P38 v8 Petrol Overheating

madbrit · Aug 13, 2021

ok couple of tests done here,

1 put new thermostat in, after replacing with new, fan clutch, pump, thermostat to top rad hose (as i broke the T) & cap,l go for a drive, boils over within a few miles, get back no water in header tank !!

2 put old thermostat back in and keep it open, just been for a 40 mile drive, no boiling over and water still in header tank,

I did check the small pipes off the thermostat and they are in the correct position

Before 2nd test......

Flushed the heater matrix with a hose pipe to the in pipe & had a load of bubbles out the header tank, kept this going till I also had water coming from the radiator bleed off pipe to header tank and no more bubbles

now tempted to replace the thermostat with the new one, as MIGHT of been air lock, but I really doubt it

Even after all the above and a 40 mile drive, bottom of rad is cold, so that proves a point that was made earlier

madbrit · Aug 14, 2021

I am giving this a rest for a day, have another problem with the HEVAC on my other p38 2.5 Diesel 1998

I will update this to let people know

Thanks to all

Mark Piercy · Aug 14, 2021

madbrit said:
I am giving this a rest for a day, have another problem with the HEVAC on my other p38 2.5 Diesel 1998

I will update this to let people know

Thanks to all

Sometimes a step back let's the fog clear and the mind young padawan!

Joss-mirff · Aug 22, 2021

Does this car have LPG ?

madbrit · Aug 22, 2021

Yes it does

madbrit · Aug 22, 2021

It has been suggested to me that the regulator that is water cooled maybe pressurising the water system because of a gas leak into the water system I don’t know whether this could happen but I am going to isolate the water system next week See if that makes a difference

kermit_rr · Aug 22, 2021

madbrit said:
It has been suggested to me that the regulator that is water cooled maybe pressurising the water system because of a gas leak into the water system I don’t know whether this could happen but I am going to isolate the water system next week See if that makes a difference

Yes it can happen, the seals go and let the high pressure LPG leak into the lower pressure coolant.
But that should only happen if you run on LPG, otherwise the solenoids should be shut

tomcat59alan · Aug 22, 2021

madbrit said:
It has been suggested to me that the regulator that is water cooled maybe pressurising the water system because of a gas leak into the water system I don’t know whether this could happen but I am going to isolate the water system next week See if that makes a difference

Yes it could, good call. @Joss-mirff another case of incomplete information supplied.

madbrit · Aug 22, 2021

I had a very small gas leak. Even with the gas solenoid shut off. But Monday I will re direct the water away from
The gas regulator.
Thanks all

Joss-mirff · Aug 22, 2021

I knew it, only because I had pressurising over night with car nose on downward gradient, take the exp cap off and sniff (with your nose lol) in the tank and yes a smell of propane, bought a repair kit for my Tomasseto artic reg/reducer and replaced water side large gasket and spring diaphragm one wich was covered in liquid wax, remove that too and fit the new filter. Over pressurising gone.

Joss-mirff · Aug 22, 2021

Sorry guys , it was a 2000 P38 with Thor engine 4.0 and obviously lpg seq sys fitted. Sold it for a poorly 3.6 tdv8 lol.

madbrit · Aug 22, 2021

Tanks. Wi try all that on Monday. Will let you all know

madbrit · Aug 22, 2021

If the gas valve solenoid is turned off when engine off. Then how did it pressurise the system overnight ?

kermit_rr · Aug 22, 2021

madbrit said:
If the gas valve solenoid is turned off when engine off. Then how did it pressurise the system overnight ?

Sticky solenoid not shutting off properly?

madbrit · Aug 22, 2021

Could be my
Problem !!! At last another avenue to explore. I have just bought a kit to pressurise eAch pot and see if air leaks back to Coolant circuit lines. I did pressurise the coolant system and it’s slowly leaking somewhere. Not on the floor.

kermit_rr · Aug 22, 2021

If you have a cylinder leaking into the coolant, it might only happen over a certain temp.
If it's LPG leaking, that would explain why you got a negative sniff test as it's not combusted

tomcat59alan · Aug 22, 2021

Joss-mirff said:
Sorry guys , it was a 2000 P38 with Thor engine 4.0 and obviously lpg seq sys fitted. Sold it for a poorly 3.6 tdv8 lol.

Not incomplete information from you mate.from the o. p.

never mind we'll polish our crystal balls.

Henry_b · Aug 22, 2021

Joss-mirff said:
Sorry guys , it was a 2000 P38 with Thor engine 4.0 and obviously lpg seq sys fitted. Sold it for a poorly 3.6 tdv8 lol.

Ya see what you did there was, take your leg out of a bear trap and then turn around and stick your head in instead.

Poorly and TDV8 in the same sentence is enough to make me feel ill.

madbrit · Aug 23, 2021

I shut the gas off, took out a rather large bank loan and went for a long trip on petrol, same thing loosing coolant and boiled over, but I did not disconnect the water pipes to the gas regulator, that is now done and about to try again.

Also Going to test The gas solenoid valve see if it does shut off 100%

PHEW good job I love this car

madbrit · Aug 24, 2021

disconnected the water pipes from the gas system, still loosing water and overheating, so put back together, gas solenoid seems ok

Could this be a slipped liner, what would the symptoms be ?

P38 v8 Petrol Overheating

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