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jeremy
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Post by jeremy »

All bolts stretch when tightened. A torque wrench is used to ensure a bolt is tightened enough to stretch it just enough so that there is a spring - overtighten - and it stretches and in extreme cases can actually be seen to have waisted - ie thinned in its shaft.

Head joints are specialised and with modern car reliability need special care - hence the detailed instructions for tightening - which are intended to overcome differences in tension caused by bolt/thread friction due to manufacturing tolerances and finish difference - after all these things are only used once and you will know from experience the difference running a nut down a bolt can make to the ease with which it moves.

New bolts are relatively cheap - even the manufacturers instructions for the 16 valve say the block holes should be cleaned with a tap before the bolts are inserted.

The suggestion made was that you should consider replacing all the big end shells, not one - this is entirely a matter for you - it just is few of us really enjoy taking engines to bits and doing them now may prolong the engines life. There is a theory that if they are replaced in time they will delay the oval wear pattern which causes problems.

For my part not only would I replace the liner and piston as you are doing - but I would replace the other piston rings and would see if I could replace the main bearings as well. I would also lap the valves - but this is seldom as easy as it looks as they may have pits in the seats and need re-seating. (I have not done this job on a Citroen engine and don't know how likely this is.) I would end up with an overhauled engine which hopefully would perform well for some years.
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Post by CitroJim »

Colin Winn wrote: Why new bearing shells? Won't this just throw the engine out of balance?
Surely the conrod would be happier nestling on the same bearings its mated with over 18-20 years?

CJ - I have 2 head positioning dowels - one in diametrically opposed corners. Will look for vacant space for No.8 head screw spacer, though. Didn't know to use new head bolts - don't think the book tells you that! Would have thought 'stretching' of bolts would've allowed head loosening, not tightening?


Er - not intending to skim the head - have already bought the h/gasket and the book says you need a thicker H/gasket if you've skimmed or bought re-con head! I removed it VERY carefully, with one flat at a time type turns on the nuts - so I can hope it's not warped, can't I?

Head oil filter - does it screw out or pull out (have new one bought already!)? And for the valve springs - spring compressor needed? Will doing the oil valve seals (I have these too) mess the valve/cylinder timing config that exists at the mo' - or can I change the seals without altering the valve configuration in existence ??

Cheers to all once more. Almost looking forward to getting down to the job!!

Sincerely,

Colin
If I was not so far away I'd come and give you a hand...

Yes, there are two locating dowels. I've just looked at a spre head I have in my workshop.

The bolts are elestic in fact and under tension so they keep exerting a downward pressure, keeping them and the head very tight.

As you were so careful taking the head off then I reckon you'll be fine without skimming, just ensure it is spotlessly clean everywhere. Thinking properly now, it is not as if the head came off because the head gasket blew so you'll be OK.

The head oil filter fits in an angled drilling set at 45 degrees into the head on the cambelt side. It can be pulled out with a bent piece of stiff wire. It only pushes in. Look underneath near the front (inlet side of the head) and you'll see it. It is next to the vaugely "pork chop" shaped oil return passage.

You'll need a good valve spring compressor with a deep throat specially designed for an Overhed Cam head. The valve springs are strong and not easy to get at being buried deep in the foller bores. Just replacing the oil seals will not disturb the valve clearances at all provided you put the same valves back from where they came from. The old seals can be tricky to remove due to their buried nature. I use a home-made tool that hooks around them and allows them to be pulled straight up and off. They harden with age.

As I compose this I have just seen your reply Jeremy so I shall stop now. Between us we have covered it I think. Apologies if I have said anything again you have just said Jeremy!

Looking forward to the next instalment Colin..
Jim

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Post by citronut »

it is best to have the head skimed,i would also use the old bearing shells unless they look badly worn,as the cranck will be worn,just make sure they go back exactly where they were and the same direction they where facing,the stretch bolts should be mesured to make sure they are still withinthe tolerance,it gives these mesurments in the BOL,i would still go the route of replacing the hole lump as these engines dont often fail
regards malcolm
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Post by CitroJim »

citronut wrote:the new piston comes with a new gudgion pin and a wire circlip at each end,once you have picked out one of the clips from one side of the piston use a soft drift to knock out the gudgion pin,this is when i would have the piston partly fitted into the linner to the point where the gudgion pin is just clear to drift out,
Ah Haa! Interesting! :idea: I've been looking at a piston and conrod that came out of a wrecked 205GTi engine and on that one the gudgeon pin is an interference fit in the conrod with no circlips in the piston.

In my ignorance :oops: I thought all XU5 engines had the same arrangement. That throws a a new light on it. It now stops being a quite tricky job to a dead easy one. :D Thanks for that Malcolm, I now see precisely where you are coming from on your liner refitting procedure.

My apologies for misleading you a little Colin...
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Post by CitroJim »

Colin,

You may be feeling by now that we all have our own ideas on the subject of big end shells and skimming of heads. At least it gives you a few viewpoints to consider and that is never a bad thing.

I'm all fresh from a good sleep now and this is my thoughts on these two subjects.

Head skim. Malcolm is a pro, he earns his money repairing cars and therefore he must warranty his work. In such a case a skim is the best way to ensure no further problems. I'm just an enthusiast, an engineer yes, but not in the motor trade. My thought is that if the head appears to pass muster then it is worth taking a risk. If I were doing the same job as you, I would give the head face a really good inspection. If it shows signs of any pitting or corrosion that will not readily clean off from the critical sealing areas around the fire rings and waterways then a very, very light skim is very much in order to clean it up. If however you can clean it up really well easily then all you need to do is make a quick assessment of its trueness. I have done this by removing all the dowels and the two engine hoist brackets attached to the front of the head and lying it on a piece of thick plate glass that is overall larger than the head. Thick plate glass is very true and if you can rock the head at all whilst it is on the plate then it is warped and needs a light skim to correct this. If the head cannot be rocked, it is flat. I know this is not a be all and end all test but it works for me. I have a GTi head in my workshop taken off a good engine simply because the stem seals had gone. I cleaned up the face no problem and on a plate glass test it is flat. I would not have this particular head skimmed before re-use.

Much the same applies to the big end shells. I'd give them a really good inspection. If the engine was healthy before the liner crack then chances are that the shells are OK. have a good look at them and if they are perfectly smooth and are an even dull metallic grey colour all over then it's worth taking a risk. If however, they show any signs of scoring, bright spots, any copper colouring (to show the top bearing layer has worn through to the backing) or any dark discolouration, then replace them.

When you remove the conrod from the crankshaft, I'd wrap the crank journal in tape to firstly protect it and secondly to ensure no dirt gets into the oilway drilling.

You'll not ne able to change the main bearings in any case unless you remove the whole engine as the crankshaft has to be removed.

I hope the modem connection holds up OK to read all of this Colin..
Jim

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BX Engine overhaul

Post by Colin Winn »

Hi everyone,

Well - thanks again! Yep - modem hanging in there (Modem OK - dodgy French tel. lines!).

Gonna be busy next week with clients, so may have to be off-line a bit and then come back to it all . . . as and when I get started on it, no doubt - that is after the Herald (sorry) gets a new flywheel toothed ring, clutch, wheel bearings and starter motor.

Er . . if the engine has to come out for the bearings to be replaced, then I'll just have to hope the old ones are OK, as I thought it all sounded too complicated for me, even with Citronuts' brilliant descriptions!

Citronut - if you skim, do you have to have an oversized head gasket as Hayne's say? Like I said, I've already bought a new, standard one.

Anyone had any thoughts on that big round metal 'bush' with a hole in it that fell out when I lifted the head off?

The other really difficult thing to overcome out here is the availability of 'capable people' DIY car tools - Halfords just doesn't exist here - and I'm certainly not going near a Citroen garage to hire or buy! May be able to hire or borrow from local garage, I suppose.

Thanks for the info on the head oil filter - I could see it, just couldn't work out how best to remove it - Haynes manuals are a bit naughty sometimes . . . they tend to say '... and then remove . . .' without reference to all sorts of pervading factors - bits in the way, inaccessiblity, major rusting etc..

So - no change . . . How much can I do with the engine in place (I just realised I am holding the engine up with a trolley jack because the head's off and need to get the sump off!!! May need to find a different method of supporting other than the trolley.

Jeremy - are you saying follow the Hayne's tightening 'final angle tightening' routine, or same as Citrojim said in one of his earlier replies?

Anyway, once again, thanks everyone - it's going to be an experience (I WILL recount!).

Sincerely,

Colin.

And if I can't find a valve spring compressor tool available here, how will I be able to get them out to change the seals?
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Post by citronut »

the bush you speek of goes on the head bolt at the rear left corner just behind the cam sproket,the reason for it is the thread inthe block which it goes in is directly above the water pump and the bush is a spacer to reduce the amount of bolt entering the block

now the need to use a thicker gasket is when you have the head skimed the valves will be nearer the head face and will come into contact with the pistons after reassembleing,as the tolarance is very fine
regards malcolm
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Post by Colin Winn »

Exactly what I was saying then? :lol:

So, having bought a HG already, and hoping I took the old one off well enough, I'll not skim it . . . just hope for the best!

I don't have any plate glass to lay the head on and at the mo' the valves are protruding downward and I have no valve spring compressor - so until I can get that, change the valve oil seals by their removal, I and even if I can find a flat, I have no way of knowing if the head is twisted at all.

Thankis for the advcie about the water pump head bolt spacer, Citronut - it must have come up with the bolt itself.

Cheers all once more.

COlin
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Post by citronut »

with regards to citrojim
i dont think the plate glass trick will not be acurate enough to cover all the angels the head can warp,as all tha could proove will be end to end distortion,so if all four corrners where level to each other the head would not rock,what you should check it with is an enginears straite edge,i allways have some sort of skim done as its an aufull lot of effort to go to just to find you have still got a coolant problem
regards again to citrojim

malcolm
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Post by Colin Winn »

Hallo "My BX Engine Rebuild Advisers" !

Citronut - many thanks - believe it or not I understand where you're coming from in respect of the head and 'flats' to check it with. I certainly don't have anything like that . . . . . (long pause . . . .) . . . .
SO . . . . IF I had the head skimmed (which everyone sucks their teeth at and says how expensive it'd be, we're in France, remember, the question remains (come on guys, concentrate!) - would I REALLY need the +2 thou head gasket the book says.

In which case, obviously, I could look for a suitably reasonably priced engineering firm to skim it and then go back to Citroen and ask for a thicker replacement item and return the one I have already purchased !!!

Anyway, hope that one can be answerered - I guess, Citronut, you skim as a matter-of-course, to save any aggro that'd occur if you took my way out of this, put it all back together again and found the blasted thing wasn't flat at all !!!!??!!

Must go. Cheers and continued thanks.
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Post by citronut »

over here its about 25 squide to skim the head,i always trust the enginer to take off what he thinks is needed,then if it has to have quite a bit off ,you then have got to sink the valves into the head by cutting there seats so they are the corect depth from the surface,it is usual to use the thiker gasket most of the time
regards malcolm
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Post by Colin Winn »

Thanks Citronut;

I'm amazed (and if I was in the UK, delighted) at 25 squids - talk to anyone here about skimming the head and you'd think you were planning to put a man on the moon (like the old advert, spoken in devonshire rolling accent . . ."and one day, there shall be a man on the moon"! Much mocking laughter).

And they kind of hint that it'd cost twice as much to skim as to buy a used engine lump!!

I don't know - these froggies . . .

Anyway - thanks again - will start asking around just in case I can identify someone French who can do something within or without his/her remit engineering-wise!!
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Post by 2.1td »

Hi Colin! Just my thoughts. Although you like your current BX very much to be honest you'd be better knocking it on the head and putting the money you'd pay to buy a replacement engine towards buying a tidy BX diesel. They are out there and they're as cheap as chips. If you've not driven a diesel you'll like it, especially the TD ones and the economy will more than repay you after a couple of years. Don't be put off by high mileages, they can take it. Good luck! :lol:
Be careful!
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BX Engine Rebuild - swop to Diesel?!

Post by Colin Winn »

Hallo 2.1 TD

Hmm, interesting you should say that as I'd much have preferred the diesel in the first place just from the mileage/fuel consumption ratio point of view.

Yep, they could be out here somewhere - there are scrappies where I might have been able to get a used petrol lump, but it's really difficult to know where to put limited money - with the petrol engine, at least it's a devil I know - I could prolly buy a used lump with certifed mileage, from these reputed scrappies - but who's to say the thing wouldn't cack out in the sam way mine has after 2 weeks?

And for the diesels - they'll all be getting on a bit too - and I know they'll run higher mileages, but never having had one, what should I look for in terms of engine spec (which is THE one to go for - the 19, Turbo etc...?) in terms of of wear, how much should I be looking to pay and what else, on a former petrol car, would need changing to install and run it?

Thanks for all advice - you've set me thinking!

Sincerely,

Colin
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Post by jeremy »

Just to be sensible here for a moment - the more you pay for a second hand car - the less likely you are to buy junk.

Now I know someone will come on here and tell me that someone paid him to take their car off them through e-bay and he's done 250, 000 miles in it and its so eonomical he has to drain the tank every week as it uses so little fuel- but you won't be that lucky.

So what do you want - slow but cheap - diesel or Turbo diesel if you wan to go a bit quicker. Reasonable performance but cheap - 2.1 TD For comfort you can add air conditioning into the equation.

Same goes for petrol - I cant see any point in paying for petrol but some people enjoy it so that's a matter for them.

Then think about yourself- and think about your finances - and what you like doing in your leisure time. If your answer is 'I don't mind understanding the car and knowing how it works - but there are things I'd rather do with my life than spend it mend the car' then buy a smart good newish car which hopefully won't become your life's work.
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