Oil drainback question

[NJTB]

The other day I changed my oil, and when I poured it in noticed it seemed to take a long time to drain back to where it started reading on the dipstick. I'm thinking maybe 2 minutes or a little more, then went right up to full.
In the old days, (chevy 350) when the oil was poured in, it registered on the stick almost immediately, less than a minute.
So now I'm worried the head has gunk and is slowing down the oil drainback, and REALLY don't want to pull the valve cover to check.
This vehicle has been over maintained since I've owned it, and gets oil changes every 3000 or 3500 miles with synthetic Pennzoil. There is no buildup in the oil cap area where I can see.
I'm sure someone on this list is as anal retentive as me and noticed this. Anyone? Is it a potential problem?

 

[IllogicTC]

It seems pretty normal to me. These (and many other modern) engines have a lot more little passageways oil has to go through - and there's also an anti-drainback setup in/near the oil filter, so it can't travel that way to hit the bottom more quickly. If the old oil coming out the bottom drained briskly enough and doesn't appear to have any problem indicators, I'd say you're okay.

If oil was having trouble traveling I would expect you would get a pretty annoying valvetrain noise for at least a few seconds on a cold start (rather than maybe just a couple ticks til oil gets going), and if severe enough you could get VVT codes as the VVT relies on oil pressure, or possibly even a STOP ENGINE warning on the DIC for a moment after startup, or even when randomly going down the road.

 

[NJTB]

Thanks for the reply, it's one of the rare instances I heard what I was hoping for.
This engine does have a minor noise when cold, a tap going at piston speed, but after driving a few minutes, it idles just fine. No noise, almost wouldn't know it was running. I'm not too worried about it.
Back in the day when I was a mechanic for a Cadilac/Buick/Olds/ Pontiac dealer, there were NEW cars that came in with a bearing knock. The fix was a .001 oversize bearing in #1 crankshaft main. Of course, GM's service bulletins said it was nothing to worry about, and it really wasn't from a mechanics viewpoint.
After the bearing was installed, a few of the mechanics had the engine seize before they even got it off the lift. Most worked fine.
On this engine, I worry about most everything, because I know it's pure bitch to repair.

 

[808_LS_EXT]

I wouldn't be so quick to dismiss this warning sign.

I just changed my TB’s oil and the 7 quarts flowed to the bottom of the pan as quickly as all the SBCs I've ever done.

FYI:

I recently looked at a Envoy for sale... the engine was locked up because the oil was not draining out of the cylinder head quick enough to feed the oil pump... the oil pump starved and a bearing burnt.
I could see varnish built up in the filler neck.

Also, I've come across many Dodge Intrepid 2.7L V6 with the same problem as that Envoy ...

The problem is the oil return passages are small to begin with... then get sludge built up in the cylinder head and the “returns” become clogged... basically filling the head/rocker arm cover with oil and starving the crankcase.

Are you the original owner? Do you know the engine oil change history?

If you look into your rocker arm cover through the fill hole, do you see any sludge or build up at all?

Try this:

Check your oil level after sitting for a couple of hours... full on dipstick?

Now, run the engine for 5 minutes, stop engine and immediately check level again... how much is missing from crankcase? Hopefully, very little.

But if it is more than just a little, then that's how much oil is trapped in the cylinder head… indicating restricted flow.

If I check my TB oil level immediately after stopping the engine, I’m about ¼ of a quart low.

 

[808_LS_EXT]

This vehicle has been over maintained since I've owned it, and gets oil changes every 3000 or 3500 miles with synthetic Pennzoil. There is no buildup in the oil cap area where I can see.
I'm sure someone on this list is as anal retentive as me and noticed this. Anyone? Is it a potential problem?

Well, that answers my questions... I guess I shoulda read your post thoroughly...

I still think you should try checking the level immediately after shutting it down.

 

[smokey262]

Doesn't really answer your question because he didn't indicate how many miles were on it when he got it

 

[Mooseman]

Very strange indeed. When filling from the oil fill cap, the oil hits the VVT cam phaser and then travels down along the timing chain and then directly into the oil pan. To prove this theory, you can see the phaser spinning if you open the fill cap and look inside while the engine is running. You can see what I mean by looking at my How to replace I6 timing chain and tensioner article.

 

[NJTB]

Ooh, boy.
I bought it in 2007 with 30,000 miles on it. Now the TB has 97xxx, and it's a problem I suspected was happening about a month ago. I checked the oil after running it and it was a quart low, but 5 minutes later it was full again. The truck never burned oil or made any noises that were a concern and has really run well all this time.

For the damage potential pulling the valve cover is the best idea but after the thermostat/water pump/SAIS valve/stabilizer link/stepper motor repairs this year I'm a bit tired of working on it.

My other thought is to pour a quart of diesel into the oil and let it idle for 1/2 hour, then change the oil again and hope it cleans it out.

Mooseman-I've never been inside this engine, but from your post I gather when the oil is poured in there is a passage where the timing chain is right to the oil pan?

 

[NJTB]

Can't edit, but I clicked on the link and see it now. Thanks Mooseman.

 

[ek02]

The noise you hear when the engine is cold is piston slap if it is a 4.2. I have a 2002 TB with 117,000 miles on it. I bought it from a family member at 85,000 miles. She told me it had the noise since new. It was over maintained in every way. It still has the slap and it is no worse than when i got it. It goes away when the gauge gets to 200 degrees. GM had an extended warranty policy to 100,000 miles because of complaints about the noise. They would not repair the noise because it was considered "normal". When I was a Fleet Manager with an all GM fleet, I had access to factory service bulletins. They said the reason the piston slap happens is because the pistons were not select fit to each cylinder. The block was final bored to the correct dimension and the pistons installed. Problem was, the pistons were not all exactly the same. Custom JE forged pistons that I buy are all exactly the same. Big difference in price too. A family member had a new Malibu that had a really loud piston slap that went away in a few minutes and never caused a problem.Our family Hondas are dead quiet all the time. Difference in piston quality in my opinion. I never noticed the drainback delay on my 4.2, but then I just dump 7 quarts in and go. I cant imagine you have sludge with that oil change interval, unless you only drive 2 miles a day and never get to operating temp. I have a deep knock for a few seconds after start up when the engine is really hot. That is the front upper main, but does not concern me. The second the oil pressure comes up it stops. I remember the .001 larger upper front main bearing trick. Belt tension wore it more than the rest. Customers did not like to hear that thud type knock. I would run the engine for a while, then shut it off and check the level and see how low it gets and than how long to come back to full. I tried it on mine and it went 3/4 Qt down right after shut down, and then took 4 minutes to reach full again.

 

[Mooseman]

Mooseman-I've never been inside this engine, but from your post I gather when the oil is poured in there is a passage where the timing chain is right to the oil pan?

That is correct. But if the drain back from the lifter valley is slow after running, I don't know if I'd even bother taking the valve cover off. I'd believe it in an engine that has never had an oil change and severely sludged but these engines are sensitive to oil with the VVT system and you're good on your oil changes.

 

[IllogicTC]

Diesel, or kerosene. Kerosene works, too.

Some people around here also subscribe to giving Seafoam treatments.