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You had the previous filter full of metal. Now you have a knock. If it is a bearing, it'll show up in the new filter. They are only $5.00 and take little work but if it comes out clean, you will feel at ease and can start looking elsewhere.
That's a good point. Thanks, I'll check that out.
Originally Posted by cuisinartvette
With the engine off you can smack the cat with a dead blow hammer see if you hear stuff rattling inside
If the engine is missing and you have the DM flywheel it can make a little noise.
Is the knock a steady rythmic thing? Any way to get a clip on youtube?
...
Had what I thought was a bad guide on a new motor was rockers touching the V. Cover. Not the problem likely just saying sometimes you get lucky.
Maybe a cat in the fan belt? Naw thats a squeal.
I'll give that a shot and let you know what I find. The knock is rhythmic and proportional to RPMs. I'll hopefully take and upload a video tonight.
I carefully checked rocker to VC clearance, but hopefully it's something of that nature rather than a rod knock.
Originally Posted by mtwoolford
only crankshaft designed for a two piece rear seal, i.e. pre 1986 were neutrally balanced. Although there may be more than one way to do it, "neutrally" balance one piece rear seal rotating assemblies typically had "heavy metal" slugs added to the crankshaft throws (which is expensive).
Mine is a '90, so it has the one piece rear main seal. And I could see where the crankshaft had Mallory metal welded in holes drilled in the counterweights to balance it.
Originally Posted by Kevova
You put an engine built by a questionable builder in car??? the valvetrain is a bit noisy (ticks like a sewing machine). You don't know if you have the correct balancer or flywheel; that is dependent on crank supplier (GM 400 cranks are externally balanced). it doesn't take long to beat the bearing out of an out of balance engine. You checked some clearances which were ok did you properly reassemble and re-torque everything you took apart? Engine is knocking now. oil filter picture looks normal actually. I think you need a pro to help you, because it seems you are over your head. If you had any doubt int the builder you should have found a different one. When building 383 there is a lot of clearancing that has to done to use 5.7 inch rods (which is a common practice today). The original SBC 400 used shorter rods. The longer rods can contact windage tray/scraper, the block and/or the cam. Are the rocker arms adjusted correctly? Have you contacted builder providing he stands behind his work at least through start up?
It's a long story. I bought the engine from a guy across the country and am just inferring the builder was questionable from a few things I saw once I inspected the engine in person. I knew there was a slight risk but it was worth it. And I checked the engine over thoroughly before I installed it.
Yeah, I torqued everything to spec. I'd done this once before on my old engine when I dropped the pan and replaced the bearings.
Although it is (may?) be out of balance, even at higher RPMs abnormal vibrations are not noticeable.
I also checked the clearancing, and it all looked good. Although, if I remember correctly, it has 6" rods. I clearanced the windage tray myself.
And yes, I went through the proper procedure to set valve lash as well as to verify proper valve geometry.
I tried looking up the builder, but I was unable to as they are in MD and I am in CA.
I banged on the cat with a dead blow hammer, but I'm not really sure what I heard. There was definite vibration, and perhaps some rattling (it was hard to separate the noise the hammer itself made from the noise the cat made).
Also, I finally bought an automotive stethoscope and started it up. Unfortunately (fortunately?), the knocking was much quieter than before, and I was unable to trace its origin with the stethoscope. However, here are three videos I took of it running: one from the passenger's side, another from the driver's side, and a third from beneath (the knocking was still well audible from the pan).
Mine is a '90, so it has the one piece rear main seal. And I could see where the crankshaft had Mallory metal welded in holes drilled in the counterweights to balance it.
Although it is (may?) be out of balance, even at higher RPMs abnormal vibrations are not noticeable.
I also checked the clearancing, and it all looked good. Although, if I remember correctly, it has 6" rods. I clearanced the windage tray myself.
If someone went to the expense of welding in Mallory metal slugs, I'd be pretty sure the rotating assembly is neutral balanced; now pull, pry the dust cover on the forward bottom end of the bellhousing and look at the forward (engine side of the flywheel, if it has a cast in lump or a bolted in counterweight it's for an externally balanced engine, if not, it's a neutral balanced flywheel. If you reused an OEM flywheel its almost certain to have a balance weight cast in and that would be a mismatch.
what isn't apparent is that C4 oil pans are extremely shallow, 6&7/8th inch at the deepest point in the sump, nominally 7 inches with the thickness of the oil pan gasket added in, and a lot shallower at the forward end. I've gone through a whole lot of experimentation with various pans and oil pump combinations on my C4 and other chevy small block's with shallow pans (as in a factory v8 Monza) Especially with a stroker, the forward crank throws could be tapping the pan, the mounting studs for the windage tray or the bottom of the oil pump (did you install a high volume pump?) could be interfering with the pan.
Since everything seems to come back to a knocking in the oil pan, I think it's time to drop the pan and take a lookey see. You can do it on jackstands with the engine in the car, and after the third or fourth time, it will seem quite easy (compared to what?)
Valves hitting the valve covers? Pull cover and look for dimples.
Or the bolts or weights on the fly wheel hitting unbolt to test.
I checked that clearance pretty thoroughly, but I guess checking for dimples might not be a bad idea.
I'm trying to think what the flywheel bolts would hit. The clutch housing? And is it possible to check that without pulling the engine or dropping the transmission?
Originally Posted by mtwoolford
If someone went to the expense of welding in Mallory metal slugs, I'd be pretty sure the rotating assembly is neutral balanced; now pull, pry the dust cover on the forward bottom end of the bellhousing and look at the forward (engine side of the flywheel, if it has a cast in lump or a bolted in counterweight it's for an externally balanced engine, if not, it's a neutral balanced flywheel. If you reused an OEM flywheel its almost certain to have a balance weight cast in and that would be a mismatch.
what isn't apparent is that C4 oil pans are extremely shallow, 6&7/8th inch at the deepest point in the sump, nominally 7 inches with the thickness of the oil pan gasket added in, and a lot shallower at the forward end. I've gone through a whole lot of experimentation with various pans and oil pump combinations on my C4 and other chevy small block's with shallow pans (as in a factory v8 Monza) Especially with a stroker, the forward crank throws could be tapping the pan, the mounting studs for the windage tray or the bottom of the oil pump (did you install a high volume pump?) could be interfering with the pan.
Since everything seems to come back to a knocking in the oil pan, I think it's time to drop the pan and take a lookey see. You can do it on jackstands with the engine in the car, and after the third or fourth time, it will seem quite easy (compared to what?)
If I remember correctly from when I removed it, the flywheel does not have a lump on it, but it has shallow holes drilled.
Yeah, I noticed it was shallow when I installed the engine. It came with a nice Moroso pan, but I was unable to use it because of clearance issues.
Huh, that's an interesting possibility. That would certainly be better than a rod knock. I do have a high volume pump. Wouldn't issues like that have showed up the first time I started it though, not 400mi later?
Have you ever dropped the pan of a 383 in a C4? I did it with the factory engine to replace bearings and it was tough to get the pan off. I had to turn the crank just right so it would clear in the front, and I'm not sure if it would clear at all with a 383's larger crank.
Originally Posted by Kevova
It doesn't sound like a bearing knock. I agree you need to " pull the tin" and look. If you pull the pan I would check crank endplay also.
That seems to be the consensus. Guess I'll look into if it's possible in-car with a 383 in a C4 and maybe get started tonight.
When you pull starter you be able to see weight if present on flywheel while rolling engine over with wrench. A bore scope would be handy to looking around. Have you run engine with out belt on? It is possible you are catching a bearing early where it just has excessive clearance. Good luck
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An uncommon knocking sound can come from carbon buildup in the combustion chamber. The piston is wacking that pile of carbon causing the noise. I mention this since you commented pulling the spark plug wires with no change to the sound. Which might lead one to believe theres a carbon issue. running some seafoam or marvel mystery oil down the intake could resolve the matter quickly.
But then you mentioned the antifreeze puddle and the smell of exhaust.
Not a carbon build up issue. The engine was never run when he purchased it and it had new pistons. He pretty much had it tore down to the bare block to check all before putting it back together.
All right, I decided I'm going to pull the engine back out. I went over all the things I need to do to it that are only possible or just easier with the engine out:
Finding source of knocking
Finding source of valvetrain noise
Fixing possible leaky RMS/finding leak
Checking crank-transmission alignment
Finding source of intermittent electrical power loss
Rebalancing flywheel
Resealing leaky head stud
Fixing wiring harness routing
and it just makes sense to remove the engine. I don't know if I'll be able to get the pan off with the larger 383 crank, and to drop the pan and pull the valve covers (for an unrelated problem) with it in the car I'll already be taking off a lot of stuff needed to take the engine out.
I've pulled the engine once before (to replace it with the engine currently installed) so doing it again shouldn't be too hard. Let's hope second time's the charm.
I've gotten almost everything disconnected in order to pull the engine, and while doing so I noticed that a couple exhaust manifold bolts on the passenger side had oil on their threads/on the tip of the bolt (my only thought is that oil ran into the bolt holes when I primed the oil pump?), and I saw there was a definite exhaust leak on the #6 cylinder.
Last edited by C4ProjectCar; 06-06-2016 at 03:20 PM.
I got the engine out and the pan off, but I can't seem to find anything wrong in there. Although the residual oil in the pan was pretty metallic, none of the rods wiggled on the crank to confirm my suspicions of a rod knock, and I can't see anywhere anything was hitting on something. Do you guys have any suggestions for things to check?
You actually need to see what the bearings look like. You stated earlier engine wasn't spotless when you got it. Debris could have worked it was thru oil system. I would look at cylinder bores for scuffing from the bottom both sides. Granted you won't see top 1/3 of bore but if there is scuff at the bottom....I think you just have to keep looking. You don't want to take it out and apart twice. Don't forget to check crank end play since it's a manual sometimes thrust bearing or journal on crank can wear causing crank to "walk". It tends to happen were a "high pressure" pressure plate is used.
Just pulled the #7 and #8 rod caps, but I realized I'm not sure what normal bearing wear looks like: only ones I've ever seen were either totally worn out or brand new. These don't look good to me though.
#7 rod bearing
#8 rod bearing (the one I suspected was making noise)
Antfarmer,
Since the noise persisted with each cylinder's spark plug disconnected, I don't think it was the exhaust leak.
Edit:
At first I didn't notice any endplay, but by lightly prying between a main cap and the counterweight I was able to wiggle the crank back and forth a little bit.
This half of the thrust bearing looks very worn out to me. What would cause this?
Last edited by C4ProjectCar; 06-10-2016 at 07:35 PM.
Ive never seen shiny brgs before. I suspect those are cheaper bi-metalic brgs with alum alloy over steel where as good tri-metalic brgs have thin lead alloy layer over copper alloy middle layer over steel shell and u would see some copper if failed. But they dont look catastrophic enough to make any noise.
And if u were having crank thrust issues wouldnt u see some damage to the cranks thrust face?
Well im sorry to say this but if mine and i didnt want to rebuild it again i would carefully remove the pistons and torque down the crank to see i can spin it by hand. Also check for any end play. I am kinda worried how the rings will seal after u R&R them but if your careful enough a ring sleeve tool should get them back in w/o damage. Yes u will need new head gaskets for this and clean the deck(s) also. Well maybe a good look with the heads off may help to and bring some surprises (a good look at the pistons could help too). It just that a correctly fitted crank will rotate using 1 hand only to turn it even after torqued down.
Dont know what else to say w/o being there myself.
I don't know what type of bearing they are, but the thrust bearing at least looks like it has a layer of copper in it. Shouldn't the others be the same?
Would I? I really don't know much about the subject. I looked at the thrust faces and they look fine, although the rear face seems to have a tiny ridge or groove I can feel with my fingernail.
I'd be kinda nervous to have to reinstall the pistons, but then again I also don't want to have to do this again. I do recall that before I installed the valvetrain the crank rotated very easily.
Also, I found a problem outside the engine that may have been the source of the knock.
Is this what a bad cat looks like?
I've decided those pieces must be from my precat. After I cleaned everything out of the main cat just a perfectly flat surface of the catalyst was left, not a jagged, broken face. That makes sense, too, given how suddenly my performance decreased. Makes sense that the precat was cracked, then suddenly broke apart and clogged the main cat, causing decreased performance and glowing manifolds.
Last edited by C4ProjectCar; 06-11-2016 at 01:30 AM.
06-01-2016, 12:00 AM
