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Discussion Starter · #1 ·
I'm posting this in the optimistic hope that bottom end of my 2.5 doesn't need a complete rebuild.

Car starts and runs fine, but once the engine is up to temperature, the oil pressure drops to 0 at idle. It will come back up about 15% under acceleration, but that's it. On a long drive a few weeks ago the engine started making some really awful noises which I assume to be rod knock. Shot bearings, right?

This is my second summer with this car. It has only 55k miles. Prior to that it was stored for 17 years so I suppose the bearings could have been damaged when it was put back on the road. But there were no issues last summer. This year it went in for some major service and I assume they changed the oil... anyway it hasn't been the same since that service.

Could I get by with a different type of oil? Is there some sort of "Alfa trick" that can help out in this situation? Anything else to check?

Thank you!
 

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Not sure about the noises but since all the issues began after an oil change I'd hurry and change it again. Perhaps they put in an oil that is too 'thin'? I used to use Castrol GTX20W-50 until they changed the formula. Now I use Rotella 15W-40 or Rotella synthetic 5W-40. It is not uncommon for Alfa gauges to read nearly zero with hot oil at idle. (And the gauge sender is not known for long life & absolute accuracy.) Hooking up a mechanical gauge temporarily will give you a better reading of actual oil pressure.

Another thing to check is for coolant contaminating the oil. Coolant makes a lousy lubricant and can ruin bearings quickly. Coolant contaminated oil tends to have a 'milkshake' look if you check on the dipstick and the underside of the oil fill cap.
 

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I'm posting this in the optimistic hope that bottom end of my 2.5 doesn't need a complete rebuild.

Car starts and runs fine, but once the engine is up to temperature, the oil pressure drops to 0 at idle. It will come back up about 15% under acceleration, but that's it. On a long drive a few weeks ago the engine started making some really awful noises which I assume to be rod knock. Shot bearings, right?

This is my second summer with this car. It has only 55k miles. Prior to that it was stored for 17 years so I suppose the bearings could have been damaged when it was put back on the road. But there were no issues last summer. This year it went in for some major service and I assume they changed the oil... anyway it hasn't been the same since that service.

Could I get by with a different type of oil? Is there some sort of "Alfa trick" that can help out in this situation? Anything else to check?

Thank you!

I could be way off, but the way you've described this is that you obtained a car that sat for many years and didn't change the oil...

Oil doesn't "wear out" but it starts to hold a lot of dirt and contaminants that reduce its lubrication properties. 17 years of moisture and dirt and whatever else (or sludge that broke free) could very easily have damaged a bearing.

If it went in for a major service, it isn't unreasonable to expect that the oil change would have been noted (and what type). As mentioned above, the "too thin" of an oil might cause problems (and contributed to break free any sludge that may have been present and thus blocking a journal).

I'd check your oil first, make sure it's up to level. Then check the drain plug magnet. Look carefully at the drained oil and drain plug. If it is talking to you, listen carefully.
 

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Well if it is making bad noises and the oil pressure is zero...it is probably not good. Do a few checks but you have probably damaged a bearing.

I have a good 2.5 long block ....Cheap..if you want it. I see you are in
CT...a long days drive from Chicago

Sorry to hear..it just happened to me last week on a 164 3 liter that had not been driven in 6 or 7 years...Rear main bearing failed and took out the rear most rod bearing.....now I am rebuilding the engine....

All the best.

David Alexander
Riverside, IL

4 Alfas...
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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You've been driving the car with the oil pressure reading basically zero? Really?

Prudence would have had you FIRST check to make sure the oil is in the engine first of all. Saw a Milano where the guy ended up with double filter gaskets after he changed the filter, and they blew out, leaving oil on the road, not in the engine. Wondered why the gauge read basically zero. Make sure the filter is not leaking at the gasket. Change the oil and filter again.

Lighter weight oil such as 10W-40 will still give you reasonable oil pressure. Not as high as 20W-50, but reasonable, esp at that low mileage. The engine is barely broken in. Your receipts from the service should tell you what oil was used, and whether or not they changed the filter. Do a search on this site for new oil recommendations.

THEN you would hook up an external pressure gauge to confirm what the pressure really is. You DO have to check. Oil is the engine's life blood. IF it reads good pressure, then you have some other problem for the noise. Tensioner bearing, water pump, power steering pump, a/c pump?

THEN you would check to see that the pressure gauge sender is not kaput. They do that you know. They have a short lifetime. Same problem with the 164. Pressure at cold start up reads almost good, but as soon as the oil warms, the gauge drops to pretty much zero. Bad sender. Let's hope that is the problem and you have some other minor thing causing noise.

IF the external gauge reads basically zero, then you do have a big problem and you probably wiped all the bearings by driving the car.

good luck,
 

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You can buy a cheapo oil pressure tester at Harbor Freight and pull the oil pressure sensor at the back of the block and attach the tester. That can tell you if it is the sensor or gauge.

If it turns out you need a bottom end (or even the whole engine) let me know. I just pulled a nicely running 2.5 out of my GTV6 about 6 weeks ago and dropped in a 3.0, and I'm pretty close to you relatively speaking.

Kevin
 

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Well, so far I'm reading through your post and there is a lot of assumptions and some causal effect, but rather short on facts.

What major service did the vehicle receive? What happened on that long drive, were you able to drive it back home, (along with the noise), did it suffer from any performance issues? Does it start and run now (with or without noise)?

My Alfa displays 100psi at startup and goes to 20-25psi after warm (Castrol GTX 20W-50). However, the first time I took her on the highway cruisin' at 70mph & peripheral vision caught the pressure had dropped to zero and I nearly crapped my panties! I let off the gas and it jumped back up. Hmmm, happy foot back drown (80mph) and it dropped again. ***? Anyway, I settled down as I knew: if the oil pressure had actually gone to zero, I'd know all about it in short order! Still, was not real appreciative of Lil Hemi putting me through that. Got home and oil pressure switch spade connector was barely hanging on...

BTW - Noone in their right mind would bring an engine out of a 17-year rumplestiltskin without flushing gas tank, coolant, oil, & transaxle fluid. Even so, it's unlikely you would suffer from a bottom-end issue unless you actually did lose all your oil. Unless...
 

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Gee I wonder did you pull the dip stick and check oil level?
 

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Discussion Starter · #10 ·
hey guys - thanks for the input. Swapping out the oil today (been out of country). Yes - there is oil in the car - duh! Will keep you posted. Thanks again for the comments.
 

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Discussion Starter · #11 ·
@kredden - I might have bumped into you this summer at the Overhead Cam Bake - Stafford Springs. I was there with "French Toast" - Peugeot 405 Mi16. We won "most heroic fix."
 

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Discussion Starter · #16 ·
@bs - you'll have to enjoy some french delicacies next summer for sure.

Anyway I filled 'er up with Agip 20/50 and took a quick drive when she warmed up. The noise was not a loud as I remembered (but that last time was after almost an hour of driving and it was almost 100 degress that day). So too soon to say the oil change "fixed" it. Also difficult to isolate all the various "alfa" sounds from under the hood. As part of this recent service I had the mechanical tensioner installed so I believe that could also be a new noise maker.

Here are some pics of the guages at idle (engine fully warmed) and with some throttle. Everything look normal?





And here is the car:





Thanks!
 

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@bs - you'll have to enjoy some french delicacies next summer for sure.

Anyway I filled 'er up with Agip 20/50 and took a quick drive when she warmed up. The noise was not a loud as I remembered (but that last time was after almost an hour of driving and it was almost 100 degress that day). So too soon to say the oil change "fixed" it. Also difficult to isolate all the various "alfa" sounds from under the hood. As part of this recent service I had the mechanical tensioner installed so I believe that could also be a new noise maker.

Here are some pics of the guages at idle (engine fully warmed) and with some throttle. Everything look normal?
If the tensioner was replaced, there is always the chance that the belt slipped a tooth. You should probably check the cam timing marks to be safe.

bs
 

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And Alfa oil pressure senders are not known for their longevity & accuracy. Does the Milano have a low oil pressure warning light? If so and that never came on (assuming the bulb works...) chances are the oil pressure is fine but the sender is bad. One 'fix' is to drill a small hole in the top of the sender to relieve any build up of internal pressure. The theory is a small internal leak allows oil to get into the case which, being incompressable, prevents the internal bits from moving as they should to measure the oil pressure. From reports of those who tried that trick the success is 50/50 or better.

Some oily reading material:
Bad oil pressure
Oil pressure

An easy test for the gauge is to remove the wire from the sender, connect it to a ground (any bare metal on the engine for example) and switch on the ignition. Thus grounded the needle should go to max.


Hmm, no pictures of the "French Toast"?!?
 
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