HG repair requirements

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MikeT
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HG repair requirements

Post by MikeT »

I've yet to absorb the Haynes instructions but can anyone please advise me on what is required for a head gasket repair on the 1.9TD? Obviously I need a complete head gasket set but all are not equal. Some companies make inferior cheap copies, OEM will probably be the same old original design while other companies put R&D into making better than original types using improved and better materials etc. I can even get a bespoke HG made to order that's guaranteed indestructable. Anyone have any recommendations and/or links to suppliers I could seek advice from?

Equally, having the right tools is important. Are there any special tools I need such as the cam/pump locking kits, headbolt hole taps, etc?

I could take the head to be checked for warpage or cracks but what about the block - will that need checking and how?

I intend to take my time and will have forgotten most of what I'd undone when it comes to the rebuild so I'm considering video filming and recording verbal notes from the engine bay as I work so I can put everything back the way it came off. Does anyone have further tips or a better idea?

Also, as previously mentioned, it's worth doing other jobs such as cambelt, water pump etc. The matrix may need replacing as well. Is anything else worth adding to the list of work? i.e I'm thinking of "revising" the EGR, fitting a turbo gauge into the spare cutout in the dash , running some extra wiring through the firewall for future electrics, maybe servicing the turbo & intercooler. I'm also tempted to match the ports and remove any flashing or mould imperfections (if they exist) etc.

Anything I'm not aware of, no matter how trivial it may seem, please let me know what you know. Many thanks in advance.
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Post by CitroJim »

Mike,

I believe there is a laminated steel "repair" gasket available. The time I did an XUD head, I used a GSF kit and this was very good quality and has been OK.

Surprisingly, very few really special tools are needed. A good general automotive toolkit has nearly everything you need.

Additionally, a big breaker bar, a meaty, high quality T55 Torx bit, an Angle Gauge (for angle tightening the head bolts) will be needed. Use good quality stuff.

Locking pins are 8mm bolts and an old head bolt can be fluted to work as a tap for the head studs.

Not special tools as such but you'll find a selection of 13mm spanners invaluable, cranked rings, flat rings, ratchet rings, open enders and my all-time favourite tool, the stubby "lazy C" 11mm and 13mm ring. Where one sort won't quite do the job, due to poor access, another differently shaped one might. This is especially true in the case of the manifold nuts!

I also recommend a good quality 1/4" drive socket set with a long flexible drive for reaching inaccessible fixings. I find my little baby 1/4" set invaluable for all sorts of fiddly jobs and is ny 2nd favourite tool after my Lazy C spanner :lol:

You MUST have the head skimmed and pressure tested, end of. The block will not warp and all it needs is a really good clean and polish with Scotchbrite.

Take a load of digital photos Mike and write a daily blog, much as I did for the clutch. You can always refer back to that. Also, buy a gross of sandwich bags and an indelible pen. Use these bags for all the nuts, bolts, brackets and so on and label where each cam from with care. That is, unless you like jigsaw puzzles.

There is nothing worse than wondering where that paticular bolt came from or what bolt secures that particular item and not being 100% sure.

As for other work, it would be muppetry not to replace the cambelt and water pump whilst you are there. Also tensioners. Take an opportunity to check the little filter in the turbo oil inlet. Something which is very hard to access when all is together.
Jim

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Post by MikeT »

Cheers Jim.

GSF sell several gaskets and sets for 1.9TD but lack details of differences and contents, two do mention notches but nothing else. :?

I'll study Haynes later and will no doubt be back with more questions :lol:
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Post by Peter.N. »

I got my laminated steel gasket form Citroen, they are expensive but its unlikely you will have to do the job again. Mine has done over 50k now and I have only topped the water up about three times.
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Post by steviewonder7 »

Forgive me for my ignorance,but why does the cylinder head have to be skimmed when replacing the head gasket,especially if the head is not warped?
Is the gasket not the same thickness therefore changing the compression ratio?
Please take a bite out of my ignorance and make me wiser
:o

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Post by MikeT »

Hi Peter, I've read that MLS deals very well with Ali-alloy heads on cast blocks, are they a recent invention - i.e. after the XUD was designed/built? However, it's a bit disconcerting to know you still have to top up unless we're talking dribbles? :lol:

It's a fair question Steve and, in fact, I have been advised that skimming is to be avoided if possible. It's often unnecessary and a waste of money if the surface is flat. This is coming from someone with decades of race engine building experience.

What I suspect is that as it's easier to be safe than sorry - a skim will ensure the surface is flat. A garage doesn't care how it spends your money and a skim saves/earns them time/money not having to check the surface is true. The average DIY mechanic may not know how to check this for certain (which includes me!) so again, a skim is the better choice.

As for altering compression ratio's, I'm even more ignorant but it stands to reason, that the cylinder area is reduced with each skim increasing the compression but to what degree is beyond me.

Another warning I have received is not to use scotchbright or any such abrasive as this can leave low spots. It is quite possible, for instance, that my head gasket leak could be purely down to this mistake if it's had a previous HG replacement recently. I have yet to determine why my head gasket failed as it simply shouldn't happen IMO.
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Post by lexi »

Hats of to you Mike for having a go at this. The question of Gasket is one I would also like to know. If Iam using aftermarket I normally go with Payen which are very good. It may be that Citroen used a few different gaskets as production went along owing to supply and price etc. It would be nice to know what they are supplying now in the Citroen box.

The amount skimmed is usually so small as not to make a difference.

Many a HG. job has been wasted by not making sure head is flat /skimmed. At 105 thousand mine is OK ATM.
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Post by CitroJim »

steviewonder7 wrote:Forgive me for my ignorance,but why does the cylinder head have to be skimmed when replacing the head gasket,especially if the head is not warped?
A good question Steve :D

When you remove a head that has been in use for a while, you'll find the surface is incredibly dirty with bits of gasket stuck to it, small corrosion pits if the coolant has not been maintained in good condition, slight damage where the gasket fire-ring blew and quite possibly, light imprints in the relatively soft aluminium from the old gasket fire rings. The head surface is very hard to effectively clean of all this without incurring further damage and causing the low spots Mike speaks of, particularly if you attack it with something really abrasive or try scraping the muck off. A very light skim, say, no more than a 'thou or so, will clean things up a treat and even if reasonably true, it'll make it billiard table flat and smooth. The other aspect of having it skimmed is the chemical clean and presssure test it is subjected to. This pressure test tests head integrity and ensures the head is free of cracks. It would be a terrible shame to reassemble a head to the engine only to find the original fault was caused by a crack.

Mike, you're right about using Scotchbrite on the head surface maybe but on the block face it is fine. You'd have to be extremely heavy-handed and have some incredibly harsh Scotchbrite to put a low spot in an iron block!!! It's great for lots of clean-up jobs and pretty safe stuff to use. I've used it for removing, amongst other things, light rust from cam lobes from an otherwise good that had been standing around a bit in a damp place. Are you horrified by that?

The trade skim to ensure the integrity of their repair. Cost is around £25 or so. Money well spent for a bit of peace of mind.

You may get away witout a light skim if you can carefully clean it up and know for sure the gasket gently failed from sheer old-age but to be on the safe side, a light skim is very highly recommended.
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Post by CitroJim »

This is what a head looks like just after removal and this is actually quite clean!!! They are normally much, much worse.

Image

This was off a 1.9TD with a snapped cambelt and broken cam caps and needing a new head as a result. This is the state of the head surface where the gasket had not blown.

Still a nice clean-up job needing to be done.

As an aside, this engine had been running 100% veg for some time.
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Post by steviewonder7 »

Thanks for the replies and info chaps...now I'm a little wiser :wink:
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Post by Peter.N. »

Hi Mike

The steel gasket I fitted to mine was the first of its type I had seen. I tried to get one from GSF but they apparently didn't do one for the Mk2 XM so I was forced to get a genuine Citroen one. It was described as a 'repair gasket' and only comes in one thickness. I don't think they have been about long enough to have aquired a reputation but they certainly look and feel the business and are certainly stronger than the copper type. When I refered to topping up the water, it didn't actually ask me to, I just looked in the reservoir and it was below the normal mark, but that seems to be how it runs. Three times in three years isn't bad! :)

Steve.

As has been stated, there will always be some irregularities on the head surface and the few thou they take off will not make much difference to the compression. You would have to take a considerable ammount off to cause any mechanical damage. If the compression is increased a little it will make for better starting. The thickness of the Citroen gasket I used was somewhat greater than the original which made it a little more difficult to start but after about 10k miles, when everything had carboned up again it was back to normal.
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Post by MikeT »

citrojim wrote:The other aspect of having it skimmed is the chemical clean and presssure test it is subjected to.
That, I will not hesistate to do, no argument here.
citrojim wrote:You'd have to be extremely heavy-handed....
I can do that! :oops:

citrojim wrote:I've used it for....cam lobes..... Are you horrified by that?
Nope, not my cam :lol:
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Post by citronut »

when i have these heads skimed i also have the valve depth checked, as the valves are very close to the pistons, and if more than a certain amount is skimed of the head the valves will contact the pistons
regards malcolm

ps.
i had my old BX 1.9 head gas flowed a few years ago, whilst i had it apart to replace the head gasket. what a differance, she now drives at 30 in 4th gear were before she didnt like 4th much bellow 40
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Post by MikeT »

Just a few questions cropped up.

What's with the angle gauge :lol: When I do spark plugs it's finger tight plus a quarter turn. What's with this 180 and 220 degrees carp :lol:

Ok, so how do they work other than provide a dial to read, do they click or stop when you hit the target? I got a compass! 8)

I've read through Haynes removal procedure and it seems possible. Odd there's no mention of the cam cover, does this stay in place throughout? And what's that single locating dowel all about, why didn't they fit two? Would a long rod suffice or does it have to be an exact fitting bolt?

Measuring the clearance is noted! Haynes also tells me that I need to measure the piston protrusion to get the correct gasket thickness/notches?
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Post by CitroJim »

MikeT wrote: What's with the angle gauge :lol: When I do spark plugs it's finger tight plus a quarter turn. What's with this 180 and 220 degrees carp :lol:
It's because the head bolts are stretch bolts Mike. Basically, you tighten them to a given (quite low) torque and then tighten them through the stated number of degrees. This stretches them a precise amount and the tension that results (like elastic) pulls the head down on the block/gasket with the right pressure. Stretch bolts also help to maintain a constant clamping pressure under changes of temperature. Stretch bolts should never be reused, despite indications that if they have not stretched beyond a given length they can be.

You have to be careful removing them. They will twist under torque (they're stretchy both up/down and round and around) If you exceed their rotational elasticity, they will snap. Apply torque from a long breaker bar until you feel them just begin to twist and then give them a chance to "follow you round" whilst you maintain a constant torque on them. It feels funny at first but try to picture yourself undoing a rubber bolt :lol: Don't on any account "snatch" at them. A sure recepie for disaster.

MikeT wrote: Ok, so how do they work other than provide a dial to read, do they click or stop when you hit the target? I got a compass! 8)
An angle gauge is just a degree dial with a pointer attached to a 1/2" drive centre. The gauge slips over the square drive of your breaker bar. You zero the gauge at the commencement of tightening and lean on the breaker bar until the dial reads the required degrees.

This angle tightening is why you must very carefully clean the block threads and take exact note of the guidance on oiling the head bolt threads. It is crucial that the initial torque setting is correct and this can only be achieved when the threads are carefully prepared as directed. After-market head bolts may advise a slightly different initial torque/oiling regime/ final degrees to that stated in the BoL. Follow the instructions on the head bolt box.

220 degrees of angle tightening on a head bolt is seriously tight. You'll need a good breaker bar and to have had three Weetabix for breakfast. :lol:

I'd plump for a "repair" gasket Mike and then you can more or less disregard piston protrusion. "Repair" gaskets are a little thicker than standard. Else, follow the advice of your chosen skimmer as after skimming, the notch count on your original gasket ceases to be relevant.

Whilst there is no apparant need to remove the cam cover when removing the head you'll find you'll need to in order to remove/refit the inlet manifold. You'll have to at some point anyway to check the valve clearances and prepare it for skimming. Be very careful to keep all buckets, shims, collets, caps and valves in strict order (those plactic bags again!). Give the valves a light lapping-in when you reassemble the head. Be thankful it's only an 8V head. Lapping 16 of them really makes your arms ache :twisted:

The dowel locates the head to the block. One is adequate. Don't loose it and make sure it is removed before skimming in case the skimmer looses it. Have a natter with your skimmer to ask how he'd like you to prepare the head. Don't be surprised if he says leave the valves (but not the buckets and shims) in. It helps with pressure testing.

Finally, don't overlook the little plastic oil strainer in the head drilling that feeds oil to the cam gallery. You'll find a new one in your gasket set. It looks like a baby version of the conical filter in the LHM reservoir.
Jim

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