After Head Swap, still a knocking sound - Bad Crank bearing?

53BigDog · Nov 20, 2005

Ok just completed the PI head swap hoping to fix my knocking (more of a clang) sound. When the engine is running it sounds like a steady clang clang clang. Then only other thing I can think of seeing that I rebuilt the entire upper part of the engine is that I have a bad crank bearing. Anyone experience this?

tomustang · Nov 20, 2005

ouch you realise you are going to do double the work now? that's a spun bearing

COramprat · Nov 20, 2005

You need to determinme whare it is coming from. Get down and listen closely from all point above and below the car. I wouldn't automatically assume it was a bad bearing until I knoocked out the simple possiblities.

Alot of noises will resonate throughout the engine bay so you will have to do some pretty good listening...maybe get a stethescope to determine where the noise originates.

53BigDog · Nov 20, 2005

Yea I know, double the work......that sucks

I'm pretty sure its from down below. I will get underneath and listen. If it is and repair is needed, what should I do preventatively or to upgrade while I have everything apart.

tomustang · Nov 20, 2005

Stop driving it Drain the coolant and inspect it, also tear apart the oil filter. Should find metal flakes but not all the time

If you can look for an aluminum block and have someone build it for you

COramprat · Nov 20, 2005

If it is a crank bearing, start the car then pull each plug wire/cop one at a time. If the noise stops then it is a bearing problem in that cylinder.

53BigDog · Nov 20, 2005

Tom - I haven't driven it in about 2 months...been doing the head swap. Replaced coolant and oil during the swap.

prat - how will disconnecting a plug tell me what cylinder the bearing is bad?

bdcardinal · Nov 20, 2005

there wont be any stress on that cylinder from it firing. usually that will make the noise go away. however if you are taking it apart, replace all teh bearings.

53BigDog · Nov 26, 2005

are there any other upgrades or maintenance? piston rings, etc? that shuold be done?

mrvax · Nov 26, 2005

If you just want to fix the problem then you'll have to drop the oil pan. I'd guess that you'd have to raise the engine to do that. Replace all the connectiing rod to crank bearings if one of them is bad. Check the crank journals carefully to make sure they are not scratched. If they are, the crank will have to be repaired.

Hate to say this but it may be easier to get a bottom end that is "known good" and put your new heads on it.

It could also be a main bearing. Have to tear it apart to find the cause.

tomustang · Nov 26, 2005

mrvax said:
Check the crank journals carefully to make sure they are not scratched. If they are, the crank will have to be repaired.

Usually the bearing gets marked onto the journal, still you have to remove the crank to inspect it anyway.

mrvax · Nov 26, 2005

tomustang said:
Usually the bearing gets marked onto the journal, still you have to remove the crank to inspect it anyway.

Your right Tom. If he has bottom end noise, it's almost certain everything has to come apart. Sucks. I'd probably just get a used bottom end if I could find a good one. With cash on hand, it would be a good time to get some forged stuff.

tomustang · Nov 26, 2005

mrvax said:
Your right Tom. If he has bottom end noise, it's almost certain everything has to come apart. Sucks. I'd probably just get a used bottom end if I could find a good one. With cash on hand, it would be a good time to get some forged stuff.

Either way the block has to be machined to run new or used internals so it will just come down to how much you plan on paying for a kit

In the pic it's hard to see but the bearing got flattened out and left it's signature on the crank

View attachment 496640

Edit: second one from the front, you can see it in the middle

COramprat · Nov 26, 2005

bdcardinal said:
there wont be any stress on that cylinder from it firing. usually that will make the noise go away. however if you are taking it apart, replace all teh bearings.

:Word:

69Rcode_Mach1 · Nov 26, 2005

Yes like it has been recommended check the bearings, examine the crank and rods properly. The spun bearing cuts off oil flow and can lead to damage.

53BigDog · Nov 26, 2005

Yea I figured I'd pull the engine and get the bottom end finished and machined and then after its all back together it would practically be a new engine.

After Head Swap, still a knocking sound - Bad Crank bearing?

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