KZN185 another head gone (part 2)

[karl higgs]

Just to confirm that the cylinder head on my 96 KZN185 has cracked (picture attached).
In all honesty, the removal of the head is a very simple straightforward job, nothing complicated in any way, no seized bolts etc and plenty of room to move spanners, sockets and banana fingers around.
Anyway, as you can see it has cracked around the swirl chamber of number 3 cylinder and appears to be heading off into the inlet valve seat.
Fortunately (I hope) it has been caught in time and no further damage has been caused, as there was no loss in coolant and like I said in my previous thread, all was good one day and the next day pressure in the system whilst sitting at the traffic lights.
I removed the thermostat last night, heated it up to the opening temperature of 82 degrees and no movement?, carried on heating up to 95 degrees (apparently it should now be open at 10mm or more) mine had opened about 1mm, 104 degrees and boiling like mad, eventually it started to open, but only to 5mm.
So has this issue been down to a faulty thermostat all along? Obviously, it has been causing a big restriction in the cooling system when hot (very hot); also, I notice on removal of the thermostat housing, a lot of weeping and white powdery corrosion where the lower hose joins to the thermostat-housing pipe, again there must have been pressure at this point (thermostat not opening correctly?).
Therefore if in doubt and your truck is okay at present (but then again the weekness may already be present and yet to show itself), change the thermostat as a matter of cause as I am now convinced that this has been the cause of my cracked head, check your lower hose to see if there is any corrosion where the lower hose meets the thermostat housing, mine looked like lumps of Stalactite, so had been weeping for some time.

[yoshie]

Good heads up mate, thank you for passing on.

[karl higgs]

Just to confirm that the cylinder head on my 96 KZN185 has cracked (picture attached).
In all honesty, the removal of the head is a very simple straightforward job, nothing complicated in any way, no seized bolts etc and plenty of room to move spanners, sockets and banana fingers around.
Anyway, as you can see it has cracked around the swirl chamber of number 3 cylinder and appears to be heading off into the inlet valve seat.
Fortunately (I hope) it has been caught in time and no further damage has been caused, as there was no loss in coolant and like I said in my previous thread, all was good one day and the next day pressure in the system whilst sitting at the traffic lights.
I removed the thermostat last night, heated it up to the opening temperature of 82 degrees and no movement?, carried on heating up to 95 degrees (apparently it should now be open at 10mm or more) mine had opened about 1mm, 104 degrees and boiling like mad, eventually it started to open, but only to 5mm.
So has this issue been down to a faulty thermostat all along? Obviously, it has been causing a big restriction in the cooling system when hot (very hot); also, I notice on removal of the thermostat housing, a lot of weeping and white powdery corrosion where the lower hose joins to the thermostat-housing pipe, again there must have been pressure at this point (thermostat not opening correctly?).
Therefore if in doubt and your truck is okay at present (but then again the weekness may already be present and yet to show itself), change the thermostat as a matter of cause as I am now convinced that this has been the cause of my cracked head, check your lower hose to see if there is any corrosion where the lower hose meets the thermostat housing, mine looked like lumps of Stalactite, so had been weeping for some time.

I forgot to mention and I know it has been said over and over again, but do not rely on the temperature gauge on these trucks as they are so inaccurate and slow to register. I checked the sensor/gauge at boiling point and the needle did not budge until the water had been boiling for a good 3-4 minutes and then ever so slowly, it decided to wake up.

[karl higgs]

Just to confirm that the cylinder head on my 96 KZN185 has cracked (picture attached).
In all honesty, the removal of the head is a very simple straightforward job, nothing complicated in any way, no seized bolts etc and plenty of room to move spanners, sockets and banana fingers around.
Anyway, as you can see it has cracked around the swirl chamber of number 3 cylinder and appears to be heading off into the inlet valve seat.
Fortunately (I hope) it has been caught in time and no further damage has been caused, as there was no loss in coolant and like I said in my previous thread, all was good one day and the next day pressure in the system whilst sitting at the traffic lights.
I removed the thermostat last night, heated it up to the opening temperature of 82 degrees and no movement?, carried on heating up to 95 degrees (apparently it should now be open at 10mm or more) mine had opened about 1mm, 104 degrees and boiling like mad, eventually it started to open, but only to 5mm.
So has this issue been down to a faulty thermostat all along? Obviously, it has been causing a big restriction in the cooling system when hot (very hot); also, I notice on removal of the thermostat housing, a lot of weeping and white powdery corrosion where the lower hose joins to the thermostat-housing pipe, again there must have been pressure at this point (thermostat not opening correctly?).
Therefore if in doubt and your truck is okay at present (but then again the weekness may already be present and yet to show itself), change the thermostat as a matter of cause as I am now convinced that this has been the cause of my cracked head, check your lower hose to see if there is any corrosion where the lower hose meets the thermostat housing, mine looked like lumps of Stalactite, so had been weeping for some time.

Sorry I meant to say that the crack is heading towards the "exhaust valve" and not the inlet valve of number 3 cyclinder.

[J i m s t e r]

check your lower hose to see if there is any corrosion where the lower hose meets the thermostat housing, mine looked like lumps of Stalactite, so had been weeping for some time.

Karl, have you got any photos of this? I'll have a good look when I am servicing the truck at the weekend.

[karl higgs]

Sorry I meant to say that the crack is heading towards the "exhaust valve" and not the inlet valve of number 3 cyclinder.

Cyclinder? sorry cylinder, (typo error) my hands are working quicker than my brain can register, an age thing apparently, or man thing depending on who you listen to

[karl higgs]

Karl, have you got any photos of this? I'll have a good look when I am servicing the truck at the weekend.

Jimster, I'll upload some images shortly, camera is on charge at the moment. However its quite simple to locate, get down under the truck, follow the lower rubber radiator hose up to where it joins the thermostat housing. The rubber pipe at this point on my truck had swollen up with corrosion, god knows how it had been keeping coolant in for so long, as there was such a deformed build up of corrosion around the end of the alloy pipe, the hose clip had opened up as well.