oil pressure
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Danger! Will Robinson, Danger! I think the gauge and the warning light have different senders. Thus I'd be very concerned that you do have very low oil pressure. If it was just the gauge reading low, checking its wire connections and perhaps replacing the sender might be the first thing to do.
Also, in addition to a faulty pressure relief valve, I've read about Alfa crankshafts loosing an oil gallery plug (with obvious loss of oil pressure...)
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Twistlock:
- I'm not convinced that you have low oil pressure. As ghnl said, until you have checked it with a mechanical gauge, you are pretty much guessing. The figures that your Alfa electric gauge is reporting aren't that horrible. Are these with the engine hot? How many miles on the engine? Does changing the oil increase the pressure?
- I strongly doubt the pressure relief valve in your oil pump would be the cause if you do have low pressure - they generally stick closed when they fail, resulting in too much pressure / sheared pump shafts. No way crud on the screen would just cause low pressure - by the time it had an effect, the engine would just self-destruct.
- Again, as ghnl said, missing crankshaft plugs or worn bearings are far more likely causes of low oil pressure
- Replacing the oil pump requires disassembling the entire engine. Yea, I know - your cousin did it by dropping the oil pan and snaking the old one out & new one in. Well, I've never been able to get the pan off with the engine in place, and even if I could, the oil pump needs to be aligned in the front cover to ensure that it isn't binding (a long story that's probably been covered in another thread). Once you have disassembled the bottom end enough to replace the pump, you ought to check the crankshaft journals, and replace the bearings.
- I'd just suggest just driving it, and not worrying. Until you hear some rod knock.
- I'm not convinced that you have low oil pressure. As ghnl said, until you have checked it with a mechanical gauge, you are pretty much guessing. The figures that your Alfa electric gauge is reporting aren't that horrible. Are these with the engine hot? How many miles on the engine? Does changing the oil increase the pressure?
- I strongly doubt the pressure relief valve in your oil pump would be the cause if you do have low pressure - they generally stick closed when they fail, resulting in too much pressure / sheared pump shafts. No way crud on the screen would just cause low pressure - by the time it had an effect, the engine would just self-destruct.
- Again, as ghnl said, missing crankshaft plugs or worn bearings are far more likely causes of low oil pressure
- Replacing the oil pump requires disassembling the entire engine. Yea, I know - your cousin did it by dropping the oil pan and snaking the old one out & new one in. Well, I've never been able to get the pan off with the engine in place, and even if I could, the oil pump needs to be aligned in the front cover to ensure that it isn't binding (a long story that's probably been covered in another thread). Once you have disassembled the bottom end enough to replace the pump, you ought to check the crankshaft journals, and replace the bearings.
- I'd just suggest just driving it, and not worrying. Until you hear some rod knock.
Thank you for that info,,, My alfa has 42000 origional miles,it was givin to me by family...I started to rebuil most of it but the engine was running fine ontill the oil pressure dropped...Im going to check the pressure manually & get back to everyone...
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129 Posts
What??? I changed the oil pump in my Spider a couple of months ago. I only had to remove the sump guard and bottom section of the sump. A few hours total. In fact, it took me the longest to get the banged-up and bent sump guard back in place. No special tools required.
Yepp, I have done like this on my 1750 GTV. No problem and takes an hour or so. No need to overdo it. The gauge and warning light have different senders. The gauge sender is under the fourth barrel, intake side. The light sender at the front , exhaust side.
The electrical oil pressure senders are notorious for failing. Mine went at the first start after an oil change. You can check the gauge by eathing the lead from the sender.
On carburatored versions the sender is a pest to reach, so mine defective one is still in place.
Erik
On carburatored versions the sender is a pest to reach, so mine defective one is still in place.
Erik
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Old rule of thumb (probably not always applicable, but a start) 10 psi/1000rpm.
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Sender for the gauge is no picnic either on a Spica model.
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129 Posts
I've seen a few different senders for the gauge, but I think I used a 15mm open end wrench that I'd cut short (maybe 5" long) the last time. It's a pipe thread, so once you break it loose it spins off by hand.
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Art Vandeley and I had the following dialog yesterday:
me: "Replacing the oil pump requires disassembling the entire engine."
Art: "What??? I changed the oil pump in my Spider a couple of months ago. I only had to remove the sump guard and bottom section of the sump."
In thinking about it, I agree with some of what Art is saying. A few years back, I had tried to remove the ENTIRE oil pan with the engine in place. I got it unbolted OK, but when I tried to slide it forward, it hung up on the oil pump. So, in my mind, the pan couldn't be removed with the engine installed. But, Art points out that the lower part of the pan - the sump - can be removed, giving access to the three bolts holding in the oil pump, which would allow the pump to be removed. OK, I stand corrected.
However, I still maintain that it is chancy to bolt in an oil pump without checking that its shaft isn't binding in the bore in the front cover. And, it's tough to do this with the engine assembled, because the gears between the pump and crankshaft prevent you from rotating just the pump to make sure it turns freely. Just bolting in a new pump is the sort of thing that might work OK 7 times out of 10. But, sometimes you need to fiddle with the relative tightness of the 3 bolts to get things aligned properly.
If you have a loose front cover & oil pump in your garage, try it. Bolt the pump on with an O ring, torquing the 3 bolts tight. Try to turn the pump shaft with a large screwdriver in the distributor drive cogs. Many times it will be very tight. If you unknowingly assemble an engine with this condition, the result will be the oil pump drive shaft shearing after a few hundred miles. They always break at the hole in the shaft where the roll pin goes that secures the drive gear to the shaft.
me: "Replacing the oil pump requires disassembling the entire engine."
Art: "What??? I changed the oil pump in my Spider a couple of months ago. I only had to remove the sump guard and bottom section of the sump."
In thinking about it, I agree with some of what Art is saying. A few years back, I had tried to remove the ENTIRE oil pan with the engine in place. I got it unbolted OK, but when I tried to slide it forward, it hung up on the oil pump. So, in my mind, the pan couldn't be removed with the engine installed. But, Art points out that the lower part of the pan - the sump - can be removed, giving access to the three bolts holding in the oil pump, which would allow the pump to be removed. OK, I stand corrected.
However, I still maintain that it is chancy to bolt in an oil pump without checking that its shaft isn't binding in the bore in the front cover. And, it's tough to do this with the engine assembled, because the gears between the pump and crankshaft prevent you from rotating just the pump to make sure it turns freely. Just bolting in a new pump is the sort of thing that might work OK 7 times out of 10. But, sometimes you need to fiddle with the relative tightness of the 3 bolts to get things aligned properly.
If you have a loose front cover & oil pump in your garage, try it. Bolt the pump on with an O ring, torquing the 3 bolts tight. Try to turn the pump shaft with a large screwdriver in the distributor drive cogs. Many times it will be very tight. If you unknowingly assemble an engine with this condition, the result will be the oil pump drive shaft shearing after a few hundred miles. They always break at the hole in the shaft where the roll pin goes that secures the drive gear to the shaft.
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129 Posts
There's an old Alfa TSB with instructions. Basically you bolt in the pump finger-tight, turn over the engine a few times (I rolled the car, then used the starter), and then bolt the pump down wrench-tight. I agree there may be some risk, but when that procedure is followed, I'm going to say it's got to be a minimal risk.
It can easily be done with the engine in the bay. Undo the engine supports, raise the engine a nd place something under the supports. Then remove the nuts and bolts holding the entire sump, remove it forward. Found this photo on the web:
No need to overdo things. Quote from the web: No need to remove the engine for this kind of operation. Place a hydraulic jack and use a piece of wood under the oil sump so you do not damage the alloy fins. Loosen the engine supports. Raise the entire engine as much as possible. Normally it's enough when the gearbox hits the body, so you may place something between the engine supports and the engine bay. The dots on the photo show how I do it. The green dot shows the oil filter support.
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Then raise the entire car and use supporting jacks for safety. Never ever work under the car if it's not secured by jacks. If you haven't already drained the engine oil, this is the time to do so. Otherwise you will need to wash your hair in kerosene. Undo the bolts and nuts securing the sump to the engine block. Gently draw the sump forward to get access to the crankshaft.
No need to overdo things. Quote from the web: No need to remove the engine for this kind of operation. Place a hydraulic jack and use a piece of wood under the oil sump so you do not damage the alloy fins. Loosen the engine supports. Raise the entire engine as much as possible. Normally it's enough when the gearbox hits the body, so you may place something between the engine supports and the engine bay. The dots on the photo show how I do it. The green dot shows the oil filter support.
Then raise the entire car and use supporting jacks for safety. Never ever work under the car if it's not secured by jacks. If you haven't already drained the engine oil, this is the time to do so. Otherwise you will need to wash your hair in kerosene. Undo the bolts and nuts securing the sump to the engine block. Gently draw the sump forward to get access to the crankshaft.
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