Vauxhall Astra timing trouble

Yup, if it's running like a bag of nails then it's normally just the timing that's at fault.

With regards to the chain its usual to have a direct pull from the cam to the crank pulleys, the slack is taken up, with tensioners on the return side.

Lots of things can happen in there.

Hello,

We have collected the car from the garage. I don't know whether we have been very lucky or very unlucky. The good news is that the timing chain was ok and the engine was not damaged. The bad news is that the garage were convinced it was the timing chain and wasted a lot of time (which we have been charged for) removing half the engine to look at the chain before doing anything else.

When they found the chain to be ok, as Rob said in his post (quoted above), they did a compression test. When they got to the fourth plug they found the plug was broken and this was the cause of the noise: the car was firing on only three cylinders.

It's very interesting that Rob's post says to remove the plugs and look down the holes. Wouldn't it make sense for the garage to have done this before looking at the chain? I'm puzzled why they didn't start with the quick and easy checks before starting the biggest and most expensive one? As usual, I didn't think of this until I got home, so I didn't ask them!

As I drove home, it also occurred to me that the engine management light was on when the car broke down and I am wondering what the code would have been? Shouldn't the garage have read any codes before starting anything? Would the code have been specific enough to tell them it was a spark plug rather than the timing chain? Since the garage has cleared the light, I presume any error codes are lost forever now?

I guess we just had a faulty plug. The garage said the plugs were due for replacing but I find that hard to believe. The Haynes manual says the plugs should be changed at 4 years or 32000 miles (IIRC, I don't have the book in front of me). The plugs were changed a year or two ago when the car was about 4 years old and had covered 30 something thousand miles, so either way they were due to be done then. I can't believe that they have worn out since then; the car has not been driven long or hard since.

There used to be a colour photo showing plugs in the back of Haynes books but it seems they now use that space to advertise other books, which is a shame. The "old" plugs did not look worn to me. I realise it makes sense to replace the plugs as a set, I'm not arguing about that, but the excuse that they were ready to be changed is what I think is wrong.

Thanks, Stephen.

If they had pulled the plugs would have found three clean and one black and isolated it to that cylinder.

They could have checked the timing statically spun the engine with the plugs out to see if the rockers were working.

In other words they do not understand the basics to diagnose a problem.

Plugs wear off the back edge of the electrode. when new are square. If

Colours are not as pronounced as they were before injection and lean mixtures.

Depending on plug type (tip) we change them at 20k, after that they will go off.

sorry to hear that, I am surprised that the recovery firm did not diagnose it, they usually hook up a diagnostic first! I have found that the three cylinder ecotec is very hard on plugs and they can actually fail at about 20,000. so it may well be that yours were just knackered, but it is very rare (I can't remember the last one) to see a broken (internally) plug. Plug colour charts are pretty irrelevant these days.

Sadly, that is the conclusion I came to but I didn't think about all this until after I had paid them and driven home. They were so sure it was the chain that they didn't check the plugs first and foolishly I have paid the for the time they spent stripping and looking at the chain. I think they labour ill could have been halved if they had checked the plugs first. Oh well, that's the way the cookie crumbles. The problem is when you break down, it's a bit of a lottery where you are and what garages are near and whether they are any good and whether you know if they are any good!

Is that why they have stopped printing the back page?

I know they were Bosch that were in but I don't remember what the electrode was made of and I have no idea what make they have put in now.

I read on the internet that you can get P0301 to P0304 error codes, where the last digit tells you which cylinder is misfiring. I wonder whether that code was present or if they even read it? I have an ELM interface I bought off ebay and I have used the freeware scantool.net but it says there are on errors, so I guess whatever was there has been cleared for good, or would an expensive scanner be able to read old codes? I'm not planning on buying one to find out, just curious for next time ;)

Thanks, Stephen.

Once they're gone, they're gone, I'm afraid.

Chris

Me too!

I see some sellers on ebay are selling "vauxhall op com" diagnostic tools. Would these show me anything that a generic obd scanner would not?

Do three cylinder engines demand more of their plugs than four cylinder engines, or would you expect them to be the same? The car had done 30-something thousand miles when the plugs were changed and it has done 39k now, so less than 10k miles have passed, so I don't think the plugs were worn out, I think we were just unlucky and had a bad one.