Cylinder head damage

Started by hartster, November 21, 2007, 05:06:24 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

qta4

Its unfortunate that car owners service their cars regularly when new,in fact are passionate about it.
Service is important when car is new, but imperative when car gets older.
One of the main service items,often neglected is the coolant.
Audi specify a time that coolant must be replaced, may happen up to about 80k, but with second and 3rd owners, its often never even looked at,resulting in corrosion unseen until it drops its guts on your driveway.

Subaru are not imune to this either.
Skill is, sucessfully tightrope walking across the Niagra Falls.
Intelligence is, having the sense not to do it.

hartster

Why do you say this was caused by coolant? The marks on piston crown and head really look like the result of impacts, but I may be wrong. I'll show the head to an engine builder and see what he reckons.

When I bought this car I performed a major service and the coolant was replaced with the pucker red stuff. According to the service history the coolant was replaced roughly when it should have been during the car's life.

My Hilux suffered block corrosion from an adverse reaction between head gasket and factory coolant, resulting in blown gasket. Luckily it was subject of a global recall and Toyota NZ repaired it. Always check the recall list!

qta4

I am not saying it was caused by coolant, in an earlier thread i suggested that ihave seen detonation damage that looked like impact damage.
Post went Awol with other stuff, i simply suggested that all cars require coolant change and regular service. ???

Engine may have had impact damage, only dissasembly will show.

If impact damage is proven, then a compactor maybe a suitable end
Skill is, sucessfully tightrope walking across the Niagra Falls.
Intelligence is, having the sense not to do it.

hartster

Quote from: qta4 on November 22, 2007, 07:25:04 PM

If impact damage is proven, then a compactor maybe a suitable end


:'(

I've scrapped the car. Well, parked it in the cow shed at least, awaiting disposal. I'll strip the decent stuff (suspension, brakes) and see if anyone wants it.

Now I've gotta make a big call - stick with VAG and get a Passat / A6 AWD wagon or go with the Subaru H6.

Problem is I'm not convinced about the first B5 version, not sure that the budget will stretch to a facelift version. 

BB

Of course subarus are the same as any car and require mantenance, however you will be buying newer and jap cars particularly things like subarus are much much cheaper to maintain and far more reliable than any vag ever could be. Sorry but its true. And i love Vag, just wish they could make some decent wiring and a few better quality lesser parts, plastic water pumps humpf ::)
The end is nigh, but the end of what is the question?

hartster

My Impreza is the most reliable car I've owned in 23 years. Easily.

I don't understand this detonation damage thing. How does it happen? Any links? Would like to know.

hartster

#26
Quote from: qta4 on November 22, 2007, 07:25:04 PM
I am not saying it was caused by coolant, in an earlier thread i suggested that ihave seen detonation damage that looked like impact damage.

qta4 is correct. It's detonation damage. But I've never heard the engine pink, it ran really smooth / powerful / economical until it started missing on cold starts. This link explains detonation well: http://www.misterfixit.com/deton.htm.

I cleaned up the other head and examined the markings around the cylinders. It was also leaking on two of the cylinders next to the water jacket - darker patches where the gasket should have been tight against the head surface. Close inspection shows up more damage to the head surface, though nowhere near as bad as #2 cylinder.

Internet says causes of detonation damage are:

? Poor quality fuel (I always use 95 or 98)
? Compression ratio too high (hasn't been changed)
? Ignition timing over advanced (hasn't been changed)
? Engine overheating (has never overheated whilst I've had it)
? Lean fuel mixture (hasn't been changed)
? Spark plug incorrect (changed with OEM spec plugs at correct intervals)
? Excess carbon deposits in the combustion area (LOTS of carbon in the head / pistons)

There are some photos that look exactly like what I've got.

So from the above it's carbon deposits that look the most likely. But why would the motor coke up? Is it linked to the coolant ingress? This is new territory for me and I'm keen to understand exactly what caused this.

Pushbutton_auto

Beating up parking wardens ain't a crime.

qta4

A lot of  detonation is not audible, a possible cause is worn valve guides or seals, allowing oil into combustion chamber, can cause low level detonation.
That damage did not occur over night.
Skill is, sucessfully tightrope walking across the Niagra Falls.
Intelligence is, having the sense not to do it.

BB

You must have seen what the coolant goes like around the pipes and stuff it all crystallizes up if you have a strong coolant mix and you probably did and a very small leak. It just lets in a thick pool of sticky coollant on top of your piston and around the rings etc, then when you start it it almost hydraulics sometimes and the coollant gets carbonized and burnt and gets all stuck in there and onto the valves then bits drop off and cause those dents.
well thats what I think, and Qta4 did say detonation too, either that or a small bit of metal got sucked in and made it past the inlet valve and rattled around in there for a few goes and then got spat out the exhaust ??? This stress could have caused the head to slightly lift and blow the gasket too. The damage shouldnt actually matter unless it somewhere where it does, you will know, maybe a new gasket and chuck it back together and check that injector in case it was running lean and detonating on that pot. But the head does have that crack now eh :P
Wonder when it decided to crack there? Do you think the head just cracked and then seepage then crystallization and then the damage?
The end is nigh, but the end of what is the question?