1.2 12v Fabia, won't start

[hutchysrs50]

It's out of my hands now, The experienced engineer that's doing the cylinder head work has the job of removing it. He's been doing it 40 years so has a better chance over me!

My worry is brute force will just snap it again, possibly further down making it flush and leaving me no other options.

[Taylor93]

Regarding Piston Rings, didnt you try running a compression test dry and wet (with a bit of oil down the cylinders)?

 

IIRC If the compression increases wet compared to dry then its all good, if its stays the same it means the Piston Rings are worn.

 

But i guess tis a bit late for that, drop the sump, undo the big ends, pull the pistons out and feeler gauge those rings

[hutchysrs50]

The snapped bolts out....

[Breezy_Pete]

 

How far down the stuck bit was rusty?

[hutchysrs50]

I never checked. Will find out later.

He said it was bad, had to drill down the side of the bolt to ease it out.

[hutchysrs50]

[Breezy_Pete]

It didn't even occur to me that coolant might be able to get in to the bolt hole in the block, and corrode the bolt. Looking at that picture ^, no reason to think it's any less likely than anywhere else.  Bit of porosity somewhere in any of this cast alloy...

[hutchysrs50]

It's a possibility. It looks like a long term problem, possibly from when the car was new. Doesn't worry me in the slightest though, everything will be checked. The bolt hole is filled with paraffin and a DIY cap on the surface pressing down, so if the paraffin is gone, I have a problem... If it stays... The blocks fine.

As for the head, I can't say for sure how he will check the hole down the head to see if water or moisture is getting through. Will keep you posted as usual, plenty of pictures

[hutchysrs50]

Rest of the pictures I have, showing what I meant earlier about all the carbon build up. Can be seen heavily on the Pistons.

[sepulchrave]

Oil burning due to worn valve guides.

[hutchysrs50]

Sounds positive, I'd hate to do all this and find piston ring damage!

[sepulchrave]

Got a 2003 Fabia, 82,000 on the clock, but it's a none runner... Just had a quick look at it.

No fault codes

Got fuel pressure and plenty of petrol

Got a great spark

Compression test shows...

Cylinder 1 - 180

Cylinder 2 - 190

Cylinder 3 - 155

So compression is down on 3 but 155 should still be enough to run shouldn't it?

I'm thinking the timing chain may have failed and jumped a tooth possibly?

It has full dealer service history also.

 

 

Sounds positive, I'd hate to do all this and find piston ring damage!

 

You've already answered that question remember...^^

[hutchysrs50]

How so?

Could the low compression not be down to worn piston rings?

[Breezy_Pete]

I reckon if you turn the crank so none of the pistons are right at the top of their travel, then pour a centimetre of diesel onto each one, any large difference in how long they take to drain through to the sump should tell you a bit about the rings. Maybe?

[sepulchrave]

How so?

Could the low compression not be down to worn piston rings?

 

Nope, although it's theoretically possible, ring failure is non-existent compared to valve sealing issues, the balance of probability suggests valve guides since there is soot in all three cylinders whereas only one cylinder showed lower compression, given this engines reputation for burning valves and wearing guides that's what it'll be. The bottom end should be fine.

[hutchysrs50]

Yeah, I never checked to see if they hold petrol etc over night. It's just me being cautious I think. More than likely won't get a chance to find out now either, the head will be getting put on today if things go to plan.

I'll ring my engineer around dinner time when I'm free and see what he comes up with on the head, hopefully he finds them at fault!

On a side note, euro car parts have sent three timing chain kits now, all three have had parts missing or clearly second hand parts in the box.

[hutchysrs50]

The bolt was rusty about an inch down the threads and clean from there. Got a picture to show it.

As for the valve guides, inlets are like new and exhaust are totally knackerd, plenty of play in them.

They've been replaced now and the valves have been ground in nicely. Looks like that was the problem after all.

[hutchysrs50]

[Breezy_Pete]

Thanks for the updates and photos fella.

Apart from not quite knowing what caused that bolt to corrode, all sounding favourable then.  :beer:

[hutchysrs50]

It all cleaned up really well, the carbon all wiped off no problem and the block leveld off quite easily.

Another note is, although the head gasket hadn't failed and didn't use any water, it had a slight dip on cylinder two which has been sorted now anyway.

Orderd the rest of the parts I needed from the dealers also. The main crankshaft pulley bolt, the spacer/sleeve that sits between the pulley and the sprockets and the o-ring that goes between as well.

Before:

After:

[hutchysrs50]

Just been reading this, left me a little confused. It says if the tensioner fails it can cause cylinders to crack so the full head needs to be replaced.

I can only assume it had failed and jumped a lot of teeth and caused the piston to hit the valves.

http://www.clubpolo.co.uk/forum/index.php?showtopic=205266

[Breezy_Pete]

I wouldn't worry about it. There's more focus on making cars look pretty in that thread than on how engines work/fail.

The head doesn't really have 'cylinders', they're in the block (unless what they meant was valve guides, possibly damaged if valves got bent?).

Why no photos of the damage to the head? Why take the engine out to change the head? 

[hutchysrs50]

Yeah I suppose, a lot unsaid on that.

My next question is.... How do I prevent this from happening again?

Why do the valve guides wear out?

Is it lack of oil pressure or poor servicing?

The car has been to the dealers for every single service from new, so I know it's been looked after engine wise anyway.

I'm going to put some cheap oil in with an engine flush and run it for an hour or so then drain out and put good quality oil and filter back in just to clean out any rubbish that's dropped in the oil ports etc from taking the head off.

[sepulchrave]

My next question is.... How do I prevent this from happening again?

Why do the valve guides wear out?

Is it lack of oil pressure or poor servicing?

 

1) You can't, but it'll take at least another 60k before it becomes an issue again.

 

2) They wear out due to poor geometry in the design of the head, too much side thrust is transmitted to the valve stem from the camshaft.

 

3) Neither since the valve stem seals are designed to prevent oil getting down the valve guide.

[hutchysrs50]

Thanks, guess I'll have to just make the most of the added performance and economy while it lasts!