98V70 na volvo - appears to have died

[98v70dad]

If you had a fracture defect it could absolutely crack straight but not machine tool straight. Can you put a flat on it and see if its machine flat

I still think your reasoning from the other thread are cogent, though. Big stuff on the downstream side of the filter has to come from the oil pump.

ITs a pretty easy tear down to get that out, just put the pump in, fire it up , and see if oil pressure comes up. You can do this with an hour or two each weekend without getting the boss too upset.

Actually, after posting my plan yesterday I decided to do exactly what you suggested. Change out the oil pump and see what happens. I don't want to be cranking the engine with no oil pressure to get compression readings and I don't want to work hard enough to do the cranking by hand. I ca always pull the pan the following weekend as a precaution. I found a pump locally and may stop on the way home to buy it if the guy can confirm its not a pump for a turbo.

[abscate]

Actually, after posting my plan yesterday I decided to do exactly what you suggested

Oh no. Terrifying.

Fingers crossed.

[98v70dad]

Actually, after posting my plan yesterday I decided to do exactly what you suggested

Oh no. Terrifying.

Fingers crossed.

My thought was "why not replace what is obviously wrong first? when I have the old pump off I'll be able to verify the failure. If its been getting too little oil due to bad pick up seals or a blocked sump screen its been taking years to have an impact on the oil pump. Running the car for a few minutes to see if replacing the pump restores oil pressure isn't going to hurt much - probably.

There's a problem with my locally acquired pump. When I called to confirm that the pump he has is NOT for a turbo he waffled a bit and then said he would get back to me. Sure enough it was the wrong part. He told me he could GET me the right one - we'll see. The allure of that part was it was cheap and I could pick it up on the way home and I knew the age and condition of the engine it came of.

[abscate]

There was an 'all parts $5' parting out in the PARTS Forum - problem is the seller things he can charge people to remove things from his car for sale. Yeah, it doesn't really work like that, does it?

[RickHaleParker]

Anyhow, the parts are relatively large, 1/2 inch on the longest side of one of them and they are about 0.10 inch thick and fairly flat.

I think it came from the part circled in green. Visualize the gear shearing off the top surface. Maybe break chips off the end which would pass through in the valleys of the gears. .

[RickHaleParker]

That's one way it could happen.
The theory I was working up was that the lobes wore down, or the clearance between the outer gear and the case became too great for reasons unknown (bad PRV? broken screen? Abrasive particulate contamination?). As wear increases a misalignment between the gears results in them crashing/binding as they come together on the pressure side. The stress of which would make the lobes susceptible to breaking clean off. Once one lobe breaks free it may still try to pump oil for a short while but this sudden more extreme misalignment with one missing lobe would snowball pretty fast into total failure, I would suspect. This might better explain the 'larger chunk' of metal he found.

That theory would require debris from the crankcase. If I suspected it is the case, I would drain the crankcase through a cloth and see if I could catch some debris.

There's always a second opinion. The question is whether it's any good.

When I meet another that can separate opinion from facts, I don't feel so alone in the world.

[RickHaleParker]

That is such an elegant piece of engineering

It been around for 100 years. It is based on work started by Galloway in 1787.
You can reverse the flow of the fluid by reversing the direction of rotation. You can even reverse the energy flow. Force pressurized fluids into the intake and it becomes a pistonless rotary engine.

[mrbrian200]

Ok, I'll link the to picture of the bits to bring it into this active conversation:
We'll refer to them from left to right as A,B,C


Ok, for now I'm going to ignore the patina (when it happened) and concentrate on the bits (what happened).

Event1. Bit B in the middle I suspect is a lobe that broke off from the center gear. But it didn't push out of the pump right away. It stayed in there for a while just sort bouncing around but falling roughly back into place each time the mechanism rotated it back around toward the pressure side/outlet. Bouncing and binding around in there over time it wore down and rounded off, making it less obvious that it is actually a lobe from the center gear.

Event2. Eventually bit B wore down small enough that it tried to push out with the oil and lodged into the outlet port, the following intact gear lobes hammered it through breaking off part C from the outer casting. Both parts C and B traveled down the oil pressure channel/pipe. It's relatively small. The seal may be outside the break area of part C, or, the resulting leak back out to the pan wasn't enough to result in critically low oil pressure. The pump still pumps (pressure may not be ideal, but remained 'adequate'.

Now, we'll consider the patina (when did it happen)

E1 and E2 happened a long time ago. These parts lodged in the passage between the pump and the filter where the only partially restricted flow, and stayed there but didn't push through to the filter until....

Event 3. With the missing lobe the mechanism would bind and stick a little bit every time this area missing it's lobe came into play between 10-12 o'clock position (picture of pump further up, clockwise rotation or 2-12 o'clock counterclockwise). This accelerates wear of the remaining lobes. Eventually everything wears/misaligns enough that a nice juicy fresh chunk of the outer gear ring (C) breaks off during the final moments of an accelerated self destruction. Bit C travels down the outlet tube and gets stuck behind the previously lodged pieces C and D forming a more solid plug to oil flow. Oil pressure overcomes the plug and pushes all 3 out to the oil filter where you found them.

v70dad did you mention a knocking noise from that end of the engine for a period before final death, or was that somebody else?

However, Event 3 occurred during the pump's final minutes as a cascade failure/ self destruction was in process. (it only continued to function as a pump for a short time until the oil light came on and stayed on). There are likely more small fresh juicy bits to be found both inside the pump and and downstream before the filter.

This is still all merely speculation on my part. Maybe even an example of an overactive imagination. But it might explain both the parts and the patina. The identity/where bit B came from is what I am least confident about. It might be part of the outer casting, not a lobe from either gear. Hopefully that pump will be pulled off the car and disassembled. Hopefully there's enough left to jigsaw puzzle it back to pinpoint it's origin.

[RickHaleParker]

[98v70dad]

Anyhow, the parts are relatively large, 1/2 inch on the longest side of one of them and they are about 0.10 inch thick and fairly flat.

I think it came from the part circled in green. Visualize the gear shearing off the top surface. Maybe break chips off the end which would pass through in the valleys of the gears. .

That's my highest probability failure location and that's my theory as well. After the holidays I'm going to take off the oil pump and see what I find.