How Do I Blow A Head Gasket

[Aliens]

LPG actually burns hotter than petrol. Many people assume it is weak and cold.

Both the top and bottom main radiator hoses are firm (but not rock hard as is the case if there's a secretly split hose for example).

I believe if both hoses are hard, this means that the thermostat is open.

If water injection doesn't cool intake temps, why do some N/A burn-out cars and high-boost turbo vehicles use water injection?

As mentioned the engine fan is ALWAYS ON in this case. Many early LPG VN/VPs had the thermo fan relay cicuit re-wired so that the fan is on whenever the ignition is on. Something to do with the fact LPG burns hotter.

As also mentioned the radiator is OK. I knew this because months ago I swapped out the old factory one for a near-new one which had been tested in another vehicle and also checked by flushing it out. The new radiator did help where it caused the vehicle to cool when rolling in the wind. Beforehand, it only cooled when revving the engine.

no, don't be silly, coolant temps are regulated by the thermostat.

A) lpg burns colder than petrol
B) have you even considered that your cooling system may be to blame?


just because you topped it up with coolant dosnt mean that the thermostat isnt jammed shut or the radiator isnt blocked..

Is it series 1 or series 2 (series 1 runs a pressurized overflow tank, series 2 does not)

here is what to do, remove the thermostat, boil up a pot of water
drop the thermostat in the pot of boiling water, note if it opens, might take a few seconds but should happen

standard thermostat is 192deg F (88 Celsius for those playing at home)
waters boiling temp is 100deg C

if it fails to open, replace it,

if its series 2 the radiator cap could be broken, this is another valve that opens to allow for volumetric expansion of the coolant, it pushes coolant into the tank when hot and sucks it back in when it gets cold to prevent the system from pressurizing too much

from here, if you havnt found any issues a coolant specialist can do a "hydrocarbon"test
they put a sensor in your coolant tank and can tell if combustion gasses are entering the cooling system. if still ok look at the radiator.

there are 2 sensors for coolant, 1 for the gauge, 1 for the ecu, the ecu is turning on the engine fan and the gauge reflects the same thing so i DOUBT both sensors are faulty.

Go forth and fix....

 

[PaRaDoX]

the induction temperature its self is alot colder as the act of decompressing gasses cools it (just as compressing gasses heats it) this is why you have to run engine coolant through the converter so that it dosn't freeze over!

lpg peaks at 1990deg c and petrol peaks at 1977deg, factor in that the ambient temperature will be much lower due to the decompression of the LPG and your not really talking much difference. Most cars that run LPG run alot more timing because detonation is less likely due to the fact that LPG will auto ignite (no spark) at 450deg C where as petrol will auto ignite at 220deg C, this means less chance to pre-ignite! (ping)

never said water injection didn't cool intake temps, but on a n/a v6 motor its not needed to stop over heating, the factory cooling system SHOULD do that, if it isn't why not fix the actual problem. it will work out cheaper and be easier, ill be running meth/water injection in my car to prevent detonation/pre-ignition at higher boost.

Now were done with the science lesson,

the hoses may be firm but whats to say the thermostat isn't opening late or at a higher temp? eg. over 100deg C
id test it in by removing the thermostat and run the car till the temp stabilizes , if it over heats still then you know the thermostat wasn't at fault and you've just taken 1 step towards finding the root cause.

 

[FXST01]

What pressure radiator cap do you have on it?

 

[Aliens]

What pressure radiator cap do you have on it?

135psi.

It's actually a (new) cap on the phase 1 of series 1 surge-tank bottle (which is also new).

Today I dumped all the coolant and replaced it with 100% ethylene glycol again, so at least it won't boil anymore after shutting off the engine.

 

[Aliens]

the induction temperature its self is alot colder as the act of decompressing gasses cools it (just as compressing gasses heats it) this is why you have to run engine coolant through the converter so that it dosn't freeze over!

lpg peaks at 1990deg c and petrol peaks at 1977deg, factor in that the ambient temperature will be much lower due to the decompression of the LPG and your not really talking much difference. Most cars that run LPG run alot more timing because detonation is less likely due to the fact that LPG will auto ignite (no spark) at 450deg C where as petrol will auto ignite at 220deg C, this means less chance to pre-ignite! (ping)

never said water injection didn't cool intake temps, but on a n/a v6 motor its not needed to stop over heating, the factory cooling system SHOULD do that, if it isn't why not fix the actual problem. it will work out cheaper and be easier, ill be running meth/water injection in my car to prevent detonation/pre-ignition at higher boost.

Now were done with the science lesson,

the hoses may be firm but whats to say the thermostat isn't opening late or at a higher temp? eg. over 100deg C
id test it in by removing the thermostat and run the car till the temp stabilizes , if it over heats still then you know the thermostat wasn't at fault and you've just taken 1 step towards finding the root cause.

Here is what I KNOW from experiencing it in practice.

Petrol = higher coolant temp reading than gas.

Gas = higher ambient heat coming off engine and hotter + more-volume-consuming exhaust gases.



And the LPG by the time it enters the throttle body isn't really cold anymore.


I've literally had my face and nose in LPG exhaust and inlet manifold fumes so I know. It's partially how I test the air/fuel ratio when tuning LPG cars, along with seat-of-pants performance and how the engine sounds.






Yes the factory system normally would be more than adequate. I've had and got other Phase-1 of Series-1 engines and so I know that a properly working engine generally operates at around Notch-1 - if using high concentration good quality coolant. Never ever in all history have I had one reach close to half way - even during country, city, and towing driving - short and long term.


The engine in question isn't a standard engine. It used to be a race engine, which I modified again earlier this year for fun.



I've had (and still have got) the same type of engine with the long stroke crankshaft installed and that engine ran as cold as other same-type engines which were also in proper working order. In this engine the air-bleed line was blocked off and it STILL ran as cold as normal.


I agree with taking out the thermostat as a good test, but because it was replaced when the engine was put back together from an engine that ran cold, it doesn't appear faulty, and it's hard to change them on any Series 1 let alone with a non-standard manifold and carby on it, I'm hesitant to take it out.

I did try to imagine what temp the thermostat is opening at by checking when the hoses become firm, and notch 2-3, the hoses were firm. I believe this means it's (seemingly) opening at roughly 90 degrees.

 

[PaRaDoX]

interesting my vn s1 always ran at 1/3 temp to 1/2 temp and my vp v8 always ran at the same.

it is possibly you got a lemon thermostat end of the day its up to you, id only use water injection if you were running a crazy CR and tons of timing.

 

[Immortality]

water pump..... poor circulation. run engine from cold. monitor engine temp with laptop and note the point where the top hose gets hot. this is the point that the thermostat opens.

i though the standard V6 thermostat was 195degrees F ?

the boiling point of water is 100degrees C however a cooling system which is presurised and has coolant has a higher boiling point.

 

[Aliens]

Re: Water Pump - when running the engine with the lid taken off the surge tank bottle, there is a steady stream of coolant coming out from the air bleed hose (the very top thin hose of the tank) including at idle. Also, when revving the engine by hand slightly, there is a lot of turbulence in the surge tank.

I figured this should mean that the water pump is pumping fine?

With the coolant mixture now back to 100% ethylene glycol (for max boil point raising) and with the plastic flap removed from under the thermo fan (most of my VNs have had this removed anyway), the engine generally operates at in between H and the last notch before H, but closer to the last notch before H than the H mark itself.

This is when sitting still idling. Once moving the engine cools rapidly and often quite significantly whilst either rolling in the wind (with the lower flap off now), or revving the engine, or both. So far...

Apparently the boiling point of 100% ethylene glycol is at least about 176 degrees C according to a few different brands of coolant I looked at. I guess this also isn't including pressurisation.



Something I've noticed the several times I've changed the coolant in this engine is that once the coolant is dumped and the engine is run, it's temp goes from C to H in much less than 30 seconds. Once I start pouring cold coolant in it cools almost as quickly eventually down to around Notch-1, which is in my experience where phase-1 of series-1 (early series 1) engines generally operate at. Once bled and driving though it returns back to as above.

 

[ScoHar]

just check your thermostat, easy point to start at, and easy as to test. My guess would be your thermostat isn't opening fully and restricting the flow hence the overheating, meaning it may be cooling a little but not enough when the engine has load on it.

 

[Immortality]

with no coolant in the engine the temp gauge shouldn't really be giving readings as it's sitting in air........