2001 406 HDi - Broken Rocker Arm??

[jv6cdx]

Hi all,

My girlfriend and I have just purchased a 2001 406 HDi Estate - it's the 2.0 litre engine, with 110bhp on a Y plate.

The car was cheap enough to take a gamble on, and I bought it with a known 'misfire', as described by the seller.

The following facts are known:

1) The cambelt was changed 400 miles ago. I only have sellers word for this, no paperwork or knowledge of where it was done.

2) The car will not start when turning the key alone. If you floor the gas pedal, it will start, and rev VERY roughly, but when you take your foot off the gas, it instantly stalls.

After trying number 2, I checked the following:

A) Removed cambelt cover. Belt does look new, tension looks fine. Not yet had time to research a way to ensure the valve timing is set correctly (though I know it involves locking pins)

B) Removed rocker cover. Here is where it gets interesting. I am used to seeing hydraulic lifters, but, this one has rocker arms!!! I can see there are 8 valves, and a rocker arm for each one. However, I could see the third valve from the cambelt end (so I guess on pot 2) has got it's rocker arm missing!!

I did some digging, and found this rocker arm, in it's entirety, in a recess below the cambelt. I removed said rocker arm from here - and it is in one peice that I can see, and looks the same as the others.

I'm confused on a few levels...

If this arm hasn't broken, how has it come adrift?

If the problem is only with one valve, would it really be that hard to start, and refuse to idle? Surely the engine would idle on 3 cyls?

What is involved in changing this rocker arm? Can I just refit it, if it's complete? I'm guessing camshaft out - what then?

Also what worried me a little, is that the top of the valve stem (where the rocker joins it I guess) didn't seem to be circular for it's entire circumference, but is 'semi circular', Ie half moon shaped.

I'm determined to get this running, I am familiar with engines and am an expert with vauxhall V6 petrols, but am really new to the HDi / Diesel world.

Your advise on a course of action would be appreciated... as would your opinion of whether losing just one rocker arm would make it run so bad!!

Cheers,

James and Sophie

[steve_earwig]

That does sound rather like the cam belt broke, the previous owner put a new one on in the hope that nothing was damaged, discovered something was, didn't know the rockers are designed to break in such eventuality and got shot of it quick. We do have a few experts and genuine mechanics on here so it'll be worth waiting for their opinions. Haynes seems to say the camshaft has to come off (remove timing belt, cam cover, bearing housing & camshaft) but perhaps there is a way to get the followers out & in without removing it. I'm not sure about the end of the valve either, that don't sound quite right but whether it's bad enough to warrant replacement is anybody's guess (perhaps a picture?)

One things for certain, before you sort the rocker out you won't know if it is the only problem or if it's masking something else.

[jv6cdx]

Many thanks, Steve.

I don't mind taking the camshaft out - I've just never done one before.

Also, If I do remove the belt / camshaft, what position does the crank need to be in when I do this? Last thing I want to do is create further valve damage etc, I'm guessing pistons need to be half way down the bores..

I've read lots of info on broken rockers now, but never heard of one just 'falling off'

Unless it's broken, and just doesn't look it. Guess camshaft out, and look at the others too. (with pics)

Would one cylinder down really cause this, though? Most cars I know will idle/run on 3, albeit shaky?

Cheers v muchly!
James

[steve_earwig]

You'll need some locking pins (buy a Haynes, they're better than nothing). As far as I remember (reading ) it needs to be TDC.

I've been thinking about this, the title says broken rocker arm but in the text you're saying it's not actually broken I'm now thinking that this arm has been spat out whole 'cos of the damage to the valve stem, perhaps as a result of a broken cam belt the follower was replaced but not the damaged valve. I've also been thinking about you needing to floor it to get it to start - odds on the cam timing is out. I think you'll need to get the head off to change the valve and see if anything else is amiss. But I would prefer for you to wait for a more experienced reply (I've never had a diesel apart and the last head I had off was a Vauxhall straight 6, funnily enough)

[jv6cdx]

Sorry for the confusing title, I should have said missing, rather than broken, in the title!

I think I need to get the cam out, and look at all the other rockers / valve stems, and compare.
If the valve stems are all the same height, and all half moon shaped, I guess it could be ok.
Hopefully it won't be a head off Job, but, we shall see!

Really value your opinions Steve. Hopefuly Jasper will be along soon too

[jv6cdx]

Sorry for yet another question.

If I do have to remove the head, what is the best way of disconnecting the inlet/exhaust, to get it off?

Can it be done in situ? It all looks so cramped, and all up against the bulkhead, I have no idea how to get it all off in situ!

Cheers,
James

[lozz]

if the rocker arm isnt broken id presume someones had it in bits and not put it in right or dropped it,
when they go they smash to bits so im told
iwouidnt remove the head iwouid just check all the rocker arms and replace if nessary,

[jasper5]

Sorry for the confusing title, I should have said missing, rather than broken, in the title!

I think I need to get the cam out, and look at all the other rockers / valve stems, and compare.
If the valve stems are all the same height, and all half moon shaped, I guess it could be ok.
Hopefully it won't be a head off Job, but, we shall see!

Really value your opinions Steve. Hopefuly Jasper will be along soon too

Very strange situation you have there

Firstly, I've never had the head off one of the HDi so can't help with the manifolds (I'm sure someone will have).

I would agree with Steve, sounds like the cam belt broke and someone has not known what to do and has panic sold the car.

I think your best course of action is to take off the cam and compare the other rocker fittings with the odd one.

To set the timing up first....

Up behind the starter is a hole where you can fit a locking pin to lock the crank in the correct place (some find it easier to remove the starter to get at it....any 6mm diameter rod will do the locking), rock the crank until the pin slots in.

With the crank locked the hole in the cam pulley should be positioned at about 8 o clock, you should be able to push a locking pin ( a bolt or drill bit will do the job)through the hole in the cam pulley into a hole in the cylinder head.

The injection pump doesn't need locking.

Good luck It would be useful to hear about how things go.

[jv6cdx]

Cheers Jasper!

Just one question though, don't I need the engine in a 'safe' position, to refit the camshaft? For example, if the crank is locked at TDC, I think pot 4 will have piston fully up - so if I bolt the camshaft down, it may push the valve into the piston and damage it?

Sorry for being dumb...

[jasper5]

Cheers Jasper!

Just one question though, don't I need the engine in a 'safe' position, to refit the camshaft? For example, if the crank is locked at TDC, I think pot 4 will have piston fully up - so if I bolt the camshaft down, it may push the valve into the piston and damage it?

Sorry for being dumb...

I fully understand your hesitation, but this is how it works.....

With number one piston at TDC (number 4 is the timing belt side)....one set of valves will be fully closed whilst the other set will also be closed (if the valve timing is set right)....they will be "rocking"...in other words, one valve will be about to open whilst the other has just closed.....this is how you set up valve timing if the belt has broken and you don't know the timing marks.....check this is how it looks before you strip the cam off.

Look at the cam lobes, one set will each be trying to push a valve down whilst the other set will be at 10 and 2 o clock (approx).

If you are worried about getting the cam in the right position, mark the position of the cam with a scribe mark or a small centre punch dot on the head and the cam.

[jv6cdx]

I have found where the cam pulley locks, but NO idea on the crank!!

Have located hole behind starter (starter removed)

Thing is, the 6m / 8m bolts I've tried just don't seem to go through the flywheel. I've rotated the crank right around many times and I CANNOT find the hole

How far into the flywheel does the pin go?

If it's a tiny fraction, I may be right, but I'd have thought it should go at least a few CM in...

[jasper5]

8mm will be too big...I always thought it was a 6mm hole in the crank....maybe try a small phillips screwdriver in case 6mm is too big.

With the cam locking holes lined up the pin/screwdriver/bolt should fit into the crank a couple of centimetres at least, if not all the way through.

There is a hole there somewhere

[lozz]

haynes shows a 6mm dowel type tool, dosent look very long so id presume it wouidnt go in to far,

[jv6cdx]

Ok, cambelt removed, and camshaft taken out.

Valve 3 - some damage to top of valve stem. but it's still at full height so think will be ok.

Main problem is the 'plunger' on this rocker. It's totally stuck and mangled in the hole.

New head time?

[steve_earwig]

Plunger? Do you mean the hydraulic tappet?

A pic might help:


#1 seems to be the kiddy - if that's the tappet mangled into the head. I don't know how important the bore is, I suspect very though