threads in block as well. It runs ok ish but it soon blew its gasket again and now im worried i have an engine i cant even take apart any ideas?

I guess you'd have to take the bolt out to see if it's all there, or if there are steel shards in the threads (from the block).

You might need to undo them in sequence (and loose the head gasket in the process) to avoid warping the head by undoing only one bolt.


I spent as long on the clean up as a whole as I did taking the head off:

cleaned threads on the bolts with a brass wire brush
(some were dirty/corroded/smelt of fireworks )

cleaning the bottom of the threaded holes out
(gasket scraping debris)

running a bolt down each hole to see it went in fully
(some were a bit obstructive, but eased with use)

oil soaked the bolts and drained them for 30 mins..
(some lube, but not too much - excess in the bottom of the hole will "hydraulic lock", no lube and you get the "right torque" but insufficient pressure on the head)


Not to mention the cleaning and degreasing of the block and head faces.


Out of interest, the head with the damaged face is going for a trip to one or two engineering shops on monday - it will be interesting to see which side of the skim or scrap line it falls.

How many times can a head be skimmed? Does skimming significantly raise the compression ratio?

Giacosa said:

How many times can a head be skimmed? Does skimming significantly raise the compression ratio?

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Depends how much is removed each time, I suppose.

I don't know how much the compression increases for a given thickness of skim, but it must increase as you're reducing the volume of the combustion chamber.

Giacosa,

When you did the final bolt, did it actually clunk or just suddenly get easier to turn? The reason I ask is that the normal failure during tightening a head bolt is taking it past it's yield point. The head bolts when torqued correctly are actually stretched within their elastic limit (temporary stretching), however can take on some plastic deformation (permanent stretch or necking). If your head bolt had any plastic deformation, it would reach it's yield point quickly during re-tightening. You might just need to replace your head bolts (with the new head gasket)

This is why many manufacturers specify an amount of times that head bolts can be re used.

RS Pilot said:

Giacosa,

When you did the final bolt, did it actually clunk or just suddenly get easier to turn? The reason I ask is that the normal failure during tightening a head bolt is taking it past it's yield point. The head bolts when torqued correctly are actually stretched within their elastic limit (temporary stretching), however can take on some plastic deformation (permanent stretch or necking). If your head bolt had any plastic deformation, it would reach it's yield point quickly during re-tightening. You might just need to replace your head bolts (with the new head gasket)

This is why many manufacturers specify an amount of times that head bolts can be re used.

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At last - somebody that actually knows what they're talking about

It was a definite clunk. I also noticed that the action of the bolt became quite 'springy'. It was a new set of head bolts so shouldnt have had much chance to form plastic deformation. Tis helpful tho as it answers questions about head bolts, I wasnt aware the stretch is supposed to be temporary in head bolts. Cheers Pilot

If the bolt felt springy, I would suggest either the threads have bottomed out or as John H has suggested it's found some contamination in the tapped hole. The spring in these cases is the bolt twisting and means that you've never had any clamp load from that bolt onto the cylinder head leading to the premature failure.

When you replace the head gasket this time, work on Johns suggestion so that you are happy the head bolts will be clamping the head before they bottom out or meet some resistance.

I'm still a lttle puzzled by the clunk through

phil_harry said:

Nice one, sounds like you've had your work cut out!

Regarding the head you took off your CLX, my head looked pretty dodgey when i took it off but decided it probably had enough meat around the bores for me to get away with re using it. 5000 miles later and it is still fine, with lots of inhibitor in the water!!

I was suprised about the amount of corrosion damage, it has taught me the value of changing your coolant regularly!

Hope both repairs are a success, i am sure they will be!

Phil

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Bugger, Car is now missfiring, losing water and i have mayo. Guess i will have to consider changing the head next time

The bolt only felt springy after it had clunked on the final angle tightening. It had felt fine while tightening up il have a go at it this week see how it goes

John H said:

Out of interest, the head with the damaged face is going for a trip to one or two engineering shops on monday - it will be interesting to see which side of the skim or scrap line it falls.

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Well, it was late yesterday when I got it back:
seemed like a good deal - done by a friend of a work colleague - 30UKP.

I was told he'd taken 10 thou off, but I suspect it's rather more, as the exhaust valves now protrude beyond the head face when fully open.
I don't think they used to.
It's probably not "safe" anymore.

G.O.K. what the compression will be, but I hope it will be some time before I find out (it depends how long the repairs of the last few weeks hold up..)

Are there uprated gaskets for the 999cc available?

There are two part numbers quoted for the gasket, but I couldn't say what the difference between them is.