Oil pressure readings
Discussion
I know this has been discussed a million times but its pretty quiet here and maybe people have different opinions and experiences now.
My car shows low oil pressure compared to the last Griff I had these are the readings
cold idle 30psi
cold above 3k rpm 30psi same as cold I would have thought it should rise?
hot idle 12psi
hot above 3k rpm 28psi.
I have purchased a new sender from Power and this has made no difference whatsoever. the oil light goes out as soon as the car starts and never comes back on. If I switch the car off and immediately turn the ignition back on when cold (not tried when hot yet) the oil light takes about 2 seconds to illuminate again so I presume it must be holding some pressure after the engine shuts down so no major leaks would appreciate opinions on this.
I am getting a mechanical oil pressure check done later today so that will be interesting to see the results what do you guys think I should be getting on a healthy engine as a true reading.
Appreciate any feedback
Chris
Edit to add
The car is a 500 supercharged and is running 10-60 Millers CFS. New oil and filter just done so nice and clean oil.
My car shows low oil pressure compared to the last Griff I had these are the readings
cold idle 30psi
cold above 3k rpm 30psi same as cold I would have thought it should rise?
hot idle 12psi
hot above 3k rpm 28psi.
I have purchased a new sender from Power and this has made no difference whatsoever. the oil light goes out as soon as the car starts and never comes back on. If I switch the car off and immediately turn the ignition back on when cold (not tried when hot yet) the oil light takes about 2 seconds to illuminate again so I presume it must be holding some pressure after the engine shuts down so no major leaks would appreciate opinions on this.
I am getting a mechanical oil pressure check done later today so that will be interesting to see the results what do you guys think I should be getting on a healthy engine as a true reading.
Appreciate any feedback
Chris
Edit to add
The car is a 500 supercharged and is running 10-60 Millers CFS. New oil and filter just done so nice and clean oil.
Edited by chris52 on Wednesday 10th August 09:45
I recently rebuilt a 500 engine and the following was observed.
I calibrated the electrical gauge to a mechanical gauge
Running 5w-50 fully Synthetic
Cold Oil Temp 17C
Hot Oil Temp 93C
Cold Idle - 45 psi
Cold 3k - 45 psi
Hot Idle - 15-20 psi
Hot 3k - 30-35 psi
It sounds like your gauge is not on "zero" when its turned on. Wait 10 seconds or so before starting the engine and see if the gauge is on zero. If its not, the needle will need moving slightly. I have had to do this on a couple of gauges. Your deflection of the needle sounds about right so it just needs moving, the gauges themselves are actually quite accurate when done. Also, move the needle closer to the gauge when you move it to reduce parallax error when reading.
Bearing in mind these engines were NEVER designed for high oil pressure in the first place, the pressure release is around the 45 mark and anything higher than about 60 can start to push core plugs out!
Jody
I calibrated the electrical gauge to a mechanical gauge
Running 5w-50 fully Synthetic
Cold Oil Temp 17C
Hot Oil Temp 93C
Cold Idle - 45 psi
Cold 3k - 45 psi
Hot Idle - 15-20 psi
Hot 3k - 30-35 psi
It sounds like your gauge is not on "zero" when its turned on. Wait 10 seconds or so before starting the engine and see if the gauge is on zero. If its not, the needle will need moving slightly. I have had to do this on a couple of gauges. Your deflection of the needle sounds about right so it just needs moving, the gauges themselves are actually quite accurate when done. Also, move the needle closer to the gauge when you move it to reduce parallax error when reading.
Bearing in mind these engines were NEVER designed for high oil pressure in the first place, the pressure release is around the 45 mark and anything higher than about 60 can start to push core plugs out!
Jody
Edited by tofts on Wednesday 10th August 09:55
tofts said:
I recently rebuilt a 500 engine and the following was observed.
I calibrated the electrical gauge to a mechanical gauge
Running 5w-50 fully Synthetic
Cold Oil Temp 17C
Hot Oil Temp 93C
Cold Idle - 45 psi
Cold 3k - 45 psi
Hot Idle - 15-20 psi
Hot 3k - 30-35 psi
It sounds like your gauge is not on "zero" when its turned on. Wait 10 seconds or so before starting the engine and see if the gauge is on zero. If its not, the needle will need moving slightly. I have had to do this on a couple of gauges. Your defelction of the needle sounds about right.
Bearing in mind these engines were NEVER designed for high oil pressure in the first place, the pressure release is around the 45 mark and anything higher than about 60 can start to push core plugs out!
Push core plugs out you sure about that? I calibrated the electrical gauge to a mechanical gauge
Running 5w-50 fully Synthetic
Cold Oil Temp 17C
Hot Oil Temp 93C
Cold Idle - 45 psi
Cold 3k - 45 psi
Hot Idle - 15-20 psi
Hot 3k - 30-35 psi
It sounds like your gauge is not on "zero" when its turned on. Wait 10 seconds or so before starting the engine and see if the gauge is on zero. If its not, the needle will need moving slightly. I have had to do this on a couple of gauges. Your defelction of the needle sounds about right.
Bearing in mind these engines were NEVER designed for high oil pressure in the first place, the pressure release is around the 45 mark and anything higher than about 60 can start to push core plugs out!
A healthy Serp should run over 50 above 2.5k RPM hot and about 25 idle IMO running stock relief valve etc i.e no mods or packing Very sure. There is a plug behind the cam that is under pressure when running, and can leak/push out too much pressure exerted upon it.
As for the rest, yes I am also very sure. New oil pump, big ends 1.5 thou, mains 1 thou, rocker shafts not worn, new prv spring and prv valve, lapped in to housing for ease of movement.
PRV on the oil should only be 45 PSI stock, any more than this and it has been modified i guarantee, perhaps even by TVR, they put a grub screw behind the spring on some models to increase pressure. Down side is this reduces flow, and this engine was always designed for low pressure high flow.
J
As for the rest, yes I am also very sure. New oil pump, big ends 1.5 thou, mains 1 thou, rocker shafts not worn, new prv spring and prv valve, lapped in to housing for ease of movement.
PRV on the oil should only be 45 PSI stock, any more than this and it has been modified i guarantee, perhaps even by TVR, they put a grub screw behind the spring on some models to increase pressure. Down side is this reduces flow, and this engine was always designed for low pressure high flow.
J
Just to prove I'm not full of crap!
If oil pressure is higher than my readings, it has either been modified, or the release valve is partially stuck. Seent he latter a couple of times, had a customer come in with a pre-serp with oil pressure up at 90 psi! Which I quickly resolved for him after explaining what could happen!
Also, if you look really carefully, you can see TVR parts just re-badge parts from other places!
Edited by tofts on Wednesday 10th August 10:29
The needle is just about on 0 maybe a touch shy but not much. I know my last Griff showed about 30psi hot idle and 45 to 50psi above 3krpm. This engine had new bottom end bearings and oil pump done about 8k miles just ago before the supercharger was fitted just to freshen up everything to cope with the extra power.
Check your PRV, can be done from Rhs wheel arch by just taking wheel off. May be stuck open a tad. Should only take you 30 mins to get it out and back in again.
The piston can catch on the housing before it seats firmly inside the case a light polish of the piston and make sure there is a slight shamfer on the end so it can overcome the housing if necessary.
The piston can catch on the housing before it seats firmly inside the case a light polish of the piston and make sure there is a slight shamfer on the end so it can overcome the housing if necessary.
Cheers the PRV was a concern and another thing I was going to check. I have a spare Spring cap piston and Spring clip so if there are a fault I can sort it straight away.
Thanks for all the info guys will update later with my findings.
Chris
Thanks for all the info guys will update later with my findings.
Chris
Edited by chris52 on Wednesday 10th August 11:46
I have owned my Griffith 500 from new (1998) and found the oil pressure at idle varies both at cold and warm temperatures, according to the oil type and grade used.
The car started life, delivered from the factory with a mineral oil 20W/50 to gently "run the engine in", for the first 1000 miles (engine RPM restricted to 3,000).
The engine was flushed and filled with TVR recommended Mobil One 0W/40 fully synthetic (very costly oil in 1999). The car used a pint of the Mobil oil every 500 miles and tick-over pressure was always low (according to the dash gauge), especially when the engine was hot.
Since then, I have concluded that something like 10W/50 or even 10W/60 suits this old engine better, with minimal oil usage and the best oil pressure/oil flow compromise at all temperatures. The engine also runs mechanically quieter.
Hope this input is helpful?
The car started life, delivered from the factory with a mineral oil 20W/50 to gently "run the engine in", for the first 1000 miles (engine RPM restricted to 3,000).
The engine was flushed and filled with TVR recommended Mobil One 0W/40 fully synthetic (very costly oil in 1999). The car used a pint of the Mobil oil every 500 miles and tick-over pressure was always low (according to the dash gauge), especially when the engine was hot.
Since then, I have concluded that something like 10W/50 or even 10W/60 suits this old engine better, with minimal oil usage and the best oil pressure/oil flow compromise at all temperatures. The engine also runs mechanically quieter.
Hope this input is helpful?
GlynMo said:
Sardonicus said:
A healthy Serp should run over 50 above 2.5k RPM hot and about 25 idle IMO running stock relief valve etc i.e no mods or packing
I don't think I've ever seen a 'healthy' serp 500 in that case!Thanks Jody I must say I'm relieved that all seems ok internally. I was fairly confident but you always have that nagging feeling at the back of your mind that something may be wrong. Its strange that the gauge is basically 50% out its almost as if the gauge and the sender are not matched to each other. I have read posts about this on the Chim forum reporting exactly the same issue. This was resolved with the replacement of a Chinese sender from eBay that seems to give a better match between the two. I have ordered one now and when it arrives and is fitted I will report back. The new sender I bought from Power was £49.99 plus VAT plus postage the eBay one is £10 all in posted from China. The Chinese one looks identical with the exception of it needs its own earth lead which is a fairly simple job. Thread size is the same 1/8 NPT
Chris
Chris
chris52 said:
Ok now checked with a mechanical oil pressure tester.
Cold idle 58psi
Cold 3k rpm 60psi
Hot idle 22psi
Hot 3k rpm 55psi
Just shows you how far out these senders and gauges are.
Chris
Looks text book to me my 100K plus motor was running similar figures less 5 on the upper RPM readings with a mech gauge Cold idle 58psi
Cold 3k rpm 60psi
Hot idle 22psi
Hot 3k rpm 55psi
Just shows you how far out these senders and gauges are.
Chris
my unopened motor since 95 was then pulled the inside were very healthy Gassing Station | Griffith | Top of Page | What's New | My Stuff