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Engine Developed Pressure


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Hi all I started this thread because the liners thread was diversive enough now I need to be a little more specific with the questions an did not want to run away from the original topic.

from the other thread water loss could be indicative of liner failure and I have ruled that out, along with minor leaks from coolent system I have fixed I am now water tight.

I reckon that the head gasket has a minor flaw but as the oracals quite rightly say you dont want to rip the engine out and start stripping and i am not 100% convinced just jet.

so here is the question what pressure does the engine develop within the cylinder chambers during the cumbustion and exhaust cycles?

The reason I ask this is that during the pressure test of the cooling system I had a standing pressure within that system of 15 PSI

As you know the dye penetrant test and i will correct the previous statment here showed that thier were trace elements of Co2 within the water during normal idle running.

This would seem to sugest that the co2 post combustion was escaping across the head gasket into the block cavities and over pressurising the coolant system thus pushing the water through the expansion tank into the second tank and dumping it over board.

however this was not evident during the idle run,

Therefore the pressure must be below 15 psi at idle, could it be that during increased Rpm the pressure increases dramatically not sure does it rise significantly above 15 psi?

now the second tank in the wheel well if I seal this tank from atmosphere what reprecushions could I expect would the system cavitate if yes could would a non return valve that closes when coolent under pressure acts upon it and opens when the tank is empty prevent fluid loss.

would cappilary action allow the coolent in this tank to feed back to the main system or is not possible.

some points to consider.

regards rob :(:blink::blink:

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Off the top of my head it works out at roughly 38 bar as a peak pressure for each firing stroke. That is at max HP of 350 at the flywheel. It's a long time since i worked this stuff out so this is not gospel.

hope it helps

stu.

Driving Automotive Aristocracy Since 2004

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Off the top of my head it works out at roughly 38 bar as a peak pressure for each firing stroke. That is at max HP of 350 at the flywheel. It's a long time since i worked this stuff out so this is not gospel.

hope it helps

stu.

<{POST_SNAPBACK}>

yep it does help Stu at 38 Bar equivilant 558 Psi I would expect the water in the block to be blowing out constantly via the second expansion tank and that is not happening definatly food for thought there thanks M8.

regards robert

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  • 3 weeks later...
Hi all I started this thread because the liners thread was diversive enough now I need to be a little more specific with the questions an did not want to run away from the original topic.

from the other thread water loss could be indicative of liner failure and I have ruled that out, along with minor leaks from coolent system I have fixed I am now water tight.

I reckon that the head gasket has a minor flaw but as the oracals quite rightly say you dont want to rip the engine out and start stripping and i am not 100% convinced just jet.

so here is the question what pressure does the engine develop within the cylinder chambers during the cumbustion and exhaust cycles?

The reason I ask this is that during the pressure test of the cooling system I had a standing pressure within that system of 15 PSI

As you know the dye penetrant test and i will correct the previous statment here showed that thier were trace elements of Co2 within the water during normal idle running.

This would seem to sugest that the co2 post combustion was escaping across the head gasket into the block cavities and over pressurising the coolant system thus pushing the water through the expansion tank into the second tank and dumping it over board.

however this was not evident during the idle run,

Therefore the pressure must be below 15 psi at idle, could it be that during increased Rpm the pressure increases dramatically not sure does it rise significantly above 15 psi?

now the second tank in the wheel well if I seal this tank from atmosphere what reprecushions could I expect would the system cavitate if yes could would a non return valve that closes when coolent under pressure acts upon it and opens when the tank is empty prevent fluid loss.

would cappilary action allow the coolent in this tank to feed back to the main system or is not possible.

some points to consider.

regards rob :mellow:  :P  :P

<{POST_SNAPBACK}>

hello...compression would be at least 200psi....cooling system at around 15psi..if you have not got an external leak..then the engine is eatings its own cooling water fact...double check state of both seals on main header tank cap....when the engine temp is high the main tank vents to wheel arch tank...as it gets back to normal the water is sucked back into system.

Normally now... one would remove Oil and Sump..pressure rise over night....and look up into Crankcase to observe the liner leaking....

[email protected] or 07976 609881

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