I think I ruined my engine

Kirby1374

Kirby1374

Senior Member
I just completed tightening the clearances on my mains and rods. I used the foil interference method. As I got to the last rod the engine was getting a little stiff but once I got it spinning it seemed fine. I got it all together and started it up. I ran great, less vibration. It was getting a little warm (the timing isn't quite right yet) so I shut it down. Now the engine seems locked. I guess I need to pull the pan again and hope I didn't ruin something.

Can someone tell me something to help me not feel sick to my stomach?
 
As you removed shims did you give the engine at least one full revolution for each bearing adjusted. If the crank has any egg shaped journals then you might have used the foil on the thin side, so now the crank might be too tight.

Can you hand crank it at all?
 
This can be normal if you set it up on the tight side of the clearances and have a weak starter or battery. Once things cool down it should turn over normally. Just treat it like you're breaking in a new engine, low revs, and the like until the engine frees up a bit. If set up tight, remember heat expands metals so that's why its locked up.
 
Tom Wesenberg said:
As you removed shims did you give the engine at least one full revolution for each bearing adjusted. If the crank has any egg shaped journals then you might have used the foil on the thin side, so now the crank might be too tight.

Can you hand crank it at all?
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no I did not do a full revolution on my foil job.

Now that it has cooled I can turn it with the hand crank but it is still tight.
 
azmodela said:
This can be normal if you set it up on the tight side of the clearances and have a weak starter or battery. Once things cool down it should turn over normally. Just treat it like you're breaking in a new engine, low revs, and the like until the engine frees up a bit. If set up tight, remember heat expands metals so that's why its locked up.
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That's what seems like has happened. So I should just keep trying to run it?
 
I started it again. It runs great.

one more troublesome thing; before all this work my oil pressure gauge said around 10 at a fast idle. now it reads 5 and barely any at slow idle. maybe my pump isn't working either, or my cheap gauge got something in it. It is a mechanical that screws onto the block, not in the cab.
 
I say NO. Fix it properly. Readjust each bearing as before and rotate the engine after every adjustment. No sense ruining a good engine
 
Kirby1374 said:
So you don't think that it will loosen up with running? What could I be ruining?
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The bearings.

If they are too tight, and you try to "run them in" too aggressively, they might get hot enough to "run the babbit out" ( literally heat the bearing metal to its melting point and have it run / thrown out of the bearing caps ).

Then they will be "too-loose". Permanently. The only solution then is to pull the engine and send it out to have new babbit poured.


I suppose you could try "running them in" by pulling the spark plugs and spinning the engine over with the starter in 20 -second bursts, giving the starter a couple minutes to cool between uses, then see how "tight" the engine is with the hand crank...

Better to be safe than sorry, in my opinion... drop the pan and check them again.
 
Special Coupe Frank said:
The bearings.

If they are too tight, and you try to "run them in" too aggressively, they might get hot enough to "run the babbit out" ( literally heat the bearing metal to its melting point and have it run / thrown out of the bearing caps ).

Then they will be "too-loose". Permanently. The only solution then is to pull the engine and send it out to have new babbit poured.


I suppose you could try "running them in" by pulling the spark plugs and spinning the engine over with the starter in 20 -second bursts, giving the starter a couple minutes to cool between uses, then see how "tight" the engine is with the hand crank...


Better to be safe than sorry, in my opinion... drop the pan and check them again.
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ya, I thought that would be the case. I just wanted someone else to pronounce my doom.

I did a new head gasket and ground the valves so the pressure with the spark plugs in has also increased a whole lot. So I have 2 tightness issues really.

Right now the engine feels warm and the starter spins it easily. With the crank it is real tight then then a valve opens and is still tight but spins much easier till the next comp stroke.


Maybe I panicked, or maybe I was really glad to get it all back together only to maybe face doing it all again.
 
Kirby1374 said:
I started it again. It runs great.

one more troublesome thing; before all this work my oil pressure gauge said around 10 at a fast idle. now it reads 5 and barely any at slow idle. maybe my pump isn't working either, or my cheap gauge got something in it. It is a mechanical that screws onto the block, not in the cab.
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Don't worry about the bearings, if it was set up properly by the engine builder in the beginning, it will be fine today. Think about what the goal was, to tighten up the bearings and that's what you did. It sounds like you did things properly.

Ignore the oil gauge, it's more of an indication that the oil pump is pumping and that's all. If the engine is cold, they might show 10 lbs, but when warm it won't show anything.

Don't worry about what you've discussed, just drive it! It's been around for 80 years, what you've done in the last week won't kill it!
 
Just to make things clear, when I said to give the engine at least one full revolution after each bearing adjustment, that of course means AFTER the foil is removed and the bearing cap is tightened.

If you can hand crank the engine, I think it will be OK. Start the engine and let it idle for 10 minutes, then shut it down and let it cool to room temperature, then repeat this at least 2 or 3 more times adding a few minutes each time. As soon as you shut it off after the warmup, see if you can hand crank it OK. As mentioned you don't want the babbit to get so hot that it melts.
 
Tom Wesenberg said:
Just to make things clear, when I said to give the engine at least one full revolution after each bearing adjustment, that of course means AFTER the foil is removed and the bearing cap is tightened.

If you can hand crank the engine, I think it will be OK. Start the engine and let it idle for 10 minutes, then shut it down and let it cool to room temperature, then repeat this at least 2 or 3 more times adding a few minutes each time. As soon as you shut it off after the warmup, see if you can hand crank it OK. As mentioned you don't want the babbit to get so hot that it melts.
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I guess I have already been doing this. I have started it 3 times now getting a bit looser each time. I have not ran it for as long of periods as you mentioned.
 
1931 flamingo said:
Kirby1374: Off topic: I notice you're running 16" on your avitar, what size/brand tires?
Paul in CT
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They are 650-16 Nanco very cheap Chinese tires. I got them off eBay. The fella also used to sell them on the HAMB. I think his supply has ran out though.
 
Hey, how many of you all are keeping up on the 365 days in a Model A? My motor spins faster than Jonathan's at first start up after new babbit.
 
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