liners can slip after an overheat or they can slip after a crack appears in the block. i don't know if a slipped liner can cause a crack.
you can have a crack without the liner slipping, but a liner slipping without a crack won't enable the passage of exhaust gasses to the coolant

is it time to do another sniff test? ask your friendly MOT guy if he'll wave his analyser over your coolant tank
 
A slipped liner will usually give you a constant tap tap tap at engine speed. Liners usually slip when the block cracks through a water passage behind a liner, allowing coolant to come in contact with the liner, lubricating it and allowing it to slip. Following that, you end up with coolant creeping up the liner and getting into the combustion chamber.

Have you checked your spark plugs to see if any are steam cleaned?
 
Someone has told me that a blocked heater matrix can cause overheating, do you know of this happening?
 
madbrit said:
Someone has told me that a blocked heater matrix can cause overheating, do you know of this happening?
Click to expand...
I can't see that. The front of the inlet manifold passes some coolant to the heater and the rest to the radiator. If you blocked the heater (which doesn't do much during the summer) then all coolant will go to the radiator
 
That’s what I thought. But reading up it is an important part of the cooling system. Hot water is always going through the matrix. It’s only the flaps left and right that stop hot air coming into the car and regulated. The water to the matrix is not regulated at all and is constant
 
madbrit said:
That’s what I thought. But reading up it is an important part of the cooling system. Hot water is always going through the matrix. It’s only the flaps left and right that stop hot air coming into the car and regulated. The water to the matrix is not regulated at all and is constant
Click to expand...
Yep that's true, but it's not dumping heat anywhere when the blend flaps are closed, so it's not aiding in the engine cooling. Equally it's not causing a restriction and heat buildup if it were blocked. At least that's my view
 
I have now bypass the matrix and off for another trip soon, see what happens, just trying everything before I start stripping the engine, like getting my other P38, 1998 2,5 DSE MOT's that's Thursday, so a days just checking it through tomorrow
 
Thanks, that is a job for tomorrow, along with compression test and pressure test each cylinder to see if any leaks back to cooling system
 
didnt get round to it today, as have more problems with the 2.5 diesel, started another post to do with airbag warning light
 
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