Think I just spun a rod bearing.

[jimtash]

1000 mile motor and I think the worst has happened. Took the car out for spin and revved it good but nothing close to abuse. Notice a knock and the oil light on at idle but disappearing when I gas it. Nor is it missing. I feel the knock up top in the head and hoping it's there but that's wishful thinking right?

What do I do?

 

[jimtash]

Well of course.

Plastigauged them all and they were all in spec. One was on the loose end but still in spec.

 

[jimtash]

Dude, I just rebuilt it. It literally has only 1000 mile it. It happened tonight and I drove it home knocking.

 

[rubydist]

its a little hard to read this thread w/ Zach's questions having been deleted.....

you plastigaged them when you rebuilt it, or tonight?

 

[jimtash]

This is a brand new rebuild it's got less than a 1000 miles on it. I checked all the clearances before assembling it and they were all within spec. One of the rods was on the loose end but still in spec.

No warning sign, the engine was and is full of fresh oil and yet it knocks and it just started tonight. I can feel it in the front valve cover and the oil pressure light comes on at idle and disappears when the engine is revved. It's not missing either.

This is the sign of rod bearing failure, right?

 

[zach44102]

its a little hard to read this thread w/ Zach's questions having been deleted.....

you plastigaged them when you rebuilt it, or tonight?

I told him to put it back together with new bearings if the crank is not scored and it was plasticgauged and came to within spec. But I guess rebuilt motors cant break.

 

[Racer X]

Why was the motor rebuilt in the first place?

 

[jimtash]

Why was the motor rebuilt in the first place?

To replace the worn out engine in my car.

 

[Racer X]

If you don't know the history of this motor, and you spun a rod bearing in a matter of 1000 miles, either it had an oiling issue, or a crank issue. Although with the knocking, you may now have both.

I would mic this crank if possible. Also, give the oil pump a good once over to make sure it's in good shape.

 

[jimtash]

This just happened tonight, like an hour ago. The engine is still in the car. I took it for a spin and coming back home it started knocking. I really had no choice but to drive it home.

When I pull the oil pan I'll go from there. The knocking sound is coming from the top though. Sounds like a piston hitting the valve but that wouldn't affect oil pressure at idle. The pressure light is on at idle and goes away with revs. With a spun bearing, would it affect oil pressure off idle as well?

 

[shotime1994]

These engines are non interference. So no piston hitting the valve.

 

[jimtash]

These engines are non interference. So no piston hitting the valve.

Since I'm getting a noise up top, would a broken valve spring possibly cause contact with the piston and also affect oil pressure at the same time? The engine isn't missing at all. Other than the knock, it ran fine and still had good power.

 

[shotime1994]

http://www.shoforum.com/showthread.php?t=117991 go to the 6th reply does your car sound like that? Its probably a rod noise that your hearing up top.

 

[jimtash]

http://www.shoforum.com/showthread.php?t=117991 go to the 6th reply does your car sound like that? Its probably a rod noise that your hearing up top.

Somewhat except the knock is consistent especially with the revs and it idles rpm wise just fine.

 

[shotime1994]

You probably spun a rod. Tear the low end apart and look at the crank. Why do you think the old engine was worn?

 

[jimtash]

You probably spun a rod. Tear the low end apart and look at the crank. Why do you think the old engine was worn?

Burned oil and lots of it. Especially under load.

I've got a spare crank and a full set of pistons as well plus whatever I can salvage off the old engine. I just would rather not go through the motion of building another engine and having to install it. This one ran so good and what gets me is tonight that I didn't take it past redline. Had some fun in it but nothing extraordinary.

 

[SHOtimer]

Did you 'rebuild' it, or have a machine shop do it?

What was included in the rebuild?

Doug

 

[jimtash]

I rebuilt it. Plastigauged it and everything was in spec. Thinking the bearing with the loosest tolerance (although still in spec) gave out. But how? The engine has plenty of oil in it. Not only that, but I took the car to Atlanta and back a few weekends ago and gave it a good run with no problems. Probably put 400 miles on it that day alone. You'd think the bearing would've gone then if it is a bearing.

The block was lightly honed and the ring gaps are in spec.

The crank, piston, and rods are a matched set and were placed in the same order they were taken out. Cleaned and checked at a local machine shop I use.

The heads I bought used because they were ported and the price was right. Cleaned the valves, new seals, and everything went together fine. I didn't check the valvesprings for pressure though nor did they seem out of the ordinary. But I did have to replace two valves in two different chambers because they were bent. One intake and one exhaust. Think is might be a valve?

 

[jimtash]

This morning I started it and the knock was gone until the oil started to warm up and the motor revved up to about 3k and then it just slightly started but stopped once back down to idle. Oil pressure was good and the light never came on even after the knock.

Might be able to salvage the thing after all?

 

[Racer X]

Borrowed time. You're on it.

Unless you want to ruin that motor but good, put it apart again and see which bearing failed. Also get the crank mic'd to make sure it's healthy.

Spend some time doing it the right way now, or spend some time and a lot more $$$ by waiting until the bearing welds itself to the crank. Your call.