Oil Gauge Pressure Readings!!!
Discussion
Hi All
I'm the owner of a Chimarea 4L. Noticed the other day that when idling the pressure gauge read about 5psi, suddenly worried, I kept an eye on it. When the engine was reving higher as I went along it would move back to about 28-30psi. It never goes higher that 30psi. Oil level on dip stick is fine. When started from the cold the gauge shows 30psi. Seems to drop when warmed up and idling.
Many thanks in advance for any help
I'm the owner of a Chimarea 4L. Noticed the other day that when idling the pressure gauge read about 5psi, suddenly worried, I kept an eye on it. When the engine was reving higher as I went along it would move back to about 28-30psi. It never goes higher that 30psi. Oil level on dip stick is fine. When started from the cold the gauge shows 30psi. Seems to drop when warmed up and idling.
Many thanks in advance for any help
Has something changed such that it is doing this or has it always? The gauges (and senders) are notoriously imprecise and variable in outputs so absolute figures are not as reliable an indicator as consistency of behaviour. Take it the oil pressure light goes out pretty quickly on start up?
Assuming the car has a serpentine engine then those figures are a little lower than might be considered typical but probably nothing at all amiss with it mechanically... a decent mechanic would be able to do a pressure test for peace of mind however.
What weight oil are you using?
Assuming the car has a serpentine engine then those figures are a little lower than might be considered typical but probably nothing at all amiss with it mechanically... a decent mechanic would be able to do a pressure test for peace of mind however.
What weight oil are you using?
You may just have encountered the first (of many) TVR quirks rather than a real problem. The oil pressure senders are fairly notorious in the fact that they were often mis-matched to the gauges fitted resulting in often incorrect pressure readings. Personally I would learn as much as possible about the engine maintenance/repair history to be happy with what you have to start with and providing you are satisfied that you have a decent motor (no significant blue exhaust smoke etc.) regard your current readings as a "norm". Keep your eye on things and react if things change significantly, remember there is a nasty rumour that Summer is coming, bringing warmer temperatures and potentially lower pressure readings.
How many miles has your engine done & if high (80,000 +) has it been rebuilt to any degree?
Welcome to the magical and often eccentric world of TVR ownership!
How many miles has your engine done & if high (80,000 +) has it been rebuilt to any degree?
Welcome to the magical and often eccentric world of TVR ownership!
Hi Pupp
Oil light goes out upon start up and doesn't come on again even when pressure is showing low on the gauge.Car runs ok so did wonder if it was just a gauge thing, although if it works up to 30psi wondered why it doesn't move higher. Isn't 30psi still low when engine is warm?
Service was done by Neil Garner TVR so guess the correct oil was used. My is a T reg (98) by the way.
Oil light goes out upon start up and doesn't come on again even when pressure is showing low on the gauge.Car runs ok so did wonder if it was just a gauge thing, although if it works up to 30psi wondered why it doesn't move higher. Isn't 30psi still low when engine is warm?
Service was done by Neil Garner TVR so guess the correct oil was used. My is a T reg (98) by the way.
One thing I have notice with the gauges, is they go out of spec, the gauge should be on 0 when the ignition is on and often drifts over time. If its not It needs a little bit of calibration, I think you have nothing to worry about. by the sounds of it, your needle is indicating about the right pressures, its just in the wrong place to sgtart off with!
I just repaired a griff gauge for a customer where it was the same as above, reading "right" just in the wrong place. A mechanical gauge confirmed all was well!
Its actually very easy to do and will take you about an hour. I suspect it is this as at 5psi, the warning light would flicker as well!
Also, the weight of your oil will have almost no discernible difference on pressure as at 80 deg, the viscocity of 30/40/50 oil is very similar. One of the reasons I think 20-50 is too thick when cold, but that's a subject for another topic and I have done to death elsewhere.
I just repaired a griff gauge for a customer where it was the same as above, reading "right" just in the wrong place. A mechanical gauge confirmed all was well!
Its actually very easy to do and will take you about an hour. I suspect it is this as at 5psi, the warning light would flicker as well!
Also, the weight of your oil will have almost no discernible difference on pressure as at 80 deg, the viscocity of 30/40/50 oil is very similar. One of the reasons I think 20-50 is too thick when cold, but that's a subject for another topic and I have done to death elsewhere.
Edited by tofts on Monday 13th June 22:32
The gauge is likely to be at its most accurate when viewed within the first few miles of start up,
As the sender and oil gets hotter the gauge tends to,show a lower reading.
I take the cooler engine temp readings as a guide and go from there.
My engines been rebuilt and when hot the gauge often reads 10-15 psi or lower when at idle,
Even cold my engines gauge rarely goes about 44 psi at 2500 revs.
Some gauges read 50 psi and don't move at all,, I don't trust them!!!
Others like mine read horribly low but are more accurate throughout the range but all appear to read lower than the actual pressure the engine produces.
As already pointed out, if the reading was so,low the oil light would flicker on so even though the gauge might be reading 5 psi the engine clearly is running higher pressure than that.
Tvr Power built my engine, I've panicked and hassled Dom into looking at mine a few times now, fearing low oil pressure but as he points out with an air of utter confidence, it's probably running 20 psi higher than the gauge shows.
As the sender and oil gets hotter the gauge tends to,show a lower reading.
I take the cooler engine temp readings as a guide and go from there.
My engines been rebuilt and when hot the gauge often reads 10-15 psi or lower when at idle,
Even cold my engines gauge rarely goes about 44 psi at 2500 revs.
Some gauges read 50 psi and don't move at all,, I don't trust them!!!
Others like mine read horribly low but are more accurate throughout the range but all appear to read lower than the actual pressure the engine produces.
As already pointed out, if the reading was so,low the oil light would flicker on so even though the gauge might be reading 5 psi the engine clearly is running higher pressure than that.
Tvr Power built my engine, I've panicked and hassled Dom into looking at mine a few times now, fearing low oil pressure but as he points out with an air of utter confidence, it's probably running 20 psi higher than the gauge shows.
When my car had the original oil pressure sender, it gave very similar readings - about 5 psi when idling hot, and up to about 30 psi when idling cold or when at 2,500+ rpm. I was concerned, so I phoned Jason at Str8Six who reassured me that this is typical of the inaccurate (poorly matched) sender, and that the real oil pressure was almost certainly fine.
So I don't think you have anything to worry about, especially if your oil light is not illuminating. The oil light is driven via a completely separate pressure switch that has nothing to do with the sender that drives the gauge, so you would only believe a low indication on the gauge if it's also causing the light to flicker - assuming the light comes on correctly when you first turn the ignition on before starting and then extinguishes very shortly after starting. I regard the light as being the true low-pressure warning, and I use the gauge as an indirect way of seeing what the oil temperature is - the indicated pressure naturally comes down as the oil warms up and the viscosity decreases.
Since then, my sender failed and started giving truly stupid readings. I replaced it with a cheap eBay replacement - see this thread for details. Now I get no lower than 30 psi ever, including hot idle, and when cold or above 2,500 rpm I get about 55 psi on the gauge. Between idle and about 2,000 rpm I get readings between 30-50 psi depending on revs. These readings are much more realistic. This sender has been on for a few years now, and it was easy to fit - although it did require a separate earth wire (the original earths through the body of the sender). Easily done though - I just ran a length of wire to the earthing point behind the driver's side wheel and attached it using a ring connector and crimped it on. I asked Str8Six to cast a critical eye over my work when it next went in for servicing.
So I don't think you have anything to worry about, especially if your oil light is not illuminating. The oil light is driven via a completely separate pressure switch that has nothing to do with the sender that drives the gauge, so you would only believe a low indication on the gauge if it's also causing the light to flicker - assuming the light comes on correctly when you first turn the ignition on before starting and then extinguishes very shortly after starting. I regard the light as being the true low-pressure warning, and I use the gauge as an indirect way of seeing what the oil temperature is - the indicated pressure naturally comes down as the oil warms up and the viscosity decreases.
Since then, my sender failed and started giving truly stupid readings. I replaced it with a cheap eBay replacement - see this thread for details. Now I get no lower than 30 psi ever, including hot idle, and when cold or above 2,500 rpm I get about 55 psi on the gauge. Between idle and about 2,000 rpm I get readings between 30-50 psi depending on revs. These readings are much more realistic. This sender has been on for a few years now, and it was easy to fit - although it did require a separate earth wire (the original earths through the body of the sender). Easily done though - I just ran a length of wire to the earthing point behind the driver's side wheel and attached it using a ring connector and crimped it on. I asked Str8Six to cast a critical eye over my work when it next went in for servicing.
Hi All
Many thanks for that, it has put my mind at rest. I suspect the gauge might just be playing up or maybe its always been like that but I hadn't noticed before. Anyway I will use the oil light as a true indicator of low oil pressure in the future. Mine comes on when key inserted but then nothing while engine running so will assume all good.
Many thanks for that, it has put my mind at rest. I suspect the gauge might just be playing up or maybe its always been like that but I hadn't noticed before. Anyway I will use the oil light as a true indicator of low oil pressure in the future. Mine comes on when key inserted but then nothing while engine running so will assume all good.
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