Just like the heading says. Has anyone with a motor that runs fine, but had a UOA that has numbers that made them nervous, actually do motor work based on the numbers?.,,,
Has anyone changed or rebuilt a motor based on their UOA?.,,
- Thread starter BigCahuna
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Not an engine rebuild, but I have replaced components. 5.4 3v Ford timing, 22RE timing when UOA showed high aluminum.
I have rebuilt a rear differential that seemed fine but had a HUGE iron spike. Upon disassembly the lower pinion race was coming apart.
I have rebuilt a rear differential that seemed fine but had a HUGE iron spike. Upon disassembly the lower pinion race was coming apart.
BMW S54 3.2ltr 6 in my M Coupe. At 62,000 miles copper and lead 3x average...rod bearings BAD. $2000 job saved the engine.
Yup, we do a UOA every oil change on the airplane we fly and we did our recent overhaul based on a very conservative interpretation of wear metals trend, compression, oil consumption and the manufacturers recommended TBO.
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I've been alerted by UOA on the (infamous) leaking GM Intake gaskets. 442 ppm Potassium...Gee, I've got Antifreeze in the oil; and there isn't a mechanic in the nation that could have looked at that honey colored dipstick and determined that. If the issue HADN'T been caught and fixed, a hydro locked engine could have been a very real possibility.
FWIW, a BITOG myth that seems alive and well is OCD oil changes due to the color of the oil. I've got samples of oil with 8K miles on it and with 38K miles on it; I challenge anyone to tell the difference visually. In a (normal healthy) engine, the color of the oil tells NOTHING other than the color of the oil.
FWIW, a BITOG myth that seems alive and well is OCD oil changes due to the color of the oil. I've got samples of oil with 8K miles on it and with 38K miles on it; I challenge anyone to tell the difference visually. In a (normal healthy) engine, the color of the oil tells NOTHING other than the color of the oil.
I remember reading one guy here who saw increasing wear metals in a UOA for an older car, and then quickly decided to sell it.
Originally Posted by Gasbuggy
I think the better question is how many have traded in or sold based on UOA?
Originally Posted by Gasbuggy
I think the better question is how many have traded in or sold based on UOA?
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For those of you who have caught major problems before they became prohibitively expensive, through a UOA--I am just wondering (because I'm not a mechanic) about the thought processes here.
OK, you see high iron, and you say, OK I'm going to disassemble my engine until I see lots of wear scars? High copper and lead combined, would lead you to dig right through to the bearings? I don't trust myself to dig into the innards of an engine (I chose not to do spark plugs on the Sienna; book time for that job was 3 hours)--but could I take the car to the mechanic and say, look for a source of lead, or copper, or iron that is wearing abnormally?
If this is something that I could pay a mechanic to do, this would probably be enough to get me to start doing UOAs on both of these cars. The extended OCI would pay for most if not all of the UOA, and the lead time for a potential major problem could definitely come in handy.
OK, you see high iron, and you say, OK I'm going to disassemble my engine until I see lots of wear scars? High copper and lead combined, would lead you to dig right through to the bearings? I don't trust myself to dig into the innards of an engine (I chose not to do spark plugs on the Sienna; book time for that job was 3 hours)--but could I take the car to the mechanic and say, look for a source of lead, or copper, or iron that is wearing abnormally?
If this is something that I could pay a mechanic to do, this would probably be enough to get me to start doing UOAs on both of these cars. The extended OCI would pay for most if not all of the UOA, and the lead time for a potential major problem could definitely come in handy.
Originally Posted by paulri
OK I'm going to disassemble my engine until I see lots of wear scars? High copper and lead combined, would lead you to dig right through to the bearings? I don't trust myself to dig into the innards of an engine
There's a story floating around here where a guy got a high Lead spike
...and pulled the relatively new engine out of his Corvette,
just to find out the bearings all looked just fine
OK I'm going to disassemble my engine until I see lots of wear scars? High copper and lead combined, would lead you to dig right through to the bearings? I don't trust myself to dig into the innards of an engine
There's a story floating around here where a guy got a high Lead spike
...and pulled the relatively new engine out of his Corvette,
just to find out the bearings all looked just fine
I haven't done any repairs based on UOA results, but I have made a maintenance-related decision. On my old '96 M3, I saw rising potassium numbers over time; that, plus some mysterious coolant-related symptoms, were solid evidence that the head gasket was just starting to fail. At that point, I stopped using super expensive boutique synthetics and switched to Mobil 1 0W-40 (back when it had BMW LL-01 approval). Then I started planning my next move, which ended up being to sell the car and move on. Turns out the head gasket was definitely failing. As soon as I noticed it starting to overheat, I parked it and put it up for sale as it was.
In my current car, rod bearings are a known potential wear item, so I'll be watching for aluminum and tin in a roughly 9:1 ratio (based on correspondence with the bearings' manufacturer). If that happens before the next time I drop the oil pan, I'll plan for another bearing change or get out of the car.
In my current car, rod bearings are a known potential wear item, so I'll be watching for aluminum and tin in a roughly 9:1 ratio (based on correspondence with the bearings' manufacturer). If that happens before the next time I drop the oil pan, I'll plan for another bearing change or get out of the car.
Originally Posted by paulri
For those of you who have caught major problems before they became prohibitively expensive, through a UOA--I am just wondering (because I'm not a mechanic) about the thought processes here.
OK, you see high iron, and you say, OK I'm going to disassemble my engine until I see lots of wear scars? High copper and lead combined, would lead you to dig right through to the bearings? I don't trust myself to dig into the innards of an engine (I chose not to do spark plugs on the Sienna; book time for that job was 3 hours)--but could I take the car to the mechanic and say, look for a source of lead, or copper, or iron that is wearing abnormally?
If this is something that I could pay a mechanic to do, this would probably be enough to get me to start doing UOAs on both of these cars. The extended OCI would pay for most if not all of the UOA, and the lead time for a potential major problem could definitely come in handy.
This is exactly the right kind of question to be asking: What are you actually going to do with the info from a UOA?
UOAs make sense for tracking wear when there's a likely failure mode that:
1. Shows up in a clear and predictable way on the UOA, and
2. Is worth trying to catch before it produces other symptoms.
In practice, that's almost never the case for passenger vehicles.
For most of the engines on the road, the most likely wear-related failures will be compression loss, head gasket failure, etc. -- all of which can and should be diagnosed by other methods before being addressed. They can show up on a UOA, but would have to be verified by those other methods anyway, and in most cases aren't even worth addressing until they cause noticeable functional problems.
If your engine is prone to something like excess bearing wear leading to seizure or something with no other symptoms, that's another story. But very few engines will ever have that kind of problem, and of those, only some will produce wear metals that might show up on a UOA.
This is why I stopped doing it on my E36 M3, why I didn't bother on my RX-8, why I'm starting back up again on my current car, and why I'd advise almost everyone not to bother with UOAs for tracking wear.
What UOAs are really useful for in most cases is finding other issues (e.g. dirt contamination, fuel dilution) and seeing if your OCIs are too long. But that's another story.
For those of you who have caught major problems before they became prohibitively expensive, through a UOA--I am just wondering (because I'm not a mechanic) about the thought processes here.
OK, you see high iron, and you say, OK I'm going to disassemble my engine until I see lots of wear scars? High copper and lead combined, would lead you to dig right through to the bearings? I don't trust myself to dig into the innards of an engine (I chose not to do spark plugs on the Sienna; book time for that job was 3 hours)--but could I take the car to the mechanic and say, look for a source of lead, or copper, or iron that is wearing abnormally?
If this is something that I could pay a mechanic to do, this would probably be enough to get me to start doing UOAs on both of these cars. The extended OCI would pay for most if not all of the UOA, and the lead time for a potential major problem could definitely come in handy.
This is exactly the right kind of question to be asking: What are you actually going to do with the info from a UOA?
UOAs make sense for tracking wear when there's a likely failure mode that:
1. Shows up in a clear and predictable way on the UOA, and
2. Is worth trying to catch before it produces other symptoms.
In practice, that's almost never the case for passenger vehicles.
For most of the engines on the road, the most likely wear-related failures will be compression loss, head gasket failure, etc. -- all of which can and should be diagnosed by other methods before being addressed. They can show up on a UOA, but would have to be verified by those other methods anyway, and in most cases aren't even worth addressing until they cause noticeable functional problems.
If your engine is prone to something like excess bearing wear leading to seizure or something with no other symptoms, that's another story. But very few engines will ever have that kind of problem, and of those, only some will produce wear metals that might show up on a UOA.
This is why I stopped doing it on my E36 M3, why I didn't bother on my RX-8, why I'm starting back up again on my current car, and why I'd advise almost everyone not to bother with UOAs for tracking wear.
What UOAs are really useful for in most cases is finding other issues (e.g. dirt contamination, fuel dilution) and seeing if your OCIs are too long. But that's another story.
I've done a couple head gaskets based on UOA's showing coolant seeping into the oil. And like Ihatetochangeoil said, you would have no idea on the dipstick that there was an issue.
I bought my car 8 years ago. The previous owner had been letting it overheat for at least the last few days (beyond that, who knows). That problem was quickly resolved after purchase, but I was noticing possible indications of a "slight" (if there is such a thing) head gasket issue. But the situation has been stable for all this time, so I'm not sure what's really going on.
I never did a UOA, but if I had, and it showed coolant contamination, it would only have made sense to react to that. Depending on severity, either shorten the OCIs and plan for some top end surgery, or stop driving it altogether until said surgery.
The engine is 33 years old and I've pretty much decided I want to overhaul it anyway for other reasons, so the info would only be "interesting" at this point and probably wouldn't change my plans for the car.
I never did a UOA, but if I had, and it showed coolant contamination, it would only have made sense to react to that. Depending on severity, either shorten the OCIs and plan for some top end surgery, or stop driving it altogether until said surgery.
The engine is 33 years old and I've pretty much decided I want to overhaul it anyway for other reasons, so the info would only be "interesting" at this point and probably wouldn't change my plans for the car.
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