Is This Terminal? Part 4 – Some Answers at Last

rory_perrett · Post by **rory_perrett** » 31 May 2006, 20:57

Question first – how much damage is likely to be done by a cam sprocket being 2 teeth off on the timing?

Well the engine is out of my sick sounding Xantia 2.1 TD, have a look at the 3 previous post for the background, and some of what has happened has become apparent.

The getting hot thing was a complete red herring, pure coincidence and not part of the problem.

Previously the auxiliary belt partially failed, it started to split around its length and the end started flailing around, lost about 2 ribs worth of the width eventually. After replacement I thought no more of it. HOWEVER,and I don’t know how it managed to find its way in, some of the auxiliary belt that had stripped off found its way into the timing belt cover and probably got tangled around the timing belt / sprockets. The cam was 2 teeth out (Cam running behind crank and fuel pump). I suspect it had jumped 1 tooth which caused the lack of power, black smoke and rough running / clatter. Then it jumped another tooth that caused the increased roughness and noise.

Hind sight is a wonderful thing but I now kicking myself for not checking the timing with the engine in the car when it first happen as I suspect any damage would have been minimal at that stage.

As I’ve got this far I think I might as well take the head off and have a look. I’m in a bit of a dilemma as to how much to spend at 190,000 miles it’s not had a clutch so I suppose that could do with being done while the engine and gearbox is out. While I’m at it a new cam belt wouldn’t go a miss and at this mileage its probably wise to do the water pump etc etc., about £300 – just hope it all still works when I try and put it all back together again.

jeremy · Post by **jeremy** » 31 May 2006, 21:43

Valves in a diesel run parallel to the cylinder bore - so if struck by the piston are simply forced back on to their seats. This commonly does severe damage - like smashing the camshaft on 8 valve XUD engines.

On the 2.1 the valves are operated by rockers - and they will smash if impact has taken place.

So if you remove the rocker cover and have a look you will see if damage has occurred - and if not I would just fit a new belt and do any other obvious jobs.

Post by **Peter.N.** » 31 May 2006, 22:19

I would concur. Its certainly worth trying replacing the cambelt and seeing what happens, as, having fitted a new head gasket to my 2.1 td XM, I can tell you that getting the valve gear off and on again is not easy!

DaveW · Post by **DaveW** » 31 May 2006, 23:29

I don't know how much different the 2.1 unit is to the 1.9 TD one, but I do know that on the latter engine a two tooth difference will still give just enough clearence for the pistons to miss the valves. (don't ask !)

Dave.

Post by **Peter.N.** » 01 Jun 2006, 08:19

The 2.1 has hydraulic tappets which means it has a seperate camshaft carrier bolted to the head with many very tight allen screws! As you cannot remove the manifold and turbocharger with the engine in situ they have to come off with the head and clearances are very tight. If that hasn't put you off and you want to know more.....ask.

f00lzz · Post by **f00lzz** » 01 Jun 2006, 09:56

rory_perrett wrote:Previously the auxiliary belt partially failed, it started to split around its length and the end started flailing around, lost about 2 ribs worth of the width eventually. After replacement I thought no more of it. HOWEVER,and I don’t know how it managed to find its way in, some of the auxiliary belt that had stripped off found its way into the timing belt cover and probably got tangled around the timing belt / sprockets.

The result of a 'shredding' auxillary belt...

The auxillary belt entered the cover, formed a ball of rubber and smashed the sprocket, resulting in a broken cambelt, camshaft and two bent valves. Nice!

rory_perrett · Post by **rory_perrett** » 01 Jun 2006, 10:12

After looking at the picture from Foolzz I guess I might have got off lightly.

PeterN I need to know all I can!

I have the relative luxury of the engine and gearbox sitting on the garage floor and no real time pressure to get everything back together.

More questions I’m afraid chaps.

Manifolds – I’ve undone all I can see in terms of nuts and bolts for both the inlet and the exhaust manifolds including turbo oil pipes etc but they seem very reluctant to move, am I missing something?

Is it possible to remove the cylinder head, cam shaft carrier and manifolds from the block as a single unit?

Post by **Peter.N.** » 01 Jun 2006, 14:46

That is indeed a luxury! Ignore everything I have said so far. The problem now is that you cant run it to assess the damage, if any. If you can turn the engine over with a bar and socket on the crankshaft pulley, see if you can feel four good compressions, every half turn should bring it on to compression and it should offer quite a lot of resistance and then slack when you have past it. If you have good compressions on all four, it won't be necessary to dismantle the engine. The only reservation I would have is that if its done over 100k miles the head gasket could fail anytime in the next 50k and its so much easier to do it with the engine out, but that's something you will have to decide. If you do want to take the head off, I will give you some more info.

Post by **Peter.N.** » 01 Jun 2006, 14:51

Sorry, just looked at the rest of your post!
The exhaust manifold bolts do tend to be difficult to move, try a slightly smaller socket (AF) and hammer it on.

Unfortunatly you cannot remove the head without taking the cam carrier off first as you cant get to the head bolts, but with the engine out and the manifolds off, its a much easier job.

rory_perrett · Post by **rory_perrett** » 01 Jun 2006, 16:03

Peter N 190,000 miles so perhaps I'm on borrowed time with the head gasket. The stand in Xantia 1.9td is at 135,000 so I hope it hangs on in there because while ever that’s running there no pressure to fix the 2.1.

There is certainly some compression on some if not all I remember form when I was turning it to check the timing. I will see whether it feels the same on all four. One thing I did notice which I thought was strange, although I haven’t thought it through, was that having taken off the upper manifold I put some plastic bungs in open ends (just happened to have 4 that were exactly the right size) to keep the water out while I was de-greasing it. Anyway while I was turning the engine to look at the timing a couple of them popped off (quite a bang) indicating that the inlet manifold was being pressurised. Not something I'd expect.

This thread may still have a way to run.

Post by **Peter.N.** » 01 Jun 2006, 17:40

The top manifold is the intake, so you shouldn't have pressure there unless either the inlet valves are not seating which could indicate damage or, it could just be because the timing is still out. Refit the timing belt in the correct position and try again.

I certainly think that it would be worthwhile changing the head gasket at that mileage, I had to do mine at 120k! If the oil is changed regularly these engines will go on almost forever, the last XM I sold had covered 292k.

Citroen do what they call a 'repair' gasket, it is made of laminated steel and looks as though it should last forever. Make sure you get the cylinder head machined flat before you replace it.

rory_perrett · Post by **rory_perrett** » 01 Jun 2006, 23:22

Progress tonight – got of work at 7 instead of 9 as expected, so some bonus time in the garage. With cam belt on and the timing set correctly it feels like these similar compression on all 4 cylinders. Very unscientific but using a torque wrench to turn it round gave similar readings for the force required to turn it for all cylinders. (Funny I can’t find a torque reading for measuring the compression anywhere in the Haynes Manual) Seriously I’m taking that as good news especially as it “felt” normal. No roughness or funny noises. The manifolds are now off, for once I believe Haynes that trying to remove them with the engine in the car is madness.

Still kicking myself for not checking the timing while the engine was in the car but is sounded sooooooo sick I just couldn’t believe that there was no mechanical failure / damage in there. As I’ve come this far I think for piece of mind the head has got to come off, seems good insurance for the additional cost of a head gasket and a set of head bolts. Part of me thinks that I should leave well alone of its been fine, lack of confidence makes me fear that if I have a head gasket failure in the future I will be because I have disturbed it all or not put it together properly.

f00lzz · Post by **f00lzz** » 02 Jun 2006, 08:05

Do it!

You will never feel 'right' about it if you don't

Post by **Peter.N.** » 02 Jun 2006, 09:45

Yes, I agree with foolzz, doing it with the engine out is a whole different ball game. It took me about 20 hours and a lot of grazed knuckles and back ache to do it in the car, it should take you only a fraction of that time with it out.

If you have a Haynes manual that will point you in the right direction. You will need to take the belt tensioner assembly off the head in order to get it machined as they will need a completely flat surface.

Also, there is no gasket for the cam carrier to cylinder head joint, so you will need to use silicon sealer. I applied a bead all around the carrier the night before I reassembled it, this way it sets and you dont scrape it off reassembling it.

I did mine about 25k ago and it has run faultlessly since, I think I have only topped the water up about twice.

Just in case you dont have a manual, all the tappets and rockers have to go back in the same place so mark them carefully.

rory_perrett · Post by **rory_perrett** » 02 Jun 2006, 14:31

Thanks Peter, got the Haynes so full speed ahead this weekend hopefully. Spotted the bit about the silicon but need to ask if there is anything special about it or did you use ordinary DIY silicon sealant?

As it doesn’t appear to have overheated or blown the head gasket I wasn’t planning on getting the head skimmed. I will check for distortion but if it looks ok I was going to put it straight back on with a new gasket.

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