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Before I put my 86 Grad to sleep for the winter, I changed the filter and oil (Shell Rotella T 15/40). When I took her out of hibernation, I felt that I did not need to change the filter and oil, so I simply started to drive her. My oil pressure has always dropped when idling, but now I get a reading of about half way between the 0 mark and the 57 mark when cruising at 2500 RPM. Even on hard acceleration the gauge never goes over the 57 mark. The dipstick shows an adequate amount of oil, but I am concerned that I am experiencing low oil pressure.

BTW, what is the preferred choice in an oil filter for an 86 Grad? At one time, I used a Fram, but I am no fan of Frams (try saying that quickly over and over) and would like to know what would be a better filter.

I also need to flush my coolant and possibly replace the thermostat on my 87 Spider. Any recommendations on a thermostat? Any thoughts on coolants? Has anyone ever tried Water Wetter?

Lotsa questions, but I have not seen and cannot find a thread that addresses these issues.

Thanks for any responses,
Dean
 

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I don't think any of the gauges can read at all, but I understand they do indicate certain values :)

Purolator would be a much better choice than Fram, and is also easily available at the local parts counters.

You might have a failing sender unit or goofy connection on the gauge proper making for those numbers.
Temporarily hook up a mechanical gauge to confirm.

If it does prove to be the case that your pressures are those values, you might want to look more deeply into information regarding the oil pump, specifically the pressure relief valve, paruse info on the crank plugs, and mabe some shell bearing data as any of those are plausible reasons for falling pressures.
 

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The gauges on our cars are more of a general indicator than a device for accurate measurements.

As for the oil pressure readings, the pressure sender (located on the right side rear of the block) is the usual suspect when readings get flukey. Typically, the oil pressure will be highest with a cold engine. During normal driving with a warm engine it should show 50-75 psi and typically much less at idle.

You can test the gauge by turning on the ignition and removing the wire from the sender and touching it to 'ground' (any unpainted metal parts). When thus grounded the needle should move all the way to maximum.

I would suggest a new sender. If it still reads low then consider having the pressure checked with a mechanical guage. It is possible to get low oil pressure if a crankshaft plug falls out.

Realistically, any filter is likely to be OK. Fram has gotten a bad reputation as cheaply made but if you change it at appropriate intervals it should be fine. That said, I tend to use Purolator or Wix or the ones WalMart sells (black filter - I can't recall the name). SuperTech - I think that is the one at Walmart.
 

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In another thread, I indicated that my pressure always showed low (never higher than 55) since I got the car. Then this Spring, it just "nudged" off 0 and never went higher than that. Faulty sender...replaced and now I'm seeing gauge readings I've never seen before :). And my wrench did confirm that the gauge in the car does agree with what his gauges are showing (nice to know).

If the warning light isn't coming on, there's probably no reason to panic, but have it checked.
 

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I have the opposite (but related) problem on my Duetto. My mechanic told me at my "post purchase inspection" in January that I have good oil pressure (based on his mechanical gauge) and that the sender works fine but I needed a new gauge because it was faulty and showed zero. I got a new gauge, hooked it up, and now the needle always shows at 114. Could I have wires crisscrossed or some other goofy mistake?
Thanks.
 

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Thanks, Tifosi. Of course; How silly of me to assume one type of gauge matching to one type of sender. :) Will investigate tmrw and report back my findings. I never would have figured this out without the AlfaBB.
 

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When I change the oil it reads a little higher (10w-40 Mobil One HM & purolator filter) Been that way the last 75k miles.
 

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@ Richard:
You take that pic at 60mph? Naughty monkey :)
Oil looks acceptable, but your voltage is absolutely bleeding edge minimum especially given the RPM. Should be much closer to 13.5~ish normally and a max not to exceed 14.3
Anything sub 12.5 is literally not charging the battery but mearly breaking even as a fully charged serviceable 12V DC battery will test at around 12.5 or so. 12 flat is actually discharging the battery a tiny bit at a time, or if you prefer, not keeping it topped up to its full potential.

I wonder if there's a way to calibrate the sub gauges in the monopod like the speedo....

@ Franny Alfa:
Don't quote me on it, but I think the two types available were Veglia and Jaeger.
Either way it should be as easy as looking at the faces of the old gauge and the replacement to see if they are the same make.
 

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Thanks, Tifosi. I swaped Jaeger gauge for Jaeger gauge. Got car back today. Good news is needle on new gauge actually moves now instead of being pinned at 114 all the time. Bad news is gauge reads 114 when running and 57 at idle. That can't be right, or can it? Any thoughts much appreciated.
 

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@ Richard:
You take that pic at 60mph? Naughty monkey :)
Oil looks acceptable, but your voltage is absolutely bleeding edge minimum especially given the RPM. Should be much closer to 13.5~ish normally and a max not to exceed 14.3
Anything sub 12.5 is literally not charging the battery but mearly breaking even as a fully charged serviceable 12V DC battery will test at around 12.5 or so. 12 flat is actually discharging the battery a tiny bit at a time, or if you prefer, not keeping it topped up to its full potential.
But I was not on my cell phone (wind noise to loud). Since that picture I have added a new ground wire and new wire 4 ga. from alternator to junction box. That added .5v to junction box reading but still the gauge reads always .5v less. The gauge normally reads 12.5 and junction box 13.0 now. I have noticed less drop in voltage now with lights on (also added lighting relays at same time).
 
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