In nearly all the Fiats that I have had, the pressure sending unit located in the oil filter housing eventually goes bad and falsely indicates lower and lower oil pressure. If you replace this sensor, I bet you'll see that your oil pressure is really much higher.
I've never had a problem with the gauge itself going bad over time. I have seen a few cars where the oil pressure warning light flickered when the oil was really hot and the idle was low (say, less than 600 rpm). As the oil pressure (by the gauge) seemed fine (greater than 40 psi) when the engine was revved up, I just lived with it.
maluminse wrote:Rebuild of the car piece by piece. ha
Welcome to the club! Once you get over these little bumps, you'll be ready to actually plan to do something(!) instead of responding to problems! Hang in there!
Jeff Aurand
Portland, OR
'72 124 Sport Coupe
'86 Bertone X "Anna"
'70 Volvo 145 "Edna", since 1989
'87 Maserati Biturbo Spyder 2800i
Hi, Coincidentally I had same problem on Monday. I've had my BS1 1608cc 1972 for nearly a year and for the first time oil pressure gauge went from about 40 psi down to fluctuating wildly around half that or less after an hours run. Cold day, water never showing above 90, oil warning light works at start but never came on after.
I slowed right down and will try it again this weekend. Found post from Brad Artigue and others commenting that the gauge sender shouldn't be trusted to last forever and not to worry as accuracy not reliable. Am considering buying a pressure test kit (gauge, flex hose, adapters) but see that both sender and pressure warning light switch holes are deep down to right of the filter so a bugger to get too (excuse English slang).
The way I understand it, the diaphragm in the sensor develops a small leak and at start-up there is still a differential across the membrane (so the gauge reads pressure) and as the pressure equalizes thru the hole the indicated pressure on the gauge goes away.
Jeff Aurand
Portland, OR
'72 124 Sport Coupe
'86 Bertone X "Anna"
'70 Volvo 145 "Edna", since 1989
'87 Maserati Biturbo Spyder 2800i
I am another fiat owner with the same observation. I have an 84 and was worried that I had bad low pressure. Starts at ~30 but once engine is warmed up it drops to very low. If on highway its ok at 30 but once I hit a stop sight it appears to be very near zero. I have replace the sender and also the gauge with no effect, still same low pressure pattern. I picked up a mechanical gauge to add in parallel but haven't been able to locate a metric to SAE fitting for the tubing. Somebody told me this is common on our cars. I use non synthetic oil.
Victor
1971 MGB Roadster (sold)
1977 fiat 124 (sold)
2010 Prius
2001 Sequoia
2006 20' REgal bowrider boat.
1984 Pinanfarina
What everyone said above is spot on. I know you can buy new gauge senders, but I don't know if a "correct" replacement is any better than an original. They all register something & tend to read an actual number when you have 3k+ RPM, but if you want accurate information, try a different type of gauge. I think this is why some of us call them "vaguelia" gauges. The warning light, on the other hand, always seems to be accurate & if you're getting a flicker at idle that goes away when you blip the throttle, it's likely your engine is in the process of digesting some bearings & it's worth pulling the pan & checking.
Though I do not have this on all of my Fiats, I do have a mechanical gauge on my '73 124 Spider & I have a non-veglia electric gauge on my '79 X1/9. You sort of can't beat the mechanical gauges for accuracy, but routing a 3mm (?) oil line into the cabin is a freaky concept for some people, plus if you're hung up on the gauges looking factory, you'd have to either get over it or learn how to fabricate custom faceplates for your gauges (which is what I friend of mine or two have done).
Chris Granju
Knoxville, TN
'71 FIAT 124BS (pretty), '72 FIAT 124BC,'76 FIAT 128 Wagon(ratbeast), '85 Bertone X 1/9, '70 124BC (project), 79 X1/9 (hot rod in rehab), '73 124BS (2L, mean), '74 124 Special TC, '73 124CS, '73 124 Familiare
This is spot on advice. As a precaution I would get under the can and just look at the oil pan if you have not already. Many owners put a pan guard in as the oil pan is subject to damage that then reduces the oil sucked up in the pump/sending unit at the bottom of the pan. does not sound like your issue. However, It's always good to look at the pan, better to be safe than sorry.
My 68 oil pressure is the same as mentioned above. When I got the car I was worried about the readings. My Fiat mechanic told me to ignore the gauge pressure reading but never ignore the light. He also told me that the best gauge is me and to check the oil regularly. "Cause if there's no smoke and there's no puddles, then there's no oil"
