Gizzmo wrote:Sometimes it will stay at 130 deg for a few minutes, sometimes it will drop in a few seconds.
When it does drop, it does so quickly.
Easy check.
.
.
.
Sort the cooling system levels out again.
.
.
expansion tank at the correct levels.
.
.
.
Stick a coke bottle at the expansion tank overflow.
.
.
and then take it for a hard boost session.
.
.
.
If you're running 1.5+ bar.
.
you're going to exceed the coolant pressure threshold and thus.
.
the expansion tank will get excess gas
/ fluid through it which will spill out.
.
.
In reality, no coolant should come out of the overflow of the expansion tank
( unless over filled
)
Like others have mentioned, the cavitation is caused by combustion gas.
.
.not pump impellar issues
( they're metal
) or flow rates etc.
.
.
this will either be through the head gasket or through a cracked block.
.
.
.
Temps will rise suddenly as you're displacing the coolant with gas around the block.
.
.
you'll feel the heater go cold before itshoots up
( early warning
!
).
.
The temp probe is a little slow to react in reality.
.
.
Could of things in the build.
.
.
.
History of the block.
.
.
??!
Did it overheat before the rebuild
??!
Where I'm coming from, you may have skimmed the head, new head gasket, but did you have the block decked.
.
.
it might answer some of the gas passing issues.
.
Either way.
.
.
moneys on combustion gas displacement, where its coming from can be only from two areas.
Dont forget to check the simple things.
.
loss of coolant.
.
.
The rad bleed nipple is prone to leaking.
.
mine leaked without realising it.
.
.
the coolant shortage at the front will cause considerable air locks within the system too.
.
.
.
So recap
:
-Check for leaks at the front
-Carry out said coke bottle approach
-Run the engine with the filler cap off, check for the rising bubbles
( when hot
) and stick a gas analyser over it to see if its carbon monoxide
Other things that will throw you.
.
.
.
You may start to see the water pump start to leak under pressure
.
.
.
Once the coolant system builds pressure, you may see a stream of coolant come from the water pump.
.
this will not be the reason but the resultant problem from the overheating.
When the block overheats, there is normally a lack of coolant around the block
/ pump.
This
"dry" running will score the carbon bearings in the pump which will then allow it to pass coolant under pressure
!
So before you react to the leak.
.
.
dont go through all the trouble in changing it out when its a downstream issue which has been caused by the overheating.
On that note too.
.
.
I advised strongly to anyone thats had overheating problems where you've boiled it over considerably to change the water pump too after rectification.
Block sleeving.
.
.
I've done it
!!
These engines wont get the better of me.
.
.
!!
I've split 2 blocks soo far.
.
.
One ran at a mere 1.3 bar.
.
the other 1.6 bar daily.
.
with a burst to 2 bar.
.
.
.
!!
Luck of the draw for block integrity
!
