Ford 1.8tdci piston ring change?

[dweeble]

Longish one

Bought a 09 Focus1.8tdci in November. Last few weeks she felt very very slightly down on power, got my mechanic to try her, he thought she was fine. Then last week one day she was sluggish to start (knacked glow plug feeling) then the next morning she caught, died and then wouldn't catch at all. AA diagnosed timing belt, mechanic agreed when she arrived there. No, belt fine (and had been changed as dealer said) so head off. Gasket, cam, etc looks 100% OK but 3 and 4 cylinders (having read zero compression) black and oily. Other two dry.

Poor chap then dropped the sump but then discovers far more needs to come off to unbolt the bearings. He rang me in some grump at 0700 today (!) to discuss options, his inclination is to get a used engine. My feeling was that having gone so far we might as well see if pistons are OK and thus end up with lightly rebuilt engine with rings changed....agreed to discuss tomorrow. But doing some digging it appears the Zetec/Lynx/Dutarorq/whatever has mains which are only factory replaceable, and in any case there is a sort of massive cast bracket which risks block distortion when you undo it. So we pull the piston, put on new rings and the thing never goes back together properly. Aaaaaargh.

Thoughts and ideas please......weird problem in any case, all experiences welcomed!

[stevieturbo]

This is clearly another "what in the name of fk" threads.

Firstly....timing belt is a bit of a random diagnosis from someone doing roadside recovery...only then for someone to say the belt is fine

You say the engine has been stripped ( why, seems only a mystery )....and then later you say 2 cylinders have NO compression ? Well if the engine is stripped...it would be difficult to carry out that test.

1. chronologymatters.

And I highlight NO in bold, as #detailsmatter. So did those cylinders have NO compression at al...or just low, or some, or other ? And exactly when was this test performed ?

And then you say he wants to remove bearings ??? WHYYYYY ????

WTF is this "mechanic" doing ?

[dweeble]

Err...sorry about the chronology, very good point.

To clarify...both AA man and mechanic, both highly experienced (mechanic is very highly regarded locally), diagnosed on non-starting (suddenly, from being fine) and turning over fast. Seemed plausible.

Compression test was carried out after checking the timing belt and finding it OK,. Compression was good on the two cylinders which subsequently proved clean and un oily, virtually zero (just lifitng the needle) on 3 and 4, the oily ones.

Assumption was head gasket failure, thus removal of head.

Then oily bores suggested failed rings, next step try to remove big ends to remove pistion and check ring condition.

Logical, I think?

Sorry if drafting was below my usual standards. But a slightly more supportive reaction would have been nice?

[stevieturbo]

dweeble said:

Err...sorry about the chronology, very good point.

To clarify...both AA man and mechanic, both highly experienced (mechanic is very highly regarded locally), diagnosed on non-starting (suddenly, from being fine) and turning over fast. Seemed plausible.

Compression test was carried out after checking the timing belt and finding it OK,. Compression was good on the two cylinders which subsequently proved clean and un oily, virtually zero (just lifitng the needle) on 3 and 4, the oily ones.

Assumption was head gasket failure, thus removal of head.

Then oily bores suggested failed rings, next step try to remove big ends to remove piston and check ring condition.

Logical, I think?

Sorry if drafting was below my usual standards. But a slightly more supportive reaction would have been nice?

I have never seen an engine show zero on a compression test that had a blown head gasket. It has always registered something. So HG may be plausible depending how low.

Although that would also be audible when cranking....ie not a fast cranking, but you would hear the distinct rhythm.
A relative compression test would also identify which cylinders before pulling things apart.

Likewise, before pulling it apart, use a pulse sensor and scope crankcase pressure would help identify if there was any leakage from combustion chamber side of things into the crankcase ( ie rings )
And likewise testing intake and exhaust to see if leakage is occurring either of those routes.

That would at least establish where any leakage is going....as presumably it is not into the cooling system, as you make no mention of loss of water etc.

Chances of the rings causing the problem described ( oily bores ) on only two cylinders, is almost zero. It makes little sense for 2 to just fail that badly it's letting all compression out. I've seen pistons bust into pieces but still running, with rings broken too...but still make ok compression..
Pistons/rings seem a most unlikely source of the "no" compression

As it's all apart, first port of call if you say HG was ok, would be have the cylinder head properly tested, camshafts/valves etc for anything there that would cause loss of cylinder pressure.
Very low or zero readings are very often valve sealing related.

[dweeble]

This "Likewise, before pulling it apart, use a pulse sensor and scope crankcase pressure would help identify if there was any leakage from combustion chamber side of things into the crankcase ( ie rings )
And likewise testing intake and exhaust to see if leakage is occurring either of those routes." makes sense....but we're past that, I fear...

Trying to get my head round leaking valves allowing bores to oil up....or am I being stupid?

ETA Also, surely a leaking valve would show up progressively? He's turned the cam over and it all seems to be opening and closing normally.

In fact, it's the sudden move from barely perceptible to non-runner which is so odd. To confirm, water clean and shows no loss, oil ditto.

Edited by dweeble on Sunday 14th March 16:25

[stevieturbo]

dweeble said:

This "Likewise, before pulling it apart, use a pulse sensor and scope crankcase pressure would help identify if there was any leakage from combustion chamber side of things into the crankcase ( ie rings )
And likewise testing intake and exhaust to see if leakage is occurring either of those routes." makes sense....but we're past that, I fear...

Trying to get my head round leaking valves allowing bores to oil up....or am I being stupid?

ETA Also, surely a leaking valve would show up progressively? He's turned the cam over and it all seems to be opening and closing normally.

In fact, it's the sudden move from barely perceptible to non-runner which is so odd. To confirm, water clean and shows no loss, oil ditto.

For most part, intake and exhaust valves paly no role in whether oil could get into the engine. If the valve guides were that badly worn, there would have been symptoms a long time ago. ie it'd be smoking, using oil, something.

More diagnosis prior to stripping it, would have yielded more info, but as you say it's past that point now.

I just don't see how it is possible for it not to be blatantly obvious at this point as to the cause of 2 cylinders having no/almost no compression.

The head needs inspected properly to ensure all valves are sealing ( when they're supposed to ) with camshaft installed and fully built up.

I don't think it's one of those engines with the silly pressed on cam lobes that can move, but checking all lobes are in good order would make sense too.

[dweeble]

Exactly, it's so weird. The head and cam are still in one piece, he has turned it over and over and it eyeballs fine, certainly nothing to indicate a sudden dramatic loss of compression.

Failed rings seem the obvious, thus thinking about pulling the big ends off to inspect them....but then why two oily bores? Perhaps one had failed , then when the other went it all became too much for the engine to run?

Or perhaps there's a demon at work !!!!

[stevieturbo]

dweeble said:

Exactly, it's so weird. The head and cam are still in one piece, he has turned it over and over and it eyeballs fine, certainly nothing to indicate a sudden dramatic loss of compression.

Failed rings seem the obvious, thus thinking about pulling the big ends off to inspect them....but then why two oily bores? Perhaps one had failed , then when the other went it all became too much for the engine to run?

Or perhaps there's a demon at work !!!!

Failed rings are anything but obvious, they're the least likely.

[bungz]

Such a shame but with that absolute mess you will likely never find the cause of the problem.

Sounds like the mechanic has zero idea of working on a Lynx.

Best bet would now be getting a refurb block I would say but then what is a 2009 reg focus worth? 1500-2000? Not hard to come by either.

Edit never heard of failed rings in a 1.8 tdci either.

[dweeble]

Failed rings you've never come across? Neither had my mechanic, on that car. And it would be nice if you bore in mind that one hopes for constructive advice here, not bad-mouthing someone whose work you have no experience of.

[stevieturbo]

dweeble said:

Failed rings you've never come across? Neither had my mechanic, on that car. And it would be nice if you bore in mind that one hopes for constructive advice here, not bad-mouthing someone whose work you have no experience of.

diagnosing failed rings in this scenario...is a good amount of experience to start to judge.

Likewise stripping an engine without a good amount of justification for it.

Hopefully the actual issue is found...

[dweeble]

I'll take a real mechanic with over 40 years experience over a keyboard warrior any day.. Bye bye pistonheads,

[stevieturbo]

dweeble said:

I'll take a real mechanic with over 40 years experience over a keyboard warrior any day.. Bye bye pistonheads,

Good luck. I've probably more experience diagnosing faults than whoever your chosen one is though.

It's strange when people get upset because they get the right answers, not the ones they want to hear.

Edited by stevieturbo on Monday 15th March 19:36

[bearman68]

If Dweeble is still with us, I would go for a used replacement engine - but whoever said that a 2009 Focus is worth £1500, and therefore not worth the effort is probably bang on the money.
I'd buy it for a couple of hundred though.