Discussion
I know that there have been previous posts on this, but it appears not covering this particular problem.
First I have to say that I check the oil level regularily and it has always been OK and ahrdly needed topping up at all, I know that I have a slight leak on the sump, but Racing Green said it is not serious and can be sorted at the next service in July.
The problem I have is that the pressure seems OK at strt-up, but yesterday when hot and I stopped the guage was registering below zero. When I was moving it reose up again, but evertime I stopped it dropped down to zero again. I checked the level of oil when I stopped and level is fine. Any ideas? Is the guage up the shoot?
First I have to say that I check the oil level regularily and it has always been OK and ahrdly needed topping up at all, I know that I have a slight leak on the sump, but Racing Green said it is not serious and can be sorted at the next service in July.
The problem I have is that the pressure seems OK at strt-up, but yesterday when hot and I stopped the guage was registering below zero. When I was moving it reose up again, but evertime I stopped it dropped down to zero again. I checked the level of oil when I stopped and level is fine. Any ideas? Is the guage up the shoot?
razorman said:
The problem I have is that the pressure seems OK at strt-up, but yesterday when hot and I stopped the guage was registering below zero. When I was moving it reose up again, but evertime I stopped it dropped down to zero again. I checked the level of oil when I stopped and level is fine. Any ideas? Is the guage up the shoot?
I had the very same symptoms start suddenly in the middle of a recent track day, twas very alarming glancing down at the oil pressures gauge at 5000rpn and full throttle to see it registering zero!!!
Thing is tho, it didnt make any sense as the engine didn't immediately lunch itself, nor did it sound anything other than sweet. As soon as i was off the throttle the gauge shot back up again and I thought it was oil surge. Back in the pits however (checked sump full) all was normal until revving over 4k rpm when the gauge would plummet down to sub-zero and spring back up as soon as back off the throttle. Me thinks 
sender problem, or relief valve problem?? Crawl under car and wiggle the connector and hey presto all works fine - for a while. Was still temperamental after this. Ended up removing and dismantling the sender and at the same time adjusting and calibrating it against accuracy checked mechanical gauge (which also confirmed normal oil system pressures). Re-assembled all and tightened up the spade connector to the sender . Been perfect since and nice to know its showing fairly accurate readings. i actually think the whole problem was down to the spade connector in retrospect, 30 seconds careful application with a pair of pliers was probably all that was required. Either way it was a lot easier than stripping the front end / oil pump etc.
I did give a brief account of this recently in another oil pressure thread. www.pistonheads.com/gassing/topic.asp?f=8&h=&t=182737
>> Edited by tahiti450 on Sunday 5th June 20:55
>> Edited by tahiti450 on Sunday 5th June 21:09
>> Edited by tahiti450 on Sunday 5th June 21:10
The oil pressure sender or a loose spade connector is the usual culprit for low oil pressure readings (or non at all).
My advice on oil is use a good quality not necessarily full synth but change it frequently i.e no more than 6K miles or 6 months. Sooner if it is tracked a lot.Good quality oil is relatively cheap these days.
15W/40 and above SAE. The later serp engine with better pump will tolerate 5W, but do not use Mobil 1 0W/40 their motorsport 15W/50 is good but pricey.
My advice on oil is use a good quality not necessarily full synth but change it frequently i.e no more than 6K miles or 6 months. Sooner if it is tracked a lot.Good quality oil is relatively cheap these days.
15W/40 and above SAE. The later serp engine with better pump will tolerate 5W, but do not use Mobil 1 0W/40 their motorsport 15W/50 is good but pricey.
What tahiti450 said. I had his problem recently - changed the sender which improved matters briefly. When they next looked at it the found that the connection was shorting out as the engine twisted under load.
You may have a similar problem. I'd start with the connections and move to the sender after that.
You may have a similar problem. I'd start with the connections and move to the sender after that.
My Griff would read fine,55 from cold and hold it until the revs dropped, once dropped would not go above 35. Change of sender and back to normal, 55 from cold and never below 30. But mine has a resistor across it (1k) so it can never read below Zero as it used to do and give false readings. If the wire was to short to neg/chassis the reading would shoot up and if the wire came off it would drop.
Ahhhh-Corner! said:
As a newby to the Chimaera world, what is the normal behaviour for the oil pressure gauge? I appreciate that the oil pressure will raise under load (rpm), but what is normal?
AC
I included a link to a previous post in my post above, it might help. Beware oil pressure readings can be very "approximate" to put it politely for the reasons stated.
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