Inspecting bearings without removing engine

[Learjet]

The car was imported from Italy about 8 years ago where the engine had been overhauled just before delivery and the odometer zeroed. It now shows 18,000 kms. Below 4,500 rpm and lowish loads there was no knocking but only became apparent at the last Goodwood track day in August when people could hear a knock as I accelerated out of the chicane.
I am going to put a good shells in and do a plasti gauge check and compare results with the other big ends. Running my finger nail across the journal I cannot feel any ridges. What other checks can I do?
#1 gets its oil from # 1 main. If the passage way is blocked what is a good way of cleaning it out. (Don't forget engine is in situ)
Thanks for your help and tips.

[Huib]

The picture is not sharp nor in the right contrast range. Too much white background. I feel more than I see that it overheated. In that case you have to check if the conrod is straight and the oil channel in the crankshaft needs checking. If the car ran 18.000 km I doubt the shell was mounted the wrong way around.

From under the car you can see if the plugs in the crankshaft are original or taken out and remounted / replaced. If not replaced it is 99 percent certain that the oil channel is blocked. If replaced it is 89% sure. Don't overlook the fact that the cosmos made me add the mentioning of taking a step backward. Your reference to Goodwood suggests a preference for going fast forward. Adding crawling backward to the exercises may be helpful to enjoy solving the problem. I would even add walking backward with the sitting bones in long sit.

[Learjet]

I agree the shells show signs of overheating so it must be an oil supply problem.
Do not know if the hex crankshaft plugs have been previously removed but they look in very new condition, so either not been touched or they are new.
If I can get the plugs out what is the best procedure for cleaning out the crankshaft, remember I am on my back on the garage floor!
Thanks

[Learjet]

All the main bearing shells are in perfect condition and as # 1 big end gets its oil from #1 main I assume any oil blockage must be between the two of them, or is that too simplistic

[racing]

No Oil seems to be clear on my opinion.

And if it was my engine i would remove the motor
and disassemble it. Clean completely
and measure the crankshaft
Remove plugs and all channels
clean. Also from the crankcase
No other opions from my Point of view
to avoid a later desaster that will cost a lot of money.

all the best

Andreas

[Huib]

I agree with Andreas. The cavities in the cranks function as centrifugal filters. The cavities are relatively large. It would be very illogical if the one cavity is full and the others empty.

[Learjet]

Thanks for your sound advise, and will heed it. However, I do not like unsolved mysteries and always like to know how it happened. The full story is:
1/ Goodwood track day 2021. At the end of the day when the oil really hot spectators noticed a knocking noise when under load. I had been altering the timing to trouble shoot poor engine performance and thought I had over advanced. I retarded and drove home 80 miles with no noise.
2/ 2022: Drove about 2,000 miles. No noise
3/ 2023: 3,500 miles including a 2,500 mile trip to Italy over the Alps. No noise
4/ Goodwood 2023. A repeat of 1/ above.
5/ The engine runs really well with good oil pressure and uses very little oil
6/ I have owned the car for 3 years and have always thought it sounded a bit "endy" on start up for 1-2 seconds but read some where that Fulvia engines can sound like this????
Assuming the damage has been caused by lack of lubrication and the damage was there in 2021, is it possible that it could drive 4,500 miles without self destructing????
I have attached a new picture of the shells that show the damage better. The tangs are missing. How could they break off and where did they go???
I know a bit about engines but am no expert but I would really like to understand what went wrong before spending loads of money.
Thanks again
download/file.php?mode=view&id=58958

[Learjet]

PS. The broken shell is from bottom cap. The top shell was firmly in the cap. I have inserted shells from #4 just to test fit and they fit well in the caps so they have not been heat distorted.
I have attached a picture of the underside of the shells. There is some scoring so is this a definite sign the shell has been spinning? I am not knowledgeable enough to cohttps://forum.viva-lancia.com/download/file.php?mode=view&id=58959mment. When I removed the cap both halves of the shells were in the correct position.

[racing]

There are a lot of possible reasons.
But the main point will be the Oil sludge in the inlet bores of the crankshaft. I have Open a well running engine with
good oilpresure. The bores were complet closed. The Crankshaft bearing of the first Bearing point was also complete gone but not broken.
The pleuel bearings not good but with normal wear.

What i have also found was different size of the shell
on one bearing point. No joke. So check also the numbers of the shalls and the diameter of this bearing point.
And I can‘t believe that the crankshaft didn‘t have any damages or significant wear.

The broken parts may be gone by oilchange or inside the Engine
Channels

[Learjet]

Thanks for that
Only the #1 big end was bad (photos) the other 6 all good and all plasti gauge to 2.25 thou including #1 with good shells in.
#1 big end journal good with very slight scoring along 1mm edge of journal suggesting shells may have slipped sideways at some stage.
I am not 100% sure because as I dropped the cap I was so surprised to what I saw ( the small bit dropped out and was resting on the bigger bit as i lowered the cap) but reconstructing the event I am sure this big end cap was installed 180 degrees out. ie the shells were in the caps correctly but installed tang to tang not tang to flat end. Could this cause the damage in the photos? The engine has done about 18,000 kms since overhaul.