Odd oil pressure problem in '89 Spider - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 9 (permalink) Old 07-30-2019, 08:51 AM Thread Starter
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Odd oil pressure problem in '89 Spider

My "89 Spider (87k miles) is in pretty good shape, uses maybe a quart of oil every 1000 miles, starts and runs well. Up until about two months ago, when started, the oil pressure would register 57 psi almost immediately and would drop hardly at all when idling. Likewise, the temperature always warmed to a rock steady 175, no matter what.

Then about two months ago, I made a mistake I've never made before in my life: I didn't replace the oil-filler cap after adding a quart of oil.

I drove the car for about 20 miles before the dropping oil-pressure caught my attention. Opening the hood, I saw that the cam chain had slung oil out the filler hole and all over the place under the hood. I'd lost about 1.5 quarts of oil. Obviously very uncool, but for a car with a seven-quart capacity, not fatal.

So I filled it up with oil, replaced the cap (which was still resting between the cam covers), and figured no harm had been done.

But now, when I start the car, the oil pressure remains close to 0 until I rev it a few times (i never had to rev it before). Once warmed up and going down the highway, the pressure will get up to about 50. But if I stop at an intersection, the pressure will drop to zero.

The engine isn't using any oil and when I look at the dipstick, the oil looks very clean. Everything seems properly in place.

Also, perhaps coincidentally, the temperature now runs a bit hotter (180-185), but not dramatically so. Still, it is a change from the absolutely rock-steady 175 I had before.

Any ideas? Could some oil passageway in the engine be blocked? Could my gauges be lying to me (even though the tach and speedo seem to be fine)?

Thanks!
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post #2 of 9 (permalink) Old 07-30-2019, 10:13 AM
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You should be fine. There were 5.5 quarts of oil left.

the gauges and senders aren't the best.

VERIFY actual oil pressure using a mechanical test gauge to be sure.

It's Giuseppe's giubos, not Guido's guibos, on my 78 Spider and Sport Sedan
REFRESH CONNECTIONS BEFORE REPLACING COMPONENTS
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post #3 of 9 (permalink) Old 07-30-2019, 11:15 AM
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The oil pressure sender is notoriously unreliable. Verify the oil pressure with a mechanical gauge -or- replace the sender (which is what you'd do after verifying the oil pressure with the mechanical gauge...).

Check that the radiator is actually full of coolant. The system is supposed to push excess coolant out to the reservoir when the engine warms up then suck it back in when it cools. But if the cap or the hose from the radiator to the reservoir is faulty coolant will often go to the reservoir but not get sucked back as it cools down. After a few such cycles the reservoir will be full but the radiator will be low.

- - Eric
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post #4 of 9 (permalink) Old 07-30-2019, 11:39 AM Thread Starter
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Thanks guys!

I'll check the sender and the coolant/radiator cap and see what happens.
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post #5 of 9 (permalink) Old 08-01-2019, 07:26 AM
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For whatever reason, my experience is 2000s, especially Bosch cars, can show lower pressure than earlier engines but run fine forever (thanks to nitrided crank). They are reputed to drop their crank oil gallery plugs due to the hardness of the crank material, but I have never found one like that when opened up. So not sure. Yes, verify actual pressure with mechanical gauge.

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post #6 of 9 (permalink) Old 08-01-2019, 07:38 AM Thread Starter
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Thanks! I'm still looking for a wrench that will remove the sending unit. Once I can check the real pressure, I'll feel better.

As far as the cooling went, Eric was right. The overflow tank was full but the radiator was not. The radiator wasn't down too much (around a quart), but after filling it back up to the top, the temp gauge returned to its normal behavior.
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post #7 of 9 (permalink) Old 08-01-2019, 08:33 AM
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Quote:
Originally Posted by Veloce89 View Post
Thanks! I'm still looking for a wrench that will remove the sending unit.
I use a bicycle wrench. They are stamped out of 1/8" steel. The senders I've seen are usually 14mm but sometimes 17mm. If needed the bike wrench can be cut or bent to fit the available space. Once you get it loosened about 1/2 turn it'll come out the rest of the way by hand.

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As far as the cooling went, Eric was right.
Even the blind squirrel finds the occasional nut...

- - Eric
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~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
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post #8 of 9 (permalink) Old 08-01-2019, 08:34 AM
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I ground down a 14mm to be thin enough, and it has a short handle. Some are 17mm, but mostly older ones.
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post #9 of 9 (permalink) Old 08-01-2019, 12:35 PM
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@Andrew and @ghnl are both right on. In lieu of finding a shop to test your oil pressure with a mechanical gauge, you could just buy a new sender and install it and see if that fixes the problem. Remember to make sure that the copper or silver sealing washer comes off with the old sender, and that you install a new one with the new sender.

ALFA ANDY
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