Burnt Oil In Valve Cover: How Dirty is Too Dirty

[Muzez]

Hi Guys.

Pulled my Valve cover today to adjust the valve lash and noticed that there is a lot of burnt oil on the value train. Is this normal? Or a sign of overheating?

I have only had the car for about a year and a half. It’s had two oil changes in that time over about 400 miles of total driving distance so I don’t think it is due to my care, but no idea about the P.O. I haven’t seen it overheating in the time that I have had it. I do drive a mostly in the city which may have some impact.

If it’s not a big deal, will just clean it up with some acetone and go about my adjustment. If you guys have any suggestions for things to check, let me know!

[Zed Head]

That actually looks very clean.  Not really worth doing more to.  If you start using a detergent oil most of that will clean up as the engine runs.

The brown color isn't from overheating it's probably just from blowby, combustion byproducts that have deposited up there.  Not hurting anything.

The brown color on the cam lobes is because the anti-rattle springs keep the rocker arms off of the cam base circle if the lash is set correctly.  There's no rubbing there, which is good.  It's also a good sign that you don't have any sunken valves since that will reduce the lash.  Can't remember the year of your car (you should create a signature on your profile with information), but sunk valves were a problem before about 1976.

Check the notch and groove on the timing chain sprocket to get an idea of timing chain wear.  Make sure the tight side of the chain is tight and the timing mark is on zero.

[Muzez]

2 hours ago, Zed Head said:

That actually looks very clean.  Not really worth doing more to.  If you start using a detergent oil most of that will clean up as the engine runs.

The brown color isn't from overheating it's probably just from blowby, combustion byproducts that have deposited up there.  Not hurting anything.

Thanks for the detail @Zed Head! Good to know. I have only been under the valve cover of a new engine which had not seen oil, So when I popped this today, there was a moment of panic haha. Any recommendations for a detergent oil with enough zinc content for an L series? Was using a Rotella with zinc additive at the recommendation of some local Z enthusiasts, but I also see Redline and Mobile 1 are recommended around here. 

2 hours ago, Zed Head said:

Can't remember the year of your car (you should create a signature on your profile with information), but sunk valves were a problem before about 1976.

Car is a 1977, so we should be good there. And good hint on the signature. I thought I added it a few weeks ago by populating the "my car" section but now I found the signature prompt buried in a menu haha. 

2 hours ago, Zed Head said:

Check the notch and groove on the timing chain sprocket to get an idea of timing chain wear.  Make sure the tight side of the chain is tight and the timing mark is on zero.

Will take a look tomorrow. Fighting the Thanksgiving Turkey nap at the moment haha. 

[Muzez]

On 11/26/2020 at 4:26 PM, Zed Head said:

Check the notch and groove on the timing chain sprocket to get an idea of timing chain wear.  Make sure the tight side of the chain is tight and the timing mark is on zero.

Hey @Zed Head  two quick follow ups

Checked the timing today. The oblong groove is just before the location notch. The hole above and to the left is the #2 timing mark so we are in between 2 and 3.

Q1: Does the fact that the groove is almost aligned with the notch mean this is something I need to keep an eye on? Or it’s time to change?

Q2: There is oil sitting above the 5 and 6 pistons. Is there be a drain back there? Or the only drain is At the front where the timing chain is?

[siteunseen]

It needs to be to the left a little. But #1 should be back some more. Looks like you went a little too far. I think you're okay. Like Zed said the oil will clean up with new change and adjustment. 

 

[siteunseen]

I should let him take this since you ask hin, not me.

 

[Zed Head]

The FSM shows the "Okay" range as pretty much across the groove.  The notch starts at one side and as the chain wears it ends up at the other side.  If you're in the middle, you can't make it better.

And I think you're still in the "1" hole, see picture.  Your engine seems to be in good shape.  Almost disappointing, nothing to work on.  Something will crop up...

[Muzez]

8 hours ago, Zed Head said:

The FSM shows the "Okay" range as pretty much across the groove.  The notch starts at one side and as the chain wears it ends up at the other side.  If you're in the middle, you can't make it better.

And I think you're still in the "1" hole, see picture.  Your engine seems to be in good shape.  Almost disappointing, nothing to work on.  Something will crop up...

re “OK” range, that is great! No need to replace parts if not warranted haha. 
 

re: “something will pop up” please knock on wood for nothing to pop up haha. I am okay delaying any major issues indefinitely. 😛 I have more than enough work this winter between replacing the fuel injector connectors, troubleshooting the BCDD, finding my vacuum leak, and sealing my exhaust leak haha

8 hours ago, siteunseen said:

I should let him take this since you ask hin, not me.

 

Contributions are always welcome @siteunseen  I have a lot to learn and many hands make light work. 🙂 

[Muzez]

@siteunseen & @Zed Head one more thing. You mentioned that I am in the #1 hole. Just saw the #1 below the window you guys highlighted. So what does the #2 indent at the top of the pulley mean just below the chain? Is that where to set the bright chain for the #2 window then?

[Zed Head]

Engine Mechanical chapter.  There's a lot in it you can go through it many times and always pick up something new.  The bright link is not really needed if you have the notch, and the ignition timing marks on the damper.

Get Monroe's "How To Rebuild... book.  https://www.amazon.com/Rebuild-Your-Nissan-Datsun-Engine-ebook/dp/B006VUICHG

[240260280]

You are on cam position #1.  That is fine.  Your mechanical valve timing is a little advanced as shown by the triangle indicator which is fine.  Seems to be a new non-stretched chain.

When you get a couple hundred thousand miles on your Z then you can go to position #2  to take up chain slack.  You have no worries and are good to go.

[Dave WM]

get a close up of the tight side timing chain guide. looking for wear in the plastic part. Note using the wrong bolt in thermostat housing can ruin your day, its a through hole that can allow a too long bolt to press that guide into the chain. Check your water pump for play in the shaft. I agree with the others, the engine looks pretty clean to me.