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X12XE headgasket & timing chain etc

131K views 69 replies 21 participants last post by  Quital 
#1 ·
A few folk asked for a thread on progress with this engine. So having been told by the physiotherapist that I can do a bit of light work I made a start this morning. (This is good news because before the operation I was told it would be weeks before I could do anything - however the surgeon did a slightly different procedure which seems to have been superbly effective.)

Some of you may know I bought the car as a HG failure, it had overheated on the motorway and run until the engine died. It still fired up from cold so I was able to drive it onto a recovery wagon and bring it home.

I put some coolant into the system and ran it for a few seconds - which resulted in the coolant system pressurising. So off with its head!

Surprisingly the HG looks intact, and there's no sign of a cylinder having been 'steam cleaned'. The seal on the timing chain cover where it meets the cylinder head is another story.

Here's the HG


Cylinder head


Engine block and upper timing chain cover


Seal on rear of water pump at the face between the timing cover and the head


Since there's no clear evidence that the HG had actually gone I shall need to investigate further - there's clearly water in the oil, and clear signs that the coolant hadn't been changed for a very long time, so I'm looking for signs of corrosion elsewhere just in case.
 
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#2 ·
Note to self - always check the invoice before signing it...

I called at our local dealership to get some manifold nuts - needed 9. Never checked the paperwork, just had it on the account - opened the bag to find 91 nuts :palm:

The debate now is whether to do it right and drop the sump off, which is a pain because at the moment there's a trolley jack under the sump - due to the engine mount being off and since there's no head I can't hang it off a beam.

I also have a very very sore shoulder which I guess says I overdid it yesterday.
 
#3 ·
If you take a close look at the photos above then you'll see what the problem might be. In the 3rd photo look at the two head bolt holes to the extreme right hand side, and in the 4th photo look at the hole to the top right and compare it to the holes adjacent to no.1 cylinder.

They're full of oil - and that didn't get there when I took the head off.





That HG has been off before (I found plenty of evidence that the engine had been previously dismantled) and when that was done oil has got into those holes which has prevented the head bolts from properly seating.

I remember when I took them out that some of the bolts were covered in oil and I needed to look into that - and then I forgot. So credit for pointing it out goes elsewhere.
 
#5 ·
Yes - or rather it would have shown on the torque wrench as being tightened properly, but the bolts would have been compressing (or trying to compress) oil in the holes, so they wouldn't have tightened enough. That's why the head has warped without the HG showing any obvious signs of failure.
 
#7 ·
the issue with that taurus as you probably know, is that it may have hydraulic cracked the block where they have been tightened down....
 
#8 · (Edited)
Thanks Rob - that's an issue I've been looking at. The oil in those holes stank of burnt engine, so it's been well and truly cooked.

I've cleaned the top of the block, and also the sides of the castings where the holes are. No obvious signs of stress marks. I've refitted the old head bolts, then given them a good flexing to see if that shows any signs of movement in the casting - there's nothing I can see.

The plan is to drop the sump, then remove the timing cover so I can replace that gasket plus a new timing kit.

The other options are a replacement engine - or it's even got me thinking outside of my usual box and just maybe a 1.6 8v engine. (But as you will have gathered I am totally OCD about mending cars the way they were made so that would be a whole new territory. I'd be back to the Noddy Guide - seriously, I wouldn't have a clue where to begin :palm:)
 
#9 ·
I've checked the block and the head with a straight edge - so far as I can tell using the smallest feeler gauge I've got the block is straight. The head will need to be skimmed of course - so it's being stripped down and then I'll drop it off at the machine shop.

The ball of string is how I get the lifters out because they're slippery little buggers. I tie a slipknot in the string, loop it over the head of the lifter, and they come out without a struggle.



Just in case anyone reads these ramblings, it's worth making sure you keep the journals, lifters and followers all in the right order.

 
#10 ·
taurus what is the actual name of the bit that you need to get off the Rocker Cover to get to the head, ive gotta take the top of mine off to see how bad the engine is. Funny the engine is from a 1.2 16v so your rebuild thread is coming in very helpful :)
 
#13 ·
I'm not sure which bit you're referring to - to remove the camshaft cover - (or rocker cover if you're being old fashioned - of which I approve of course) you need to remove the coil pack, the two breather pipes at the back right, the wiring for the oil switch, coolant temp sensor and the camshaft sensor - this also connects to the AFM - just unclip them and move the whole lot to one side.

Undo the cover bolts - they are captive in the cover so they don't come out - then looking at the right hand side of the cover (ie the n/s) - right in the middle there is a slot, put a stiff bit of wire formed into a hook into that slot and give it a pull. That ought to loosen the cover - don't be tempted to put a screwdriver between the cover and the head in case you distorted it.

With the cover removed you will see the camshafts and the top of the timing chain. That will give you some indication of the engine's oil service history (eg my 2.2 at 95k was bright clean metal and clear gold oil - this engine was dirty black deposits everywhere.) But it won't tell you anything about the state of the valves or the bores. To do that you'd need to either do a compression test, or remove the head and inspect visually.
 
#14 ·
So now we come to the bit of getting the valves out, and this is where you find that your standard valve spring compressor doesn't fit the Corsa deep set valves. So what you need is to get hold of some 16mm steel tube and cut it as per the photos below. This will fit into the valve area and allow you to remove the retaining collets without losing them. (They drop into the metal tube and you can retrieve them safely.)



And it fits into the compressor like this

 
#16 ·
Everything is off the head, so it will go down to the machine shop tomorrow if I can find the time.

Here is what a valve stem oil seal looks like. This engine has done 80k and the seals are hard and brittle. There's no signs on the valve heads that they've been leaking though.

 
#18 ·
Cheers Rob - it's the wiring side of things that is a total ballache for me. That would be the fallback option if it turn out that the head is cracked or the bottom end is knacked. I enjoy fixing dead engines, but you have to draw a line somewhere with the cost of parts.

The head is being pressure tested tomorrow. I'm hoping to drop the bottom end sometime this week (time permitting) - what came out of the sump was mainly water, which as I recall isn't the best lubricant.
 
#19 · (Edited)
To repair or not to repair? - that is the question.

OK - bit of a ramble, but it's worth mentioning the question - why bother repairing an engine. A mate of mine who runs his own independent workshop says he rarely carries out this kind of work these days. It's just not economically viable. Either the customer scraps the car, or they source a replacement engine.

I just like tinkering with broken engines :D - but even so there comes a point where it's more sensible to replace rather than repair. So for anyone reading this who might have a dead engine, what are the deciding factors?

First off, this is only feasible on a DIY basis - if you're paying labour charges then forget it.

Secondly, you need to assess extent of the damage. In this case the signs pointed to HG failure. Yet on dismantling the HG seems intact - so you have to ask might there be another issue which has lost the coolant, which has in turn led to massive overheating. Once that happens the alloy head will expand about three time more than the steel block, so you get distortion which crushes the HG and can damage both the head and the block. After which, when it all cools down, the classic signs of HG failure are present even though the HG wasn't the original cause of the problem.

So you need to engage your brain as well as your hands - and think it through.

I wanted to check the state of the head first, so I removed the manifolds and took the head off. The head is being tested for cracks, if it passes that test it will be skimmed, the valves regrounds, new stem oil seals, and rebuilt. At that stage a reconditioned head is worth more than the value of the car, and could be sold for almost the same price as a second hand engine.

(So providing the head is OK even if the rest of the engine is scrap I can cover my costs here. That's why it's fun messing about with broken engines.)

Ideally you'd do the same for the block, but that would make it financially unviable, so the block remains where it is and I check it with a straight edge and a strong light. Any suspicion of cracks and you take some printer's ink diluted with meths and paint it onto the area of concern - then wipe off. The ink should all wipe off - if there's the slightest mark left then there's a flaw in the casting which the ink has seeped into.

The other area to check is the bores. When an engine overheats the pistons swell more than they should and they can scuff the bores. Ideally you want to see the diagonal cross hatching pattern from when the bores where ground. Vertical marks mean damage. Run your fingers along the bores - if there's damage you will feel it.

On this engine there were marks on the bore walls caused by water damage.
I used a very light rubbing compound I use for polishing gelcoat on boats and gently wiped the bores - the marks and roughness came off, leaving a clean surface with no discernable irregularities.

On one cylinder there are slight vertical scores right at the top of the piston travel - I know this engine has had a replacement HG already, and not done well - so whether this is new or old damage I can't tell. But the lightness of the marks and their position mean it's worth a punt repairing the engine.

So how much of a punt do you take?

The minimum parts list is HG kit, head bolts, EGR gasket, manifold nuts, sump gasket, timing cover gasket, injector o rings, water pump seal, oil & filter and coolant. It makes sense to replace the timing chain whilst you're at it. Even at trade club prices the Vx dealership want towards £300 for the bits - so you shop around for genuine kit elsewhere and you can do it for half that.

So you're looking at around £150 for the parts to repair, (or about £70 without a new timing chain), plus £50 to have the head checked & skimmed, as opposed to around £300 for a decent second hand engine in working order. The choice is yours. As said, I just enjoy messing about with busted engines.
 
#20 ·
Sorry the last bit was so boring - here's a few photos to brighten things up:

Good news - the head passed the pressure test and has been skimmed, so it's ready to be rebuilt.



More good news - I was in Machine Mart buying some rust treatement and mentioned to the guy there the very narrow gap for the valve springs. The tool I made was great for getting the valves out, the collets just sat inside it, but it would be tricky to re-assemble since space is very tight. They had this kit in, which has three heads 25mm, 23mm, 19mm. The 23mm is a perfect fit. And the main body of the tool is just big enough to fit around the cylinder head. It's Clarke model no. CHT 459.



The sump is off and I dropped the baffle plate off as well so I could get at the main bearings. I'm glad to say all looks OK. There was water still in there, but no signs of metal particles or markings on the bearings.



You can see the tool used to lock the engine at TDC engaged in the web on no.1 piston - this is part of the timing kit for this engine. I'll show how the camshaft and cam sensor timing works when I rebuild the head.



Now I've got to wait for parts to arrive. I've ordered everything needed from AutoVaux since their kit is always good. I don't want to remove the timing cover just yet because there's lots of different sized bolts holding it on and I might forget which goes where. So once the new kit arrives I'll take the new timing cover gasket and trace it onto a piece of carboard with holes where every bolt goes. Then as I remove each bolt it will go into the corresponding hole in the outline of the cover - that way I won't get the bolts in the wrong order.

So in the meantime there's some rust to deal with - around the crossmember which is always a weak spot on the Corsa B. I might as well do it whilst the radiator is out. I also need to repair the front bumper which has had a mior shunt in the past (the reinforcement plate behind it had a nice dint in it), and one of the headlights is broken - but I will try to repair it rather than replace.

 
#21 ·
A bit of Jamie Oliver

I know that the head warped on this engine due to overheating, but since the HG itself may not be the primary cause there are things to be checked.

I placed the thermostat in a pan of boiling water so that it opened and stuck a bit of string into between the valve and the body, then let it cool so the string was trapped.



Then I stuck it in a pan of cold water and gradually increased the temperature. The idea is that by keeping the tension on the string tight it ought to be released when the thermostat begins to open - which is rated at 92 degrees C.



End result is that the thermostat isn't opening until 98 degrees, which means that at 107 degrees when it ought to be fully open it probably isn't. At motorway speeds you don't really want a restricted coolant flow. So I'll replace it.
 
#22 ·
Waiting for the parts to arrive I decided to get on with the driver's side wheel arch, which seems to have a fair bit of surface rust in all the usual places Corsas suffer from. So out with the lining and off with the strut. Then down to work with a scraper & wire brush.



At the moment it is surface rust only, no real rot. But once it's started it will take hold.



This is the stuff I use, it's easy to use, does a cracking job, keeps rust at bay longer than anything else I've found, but it's expensive, like £30 a litre.



And after treatment this is ready for painting. The theory is that you scrape away any loose stuff but leave the rust for the chemical treatment to convert into a ferrous layer that it impervious to oxygen. You'll never kill rust dead, but you can slow it down a lot.



Of course the minute I began with the rust treatment the Auto Vaux delivery arrived :) so whilst I was waiting for the chemical to work I rebuilt the head.

 
#23 ·
I took the timing cover off this morning. Began by removing the water pump, aux. belt tensioner, alternator. The large stub sticking out of the crankcase (bottom right) is locking it at TDC - it's the other end of the bit shown earlier engaging with the web in No.1 piston crank.

(Yes I know I shouldn't leave spanners in cylinders, but it is a very clean spanner.)



There's quite a few bolts, most of them the same size, but there's three shorter ones that bolt the water pump to the cover (as well as others that bolt the water pump through the cover to the cylinder head.) To make life easy I marked the three shorter one with a dab of paint.



One thing to watch for is that there are two dowels to locate the gasket and cover on when refitting. These are a loose fit so can come out when you remove the gasket. I made sure I didn't completely remove the gasket until I'd put the dowel back where it belonged.



Whether this damage was caused as a result of the overheating, or whether it was possibly the original fault is unclear. I suspect the former, but it's a right mess.



Everything neatly in its place and the blank holes for engine mount bolts, alternator bolts and the tensioner bolts all marked.



The end result.



The next stage was to refit the cylinder head - but I've lost my angle indicator, and I want to fit a replacement crankshaft oil seal and thermostat, so it's off for more parts (which aren't in stock of course.)
 
#24 ·
just as an aside, if i was going to all that work i would remove the engine. will you use 3-bond sealant on the timing chain gasket? i would....
 
#25 ·
Once you've taken the engine mount off there's actually plenty of room in there.

The timing cover gasket is one of those with a rubberised insert - I've never used a sealant with that kind. Doesn't it interfere with the rubber seating properly?
 
#26 ·
Not a lot got done today due to having to drive to Anglesey to pick up our girls and trailer tent - just got it all packed away and it started to rain - so that was a good result.

On the way I called in at our local parts place to collect the new thermostat and crankshaft oil seal, picked up some spare clips for the bumper, oil and air filter and plugs (and a set for my Veccy) - and got 20 litres of GM 10W-40 for £36! So that's two good results.

By the time I got back I was knackered - I think the anaesthetic is still working its way out of my system. And I still can't find my angle gauge so I'll have to buy a new one.

Anyway - enough blithering - I did at least make a start refitting the inlet to the head since it's easier to do it before fitting the head itself.

When I dismantled the inlet I noticed that the was a lot of sealant around the ports, a few missing bolts, and a big blob of sealant around the EGR pipe - I found out why! Some berk has previously overtightened the pipe flange bolts and stripped one of the threads out of the EGR body. So I had to make a stud out of a bolt.





I've also fitted new O rings to the injectors



Make sure that the clips engage properly in the groove around the top of the injector, and also that the slots in the side of the clip engage with the flared rim of the fuel rail.

(Bit blurred - but you can see the slot where the rim needs to fit.)

 
#28 ·
I think this is a fantastic thread. Thanks Taurus.
 
#32 ·
I've ordered the sealant Rob mentioned, which will take a few days to arrive so that will delay fitting the timing chain for a bit.

So in the meantime I decided it was a good chance to do oil changes on the Veccy, our daughter's Yaris and the wife's Yaris. One of the Yarises has been making a very brief rattle on startup which I suspect is because I got some fully Synthetic oil for it - so it's going back to semi-synth which it seems happier with.

All was done and there was a two buckets of old engine oil on the drive, when I knelt down and the garage door remote went off in my pocket. So up comes the garage door and catches on the wheelie bin which had been left too close, and lifts the wheelie bin into the air, until the door reaches fully open position and the wheelie bin falls off - and lands on the buckets and there's oil everywhere :palm:

So there's three cars with the bonnets up, another in the garage in bits, me in my filthiest overalls, oil flooding down the drive, (plus the odd 'tut tut' and 'oh dear') and then the estate agent arrives to arrange a viewing for the flat opposite. The look on the prospective new neighbours' faces suggested they didn't want to be living opposite a scrapyard, so they buggered off straight away - the estate agent did not look a happy bunny.
 
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