Never thought this would happen to me! Currently 156000km, and the head is cracked number 4 piston, between water port and compression chamber. New radiator fitted 3 months ago and coolant additive used and never overheated. Water started to "disappear" during the last two weeks.
I carefully inspected the head, block and gasket for the cause and found the crack on the exhaust manifold side, but on further investigation I found the head gasket only had 6 small holes ( nothing bigger than 6mm diamater) on the exhaust manifols side. This causes the water to be directed from the termostat via the head to the exhaust manifold side of the block only, vertually bypassing the inletmanifold side of the block.

I want to comment as follow:
1. 6 small holes will restrict the flow through the engine and I find this arrangement strange.
2. The crossflow through the head is a good idea but if water is allowed to pass on both sides of the pistons it will result in better heat dissipation through the block and higher flow overall.
3. Is there more than one type head gasket avaiable?

Your suggestions and assitance is appreciated
regards

it's done to cool the head evenly.

on the intake side incoming air helps cool the head.
and as you can imagine the exhaust side of the head is very hot.

so coolent is directed there by the hole you speak of.
it's not an uncommon thing, many engines use this method of coolent controll to help cool evenly.
a few 4 cyls i have built use a gasket that only had holes at the very back of the gasket.

done because the back of the engine runs hotter so coolent is directed there first.

Can understand the theory behind this, but if headgasket failures are so common to this vehicle then obviously something very basic was overlooked or there is something wrong with the design.?

I have never had this happened to any vehicle including V8's. Remember, in South Africa we can only rely on Ford for Falcon spares which limits
options. How do I solve the problem, never to happen again?

Thanks for the attention.

the head gasket failure is not realated to the water flow.

some say it's a problem with the head torque.

in my time as a mechanic most have been from head bolt failure
but the AU head bolt and gasket seem to have fixed most of the problems.

i would sugest you don't try to have your head welded. find a second hand one.
then use an AU metal gasket with AU bolts or if you can try and find an ARP bolt or stud kit and use ARP torque settings.

i'm not sure if you can get it over there but try and find a spray called
'copper gasket' and use that on the gasket too.


PS.. i don't supose you have a spare south africa spec EF XR6 ECU??

i'd love to get my hands on one

Last edited by tickford_6 on Tue May 03, 2005 12:10 am, edited 2 times in total.

One thing you can do next time you flush & refilling the coolent is run the engine 4 a while with the radiator cap off. wait til its very hot or when the termostat opens. use a wet towel & start squeesing the top radiator hose until all the air bubbles disappears. some times you'll have air pockets in the back of the cyclinder block causing hot spots. while the rest of the block is circulating & cooling the temp gage, its the hot spot area that cracks due to no pressure.

I make sure every time I do a flush theres no air in the block, usually I run it for 30 to 40 minutes with out the radiator cap until the overflow stops. this could mean topping up with coolent every termostat open cycle.

Tickford 6,

I think the overheating is directly as a result of a lack of improper cooling,
or lack of poor flow of coolant through the head.

The crack in number 4 cylinder resulted in my failure, but looking at the head it is obvious and quite visible that both 3 and 4 have progressed signs of cracking, numbers 2 and 5 started to crack but still holds and there are cracks developing on 1 and 6. Now, due to the flow of coolant it is obvious that these are the areas where one will find higher temperatures due to a lack of flow of coolant. Thus, these areas will run hotter than the others and will therefore be more susceptable to heat fatique ultimately leading to the crack and failure. The walls are thin +- 10mm, between the combustion chamber and the water jacket and therefor most likely to crack, no cracking on the other side!

Looking at the coolant flow pattern through the head it is obvious that 3 and 4 starve cooling due to the big openings at the rear of the head. It is not that easy to balance flow with pressure with such complex flow patterns. Cylinders 3 and 4 should have greater openings to facilitate more flow and aid with cooling.

I do not have the answer but working on it and what I find strange is that you guys have accepted that overheating is a problem and accepted the consiquences.
It is obvious that something is wrong?

Tickford 6,

Sory, nearly forgot to ask why the South African Xr6 ECU is so sought after.

Tickford 6,

Some more comment, the gasket probably never failed, but the crack in the head resulted in water being forced to the cylinder. So, why did the head fail?

Slick,
thanks for your comment.
I have noticed the problem with filling. I did feel the radiator hose and made sure it is properly primed. This did not help, the haed cracked! This just indicate how important the flow of coolant is!

I have experienced similar priming problems with a Golf!(my daughters car) and the worst was experienced with a Renault. But this need not be the case.

So, what now? What is the longterm solution?

Tickford 6,

The airflowing arround head is obviously not enough! Surely, the cooling as a result of airflow is very limited and limited to the outside with little or no effect on the internals. Most of the heat generated is localised and requires high flow with good conductivity.

Tickford 6,

Welding is not my first choice but what do I do, Probably only 50 (my guest)or so XR6 arround. Anything sugestions?!

Do you run your car without a termostat?. just a question

To my surprise I have discovered that the termostat was removed? I am following this up with the workshop who worked on the vehicle. Do you think this is the cause of the problem?

I thought that was the case. same symptoms as air pocks but water pump just circulate the inlet & outlet area but forget about the rest of the block. hance the fermostat, it controls the flow of coolent so you get an even distribution throu out the block.

glad you found the problem

as fair as i know your emissions regs are not as tight as ours.
and i was also told your ECUs were tunned for higher octane fuel then ours.

so the XR6s you get have more power then ours by way of tunning only.



with you cooling problem. the fact you had no thermostat could well be the problem.. the thermostat in you falcon is a double acting one.

it not only opens water flow to the rad but blocks off flow to other pasages.
when the rad pasage is closed there is a second hole the housing that directs flow back into your water pump. ( the metal pipe from the bottom of the thermostat housing goes back to you water pump)
this is done to warm the engine up evenly.

when the rad pasage opens the othe pasage is blocked off. with out a thermostat you engine is pumping hot water back into it self.

i'm not sure what over heating problem you are talking about, cracked heads are very very uncommon here. head gaskets are the problem and it has been fixed in the AU falcon by using a better gasket.