Confuzed1

iTrader: (4)

Sorry, this may be longish, but I want to give as much detail as I can. I have a .040 over SBC 400 that I recently rebuilt due to oil control rings not seating.

It now has total seal gapless rings, Clevite HP77 bearings, and I added a new oil pan and windage tray. Block was hot tanked, honed in order for the new rings to seat, and new cam bearings installed.

So I started it up for the first time since the rebuild, and I thought everything looked good – oil pressure 45-50 at cold idle at 900 RPM, no smoke, but a heard a little lifter noise that went away after the first 30 seconds, and I also heard what I thought was a big exhaust leak. I could hear a tapping noise under the car.

Then the water temp gradually sailed up to 240 degrees… cooling fan didn’t turn on at 200. Stupid aftermarket fan controls quit working. Had to shut it down. I ordered and received a new fan control (Perma-cool) from Jeg’s and hooked it up using the instructions. While I waited for this part to arrive, I tightened up the flanges where I thought the exhaust leak was coming from.

So I start it a week later, and I hear the same tapping noise under the car that I thought I fixed already. BUT – it’s not an exhaust leak – the noise is coming from the crankcase, and it probably makes a tapping noise 4 times per second. I didn’t think a lifter was causing this, because the tapping was too fast for that, and the noise gets faster with RPM’s, but quiets down a little as RPM's increase – it’s loudest at idle.

I think one of the crank throws or rods are hitting somewhere on the windage tray, but of course unless I pull this entire engine again, I can’t verify that – but it’s loudest at the oil pan. It honestly sounds like it’s a rod bearing, but I really doubt it is due to the oil pressure. And to top things off, the new fan control will only maintain 240 degrees at it’s lowest setting – which is supposed to be 160…guess that's another topic....

Anyways, I pulled each valve cover, and checked for a tapping lifter – just in case. I found all rockers tight, moving normally and no noise. So – to my question. Should I just go ahead and assume that the area where the crank is touching will eventually wear in and quit making noise?

I was considering pouring some thick oil like STP in it to see if it gets quiet, and I suppose if it does, it points to a bad rod bearing? And if it makes no difference would that tell me the crank is hitting the windage tray?

It’s a weird problem, and I guess I’m just asking what you’d do if you were in this predicament.

EDIT: BTW, oil still looks clean, no metal shavings under the valve covers. After engine is fully warm, maintains 45-50 psi oil press, and goes up to 70 psi when revved. (Hi volume pump)

RB83L69

Use a mechanic's stethoscope, and see if you can tell exactly where it's coming from.

I doubt it's the windage tray. I'd suspect the oil pan; on the side next to the oil filter; the counterweights for the #7 & #8 rod throw hitting the pan right at the top, within ½" or so of where it meets the block.

Confuzed1

iTrader: (4)

Thanks RB, no stethoscope needed...I know it's coming from inside the oil pan. And I did do a little "tweaking" on the exact area you mention, but apparently not enough. I even had to shave off a little of the inner diameter of the pan gasket in that area because the crank throw rubbed there. But the pan fit in the chassis great.

So where to go from here? Is there anyway to prove rod bearing or oil pan/windage tray causing this? - And if it is a oil pan/windage tray problem, do you think it will go away after awhile? If it's a rod bearing, it'll take care of itself unfortunately.

As mentioned above, pouring STP in it may not tell me anything...

EDIT: and BTW, the noise is eminating from inside the pan somewhere.

brutalform

Can you look to see if the starter gear is tapping the flywheel? Floorguys vette had this problem with a rebuilt 406, and we encountered this same sound you are experiencing. As it turned out, the thrust bearing, was the culprit (he used Clevite also), and the crank was slightly moving, and causing the two components to contact.

Confuzed1

iTrader: (4)

Sure, I can check it but it's not likely the starter since I had the same one bolted on before the rebuild and no noise - but a good thought. I hope the thrust is OK...I know it was within specs when I checked axial play during reassembly. - Thanks!

Anyone else have any input to the question(s) above?

Floor guy

If you want to almost eliminate the rod knock issue, pull 1 wire at a time while engine is running. If the noise quiets down when a single wire is pulled, it may point to a rod bearing. Something to try that is quick and costs nothing. Clevite has been having some quality control issues lately. Hopefully is hasn't bit you too.

MikeH

iTrader: (10)

I will go with RB on this one.. I bet its the crankhitting the side of the oil pan. right at the flange where it meets the block. I had this same problem with a generic summit pan on my 400. They need a little more clearance in this area.

sellmanb

You COULD just run it until the noise goes away assuming that it is a counterweight hitting the oil pan... but think about it... the only way that it would stop is if it took out enough of the oil pan to give itself some clearance... which would mean metal shavings floating around in your brand new engine...

so makes more sense to yah, a 15 dollar oil pan gasket and a few hours labor or rebuilding your 400 again?

Also, a mechanics stethascope should help you to determine what exact counterweight is hitting the pan, so you dont have to try and figure it out once you drop the pan... and then you can verify that it is coming from a counterweight and not the starter like stated above, or a mis-torqued flywheel/flexplate.

Confuzed1

iTrader: (4)

Thanks for the advice everyone! Since I'm working 12 hour shifts this weekend, I figured I could at least get everyone's take on this problem.

I'll check to make sure it's not the starter, check the flywheel, disconnect one plug wire at a time to see if the knock changes. I guess I'll also need to pinpoint the exact spot where this is occurring. I'll check around the oil filter area first .

I wish removing the pan was a 4 hour job...if it was I would have already done that. It's not rubbing real hard (if that's what it is), so I doubt I'll throw a bunch of metal around the crank or anything. I am more concerned with maybe a counterweight rubbing a hole through the side of the pan.....then I guess the decision to pull the pan would be made for me.

Sellmanb - I've thought about the same things - metal in the oil, etc.. So you understand my concern. The engine has about 45 minutes of run time on it so far, so after this next run to find the exact location, I plan to drain this oil and cut my filter open to see what I have - and buy a magnetic drain plug.

To say I'm frustrated with this whole car is an understatement. Maybe I need a new hobby or something -

I'll post what I find on Monday, and go from there......

Floor guy

Having just gone thru a motor failure, I will add .02 cents more. If you have noise, drop the pan. You should have .050 clearance between anything that rotates. If something is just hitting a bit it will clearance itself. As engine rpm and temp climbs, they will likely smack again. 4 hrs to drop the pan sux. I just spent 60 + hrs rebuilding a motor because I avoided dropping the pan. Believe me, it is 4 hrs well spent. Good luck and keep us posted.

Edit: Just noticed you said more than 4 hr job. Still worth it. I just assembled a 383 and had piston skirts hitting crank counterweights. Add this to your list of things to check if pan does come off.

Confuzed1

iTrader: (4)

Well, it looks like I might have good news. But I'll remain skeptical until I look further into this tomorrow. But here's what I think is going on...try not to laugh...

You know the "dust cover" that bolts on the front of the trans to prevent gravel and stuff from getting between the flywheel and case? Well - I started the car up, jacked up the front end and dove underneath before it got dark outside and felt around the oil pan. The noise seemed a little quieter than it was for some reason, but anyways - I went to check the starter and when I did, the back of my hand was contacting that plate - and I could feel the "tapping" going on clear as day...

So I pushed on the plate a little, and the noise got worse - let off, it gets quieter. So when I said above that the noise was eminating from inside the pan? - it seems like I was wrong. It was just so loud before, that it honestly sounded like it.

Now it appears the noise is from that plate hitting somewhere on the flywheel, but tomorrow I'll pull that plate off and see if the noise stops - I'm hoping it will!!

sellmanb

There are 4 bolts holding the dust cover in place, and they arent torqued down very tight, it should take you longer to jack the front of the car up and put jackstands there than it should for you to unbolt that to make sure.

The noise is still not a good thing though. You might have a broken flexplate or something, so watch out when you drop that dust cover, you might get half of a spinning disc of death falling on your head lol.

Confuzed1

iTrader: (4)

Not sure how you're car is set up, but at least on mine, the starter has to be removed in order to get the plate off. I wouldn't try it with the car running...I like all uuhh..10 of my fingers!

No flex plate to worry about, it's a 5 speed.

Come to think about it, I did have a heck of a time lining that plate up with this new oil pan though. It's used with a /windage tray that bolts to the mains. Same one used for the old factory 302's, got it from GMPP.

Thanks for the input! I'll post what I find tomorrow...

Confuzed1

iTrader: (4)

A good day today!! It was the dust cover the whole time!

Got that fixed, did a quick half*ss carb tune and hit the road for about a half an hour. It's a different car with the 9" posi, LCA's now!! I'm getting much more power to the ground. But it does feel a little different on tight turns for some reason.

My fan switch is still screwed up, but it stayed at about 180 degrees while it was moving. I can tell my carb will need more tuning because every time I opened it up, my A/F meter went to full lean. I guess I'll step up the secondary jets a couple of numbers and see what that does...

But the engine seems to have even more power overall!! Just need to tune it better.

brutalform

[QUOTE]Originally posted by Confuzed1

Got that fixed, did a quick half*ss carb tune and hit the road for about a half an hour. It's a different car with the 9" posi, LCA's now!! I'm getting much more power to the ground. But it does feel a little different on tight turns for some reason.

What carrier did you finally go with, a Detroit locker, or somthing else?

Confuzed1

iTrader: (4)

They (Moser) called it a True-trac posi. It's made by detroit locker though. Why?

brutalform

Thats probably why it feels different on the turns. Sounds like you are happy with it. IMO, you went the right route.

Confuzed1

iTrader: (4)

Thanks brutalform, but really it's too early to tell. I have about 25 miles total on it so far, but I'm still breaking it in...as well as the engine. I do know that I can't really get on it fully without worrying a bit until I get my SFC's welded in....finally.

But so far no whining, or vibration!

brutalform

Youll be fine. Like I said a while back, I dont even worry about the rear anymore. Thats the least of our problems.

Confuzed1

iTrader: (4)

Yes, I recall you saying that!

It's not the rear I'm concerned with, the T-tops creak as it is every time I go up my driveway from the street...mines NOT a '92 like yours unfortunatly.....it's a 22 year old car. I'm runnin "Collectors Plates" lol.

- Thanks for everyone's help!