WTF? Head gasket oddity

[Error404]

Got bored the other night so decided i was going to pull the head off my 3B enigne to have a look at the condition of the bores as i will be starting to rebuild the engine soon.

Found something very odd with the headgasket

It looks like there are no cut-outs for the water jacket in places, just little holes in it



Not seen anything like this before, how the **** was the car still running like this?


Still got the original hone marks on the bores though even after 160k odd miles - they don't make 'em like they used to

[Acidburn]

160k miles - correction - 193k miles

and yes see your point.

[bikerjim]

I have seen this, think its using poor water/antifreeze or infrequent changes. My 2.0l 16v coupe was just like this. Its like it gets built up over time. Have a poke and it will go through.

[mcandmar]

I remember something about the 7A gasket having smaller water ways. Might be nothing but the gasket also looks a bit big for the bore, any part number on it?

[goodall]

The brand new gaskets I have for 10v's and the gasket I fitted to my 7A only had holes in them unlike the head and block which have sort of triangular channels, my guess was the gasket is designed to be a controlled size of an orifice along its length so that theres even flow from block to head and thus meaning even cooling, otherwise since pump at he front and outlet at the front only cyl 1 get cooled.

Bit like a dual plenum intake, theres a slit the same width along its lenght which has a cross section similar to that of the throttle so that theres no change gas velocity and should mean even gas flow along length the manifold. Therefore for the gasket the small holes means the speed of the water and the pressure that has pass through each hole is similar to the pressure and speed of the water at the pump output and allows evenly distributed flow.

Make any sense, hopefully does as just done some assignments for my engineering course

[dubmeister]

As above, they are designed that way to even the cooling across all the cylinders, In uni we had a heat sensitive camera that we used to point at an engine on a test bed to measure temps at critical points on the engine.
Some specific race gaskets (non audi) come with some of the coolant holes opened up, presumably to aid flow (these engines don't idle and are normally above 4k all of the time, if they are'nt, then they have hit something big and hard!!!)

[Kieron20V]

The head gasket on my 7A was exactly like that too Alex.

[Error404]

its definately gasket material not scudge build up - so would it be detrimental to open up these holes to increase flow to the head - even if the holes were kept the same size? Also its some kind of cork type stuff, not what i expected and it does look too big for the bores, perhaps it is a 7A gasket?
I'll have a look for part numbers later on. all just seems odd to me, why are the water channels not designed differently rather than "bodge" the coolant flow equalisation with a dodgy looking head gasket modification

[goodall]

so would it be detrimental to open up these holes to increase flow to the head...

...why are the water channels not designed differently rather than "bodge" the coolant flow equalisation with a dodgy looking head gasket modification

If open them up you would have increase the flow of the water pump, as all the cooling is done by how quickly the water flows round the engine, as well how well the water picks up heat from the engine so would also have cool the water to a lower temp when returns to the engine or improve its heat conductivity

Cause then the channels be too small for sand cores to work adequately and the water jacket itself would have a smaller thermal mass to deal with spike in temp and the reduced surface area

[dubmeister]

Manufacturers don't spend millions on research for nothing!!
Don't you think that if there was a cheaper way of doing it they would try that first?
A mate who worked at Tickford spent over two years testing the EGR systems fitted to the 2l 16v engine that ended up in the mk5 escort rs2000

This one.

http://www.youtube.com/watch?v=Aec6yEU8d3k

[JP]

That looks like a normal non multilayer gasket of a NA the smaller holes are there to carefully control waterflow/speed round the head and block to give optimum cooling for it's specific application.

There is always a careful balance between how fast you want water to flow through an engine to keep it at it's required temperature. Run the water too freely and you get hotspots coupled with running an engine too cold especially on motorway use. Make it too restrictive and you get overheating. That's why some holes are smaller/larger than others.

[Error404]

that all makes sense. I checked the HG, not sign of a part number - however it is genuine audi and says 20v Turbo on one side so guess it must just be an early 3B / RR one

[Acidburn]

I saw a aby bottom end today with the same style gasget on it with the same water holes.

[piotr]

I just looked on my head gasket and its just like you are guys described,little holes for coolant channels instead off big ones like in old gasket but what I am really worried about is when you look on the left hand side on the new gasket the top hole is just not there- is it normal or is something wrong with that new gasket?image.jpg

[Greg_S]

Doesnt look quite right as you would expect them to be the same