I’ve been grappling with an issue of oil consumption, which persisted even before I addressed the head warpage by skimming the heads by 0.1mm, replacing the valve stem seals, and replacing all gaskets and head bolts.

The engine is using about 1L of oil per 1,000 km. I’ve already replaced the PCV valve with an OEM part via ebay, inspected the breather hoses, and installed a catch can, which does seem to function, though it captures little oil compared to the consumption.

Following this, I conducted a compression test, yielding these results:

- Cylinder #1: 150 PSI
- Cylinder #2: 160 PSI
- Cylinder #3: 160 PSI
- Cylinder #4: 160 PSI
- Cylinder #5: 160 PSI
- Cylinder #6: 170 PSI
- Cylinder #7: 160 PSI
- Cylinder #8: 170 PSI

Subsequently, I performed an engine flush using Liqui Moly Pro Line, refilled with Motul Specific 913D 5W30, and added LM Oil Saver and Oil Smoke Stop, ensuring the total oil volume matched the 7.8 liters specified in the manual. Additives add as per instruction, no more and no less.

Over the last couple of days, I’ve been driving the car at 3,500 to 4,500 RPM on the highway, mainly in third gear, while monitoring oil, coolant, and transmission temperatures via OBD, theorizing that if the rings were stuck, this might resolve the issue. It appears I’ve used about 0.25 quarts of oil over 200km.

My next step is to acquire a leak down tester, which should arrive in about two weeks, and then perform another compression test.

The car consistently emits a burning oil smell from the exhaust, despite replacing all seals and gaskets, I’m confident there are no leaks in the engine bay. Additionally, when driving downhill for extended periods and then accelerating, the car tends to emit smoke.

I’m seeking advice on whether my approach is sound or if there are any steps I’ve overlooked.

2003 XKR 4.2 Supercharged.

 

I would switch to 10W40 before thinking of doing anything mechanical. How many kms on the engine?

 

After fixing the heads I did add 10w40 and drove it for 2,500 km, but that did not make any difference.

The milage is under 75k miles.

 

sorry if I missed this being mentioned;

what do the spark plugs look like ? Do all of them look like oil burners, or just a few ?

Z

 

Bank 1 has a few oily ones. Here are some pictures of the plugs with cylinder numbers. Hope its clear. Thanks

 

Something looks suspect with cylinder 1. It could be a burnt valve or similar except that they will have been reground so I suspect the problem is in the piston area.

It could be worn bores or stuck/broken ring on that cylinder but whether that would use so much oil is debatable. I would check the compression again both before and after adding a few mls of engine oil to each cylinder. If the compression increases when the oil is added, then that would confirm a bore/piston/ring sealing issue.

Richard

 

stuck rings

just keep adding oil

 

Fact: Warped head .

Which you’ve fixed. I can’t recall from your other thread if know why it warped, but most often it’s from overheating. I see where you mention monitoring the engine temp via your OBD-II reader device. That not withstanding, I’m leaning toward some overheating episode happening. Otherwise, what explains the head warping and the head gasket failing ?

Wise men & women of the forum, please correct me if that’s not the case on the X-100’s and there are other typical causes for head warping incidents.

You mention that you had the oil consumption before fixing the warped head. But did you have the issue before the incident that caused the head to warp ?

The oil consumption is so excessive that it rules out many of the usual suspects.

what does the interior of the intake tube look like. It’s not oil coated ?

Actually, with that much consumption it’d be dripping with oil if the full load or part load breather was at fault.

Youve replaced the valve guide seals, so that’s one less possibility.

you have decent compression, so no broken piston or holed piston.

We are left with not many other possibilities besides the oil control rings.

They can either be broken, or stuck (as mentioned by @xalty , or seized.

I'm defining “seized” as being different than merely stuck by deposits of some sort. My training and experiences have always connected a part being seized with too much heat

Assuming you did have a serious overheating incident, which caused the head to warp and head gasket to fail, it’s very feasible that one or more oil control rings could get seized, or even broken.

I’ve seen many motorcycle piston rings that were seized subsequent to an overheating episode.

Hopefully I haven’t taken a long trip down a rabbit hole, or followed a
red herring. But it’s happened before.


Z

PS: oil consumption can be explained by having a cracked cylinder wall. But I don’t want to sound any alarms in that direction without more information.

 

Errrrr ..... not only was it little ol' me, but I also explained how to confirm whether the rings are the problem without any engine strip down. 😉

Richard

 

I guess it was both of y’all. Totally inadvertent to omit your contribution.

my bad.

Z

 

Does it smell burnt oil in the engine bay when engine is hot?
If your valve covers are leaking on to the exhaust manifold it will burn off and be nearly invisible (specially on the right side where the induction tube is covering the view).
I had this on mine, caused by a crack in the lower rear corner of my right hand valve cover.

 

I appreciate everyone's input. Here's a brief history of the car. There is only one xkr coupe in the country where I reside. I could not import a good example due to a regulation that prevents importing vehicles older than five years.



This particular car had been abandoned outdoors for several years. Upon discovering it, it was in a barely operational state with under 75k miles. Despite its issues, I was determined to restore it. The initial steps involved replacing the oil, coolant, a damaged expansion tank, coils, spark plugs, MAF, PCV, air filter, and water pump. I then noticed a coolant loss, suspecting a faulty head gasket. A block test later confirmed combustion gases in the coolant, indicating the car had been overheated and likely abandoned as a result. Additionally, the car was consuming oil, evident through exhaust emissions and leaks from the valve covers and oil pan.


I procured all genuine parts and adhered to the AJ V8 university manual to ensure the engine restoration was completed correctly and to torque specification.


The entire process took six working days, although I faced delays due to broken bolts around the intake and supercharger, which required a screw extractor for removal. The most challenging part was removing the crankshaft bolt and pulley. Thankfully, i bought the timing tool which was very useful.



Upon inspection, the engine block was in good condition, apart from cylinders 5 and 7, which were unusually clean, indicating water leaking into combustion chamber. I also replaced the OEM valve seals while the heads were at the machine shop. The heads had a slight warp that a 0.1mm skim fixed. This is the only step that I did not do myself, hence wanting to confirm if they did a proper job with the valve seals by doing a leak down test.



After reassembling the car and addressing all leaks, the car continued to consume oil, particularly noticeable by the odor it emitted (burned oil smell from exhaust). The car doesn't smoke continuously, except after a long downhill drive, and I'm unsure if it smokes on startup due to the current cold weather, which might make it appear as water vapor.



I suspect the oil consumption issue might be due to a stuck, seized, or broken oil ring, though a leak down test will provide a definitive diagnosis.



I plan to conduct another compression test (both dry and wet) once I receive the leak down tester.



In the meantime, I'll be driving the car at high RPMs (3,500 to 4,500) for 20-minute intervals after warming it up, monitoring the oil, coolant, and transmission temperatures, in hopes that this may help free any stuck rings, according to some recommendations. I'm cautious about whether this method might cause further damage to the engine.

Also the breather tube from PCV to throttle is oily, while the other tube is dry. I installed a catch can between the pcv and intake for the time being. I made sure the diameter of hoses used is the same as the breather.



Thank you once more for your advice and encouragement. The thought of disassembling the engine again is daunting.

 

Thank you for the detailed history of the car as you know it .

If only everyone began their inquiries with such detail it would be immensely helpful in troubleshooting and problem solving.

i think you are mostly on the right path.

The only problem that you might have is depending on a leak down test to pinpoint a stuck or seized oil control ring. The compression rings might hold the leak down pressure well enough to keep a problematic oil control ring from being revealed. But I’d still start with the leakdown test anyway. As you say, disassembly Is daunting. I’ve been avoiding it myself.

When you had the head(s ?) off were the cylinder walls in good condition ? No mysterious vertical marks.

Z

PS: I don’t think you’ll hurt anything by driving the car as described. It might be helpful to continuously vary the rpm as much as possible.

 

Thank you, Zray, for your insights.

While waiting for the leak down tester, I’m also considering performing a piston soak for several days, manually rotating the engine every six hours. Given it’s a V engine, I may need to address each bank separately, potentially elevating one side of the car to facilitate the soaking process.

The Berryman B12 Fuel Injector Cleaner comes highly recommended, but unfortunately, it’s not available locally. I’m exploring options for shipping it here, while also looking into possible substitutes for the B12 cleaner. Did anyone try another product.

Only downside is I will have to flush out my new oil.

Any thoughts on the piston soak method that might free oil rings?

Thanks

 

I wouldn't do anything until you have determined that the rings/bores are the problem. You could do this with the compression tester that you already have.

If the rings are the problem, you could try filling the compression space with diesel fuel and leaving it to soak before turning the engine over on the starter. You could repeat this several times and retest the compression and see if it has increased. I'm not optimistic that you will be able to unstick any rings sufficiently to make a real difference but it might be worth a shot.

Richard

 

Hello,

I've successfully completed the leak down test, and all cylinders appear to be in excellent condition with no leakage.

A couple of weeks ago I had someone follow me while driving, and it was observed that most of the smoke is coming from bank 1. My exhausts are separate, each bank has its own lone. Additionally, the EGR to intake passage is heavily soiled with soot, which aligns with it being connected to bank 1.

Interestingly, while taking the spark plugs out during the leak down test they looked in better condition than before (dry). Pics from bank 1.

With this information at hand, does it suggest that the issue might be with the lower oil rings? Not sure if it’s something else, such as SC waste gate but doubtful. I might go ahead and do the B12 piston soak. Thoughts?

Thank you.

 

Those bank 1 plugs do look much better than before. I would have thought that if there were a problem with any of the rings you would see the results on the plugs.

I wonder if the car is burning less oil now that the plugs look better?

Richard

 

Hello Richard,

I believe the spark plugs are in better condition because I drove the car between 160km/h to 200km/h without braking on the highway for 30 minutes, the day before I took the plugs out. I carried this out at night when the streets were nearly empty of cars.

After further investigation, even though I had perfect results, I've learned that a leak down test might not be able to accurately identify if the seals are compromised, as it's performed with the valves fully closed. I'm somewhat skeptical about whether the machine shop 100% correctly, or at all, replaced the seals.

Before considering a piston soak, my next step is to purchase a borescope to inspect the cylinders following a rigorous drive, and then again after the vehicle has been stationary for a day. This will help me determine if oil is leaking through the valves. I'm hoping that if there's a leak, it's due to the seals rather than the valve guides, as I'd like to avoid removing the heads again. However, I'm unclear on how to assess the condition of the guides.

I need guidance on removing and then correctly reinstalling the camshafts while keeping the heads in place, especially after replacing the stem seals. I do have the full timing tool set, as I've removed the heads previously.

Your advice would be greatly appreciated.

Thank you.

 

That's interesting. My first suspicion was valve stems and/or seals rather than rings as worn or sticking rings usually cause other symptoms whereas worn guides/seal burn oil but that's usually about it. If you've had the heads off before and have the camshaft alignment tool then it's not too difficult to remove the camshafts. However, You'll need to remove the valve springs to access the seals and I can't see how how can do that without removing the heads. Obviously, once the heads are off you can also check the play on the valve stems and replace valves and guides as necessary. You can't check this area of wear without removing the heads.
How many miles has the car done?
I should add that mine is a 4.0 normally aspirated XK8 and I don't have any experience with the forced induction version which will, inevitably, be more complicated. However, if you have downloaded the workshop manual then that should provide the information required.
Richard

 

Thank Richard,

I can remove the valve stem springs with a specific tool available for purchase. However, I'm struggling to understand how to detach and reattach the chain on the camshafts without having to remove the timing cover. I do possess the manual.

The thought of disassembling the heads is daunting because it means I have to take off the throttle and supercharger once more, possibly needing to replace the new gaskets again.

Thanks