Discussion
Happy New Year everyone.
My griff has an odd oil pressure problem. Whilst cold it starts at just over 60 psi. Then as temperature rises goes upto 90 psi. Then drops to about 40. The odd part is that it fluctuates between 40 and 90 really quickly whilst at tickover revs. Any ideas anyone. I have recently changed the oil myself, but it was doing it before this. Oil level is fine also.
My griff has an odd oil pressure problem. Whilst cold it starts at just over 60 psi. Then as temperature rises goes upto 90 psi. Then drops to about 40. The odd part is that it fluctuates between 40 and 90 really quickly whilst at tickover revs. Any ideas anyone. I have recently changed the oil myself, but it was doing it before this. Oil level is fine also.
Yes and yes. The relief valve is inside the oil pump usually behind a big bolt. Exact location depends on which day of the month the engine was made as there are many varients as is the case with the oil sensor. The main problem with the relief vavle is sticking open so that there is no pressure at all.
Steve
www.tvrbooks.co.uk
Steve
www.tvrbooks.co.uk
Zippy500
You probably have some oil pressure. Whether it is enough to prevent a complete engine breakdown I don't know and the only way to know is to fit a mechanical gauge and see. However 90psi on the meter is normally indicative of a duff connection or sensor. So I would go and have a look there first. If the lead is loose or fallen off then that will explain it. Try cleaning the contact. If that doesn't solve the problem, take the car to a dealer who will plug in a mechanical oil pressure guage and check that you have oil pressure and then will fit a nice new sensor and away you go. If it reads 90 psi then the sensor is OK and you have some other problem which could be a stuck pressure relief valve but this is very rare as they tend to fail so that there is zero oil pressure. It could be a blocked oil way. If it is, start saving as this normally means the engine is scrap.
As for replacing it yourself... the garage will have to unscrew the sensor to fit the guage and as this is when the thing breaks off in your hand, you really want to do this where it can be fixed immediately. You also need to get an exact replacement as there are many different ones fitted and it has to match both the instrument and the oil pump fitting.
Steve
www.tvrbooks.co.uk
You probably have some oil pressure. Whether it is enough to prevent a complete engine breakdown I don't know and the only way to know is to fit a mechanical gauge and see. However 90psi on the meter is normally indicative of a duff connection or sensor. So I would go and have a look there first. If the lead is loose or fallen off then that will explain it. Try cleaning the contact. If that doesn't solve the problem, take the car to a dealer who will plug in a mechanical oil pressure guage and check that you have oil pressure and then will fit a nice new sensor and away you go. If it reads 90 psi then the sensor is OK and you have some other problem which could be a stuck pressure relief valve but this is very rare as they tend to fail so that there is zero oil pressure. It could be a blocked oil way. If it is, start saving as this normally means the engine is scrap.
As for replacing it yourself... the garage will have to unscrew the sensor to fit the guage and as this is when the thing breaks off in your hand, you really want to do this where it can be fixed immediately. You also need to get an exact replacement as there are many different ones fitted and it has to match both the instrument and the oil pump fitting.
Steve
www.tvrbooks.co.uk
Oil pressure guages can be the source of much unneeded worry, as a failure is nearly always the guage - and I've had a number of guage problems in the 170,000 miles or so I've done in Griffs. On my last one it read 60 psi on start up and went down to 15 psi in traffic, but the oil light never came on. Rover derived engines need lots of oil, but if you read the V8 Rover engine book the view seems to be that pressure is secondary to availability. If the oil pressure light works use that and get the guage or sender (can be either) attended to at next service!
I have to disagree with this advice.
The oil pressure switch only comes on when the oil pressure drops to below about 7.5 psi. You can get it to go out with the gauge reading virtually zero just by cranking the engine on the starter. In otherwords it indicates a total loss of oil pressure but that is all. Running the engine for several thousand miles with very low oil pressure will cause premature wear and this can lead very quickly to an engine rebuild or dramatically shorten the engine's life.
You are right that 9/10 it is nothing to do with the engine but I would strongly recommend not taking that risk.
Steve
www.tvrbooks.co.uk
The oil pressure switch only comes on when the oil pressure drops to below about 7.5 psi. You can get it to go out with the gauge reading virtually zero just by cranking the engine on the starter. In otherwords it indicates a total loss of oil pressure but that is all. Running the engine for several thousand miles with very low oil pressure will cause premature wear and this can lead very quickly to an engine rebuild or dramatically shorten the engine's life.
You are right that 9/10 it is nothing to do with the engine but I would strongly recommend not taking that risk.
Steve
www.tvrbooks.co.uk
My last Griff 500 had a hot oil pressure of say 50 at 3000 rpm and one day fell to 30 ish at the same revs. I pulled over just as the noises began. Trailored to a local v8 guy i use for non service stuff. He predicted a fractured oil pick up pipe, sure enough, it was.Sucking half oil, half air. Job done £100. Unfortunately the rocker assys, being the last in line for oil, were starved. Just a little rattle, but i just had to replace them. Did the job myself. £450 if i remember correctly.
Watching oil pressure goes hand in hand with the water guage. Any change, get it checked.Mine could of been much worse.
David
Watching oil pressure goes hand in hand with the water guage. Any change, get it checked.Mine could of been much worse.
David
Seems like the calibration accuracy of pressure gauges on our cars is not to be relied upon so I would suggest that you establish in your own mind what is 'normal' for your car at varying engine speeds and temperatures. Any unexplained discernable drop from this level, particularly when accompanied by a knocking noise, should be cause for concern.
For info, the topic of oil grades was recently discussed in 'Chimaera' section under 'Oil' thread.
For info, the topic of oil grades was recently discussed in 'Chimaera' section under 'Oil' thread.
The only way to be sure is to have your pressure gauge checked to see if 15psi on the gauge really is 15 (and not 20 or 10). I presume you mean it is reading 15 hot and at tickover.
My Chim reads 15 at tickover when it is hot and I would be more comfortable if it was higher but it has been that for more than 10,000 miles. You tend to relax after a while if you haven't suffered drastic failure but of course my 15 could be 20 actually and somebody elses could be 10
.
Just looked at your profile, nice looking car. Looks like you've had it for a year and done 5,000 miles, has it always shown this pressure? Low pressure can not only be indicative of wear but also be the cause of accelerated wear. If you are not comfortable then perhaps it is best to get it checked.
My Chim reads 15 at tickover when it is hot and I would be more comfortable if it was higher but it has been that for more than 10,000 miles. You tend to relax after a while if you haven't suffered drastic failure but of course my 15 could be 20 actually and somebody elses could be 10
. Just looked at your profile, nice looking car. Looks like you've had it for a year and done 5,000 miles, has it always shown this pressure? Low pressure can not only be indicative of wear but also be the cause of accelerated wear. If you are not comfortable then perhaps it is best to get it checked.
Agree with most of the threads regarding wires, sensors, and relief valve all options; my Griff idled at 15psi and went of to 50psi at high revs. Varying pressure readings do point to an electrical fault but work through logically starting with the simplest as it tends to be these.
One thing though I had very high oil pressure on a previous car and the breathers were blocked with various gunge after degunging the breather pipes from the rocker cover it was back to normal.
If really concerned buy a cheap oil pressure gauge/pipe and fitting most Halford type shops stock them. Remove the switch near the oil pump and screw in, start get get a direct reading.
One thing though I had very high oil pressure on a previous car and the breathers were blocked with various gunge after degunging the breather pipes from the rocker cover it was back to normal.
If really concerned buy a cheap oil pressure gauge/pipe and fitting most Halford type shops stock them. Remove the switch near the oil pump and screw in, start get get a direct reading.
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