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Author Topic: 2.5 petrol manual estate misfiring  (Read 10352 times)

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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #15 on: 09 August 2018, 08:46:23 »

Each... Last I bought, admittedly in 2005, were £180 a side... Includes new seal and o rings.

Alternatively buy £15 ones and replace at every service...
Back in 2006 my first 3.2 Omega cost £2500, so £360 keeping it tip top seemed reasonable. 12 years on, with my Omegas worth less than £200 each, I am mean with maintenance costs. I still cling to my belief that if the breathers are clear then a leaking cam cover gasket will leak air in, not oil out. I expect to be proven wrong.
Today I blew a lot of oil out of my big breather tubes. Perhaps they were blocked.

I take a slightly different view. I don't look at what my Omega is worth, I look at what it's worth to me and if I weigh everything up, it's a hard act to replace. So whatever it needs is what it gets and only ever OE or OEM parts. Admittedly my fleet is not quite as big as yours, I only have 4 cars in total, but take a similar view with all of them. It's still cheaper to fix than to replace.

My garage service manager has just bought a very tidy 2.6 and bit off the hand of the seller at less than £1000 - he knew what he was buying more than the seller knew what he was selling. Following the used/classic/auction markets reveals that values of the best Omegas have bottomed out and are going back up again so I'm trying to keep mine in that category.

The classic market is beginning to cotton onto them as the "last great rear wheel drive large Opel/Vauxhall" and "a better drive than the equivalent Mercedes E class". If you want a comparison just look at values for the Rover SD1.
You are an enthusiastic welder, as in Car SOS, and do whatever is needed to keep your cars in good body condition. I patch cills, but when my MOT tester bashes holes in my bodies with a pry bar, I give up.
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Doctor Gollum

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Re: 2.5 petrol manual estate misfiring
« Reply #16 on: 09 August 2018, 09:00:29 »

The cost analysis for banger repairs is pretty straightforward.

Does the repair cost more than it would add in value...

Let's assume that the car is worth £800 in a safe, usable condition.

Let's assume that the following issues are present and the work is being done by you, so no labour.

1. The aircon doesn't work. Value affected by £100. Repair, new condenser plus gas, so £110. If aircon is important, you might swallow the £10. If not, leave it.

2. The waterpump has failed. Value affected by £600. Repair, water pump cambelt coolant, so £200. Fix it.

3. Cambelt snaps. Value affected by £600. Repair, new engine plus service items and fluids, say £1,000. Scrap it and save £800.

Anything not affecting the safety or usability of the car can be largely ignored.

Servicing, tyres etc should be predictable enough to budget for. For example scrapping a car that only needs four tyres is stupid, as the replacement car will likely need things addressing plus the purchase price. (obviously if you're looking to sell your car, then obviously best to maximise the value of it... but, bear in mind that spending £300 on it just to gain £200 in sale value is a waste of £100.

If you want to keep a worthless car, then you need a money no object approach to repairs, provided your household budget can accommodate it. If the budget cannot tolerate it, then cut your losses and buy something less worn out. This isn't the same thing as newer/more expensive.
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Doctor Gollum

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Re: 2.5 petrol manual estate misfiring
« Reply #17 on: 09 August 2018, 09:00:54 »

Each... Last I bought, admittedly in 2005, were £180 a side... Includes new seal and o rings.

Alternatively buy £15 ones and replace at every service...
Back in 2006 my first 3.2 Omega cost £2500, so £360 keeping it tip top seemed reasonable. 12 years on, with my Omegas worth less than £200 each, I am mean with maintenance costs. I still cling to my belief that if the breathers are clear then a leaking cam cover gasket will leak air in, not oil out. I expect to be proven wrong.
Today I blew a lot of oil out of my big breather tubes. Perhaps they were blocked.

Perhaps when engine is stopped all the oil splashed around inside covers leak out.
In your dreams...  :D
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #18 on: 09 August 2018, 09:55:35 »

Until c.1980 sump pressure was released via a gauze filled orifice somewhere high on the engine. Then clean air enthusiasts ruled that sump gases should be reburned in the engine to make them less noxious. This led to the Omega breather system. This works well until it clogs, resulting in the whole system becoming pressurised, and the pressure relieving itself at the weakest point, the cam cover gasket.

Senator owners drilled holes in the oil filler caps, inserting tubes discharging under the car. Now there's an idea.
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Tick Tock

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Re: 2.5 petrol manual estate misfiring
« Reply #19 on: 09 August 2018, 10:26:29 »

It's probably worth mentioning something you all know already, and that is leaking cam covers were never a problem with Omegas that had covered less than say 75k miles. The problems only seem to be apparent after a number of years in use, and replacement gaskets are a lottery, whether they be £130 or £15. Think of the number of cycles of the engine being run up to temperature and then cooling down after use.... perhaps somewhere in the region of 7 to 8 thousand times in a 15 year period, and that's just a guess. Most plastics can't stand that sort of punishment. Look closely and you will find hairline cracks in your covers, assuming they are the originals.

It's obvious Terry that your enthusiasm is one of the things that keep your fleet of omegas on the road, and I also admire your thrifty approach, but unless you want to be sorting out this mess every 6 months, the only solution is to bite the bullet and get some new covers. Your main dealer should be able to sell them complete with gaskets for £300 and you won't have to worry about them again.

It may hurt your pocket (and mind set) initially, but think of the joy of not leaving oil stains on peoples drives.... and the longevity of your plug leads and everything else that gets covered in engine oil!
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Nick W

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Re: 2.5 petrol manual estate misfiring
« Reply #20 on: 09 August 2018, 11:01:17 »

Back in 2006 my first 3.2 Omega cost £2500, so £360 keeping it tip top seemed reasonable. 12 years on, with my Omegas worth less than £200 each, I am mean with maintenance costs. I still cling to my belief that if the breathers are clear then a leaking cam cover gasket will leak air in, not oil out. I expect to be proven wrong.
Today I blew a lot of oil out of my big breather tubes. Perhaps they were blocked.

Perhaps when engine is stopped all the oil splashed around inside covers leak out.
In your dreams...  :D


Exactly. And it's easily proved: just unscrew the oil filler cap with the engine running. If you cover the hole with your hand, you can feel the air displaced by the rotating internals. This will find a way out if at all possible, and as it has oil suspended in it, is considered a bad thing. That's why over the last 40ish years all engines have sealed breather systems. Some of them are better than others, and the Omega one is a typical Omega feature: complex and high maintenance.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #21 on: 09 August 2018, 12:37:28 »

It's probably worth mentioning something you all know already, and that is leaking cam covers were never a problem with Omegas that had covered less than say 75k miles. The problems only seem to be apparent after a number of years in use, and replacement gaskets are a lottery, whether they be £130 or £15. Think of the number of cycles of the engine being run up to temperature and then cooling down after use.... perhaps somewhere in the region of 7 to 8 thousand times in a 15 year period, and that's just a guess. Most plastics can't stand that sort of punishment. Look closely and you will find hairline cracks in your covers, assuming they are the originals.

It's obvious Terry that your enthusiasm is one of the things that keep your fleet of omegas on the road, and I also admire your thrifty approach, but unless you want to be sorting out this mess every 6 months, the only solution is to bite the bullet and get some new covers. Your main dealer should be able to sell them complete with gaskets for £300 and you won't have to worry about them again.

It may hurt your pocket (and mind set) initially, but think of the joy of not leaving oil stains on peoples drives.... and the longevity of your plug leads and everything else that gets covered in engine oil!
Hairline cracks are just what I need! They would relieve the pressure under the cam covers and cure the problem. If the air leak was serious it could affect the engine idle, but that seems unlikely.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #22 on: 09 August 2018, 15:33:09 »

I have replaced 1-3-5 cam cover with an old spare, which came complete with gaskets.
I began to remove 2-4-6 cam cover, removed all the obstructions, wiring harness, etc. I removed no2 plug lead, and discovered, on closer inspection, that the liquid in no. 2 plug hole, and there was only a little there, was not oil, but water. Furthermore, the plug lead rubber was split, as by sparking to earth. Pic follows.

I reckon this was the cause of my misfire. I don't know how the water got there, any ideas?

Following recent suggestion that only Omegas over 75000 miles seem to suffer from failing cam cover gaskets, I wondered whether the breather box might be getting full. Not so in my case, I put a tube through the large pipe and a .060" wire through the small pipe, and all seemed well.


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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #23 on: 09 August 2018, 15:36:37 »

Sorry, wrong pic. Here is the breather box.
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Re: 2.5 petrol manual estate misfiring
« Reply #24 on: 09 August 2018, 15:56:36 »

Cant see pics, but then I can't get internet access for more than 10s every 2 minutes ;D


But water in plug wells does lead to misfires.

Added to that, a 19 is a 19, and the crank sensor is shagged. End of.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #25 on: 09 August 2018, 16:41:40 »

I hoped that plug lead would still serve, but I would like to replace it if I had a spare. And so it proved. A generous OOFer, having sold his last Omega, kindly sent me all his spares for the cost of postage. They included a no. 2 plug lead. Joy!


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dave the builder

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Re: 2.5 petrol manual estate misfiring
« Reply #26 on: 09 August 2018, 18:12:59 »

Cant see pics, but then I can't get internet access for more than 10s every 2 minutes ;D


But water in plug wells does lead to misfires.

Added to that, a 19 is a 19, and the crank sensor is shagged. End of.
Terry had the crank sensor plugged in wrong , and swapped to another ,so that would throw a code ,without the sensor being faulty
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #27 on: 09 August 2018, 22:25:08 »

Neglected to mention - plug wells 4 and 6 were bone dry, so 2-4-6 cam cover gaskets are OK.
I have just replaced the lower inlet manifold, then received advice from Fuse 19 that the failure of the engine to increase the idle rate on cold start is unusual, and probably caused by a faulty  ECU temp sensor, to change which I must remove the lower inlet manifold. Job now on hold while I seek an ECU temp sensor.
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Re: 2.5 petrol manual estate misfiring
« Reply #28 on: 10 August 2018, 07:47:11 »

Local motor factors :y
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #29 on: 10 August 2018, 12:44:41 »

Thanks, Doc. New sensor collected and fitted.
Working down there, I noticed a vacuum valve, with colourful connector, but no vacuum line to it. It seems to be attached to the breather box. This can't be right, and might explain my breather problems. The vacuum line big junction is nearby, but I see no spare pipes. At a pinch I could create one, but where is the original one?
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