oil pressure on starter aloneup?
Discussion
So I'm almost at the point of firing the cerb up for the first time in a few months. Oil has been changed as has filter. I'm turning the car over without the fuel pump running and the gauge doesn't show any pressure. Is this normal for just turning on the starter or is it likely an oil pump priming issue?
Thanks
Pete
Thanks
Pete
You may not get enough pressure to register on the starter even with the plugs out. I agonised over this for ages and tried all sorts of ways of priming the oil pump with drill powered pumps and syringes etc. Eventually I spoke to a well respected indie who said just start it - if the oil pressure doesn't come up withing 15 - 20 sec then turn it off again. I started it and had full oil pressure within a couple of seconds.
EFA
EFA
Edited by Tanguero on Tuesday 5th August 15:40
When I bought my Cerbera the fuel gauge was showing some fuel in the tank but it hadn't been started for a while, after 2 to 3 5-10 second cycles on the starter motor it was showing 60psi of oil pressure, it wouldn't start without adding fuel as the gauge was lying. I think it depends on how much oil has run back from the pump and cooler pipes as to whether it will make enough oil pressure on cranking after the oil and filter change to show on the oil pressure gauge.
It depends on the starter and the battery. If you have a new or higher power starter and a new battery they spin the engine very fast indeed and you should be able to get upto 40PSI on the starter. You will certainly get enough to see the gauge move.
If you have a weak battery or an old starter motor that turns the engine over slowly then you have no chance of raising any pressure no matter how long you crank it for.
But the advice on here is right. Just start it up and if no pressure within 10 seconds kill it. Really you should see pressure virtually immediately. My 4.5 Cerb would ping the oil pressure up to a rock steady 80PSI within a second or two when starting. My 4.7 takes about three seconds to reach 70PSI.
If you have a weak battery or an old starter motor that turns the engine over slowly then you have no chance of raising any pressure no matter how long you crank it for.
But the advice on here is right. Just start it up and if no pressure within 10 seconds kill it. Really you should see pressure virtually immediately. My 4.5 Cerb would ping the oil pressure up to a rock steady 80PSI within a second or two when starting. My 4.7 takes about three seconds to reach 70PSI.
I think it depends largely on how thoroughly the engine has drained of oil. I had mine out of the car and inverted on an engine stand - no way was it getting close to pumping oil on the starter. If it has just been left to drain through not being used or an oil change then maybe it is different.
I think it is important to change the oil pressure relief spring every 2 to 3 years. Made 30psi difference to mine when I changed it.
BTW the TVR "expert" that was servicing the car for me (and fitted the spring that I sourced and asked him to fit) had never changed one before! So don't expect it to be an item that is replaced during a service. Ask.
Paul
BTW the TVR "expert" that was servicing the car for me (and fitted the spring that I sourced and asked him to fit) had never changed one before! So don't expect it to be an item that is replaced during a service. Ask.
Paul
Storer said:
I think it is important to change the oil pressure relief spring every 2 to 3 years. Made 30psi difference to mine when I changed it.
BTW the TVR "expert" that was servicing the car for me (and fitted the spring that I sourced and asked him to fit) had never changed one before! So don't expect it to be an item that is replaced during a service. Ask.
Paul
Using a very unscientific "squeeze" test, my old one felt the same as the new but the pressure change says different BTW the TVR "expert" that was servicing the car for me (and fitted the spring that I sourced and asked him to fit) had never changed one before! So don't expect it to be an item that is replaced during a service. Ask.
Paul
Just to confuse things more, the oil pressure gauge can be a bit sticky, like all the others. So I would concentrate on the oil pressure lamp as well. The temptation is to spin it up without plugs to get the oil circulating, I can't think of any reason not to - however the advice from some well respected AJP8 engine builders is to fire it up as Tim says.
It is worth remembering that no engine is assembled dry (or shouldn't be) so there will be a film of oil on all moving parts which will be sufficient for the first start up.
If you are just changing the oil and filter then you should have got the oil warm before draining by running the engine which freshly lubricates everything. It only takes a few seconds to build system pressure with the new oil. Just don't rev the engine!
Simples!
Paul
If you are just changing the oil and filter then you should have got the oil warm before draining by running the engine which freshly lubricates everything. It only takes a few seconds to build system pressure with the new oil. Just don't rev the engine!
Simples!
Paul
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