hot spot

[Adi]

As above...what do hot spots look like and what are the symptoms when the engine is running?

where on the cylinder head and cylinder block top are the tell tale signs going to be and what do they look like ?

http://forums.lr4x4.com/uploads/1174534707..._273_759623.jpg

http://forums.lr4x4.com/uploads/1174534707..._273_831710.jpg

please point out the areas susceptible...or better yet if any one has pics of hot spot signs

thanks

Adi

[disco_al]

in the 2nd pic, they are the 4 small circular items, with a small rectangular hole in them. common problem you find is that they will crack.

you won't necessarily get any running problems, as they are there to help with the fual atomisation as it enters the cylinders.

check for small cracks around the sides, as the head casting around them can crack as well.

[BogMonster]

....and I have heard of problems (some years back now) with non genuine ones being the wrong size, meaning they rattle while the engine is running!

As above, they crack around the hole in the middle.

I believe their correct name is "precombustion chamber" and they are what makes the "indirect" bit of "indirect injection" (as opposed to "direct injection" on a Tdi for example - where the fuel is injected straight into the main cylinder).

Basically inside the little hole there is a mini combustion chamber and the combustion process starts in that rather than in the main part of the cylinder. Benefit of indirect injection is usually quieter running due to the progressive nature of the fuel igniting; downside is less power and harder starting though you can make both injection systems work perfectly well and direct injection has come such a long way with modern common rail engines that it is more normal these days.