Accusump and oil leaks
Discussion
I thought would share some experiences with you - there have been a number of topics and posts over the last few months regarding strange oil leaks, no pre-oiling and 'old oil' in Accusumps fitted to Ultimas. As a start have a look at the Canton Racing website for Accusump products which gives details regarding how they should be installed and how they work.
http://www.accusump.com
In essence they have a dual function - they provide a pressurised oil supply to the engine before starting and secondly they provide a pressurised oil supply if the oil pump doesn't pick up fluid from the sump under high 'g' forces. The product in a typical installation has an electrical solenoid valve which also acts as a type of non-return valve. The cylinder of the unit has a piston with relatively low air pressure on the side remote from the engine and this is compressed as oil enters the device under a higher pressure from the engine. This pressurised oil is then held until released by the solenoid valve. The latter happens when there is very low oil pressure - at start up or when the oil pick up is compromised. This is controlled by the oil pressure warning switch/system. The cylinder unit also includes a safety valve so if there is excess oil pressure the cylinder will not burst. This could happen for instance if the air was lost from the system and the unit was then full of oil and subjected to engine heat soak which could significantly increase the pressure in the cylinder.
Now on my car after one of my first drives I parked up in the garage and all was fine. Later when I returned there was a pool of oil under the rear of the car and across the garage floor. The oil was dripping from the bell housing area and I initially thought the rear oil seal had let go. Later a more detailed look also showed oil inside the rim of the near side wheel. Very confusing. I then realised where the oil had come from - the safety valve on the Accusump. This has two outlets from which oil will be expelled if it actuates. With the orientation on my car one fired oil at the bell housing and other at the near side rear wheel. I had also noted that the Accusump was not giving a pre-oiling function to the engine - oil was trapped in the cylinder. A detailed investigation showed two problems - which I later found are not uncommon. Firstly the pre-oiling was not working because the oil pressure warning switch was not working. Basically the solenoid valve is earthed through the switch so the full amperage goes through the switch which is really more than it is designed for and the contacts fail over time. (As soon as the ignition is turned on power is supplied to the solenoid valve and the oil pressure warning system and the power is turned off once the oil pressure switch goes open circuit as pressure actuates it). This is a likely cause of the unit not providing oil pressure at start up and why degraded oil can sometimes be found in the unit. Secondly the safety valve on my car was operating way below the normal 175 psi setting and limited heat soak was raising the pressure enough to cause it to spray oil into very unusual areas in the engine bay. The valve loses it's proper setting over time due to heat degradation. (A similar effect can occur if the piston seals fail allowing the loss of the air pressure on that side of the piston so the whole cylinder is 'hydrauliced' with oil).
A new safety valve and oil pressure warning switch sorted my system and everything now works as intended.
http://www.accusump.com
In essence they have a dual function - they provide a pressurised oil supply to the engine before starting and secondly they provide a pressurised oil supply if the oil pump doesn't pick up fluid from the sump under high 'g' forces. The product in a typical installation has an electrical solenoid valve which also acts as a type of non-return valve. The cylinder of the unit has a piston with relatively low air pressure on the side remote from the engine and this is compressed as oil enters the device under a higher pressure from the engine. This pressurised oil is then held until released by the solenoid valve. The latter happens when there is very low oil pressure - at start up or when the oil pick up is compromised. This is controlled by the oil pressure warning switch/system. The cylinder unit also includes a safety valve so if there is excess oil pressure the cylinder will not burst. This could happen for instance if the air was lost from the system and the unit was then full of oil and subjected to engine heat soak which could significantly increase the pressure in the cylinder.
Now on my car after one of my first drives I parked up in the garage and all was fine. Later when I returned there was a pool of oil under the rear of the car and across the garage floor. The oil was dripping from the bell housing area and I initially thought the rear oil seal had let go. Later a more detailed look also showed oil inside the rim of the near side wheel. Very confusing. I then realised where the oil had come from - the safety valve on the Accusump. This has two outlets from which oil will be expelled if it actuates. With the orientation on my car one fired oil at the bell housing and other at the near side rear wheel. I had also noted that the Accusump was not giving a pre-oiling function to the engine - oil was trapped in the cylinder. A detailed investigation showed two problems - which I later found are not uncommon. Firstly the pre-oiling was not working because the oil pressure warning switch was not working. Basically the solenoid valve is earthed through the switch so the full amperage goes through the switch which is really more than it is designed for and the contacts fail over time. (As soon as the ignition is turned on power is supplied to the solenoid valve and the oil pressure warning system and the power is turned off once the oil pressure switch goes open circuit as pressure actuates it). This is a likely cause of the unit not providing oil pressure at start up and why degraded oil can sometimes be found in the unit. Secondly the safety valve on my car was operating way below the normal 175 psi setting and limited heat soak was raising the pressure enough to cause it to spray oil into very unusual areas in the engine bay. The valve loses it's proper setting over time due to heat degradation. (A similar effect can occur if the piston seals fail allowing the loss of the air pressure on that side of the piston so the whole cylinder is 'hydrauliced' with oil).
A new safety valve and oil pressure warning switch sorted my system and everything now works as intended.
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