XANTIA HDi RUNNING ROUGH

[ekjdm14]

Or you could simply keep the scope on and get a straw down there and have a suck

Yummy yummy!


Not often I say this …. but on this occasion I’d rather blow

Certainly rather blow an engine than a transmission... (joke wording kept in "long form" as not strictly PC! )

In my defence, it was told to me by some nice Noo Yoik gentlemen in the scrap industry so not the fruit of my own twisted brain. (aggravating factor being that it did make me chuckle more than it should've)

[Rhothgar]

Really doesn't look like a bad piston to my eye, looks like a bit of liquid down the bottom & an otherwise healthy looking piston crown.

Agreed that's possible but to my eye there is a edge

There is an edge but it’s not a chunk missing IMHO.

Do you have a compressor? Get some eye covering and face mask, blow it out with compressed air and look again. I’ll bet the shape changes.

As I suggested, you would have NO compression if there was a hole in the piston. Also consider this! To get an impression measurement you have to turn the engine over on the starter and it has to do many revolutions. The compression gradually builds even though the valves are opening and closing.

If you remove the cam, then the valves are closed assuming the valve isn’t bent or something is not preventing it from closing.

Only issue is ensuring that the correct cylinder is at top dead center when the cam goes back on.

Just seen the straw suggestion. Instead you could get a metre or so of clear hose and suck it out without tasting it. Easily done. When you suck it up, remember to stick your finger in your mouth and cover the end of the pipe.

[Rhothgar]

Something like this:-

There are cheaper ones. Just make sure you take a photo of the end before it goes in and take a photo after it comes out to make sure none of the cheap Chinesium is left inside.

[PaulC5]

I have not been following this topic and it is too long to start at the beginning so I might not be right. However, a bit of pipe/brake bleeding hose could be used in the cylinder and the other end held up to a vacuum cleaner hose so that it sucks things up the pipe. If just a bit of liquid a syringe could be used on the brake bleeder hose end so no need to risk a mouthful.

[Rhothgar]

I have not been following this topic and it is too long to start at the beginning so I might not be right. However, a bit of pipe/brake bleeding hose could be used in the cylinder and the other end held up to a vacuum cleaner hose so that it sucks things up the pipe. If just a bit of liquid a syringe could be used on the brake bleeder hose end so no need to risk a mouthful.

An even more sensible idea. Syringe from Boots and some clear tubing to fit.

[mickthemaverick]

Thinking about it, all you need to do is lower the scope down to the puddle and see if it moves!!

[CitroJim]

A holed piston on a diesel is almost unknown... The engine is not yet dead. On life-support yes but not dead.

A bit of head work will likely see it good for a few more years

If the piston was holed, as you say Dan, there would be no compression and when Mick and I did our tests, there would have been plenty of evidence.

Off with 'er 'ead!!!

[Rhothgar]

A holed piston on a diesel is almost unknown... The engine is not yet dead. On life-support yes but not dead.

A bit of head work will likely see it good for a few more years

If the piston was holed, as you say Dan, there would be no compression and when Mick and I did our tests, there would have been plenty of evidence.

Off with 'er 'ead!!!

Life support! Love it.

A few of us are trying to encourage small steps before the “Off with her head” stage.

Just thinking that it would be useful with the cam off to gauge whether one of the valves on that cylinder is sitting lower using say a straight edge across all the other valve stem tips. This could rule out a bent valve but not a burnt valve seat.

Maybe whatever has rattled around in there causing the pitting marks on the top of the piston has now vacated the valve seat area and compression has improved? Highly unlikely that something could be temporary like that.

In fact, the worst case scenario is that the bore was scored by something and that’s why it’s losing compression.

At least, if cam is removed the valve tip stem test may well show a glaring bent valve and skull will know what he is in for.

[Stickyfinger]

The only way to rule out a bent valve is to remove the head.....even just a tiny "bend" which may still allow the valve (under pressure from the spring return/cam rotating) will cause oil usage or cam-shaft wear over a short period resulting in a scrap head/cam.

IMHO it is "best practice" to check = remove the head/you are 75% there anyway

[Rhothgar]

The only way to rule out a bent valve is to remove the head.....even just a tiny "bend" which may still allow the valve (under pressure from the spring return/cam rotating) will cause oil usage or cam-shaft wear over a short period resulting in a scrap head/cam.

IMHO it is "best practice" to check = remove the head/you are 75% there anyway

Fair comment!

Just trying to save skull too much of a headache and keep this as pain free and frugal as possible. Removing head and investigating surely means you are then into new headbolts, gasket and perhaps sensibly getting the head checked for level at an engineers at the very least.

Mind you. What else could be the cause? I'm just thinking (or maybe I'm NOT!) that there may be some other valid reason we've all missed... (Unlikely I know)

[Stickyfinger]

Removing head and investigating surely means you are then into new headbolts, gasket and perhaps sensibly getting the head checked for level at an engineers at the very least.

That is the headbolt you have to bite to do the job sadly.....place your bets

[ekjdm14]

Removing head and investigating surely means you are then into new headbolts, gasket and perhaps sensibly getting the head checked for level at an engineers at the very least.

That is the headbolt you have to bite to do the job sadly.....place your bets

Agreed, and with an MLS gasket I'd 100% recommend having the head hot tanked and skimmed at the very least if not pressure tested.

From my perspective the potential rapid wear of a valve guide is less of an issue here though since it sounded like if the head were to come off it'd likely not be going back together anyway hence the "hail Mary" idea.

Not sure who mentioned it now, but to my eye the piston didn't appear pitted at all & ever the optimist I still think it'd last another round with £5 of rocker thrown at it.

Come to think of it, as well as measuring valve heights with the cam out you could also potentially "sound out" whether there's any damage by tapping each valve in turn with a soft faced mallet. A damaged valve (even minutely bent, chipped or burned seat) would make a different sound. But all this testing and dismantling, it'd be so easy to half-azz throw a rocker in it

[moizeau]

I still reckon, cam out and chuck some spare tyre air in there, gives you an idea

[CitroJim]

I still reckon, cam out and chuck some spare tyre air in there, gives you an idea

Absolutely, and easy to do. Having the cam out before or after head removal will make no difference as it has to come out sooner or later anyway so might as well make it sooner.

[Skull]

I've gone back a couple of pages ....

Well the results of my inspection today ....it's fair to say that it needs more than a Cam-Follower

I can't tell from the camera orientation as it just gives a peep-hole view (edit: photos with fuel injector removed and camera inserted through the hole)



That looks like the final chapter @ 168K

I'm not sure whether this is a piece of the missing piston or the valve seemingly sat on a ledge or perhaps a piece held by the valve.

Skull's - piece = valve recess

It's now apparant that the 'piece' you can see in the above image is the Valve recess on the piston

I went back in between today's rain and had another look, I lowered the pistons for a better view and I can now see that the hole/puddle is at the front of the piston .... the engine is canted backwards so if it was a puddle it would be at the rear of the piston (right side of first photo below), the valve recess is more to the front on these engines so I'm still inclined [sic] to think it's a hole ....

Skull's - Piston Crown

This one shows the mirror that fell off the endoscope

Skull's - Missing mirror

I've carried on and taken out the Bearing Cap for the Camshaft and Followers and noted a chink in the Camshaft - will that be a DIY job to minimise

Skull's - Camshaft damage

Skull's - Camshaft parts

I note Rothgar's idea to try and re-test compression now that the Camshaft is removed, so all Valves should now be closed but also note his caution that this will also lose it's compression stroke position for any rebuild that might happen in the future, I haven't measured any valve spring height yet but I'm inclined to think it's decision time on 'head off' or 'new follower on and fingers crossed' .....