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Discussion Starter #1
I've had a search through the forum posts, and found a few similar discussions, but wanted some advice for my situation.

I've got a 08 Astra H 1.4 Z14XEP with 119k on the clock. Its been burning oil for a while (oil kept topped up and checked weekly), and this week the engine light finally came on. Engine codes report misfire in cyl 3, and it pretty undriveable.

Checking the plugs, cyl 1, 2, and 4 looks fine. Cyl 3 is very oily.

I've checked compression. Cyl 1, 2, and 4 are around 150-155PSI, but Cyl 3 is 25 PSI. I also did a 'wet' test - still 25 PSI in cyl 3.

I've also put a small endoscope camera down the plugs, but that didn't tell me much more beyond there's oil in the cylinder.

What advice would people give? Can I do anything further to test whether its worn piston rings, worn valve seals, head gasket failure, ???

The car is in good condition otherwise, outside and in, so although its 12 years old (owned for 10) I'm loathed to scrap or ebay it and get another car (costing me ££££s).
 

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With such a low reading on cylinder 3 it is very likely to be a burnt valve or damaged piston. Worn rings should still give a higher reading than that.
Head off time to check.
 
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Discussion Starter #4
Thanks for your response! Yes, that is what I was thinking after mulling it over and doing some further tests. Not really done anything like this before, but I have reasonable tools and a Haynes manual so will see how far I get. Any further suggestions/thoughts welcome. I'll post back (with photos) if I get the head off.
 

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Can I do anything further to test whether its worn piston rings, worn valve seals, head gasket failure,

Modern day test methods allow so much more on an insight with non intrusive testing. A scope & pressure transducer in the dipstick tube, combustion chamber, the inlet and exhaust will tell you where the compression is escaping.

These tools may seem to be specialist and obscure however a few technicians will have them and make good use of them.
 

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Thanks for your response! Yes, that is what I was thinking after mulling it over and doing some further tests. Not really done anything like this before, but I have reasonable tools and a Haynes manual so will see how far I get. Any further suggestions/thoughts welcome. I'll post back (with photos) if I get the head off.
HI. Just done a complete top end overhaul and other work on my 07 plate Meriva. Engine the same as yours or close to it. Do you live in the Glasgow area? if so I could assist you. Let me know when you can.
 

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Discussion Starter #7
Thanks for the comment and offer. Unfortunately I'm in the Midlands.

About halfway through disassembly - got some rounded exhaust manifold nuts to deal with now (2 of the 6), and similar problems with front exhaust pipe nuts onto the exhaust manifold.

How do you remove the oil dipstick guide? There's lots of evidence of it snapping which would be a pain to also fix!

Suggestions welcome!
 

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Discussion Starter #8
HI. Just done a complete top end overhaul and other work on my 07 plate Meriva. Engine the same as yours or close to it. Do you live in the Glasgow area? if so I could assist you. Let me know when you can.
Also, what was the reason for the overhaul?
 

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Thanks for the comment and offer. Unfortunately I'm in the Midlands.

About halfway through disassembly - got some rounded exhaust manifold nuts to deal with now (2 of the 6), and similar problems with front exhaust pipe nuts onto the exhaust manifold.

How do you remove the oil dipstick guide? There's lots of evidence of it snapping which would be a pain to also fix!

Suggestions welcome!
Thanks for the comment and offer. Unfortunately I'm in the Midlands.

About halfway through disassembly - got some rounded exhaust manifold nuts to deal with now (2 of the 6), and similar problems with front exhaust pipe nuts onto the exhaust manifold.

How do you remove the oil dipstick guide? There's lots of evidence of it snapping which would be a pain to also fix!

Suggestions welcome!

Hi. To remove dipstick tube, undo the torx screw which bolts the tube to the exhaust manifold. Carefully turn the tube slightly left and right and gently pull upwards and the tube will come out of the hole in the block/sump. Remove the dipstick first though. Look on e bay for new exhaust manifold studs and notes, they are of good quality and not expensive. Remove the rusty ones with some heat and a small chisel. You maybe luck and be able to tap on a smaller socket than the 13mm originally used. Take your time and they will come off. You will find that some of the studs will be waisted and require to be replaced. Change them all. Hope that helps.
 

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Also, what was the reason for the overhaul?

The engine and indeed the whole car had been sadly neglected by previous owner. Decided to replace leaking gaskets and worn timing chain and related parts due to excessive wear. So decided to do top overhaul as it was easy to remove with all else removed etc.
 

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Discussion Starter #11
Following up on my original post, I finally managed to take the head off this weekend.

Full points go to @Koicarpkeeper - see the photos below. I noticed something was possibly up with 1 of the exhaust valves on the cylinder 3 when I removed the cam cover. The cam and valve assembly appeared to be slightly tarnished and didn't match any of the others.

My plan now is to make contact with a local cylinder head engineering company (Northamptonshire) and likely get the head overhauled - replace the valve, pressure test, clean it etc., assuming any damage to the head itself due to the valve fault is recoverable.

I've looked at the cylinder and can't see or feel any scoring to the bore. However, what are the thoughts on whether
the rings should be replaced as I've got this far? The engine internals are pretty cruddy and I've read that the rings can jam up. The engine has done approx 120k miles.

What are the possible causes of this type of fault? Could it just be wear-and-tear of the valve or assembly, or a sign of a larger problem elsewhere?

Thoughts welcome, including any hints/tips on how I should proceed with the head refurb.

Cheers.

91786


91787


91789
 

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The seat on that exhaust valve still looks pretty good, although it is hard to really tell from a photo.
If it can't be recut then it is possible to have a new valve seat pressed in.
 

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Discussion Starter #13
Many thanks for your response. I'm now looking at getting the head cleaned up, new exhaust valves fitted, and pressure tested.

For new parts and gaskets, I was looking at genuine GM for the chain kit (Autovaux) and Elring for gaskets and seals. I can't decide on a replacement water pump and thermostat though (as its all off now). Autovaux have Meyle as their OE part - is this ok, or am I better looking at Febi or even genuine (twice the price)? Are my other choices ok?
 

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Discussion Starter #14
I spoke to the head services company today. He commented that the oil consumption wouldn't have been caused by this burnt valve, but rather the burnt valve was probably due to usual wear and perhaps accelerated by the oil in the cylinder, and that the rings should also be checked.

After initially pulling the head, I left around 8mm of oil on pistons 2 and 3 (3 is where the burnt valve was) when fully lowered, and the level appeared to remain stable for 7 days. On Sunday I turned the crank and placed all 4 pistons halfway up the cylinder and put further oil in 1 & 4. I noticed this morning that the level on piston 3 has gone down; the rest, including 2, appear ok.

Before I start pulling the pistons out, can anyone advise whether this makes sense or have experienced this type of fault on these engines? I'd like to take his word that the rings are probably at fault, but want to be sure this is the best course of action. As I wrote in my first post, prior to disassembly I did a 'wet' compression test and this gave the same reading as dry which pointed me towards valves. Are there two faults occurring here?

To do the rings I'll also have to work out how to support the engine without the sump or the right-hand engine support installed. Any suggestions?

Thanks again for all your comments.
 

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You can support the engine using a trolley jack under the gearbox, just make sure you put some wood to level things out, you may even be able to drop it onto a axle stand before you remove the sump, pull the pistons out, buy a cylinder honing tool from ebay, hone the bores, fit new rings to the pistons not forgetting to stagger the ring gaps, then reassemble with new big end shells, when homing the bore make sure the tool dont strike the crank as it will shatter the stone on the tool.
Best to do this than after sticking the head on to find it still smokes/consumes oil.
 

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You might aswell change the rings when your in there and hone the cylinders as stated above your future self will be happy i would also check the bearings for wear on bottom end in regards to engine you can rent an engine hoist here
Probably the safest way or you can buy for £150 if you might use in future
 

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Discussion Starter #17
To follow up on this, I took the plunge and replaced the rings. The pistons took some cleaning up! I honed the cylinders, had the head recon'd, and refitted a new genuine chain kit, oil pump, big end bearings, stretch bolts, and gaskets throughout. Car started first time, albeit pretty noisy, and that was 3 weeks ago. I've since done 600 miles and its quietened down and generally seems ok. Today I changed the oil (for fully-synth) and checked the plugs. Plugs are a little black on the 'shoulder' but not the tip or insulator, not oily, and all 4 look the same. I'll continue to monitor. At some point I'll do a compression test. Thanks for the advice and suggestions. It's been quite a journey!
 
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