is there a relief spring in the oil filter housing which may cause low oil pressure if broken or bent? i explained my issue's to a mechanic, he is not a diesel expert by any means, but just a real nice guy i can usually ask any stupid question to. he says there is a relief spring inside the oil filter housing which may cause erratic oil pressure. my issues: when i first start it the oil pressure is good. shut it off about 40 minutes later and restart it, the oil pressure is nearly gone. shut it of again about 20 minutes later, restart it and oil pressure is back up.... what the heck i say..... when it is running with little oil pressure, it runs fine, no extra noise as i would expect it to do, just keeps chugging along. so does the oil relief spring sound about right?