[mpneroz]

Need input here. Had the 3.8 turbo engine completely rebuilt, spared nothing. Car still has some type of mild engine noise (Knock?). A lifter collapses and at start up takes a little while to pump up? Changed out lifters (warranty) doing the same thing. Motor has <img src="http://forums.aaca.org/images/graemlins/frown.gif" alt="" /> new oil pump, fuel pump bearings, .030 over bore, reman GM heads and all the rest replaced by local machine shop, it's driving me nuts. Car runs strong now but noisy! Is turbo/non turbo block, crank etc the same? A lot of rebuild parts are turbo specific. What year short blocks, heads etc are interchangable?

[imported_Turbo Loyd]

Was the clearance between the oil pump gears and the cover with the oil filter checked. There are several gaskets available to make this clearance on spec and if not right you will not have sufficient oil pressure.

What is the oil pressure?

[NTX5467]

Other than the oil pump issues, were the oil galleys checked for obstructions AFTER the engine was vatted?

Seems like there is an "OEM spec" way to position the cam bearings in that motor and a "better" way that many engine builders do it to make sure that the oil supplied to the camshaft journals "leads" the rotation of the camshaft rather than "following" it. My machine shop associate explained that to me a while back. Not sure if that might affect the oil supply to the lifters, but it might.

Also, there is a recommendation to drill out the main oil galley to the same, continuous size, front to back. The "as cast" galley is finish-drilled from the front and back, but does not "meet in the middle" as you might suspect. Resulting in the galley diameter for the middle main bearing to be smaller than the rest of the galley--the same middle main bearing that usually knocked on the motors IF their maintenance was iffy (usually by about 80K miles). I believe this modification is outlined in the Buick Turbo Performance Manual (or whatever name they put on it back then).

The other thing would be to make sure that the bearing journals were of the correct sizing, even if they were "professionally" done. If the journals might be of the correct size, the chamber on the edge of the journal (the transition area between the bearing surface and the counterweight on the crank itsel) might not be done correctly. By observation, this is another area of quality control that many crankshaft shops are somewhat "lax" on.

You can either use the micrometer to measure the bearing journal and such, but using Plastigauge (if done correctly) will give you the assembled clearance when the main cap/rod cap is bolted down. Perhaps the basic clearance are a little "loose" on one journal and that's affecting the oil to the particular lifter oil passage?

What about piston type and piston clearances? Noise issues can arise there, too.

There might be some other issues (i.e., oil brand and viscosity, oil filter brand and drain-back valve type, if equipped), but I suspect they would be minor compared to internal oil galley and pump issues.

Is this a "cold engine" knock, "knock" on acceleration, "cold start" or "initial start" knock (until the engine gets oil pressure), or the lifter noise mentioned?

Just some thougths,
NTX5467

[mpneroz]

Does not knock at startup lifter collapses sometimes, other times it doesn't. Knock seems to come once car is driven for a while. One person I know suggested it might be a loose flex plate/ torque converter issue? I don't think so, but that can sound like a knock. That's a start. I ran 10-40 in the thing, seemed to be too thin. Went to straight 30 now. Gonna have to check oil pressure. Knock seems to be more prevalent at fast idle but seems like it doesn't get louder on exceleration. If you run along a stationary object (wall, highway divider) you get no knock noise back at you. Got about $1600 into it and end result isn't what I would have liked. I had origionally considered doing a 350ci Buick installation in the thing and running the V8. Almost sorry I didn't now cause the cost of ripping it apart again will be costly if I have to.

[NTX5467]

Thanks for the updated information and comments.

Some thoughts, IF the lifter "collapses", sometimes, that would point to an oil supply issue to the lifter galley. On some Chevrolet big blocks, they used to have an intermittant lifter noise after an oil change, or after sitting for a while. What was happening was air was being trapped in the lifter galley and was exiting, sometimes, via the lifter's oil supply. The fix . . . drill a .040" hole in the lifter galley screw-in oil plugs (this was a running change in production, back in the middle 1970s) so the air could get out rather than be purged via the lifter's oil supply. The engines generally sat lower in the rear, so the air would best exit front the front of the engine. Also lubed the cam sprockets/chain better too. I might be incorrect on the particular hole size, but it might be closer to .020" or .030".

From what I understand, valve train "clicks" (like a lifter that is not adjusted correctly, if it can be adjusted somehow) can also happen from valve stem-valve guide clearance issues. When that particular clearance gets out of spec, it can also lead to additional oil consumption via the valve guides (even with seals in place).

Where "knocks" take place (rpm and load wise, plus engine temperature) generally point to where the issue is originating. Main bearing knocks happen under particular conditions, just as connecting rod knocks and piston pin noises too, have their own rpm and load criteria. An old MOTOR manual has that sort of information in it, but other sources might also.

A loose flexplate would probably show up as abnormal starter noise (when starting the vehicle), due to the changing relationship of the starter drive gear and the ring gear on the flexplate (flywheel). If there's some misalignment in the engine/trans mating situation, it CAN crack the flex plate which CAN generate an unusual noise.

The "10" in 10W-40 is for "zero" degrees and the "40" is for operating temperature (say 180-210 degrees F coolant temperataure). Some multi-weight oils will tend to lose their viscosity after running for a while (such that in the 1960s, a 10W-30 would allegedly end up like a 20W-20 oil), but newer oils should remain more true to their advertised viscosity rating. A "straigt weight" oil (i.e., "30" or "40" or "20") tends to be more stable, viscosity-wise, but my experience is that a 30 oil "flows" about like 10W-40 oil flows. At room temperature (ambient) temperatures, the 10W-40 oil might flow more like a 30 oil anyway.

As the noise will not reflect from "walls", it might be that it's really a noise that is telegraphing from the engine to a body/chassis part. Some "metallic" path that was previously insulated, somehow.

Harbor Freight and some of the tool companies have stethoscopes to listen to engine noises with. The "broomstick" method can work too, but it's more cumbersome to get where you might need it to be. In this search/diagnostic situation, you'll hear just how much "noise" is really inside the motor, but the noises you're hearing should also be there too, hopefully.

I'm not sure where this is going to end up, but making sure that everything is as it should be (metallic noise paths, etc.) and possibly determine which part of the engine the noises are coming from before pulling it back apart might help in looking at various things in the engine when it's apart again. Hopefully, you can build some strategies to figure out what's happening and why BEFORE getting the engine out of the car.

Hope this might help,
NTX5467