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Hi guys

I am in the final stages of a '65 Veloce restoration and have just fired up the rebuilt 1600 Veloce engine for the first time. The oil pressure starts at around 60 psi but rapidly drops off to around 10 or worse. I'm talking within the first minute before the oil has a chance to warm up. Raising the rev's helps a bit but then it tails off again even when running around 2500 rpm. If I turn it off and wait a minute then I get the same thing, 60 psi initially tailing off rapidly. My first thought was that the pump is running out of oil in the Veloce pan but the oil level is topped up to the max mark and the car is level. The symptoms look like the pressure overflow valve is opening and it has also been suggested that a crank plug is missing. I don't have any knowledge of either of these things to know whether they are the likely cause or not.

The rebuild, using many rare NOS parts, was completed two years ago by a renowned Italian Alfa engineer with many years of experience. Regrettably I can't contact him now.

Anyone know what could be happening?

Phil
 

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The fact that you initially get pressure then lose it suggests to me that there is a problem with the pressure relief valve in the oil pump and it is sticking open.
 

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Perhaps we need more info.....you don't say what it does when you rev the engine above idle and back to idle... a low indication at idle even less than 10 is acceptable. If you rev it to like 3500-4000 after a warm up ( I realize is a new engine and we need not go too far) what is the reading you have in that range and does it return to below 10 at idle but yet indicated?
I personally think all is well if the reading at 3500--4000 is somewhere around the middle of the gauge and then just falls off as I recount and it is repeatable in the same cycles. The startup bounce to 60 might be a sticky valve but intuitively it isn't catastrophic and it might just go away after everything warms and you have any kind of oil pressure. Just me noodling.. no expertise or experience .. How long the pump has sat could be a contributor , I suppose.
 

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Perhaps we need more info.....you don't say what it does when you rev the engine above idle and back to idle... a low indication at idle even less than 10 is acceptable. If you rev it to like 3500-4000 after a warm up ( I realize is a new engine and we need not go too far) what is the reading you have in that range and does it return to below 10 at idle but yet indicated?
I personally think all is well if the reading at 3500--4000 is somewhere around the middle of the gauge and then just falls off as I recount and it is repeatable in the same cycles. The startup bounce to 60 might be a sticky valve but intuitively it isn't catastrophic and it might just go away after everything warms and you have any kind of oil pressure. Just me noodling.. no expertise or experience .. How long the pump has sat could be a contributor , I suppose.
Attached you have the original Alfa Romeo manual for the oil pressure. I am sorry I have only in Italian, but to sum up it says what follows:

"The oil prssure is adjusted from a valve that is inside the oil pump body. Go to a mechanicas if the oil pressure is outside the values indicate in the picture .....If you want to increase the oil pressure insert a spacer between the spring and the cover into the oil pump body. If it doesn't work, check oil pressure gauge with a calibrated pressure gauges for reference and, if the defect is still present, check the status of the oil pump gear, main shaft bearing and connecting rod bearing".

I hope this will helps you.

Massimo
 

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Perhaps you should try fitting a mechanical pressure gauge and see if it behaves the same way before you decide that the oil pump is the problem.
 

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Perhaps you should try fitting a mechanical pressure gauge and see if it behaves the same way before you decide that the oil pump is the problem.
A 65 veloce would have a mechanic pressure gauge, no?, but yes checking with another might be wise

Pete
 
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Keep running it with no oil pressure and you can rebuild it again and find out what is really wrong.
Is this thread just guesses with no diagnostics? First attach an accurate mechanical gauge on the block at the oil line to gauge block hole. Pressure there? Maybe a bad line to gauge or gauge. No pressure? Remove the sump. You can now access bearings and oil pump. Check bearing clearances, main and rod, with plastigauge. If they are incorrect, you need a engine out bottom end rebuild. If the #4 main cap and #4 rod are correct, these being near the "end of the line" others are likely similar. Bearings good? Pull the pump. If you are experienced with oil pump building, have at it. If not, find a reputable oil pump builder and have your pump checked for correct clearances and correct function of the relief valve circuit. While looking at the crank, be sure ALL gallery plugs are in place. If not, that may be your issue. If you feel overwhelmed by required diagnostics, have a reputable Alfa engine builder near you or elsewhere correctly diagnose the issue. Don't know a good diagnostician near you? Ask on the BB for the best Alfa shop near you.
 

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Absolutely correct Gordon. Start from known facts....get a master mechanical gauge on the engine (one that is properly calibrated for workshop use) and see what is happening, when and at what revs. Then you will be able to determine the next step.
 

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Discussion Starter #9
Guy's, thanks for the suggestions.

Taking advice I hooked up a good quality oil pressure gauge this afternoon and fired up my new Veloce engine again.
Same thing happened, in fact worse, shot up to 80 psi and tailed off rapidly. But this time because I could trust the gauge I could see there was still 15 psi so I could keep her running. This time as I watched, the pressure started to rise. Each time I re-started the engine the pressure variance narrowed, so after about 20 minutes running at between 800 and 4000 rpm I have a minimum 20psi and a max 50, which I am happy with.

Still don't know why this happened, I turned it over with the plugs out and plenty of oil everywhere before firing it up for the first time but I guess a new engine and indeed a new oil pump needs to 'bed in' before the oil pressure stabilises.

Tomorrow I will run it some more and then put the car's gauge back in the circuit to compare results and calibrate the Veglia.

Thanks again for the guidance, I think I can go back to fitting all that chrome!

Cheers all

Phil
 

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New oil pump - read this thread:
 
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