Xantia hesitates...now won't start

Toby_HDi · Post by **Toby_HDi** » 28 Dec 2008, 12:46

The pipes are definitely back the correct way round - they're colour coded and I have just gone out to check them.

I tried to start again and it does the same, however,....

...I tried to start with accelerator down and it will actually sustain itself after this, it runs albeit with lots of noise and very rough. Also, there is copious amounts of white smoke being pumped out the exhaust.

Post by **CitroJim** » 28 Dec 2008, 13:34

Toby, the white smoke indicates the car is misfiring and running on less than four cleanly. White smoke is unburned diesel so it's being injected but not being burned at all.

Two possibilities: big loss of compression on some cylinders or the injection (not cam) timing is totally out due to a duff sensor or a sensor so mis-placed or slipped that it is causing the injection timing to be a long way out. I'm trying to think if say, the cam timing with respect to the crankshaft was 180 degrees out, would this cause it but my recollections of old petrol engines getting the distributor 180 degrees out resulted in lots of pops and bangs but no running.

Is the EM light on when it's running?

It is possible you have a bent valve (or broken rockers more likely) as a result of the cam timing ending up a tooth out. That would kill compression and account for the smoke.

I think it might well be prudent now to leave it until Richard pops by and runs his experienced eye, ear and Lexia across it.

If it does turn out to be bent valves or the more likely broken rockers, don't worry, all is not lost. An HDi head-off job is not too bad (about the same as a 1.9TD XU) and if a rocker has broken, they can be replaced with the head in-situ. 2.1TD owners (similar set-up) have escaped with just broken rockers when the belt has fully let go. As on the 1.9 and 2.1TDs, the valves are perpendicular to the pistons so any contact will often break a rocker and leave the valves totally unscathed. Xac and I have very deep personal experience of this happening to Xac's engine twice!!!

In fact, it might not be a bad idea to slip the rocker box cover off and have a quick look at the rockers...

My fingers are crossed it's a sensor problem Toby...

Toby_HDi · Post by **Toby_HDi** » 28 Dec 2008, 13:46

I think I may leave alone though another thought has crossed my mind...

What if the camshaft is actually out even though the timing hole lines up? Can this be checked easily?

Another thing is (this is going to sound like a silly question) What is a rocker? I am aware of the way in which the camshaft works on a follower to actuate the valve, I just do not know what the term 'rocker' refers to

Post by **CitroJim** » 28 Dec 2008, 14:03

It's a possibility worth checking Toby. If say, the woodruff key on the cam sprocket had seared, the sprocket could slip round and thus the timing hole would have lost it's position.

Rockers. Sorry, it's an old term those of us of a certain age who grew up with BMC "A" series engines use but has now fallen out of favour.

have a look at this picture of the HDi valve train:

Item 1 is the hyraulic cam follower that bears on the cam and item 2 is what I call a "rocker"; it transmits the cam movement to the valve. If the valves shoot up violently, this is the bit that will take the full force and snap.

DickieG · Post by **DickieG** » 28 Dec 2008, 15:13

citrojim wrote:I'm trying to think if say, the cam timing with respect to the crankshaft was 180 degrees out, would this cause it but my recollections of old petrol engines getting the distributor 180 degrees out resulted in lots of pops and bangs but no running.

Thinking about that point, if the camshaft timing is out by 180° fuel would be injected but not burned initially until the second stroke by which time the fuel would no longer be a mist but larger droplets making it more difficult to ignite.

As to why it briefly fires on a couple of cylinders? Well its cold enough today for the glow plugs to be briefly turned on to fire the fuel for a couple of revolutions before the temperature in the cylinder is too cold to ignite the fuel without the glow plugs.

Why does it only fire on a couple of cylinders? You may have some duff glow plugs in there (not immediately obvious on an HDi as they are very rarely used).

Great theory but I'm more than likely talking B@!!@<#$

Feel free to comment!!

Toby_HDi · Post by **Toby_HDi** » 28 Dec 2008, 16:49

Well, I took the cam sprocket off and the woodruff key is intact.

Then took the rocker box off and lo and behold....one broken rocker. It's not under the lobe and on the spring. It has just dropped off so am assuming it's snapped. Would one rocker be enough to cause the problems I'm having?

Would it seem likely it's also 180 degrees out? Or is it just the rocker?

To add insult to injury I managed to drop one of the rocker cover bolt washers down the back of the engine, now I can't find it

Thanks again for the input, much appreciated

DickieG · Post by **DickieG** » 28 Dec 2008, 17:42

A broken rocker will cause the loss of one cylinder so it will run like a pig, the next question is are any others affected? To establish that you'll have to check the valve clearances on the other seven valves to establish whether any others have been damaged or the if any of the valves themselves have been bent.

If everything else checks out OK, fit another rocker and have another go at firing it up.

When you mention you lost a washer down the back of the engine do you mean inside or outside the engine?

Toby_HDi · Post by **Toby_HDi** » 28 Dec 2008, 18:08

This gets more and more involved.....valve clearances, that'll be camshaft out? Can see this becoming a right pain in the backside

Outside the engine. It should have dropped through but I cannot find it on the floor so do not know where it's gone

Post by **CitroJim** » 28 Dec 2008, 18:27

Good work Toby

Don't worry about the washer. If I worried about everything I've lost down the back (and front) of engines, I'd be a total wreck by now

So long as it's outside the engine, it'll do no harm and there are a multitude of (oily) places where they can lodge harmlessly. Once I lost an Allen key behind an engine and it never reappeared

I doubt there is just one rocker broken. Any valves that were open, opening or closing at the time are at risk. You need to have a good look at them all to be sure. There should be no need to remove the camshaft to do this though, a visual check and a good wiggle should be adequate.

You'll be back on the road in a day or so

And the forum HDi specialist!

Toby_HDi · Post by **Toby_HDi** » 28 Dec 2008, 18:52

True, I'll just have to go get friendly with the Citroen parts bloke.

How would I go about checking them? I don't want to wiggle parts I shouldn't and cause even more damage and therefore more work

What am I looking for?

citrojim wrote:...And the forum HDi specialist!

You'd think so the rate I'm going!

Post by **CitroJim** » 28 Dec 2008, 19:03

Toby_HDi wrote: How would I go about checking them? I don't want to wiggle parts I shouldn't and cause even more damage and therefore more work
What am I looking for?

Look at them for cracks or damage in the same places as where the broken one failed.

You can wiggle rockers and other bits as much as you like and they won't break. No worries about doing any more damage Toby.

With the broken rocker safe, carefully rotate the engine and watch the remaining rockers operating the valves. Any damaged or broken ones will soon show themselves.

Toby_HDi · Post by **Toby_HDi** » 29 Dec 2008, 11:34

I have removed the one broken rocker. The rest SEEM ok but I am running out of time this morning so will double check tomorrow morning.

I did in the end remove the camshaft as I was struggling with removing the bit still clipped onto the tappet.

I'm wondering if the one broken tappet and me possibly having the timing 180 degrees out was causing the compression problem. As mentioned, it sounded like it was running on 2 cylinders rather than 3 or 4.

So I need to make a list of parts to buy:

Any broken valve train gear (hopefully just the one rocker)
New cam oil seal
Cam bearing casting sealant (where from and what type?)
Wire wool
Timing belt (this one is getting covered in oil!)

Anything I've missed?

Thanks

Post by **CitroJim** » 29 Dec 2008, 12:06

Sounds good Toby

Can't think of anything missed off hand.

Did you find the lost washer?

Toby_HDi · Post by **Toby_HDi** » 29 Dec 2008, 12:31

No, have to get one of those too

On thinking back over the morning - if the camshaft is out but a spring is still stretched does this mean the valve is going to be bent as it's not closed itself on relieving the cam pressure?

This is turning into proper head work! Interesting, but I just want my Xantia back!

Any ideas on where to get the sealant?

Thanks

Post by **CitroJim** » 29 Dec 2008, 12:39

By stretched, I guess you mean compressed Toby. Then yes, it may

With the cam out, if you sight along the line of valve stem tops, thay should all be at substantially (within a few 10s of thous) all at the same height. Any that seriously deviate are likely to be bent.

Another good test, now you have the cam out, is to spin the engine over a few revolutions by hand slowly and feel for four equally spaced and even compressions. Be sure to return it back to the same spot so you don't loose the tuiming position. It's always a good idea to keep the crank locking pin in place at all times unless you are rotating the crank for any reason.

Sealant: Get some Blue Hylomar or Wellseal (Wellseal by preference but expensive). Both are available from any factors. Be careful with it. Both Hylomar and Wellseal are a bit on the nasty, toxic side and should never come into contact with bare skin.

I'm praying no valves are bent Toby