P38 GEMS - couple of questions on coolant change

P38 Monkey · Dec 2, 2022

A couple of questions when looking at the workshop manual - procedure for changing coolant:
1. The manual says remove the LH cylinder block drain plug but specifically says do not remove the RH one - why is that?
2. It doesn't say anything about draining the heater matrix - should I make sure the heater temperature is set to max (climate control)?
Are there any things I should look out for or be aware of?
As ever, thanks in advance for advice....

kermit_rr · Dec 2, 2022

dont know about a full drain, never done it, but heater matrix is always fully open so you dont need to worry about that
standard thermostat is fully sealed (no bleed hole) at the bottom, you you'll need to take on of the upper pipes off

P38 Monkey · Dec 2, 2022

kermit_rr said:
dont know about a full drain, never done it, but heater matrix is always fully open so you dont need to worry about that
standard thermostat is fully sealed (no bleed hole) at the bottom, you you'll need to take on of the upper pipes off

Good point on the thermostat. I am changing from IAT (of unknown age in my P38 hence the need to change) to OAT as recommended in the handbook. (Havoline XLC).
I assume the cylinder block drain plug is above the thermostat hence the need to remove the engine-side pipe.

kermit_rr · Dec 2, 2022

for what its worth.. and i might get stamped on for this.. but i put a small 'bleed hole' in the stat. it takes slightly longer to warm up, but it doesnt get quite as hot, mid-upper 80s instead of mid-upper 90s

romanrob · Dec 4, 2022

Hi Monkey...personally I just use the rad drain....drain the rad, fill with water, run the engine to temp, drain the rad again...... Fill the system with OAT to half the volume quoted for a full refill (eg 11L/ 2 for a V8)... top up with water

P38 GEMS - couple of questions on coolant change

P38 Monkey

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kermit_rr

Very

P38 Monkey

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kermit_rr

Very

romanrob

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