2f engine rebuild (spun rod) (1 Viewer)

[Yakub]

I finished my 2f rebuild a little while ago and went to do the break in. After about 10 minutes heard a screeching sound and then the engine shut off, we pulled the motor and found the culprit to be a spun rod bearing.

Took the engine back to the shop and got the crank re-machined, everything else seemed fine. In the process saw that the front main didn’t seem like it was getting any oil either.

The machine shop has no idea what caused it. We blew out all the oil passages and they seemed to have good flow out the others. I’ve talked to a lot of people and no one really knows what it could be. So I’m throwing it out to the internet. Any advice on what I should do to test it on the new assembly? I’m ready to go again, but don’t want to have the same result, especially when I have no idea what caused it.

 

[Godwin]

Was the distributor properly seated? Distributor drives the oil pump.

 

[Yakub]

Was the distributor properly seated? Distributor drives the oil pump.

I believe so, all the other rods and mains looked perfect and had good oil, the oil pressure sensor was also giving good readings, although it did not give exact psi.

 

[pjohnson]

Incorrectly installed bearing covering the oil passage?
lack of assembly lube?

Someone recently posted the exact same spun bearing issue and he determined the bearing was installed wrong.

 

[middlecalf]

Oil pump primed prior to starting?

 

[Yakub]

Primed the system till oil was hitting the top end. Potential for incorrect bearing install, this is my first rebuild, but I lined them up as I was taught and put the ones with holes where they were meant to be. I don’t think it was a lack of assembly lube because the main want getting any oil either, it just had a little more assembly lube so it didn’t cause any damage yet. The rod probably had enough oil splash up to dissolve the lube, but not enough to create a film.

 

[pb4ugo]

Did you plastigage or measure clearances during assembly?

 

[Yakub]

Did you plastigage or measure clearances during assembly?

Yup, everything came out within tolerance. Also made sure to clean the plastigage off.

 

[pjohnson]

Here's that other thread I mentioned:

Rebuilt 2F break in gone wrong

I tore down and rebuilt a 1979 2F. Machine shop did valve job, balanced rotating assembly, dipped block and honed cylinders. No boring or oversized anything. I assembled motor using FSM as guide and used assembly lube. Also added some zinc i believe to oil for break in. Primed oil pump via...

forum.ih8mud.com

 

[65swb45]

Did you or someone involved replace the front oil galley plug with a thread-in variant?

Over 30 years ago I had a machine shop rebuild an engine that put the regulator on backwards and blew out the front plug. Bright sparks that they were, they thought they would make sure it never happen again by threading the oil galley and installing a threaded plug.
The plug went in too far and cut off the first oil journal.

To all: if you find this information useful, consider hitting the like button. One of the reasons I checked out of tech last September is because of a growing sense of entitlement from posters who show no indication of having done any research (was just talking with @Dallas Todd about this yesterday) and a disrespect of analytical questions designed to make people reason their way to an answer instead of being spoonfed answers (teaching a man to fish)

 

[Yakub]

Thank you all for your replies. I took a look at the pugs but I am not sure how to test them?
Here are the pictures:

The shop stated that they did the plugs but I don’t know enough about them to know if they did anything incorrectly. I also assume that when I blew out the passages having one be blocked would have been apparent, however I don’t know enough about it. Could be possible that air could get through fine but not enough oil can. Although based on that main having all its assembly lube still I would venture that none was getting to it. The other weird thing was that there was some oil in the coolant system, we did a flush on it a few times and it seemed to resolve itself. I assumed that it was due to just regular assembly and some oil getting in, but now I am worried that there is potential for a crack in the passages in the front. Looking over engine diagrams I am not sure where this would be, but this is a junk yard block that I picked up due to the old block being unmachinable from spun main bearings.

 

[65swb45]

What ever that thing is in the front of your block is not familiar to me. Further, I’m scratching my head trying to figure out how they installed it.
All the early engines used a drift plug, which would have been seated against the very first lip in the block, the lip above where that ‘ thing’ is.
The drift plug was replaced around 1986 with a threaded plug which would have had an Allen head in the face of the plug to rotate it. Lacking a hex, a star, or even a slot, there would be no way to run a screw plug in…or out.

Which is why I am at a loss.

With the crank out, you can easily run a coat hanger down the delivery hole to the galley. Using a tape measure, you can measure the distance from the opening at the bearing hole to the far side of the oil gallery. Then compare what you get with the coat hanger. It’s not rocket science.

 

[Yakub]

Well did all that, did some more testing I thought up, everything pointed to it was fine. So I put it together and fired it up last night, break in went smooth and drove it to get food after. So far so good. Seems like I have one or two drips I’m going to have to chase down, but other than that it’s a beauty. Thank you all for your help.

 

[OldnRusty73]

I finished my 2f rebuild a little while ago and went to do the break in. After about 10 minutes heard a screeching sound and then the engine shut off, we pulled the motor and found the culprit to be a spun rod bearing. View attachment 3297526
Took the engine back to the shop and got the crank re-machined, everything else seemed fine. In the process saw that the front main didn’t seem like it was getting any oil either.
View attachment 3297531
The machine shop has no idea what caused it. We blew out all the oil passages and they seemed to have good flow out the others. I’ve talked to a lot of people and no one really knows what it could be. So I’m throwing it out to the internet. Any advice on what I should do to test it on the new assembly? I’m ready to go again, but don’t want to have the same result, especially when I have no idea what caused it.

Did you ever get an answer as to why the front main didn't get any oil? Did you have any more issues after you put it back together?

I think my 2F just seized. We heard a squealing noise, shut off the engine, and now it won't spin.