Spark Plug Reading

[tmsmini]

I have been burning oil on an engine with about 10,000 miles on it.
Today with the time change and running late it was darker when I went up the hill to work. Someone was behind me and I could clearly see as I accelerated up the hill I was burning a good bit of oil.

So tonight I did a compression check, all hovering around 200 psi with a low of 195 and a high of 205. I expected to see at least one cylinder a lot lower thinking a ring was bad. The plugs are in the picture and are not great, but not perfect. I did not drive the car at speed and then shut off mid-stream. I just drove home and pulled in the driveway, so not the best way to evaluate plugs.

I am guessing the stem seals are bad at this point. The engine did sit awhile before it was installed, but was rotated regularly.

Is there a question here somewhere, not sure...

[Willie_B]

The plugs look normal for an engine running un-leaded gas. Does it smoke on start up? That usually means stem seals.

[MPlayle]

Blue smoke, black smoke, or white smoke?

Blue = oil burning -> rings, stem seals, sucked from breathers?
Black = rich fueling -> example: big semi's accelerating and dumping black smoke
White = steam/coolant -> head gasket

[tmsmini]

The smoke on accel I could not tell the color, but there is a blue tinge on startup along with the early morning condensation but it barely smokes at start up.

[MPlayle]

Blue tinge on startup - I would tend to look toward the valve stem seals as the culprit.

[tmsmini]

There was an article at one time on replacing seals with out removing the rocker assembly. I don't remember where I saw it.

[MiniDave]

I suppose you could slacken off the valve adjusters and remove the rocker shaft, thus not having to loosen the head bolts, then put the cylinder on TDC and put air pressure into the cylinder to hold the valves closed, then remove the springs and keepers to get to the seals.

It's possible I suppose, but it seems to me if you're going to that much trouble why not just pull the head, clean all the carbon off the valves and pistons and do it right?

[tmsmini]

Yes, I agree sometimes shortcuts are not worth it.
I found this on another forum not in a  response to me, but to another question.
If it is burning that much oil then it's possible it could be piston rings and bore wear that is causing the high consumption. Before taking the head off, run the engine at about 1000 rpm, take off the oil filler cap and see if it is 'chuffing' smoke out the filler hole. If it is, then it's a bore wear issue.

This has been an interesting engine as it seem to run warmer than other A series I have had and idle oil pressure after 10K miles on hot idle is hovering around 30 psi. It will be interesting to see what happens when it really get hot around here.

[MiniDave]

If you can find someone with a cylinder leak detector, you can do that test and find out where the real problem is.

You put the piston on TDC and charge the cylinder with air pressure.....take the oil filler cap off and listen for air, nothing there the rings are good, no air out of the tail pipe or intake, the valves are good, the oil seals would be all that's left.

One thing I'd check is to make sure the crankcase can breathe so the crankcase doesn't build up pressure and force oil past the rings or seals.

[John Gervais]

I'm curious to why you're using BPR6ES plugs - resistor and projected nose?  I have a sneaky suspicion that your ignition is actually advanced a tad too much and your mixture is a bit too rich. 

I've had much nicer plugs after I started using B6ES - non-projected nose.  With good cylinder head chambers, the non-projected nose plugs burn the mixture completely, with reduced tendency towards pre-ignition.  The ground electrode runs cooler. 

Here's Doug's in-situ tool:

And a fantastic article - although it's somewhat old, it's very informative.  Pay particular attention to the 'fuel film' and how over-advanced ignition leaves a 'clean' ring at the tip of the center electrode.  Is this what I see on the spark plug furthest to the right?

My own 'lopsided' blush with tendency to over-advanced ignition ring plug from cylinder number 3 (if you look closely, you'll see that the fuel film doesn't cover the electrode completely, and even though having a lopsided fuel film is ok, the other side of the fuel film should extend directly to the electrode's tip - which it really doesn't):

My 'Mixture Ring' image shows that my mixture was actually just a tad too rich.

[MiniDave]

John, when I try to read your pdf, I get an error message that says I'm not allowed to use this section?

[John Gervais]

I might have been editing the order of the attachments - try again?

[MiniDave]

Yep, works now.....thanks.

[tmsmini]

This is an MPi engine and the recommended plugs are the RES version. Not sure why they would be different from any other A series except that is is injected.
Thanks for the article. Not sure if they modified the combustion chamber for the MPi heads, but this head was further modified by Minisport before it came to me. I also have a Calver head on another car and I should have taken a picture of the chambers to compare them when the head was off.
I do have a Harbor Freight leak down tester that I will dig out that I have not used in a long time.

This engine uses the Rover MEMS 2J ECU, so no adjustments are really available. I do have another car with the Specialist Components Typhoon ECU where everything is adjustable. I have not yet sorted out the adjustments for that car. Adjustments do not provide any advantage if the basic mechanicals are not functioning properly, like non-sealing valve stem seals. I have some basic front end maintenance to do this weekend, so I am hoping to have enough time left over to take a closer look and do the leak down test.

After reading through the article I wonder if the extended nose plugs are for some emission based reason.

[Spitz]

The OP's picture of spark plugs actually looks like it's running a little lean IMO

[tmsmini]

Finally gave up on the HF leakdown tester and got another one.
About 5 - 8 % leakage
Also adapted the TDC whistle to the leakdown tester.