New engine

Fluff15

BeenThroughItAll wrote: »

Good God, I'm well aware of how the ignition system works, but thanks for the lesson in egg-sucking.


You'll have noticed I never used the phrase 'coils controlling the ignition advance' or anything like it - merely 'for some UNHEARD-OF reason'; as in 'not having been heard of before'. I know the coils don't control the timing, but if they were in some way responsible for the spark plug being all sparky too early, the timing would inherently become advanced.


Won't have been heard of, because it's infinitesimally small in likelihood that a coil pack would fail electrically in such a way as to allow a plug to fire so early that pre-ignition would occur so as to cause cylinder over-temperature and hence valve/piston damage - however, that's not to say it *couldn't* happen.


When I wrote that post, the information available was 'overheat - new engine - coil thingy'. I proposed a single possible way a coil could be involved in overheating - specifically by being involved in a pre-ignition situation. I did NOT say that WAS the cause, or even state it was LIKELY to be the cause.

Overly defensive post for a useful piece of information, especially for those who didn't know how it worked, which it seems like the OP doesn't.

BeenThroughItAll

Fluff15 wrote: »

Overly defensive post for a useful piece of information, especially for those who didn't know how it worked, which it seems like the OP doesn't.

Read it how you like. I found the reply to my original post overly patronising, but others may have read it otherwise.


That's the great thing about humans, we're all different.

geoffW

Marktheshark wrote: »

A Common failure is the Head gasket failing between the water jacket and Cylinder, it will over heat eventually.
I would find another garage, unless they have stripped the Cylinder head and sump pan off, they wont know what damage it needs repairing.

Just how common is this head gasket failure and would it be covered by the warranty?
I have just had the same thing happen to my 3 year old Hyundai i20, just had a service and 3 days later the car lost power and wouldn't start, no sign of any steam from under the bonnet but gunge had blown out through the radiator cap. Maybe the water escaped from the engine via the exhaust? On inspection with the head removed the garage reported that the water pump was OK but the engine was full of water and a piston is badly damaged. Do you think I can claim against the garage or under the warranty or am I just unlucky?
I'm expecting a big bill.

---lee---

Do coils really store power?

Sorry, that was rhetorical.

They step voltage up or down. That is all.

facade

---lee--- wrote: »

Do coils really store power?

Sorry, that was rhetorical.

They step voltage up or down. That is all.

They store energy. You cannot store power.

roneik

A neighbor was quoted 800 quid for head gasket on a VW beetle 2 litre. I changed the coil pack ,new leads and plugs and inlet manifold gasket. Total 50quid parts no labor except mine which was free. Some very dishonest people out there. Said he had checked. Well I know that to do a compression test which he claimed takes over an hour if you know what you are doing. The manifold cover the plugs and it is a !!!!! to get off. Well I also know you do a sniff chemical test first to detect if gasket has blown. Liars and thieves a lot of them. Any Beetle owner with the Golf 2 litre engine will know why you cant say 15 minutes after receiving the car, the head gasket has gone
Anyone wanting info on plug change with or without plug boot removal tool . I will answer. No mean feat without but can be done

maninthestreet

facade wrote: »

They store energy. You cannot store power.

They don't store energy either.

roneik

Hey that bickering means my informative superior post gets bypassed. You do realize it is also childish. I like a laugh and a bit of banter but being a superior mini car driver ,I expect more. We have more in the superior car we drive, and look down at anyone not driving the said car. You have been chastised by a superior being who knows that mini drivers will soon be like a virus, No other car should be allowed on the streets. There that told ya :rotfl:

Joe_Horner

maninthestreet wrote: »

They don't store energy either.

Technically they do (as does any transformer), but only for very short periods. When current flows in the primary winding it builds up a magnetic field, which is a store of energy, in the core. When current stops flowing that field collapses and it's the energy stored in the field which is converted to high voltage in the secondary winding.

If you think about it, because there's no current flowing in the primary when the spark occurs, the energy for the spark must have been stored in the coil.

That's why, in the old days of proper ignition systems, contact gaps mattered. Well, really it's the dwell angle that mattered but the gap was an easy way to measure that. Gap too big (dwell too small) meant there wasn't enough time with the points closed for the magnetic field / energy store to build up so you got a weak spark. Gap too small (excessive dwell) meant there wasn't enough time for all of the stored energy to be transferred to the spark - again, causing a weak spark.

With modern ignition systems it becomes less critical because they use a short duration / high energy discharge on the primary side (so need less time to build the magnetic field) but the coil still "stores" energy for a few microseconds each firing cycle because that's just how a transformer works - energy moves from the primary to the magnetic core, then from the core to the secondary


eta: [/pedantic mode] Of course, from the POV of "firing early" they effectively don't store energy because they don't get any to store until the ECU says it's time to fire again

AdrianC

geoffW wrote: »

Just how common is this head gasket failure and would it be covered by the warranty?
I have just had the same thing happen to my 3 year old Hyundai i20, just had a service and 3 days later the car lost power and wouldn't start, no sign of any steam from under the bonnet but gunge had blown out through the radiator cap. Maybe the water escaped from the engine via the exhaust? On inspection with the head removed the garage reported that the water pump was OK but the engine was full of water and a piston is badly damaged. Do you think I can claim against the garage or under the warranty or am I just unlucky?
I'm expecting a big bill.

Head gaskets don't just go. They fail because of another cause - usually low coolant level or overheating.

Three days after a service, I'd be suspecting a pipe clamp was left loose or similar. But it could just as easily be a stone through the radiator on the way home from the service.