Hello again fellow forum members,

Many months have passed since my first post here. I can safely say that I now fully understand the schizophrenia we all have when it comes to our Jags: they do hate us but boy do we love them!

Some of you may have seen my thread 4.0 V8 - Misfires only at low RPMs and other related symptoms where I started the process of diagnosing a 2000 4.0 V8 S-Type that came to me from a family member where it sat neglected for a few years. A lot has happened since then and I want to thank ALL of the members of this forum that have left their knowledge and helpful tips over a span of many years, all of it extremely helpful and saved my butt plenty of times when working on the car.

Now, cutting to the chase, here is the list of everything I've done so far (bear with me if I miss something, it was a lot):

• Oil change
• Coolant flush and change
• New oil filter
• New air filter
• New fuel filter
• New spark plugs
• New water pump
• New thermostat and changed the plastic to an aluminum thermostat housing
• New coolant hose that runs beneath the intake manifold
• New isolation pad beneath the intake manifold (Yes, I know )
• New serpentine belt
• New seals and gaskets everywhere I touched (e.g. valve cover seals, new VVT solenoid seals, spark plug seals, intake manifold gaskets, water pump gaskets, IAC and throttle body gaskets, assortment of o-rings of some miscellaneous things such as the oil dipstick and so on)
• Cleaned the intake manifold of carbon
• Cleaned the valve ports and valves of carbon to the best of my ability
• Cleaned the throttle body (and carefully not to remove the coating)
• Clean the IAC
• Cleaned the MAF
• Filled the fuel rail to the brim with carb cleaner to clean the injectors during the car's first start up
• Did the throttle body reset position procedure
• Checked the battery health and cleaned the battery terminals
• Dropped some oil into the cylinders for a less "aggressive" start
• Verified that the tensioners were changed to the 3rd generation metal ones
• Torqued every single part and bolt to exact spec when getting everything back together

Yesterday it was finally time to start it back again and unfortunately the problem remains. Many months of hard work, research, Brexit related delays and problems when it came to importing parts and COVID related hurdles meant nothing. At first, everything seemed fine and smooth but, after a few minutes of idle running, the rough idle and misfires came back just like before. All the vacuum leaks that were fixed solved nothing.

There is a silver lining on all of this however and this is where I need your help.

Since I added oil to the cylinders, there was obviously a lot of smoke from oil burning on first start but, unexpectedly, there was smoke also coming out of the engine bay with some pressure. It was NOT smoke coming from beneath the car from the back, it was coming out directly from an area of the engine. The best way I can describe where it's coming from is the area around the exhaust manifold of the driver side (left hand drive). The smoke from the engine bay is only coming from that area and I was not able to pinpoint the exact source of the smoke apart from what I already mentioned. After the smoke from the initial start up cleared from the exhaust, the smoke coming from the engine bay also cleared, as such, the car is not burning oil at all right now, only the one that was in the cylinders that I added and by now already cleared.

Fortunately, I managed to take a photo soon enough to show what I am talking about. The circle is the smoke that is coming from the engine bay and the arrow is the general area where the smoke is coming from.



Can this be an exhaust manifold leak? The reason for the rough idle and misfires a few minutes after first start due to the leak affecting the o2 sensors when the car switched to closed loop? I am going insane here! Help! I want to save this cat!

PS: No check engine light or codes at all.

 

I do NOT see new on-plug (or Coil On Plug) ignition coils on your list.
They fail so often I used to keep a few in the boot when I owned my 2001 4.0 S-Type.

I still have BOXES of the old ones from working at the dealer when the X200s were NEW.

The GREEN and YELLOW label COPs were the worst. The later BLACK label ones were a bit better.

 

Hello there!

Indeed I did NOT get new coil plugs. And believe in me when I say you and other fellow forum members engraved permanently on my brain that I really need to change them. The reason I did not do it yet is simple. There was a substantial list of things to do and some major and minor vacuum leaks to fix. Those things had to be done regardless and were the most complex and time consuming ones.

The plan was, if none of what I did fixed the issue (which it didn't), coil plugs were next in line. However, as mentioned, the oil smoke "leak" appeared by pure chance and I would like to get to the root of it first.

Also, regarding the coil plugs, 6 of them are these ones:



Are those the awful ones you mentioned? The other 2 have no label/have a smooth black top with no markings.

 

What do the STFTs and LTFTs look like? The readings are a good indication if there's still a vacuum leak present.

 

I am not with the car at this time. On Friday I can give you all the details you find relevant.

Any ideas regarding where the smoke may be coming from?

 

What type of smoke are you seeing? Is it engine oil getting onto the exhaust manifold and burning off, or is it exhaust smoke?

If the smoke is exhaust gases, check the welds around the catalyst body on Bank2 as I've seen exhaust leaks from those areas, which can set a DTC and turn on the MIL. Also, check the catalyst to exhaust manifold flange for tightness and signs of carbon.

 

The smoke was only visible for a couple of minutes after the first engine start. It was smoke related to oil burning in the cylinders (which I added on purpose). As soon as the exhaust cleared, the smoke leaving from the engine bay cleared as well. Hence, why I assume it may be an exhaust leak.

Thank you so much for all the tips, I'll be sure to check all the points you mentioned.

 

Do you have a recommendation as to a preferred brand of coil-pack for the OP? Obviously, no name coil-packs from eBay are the root of many headaches, but in the aftermarket are any units better than the others, quality/reliability-wise? For the V-6, I tend to prefer NGK or Delphi, but for the early V-8, I have no clue as to what is available and what is best...

 

I have not had to replace any in a few years. The pic of the black labeled coil is the one that was most reliable.
I'm sure the brand name aftermarket coils will work fine.

 

I highly recommend that you purchase a SMOKE MACHINE. There ius a guy on Ebay or Amazion who fabricates a simple machine for less than $100.00. We use it in our shop, particularly on late model Jags and Rolls Royce. It will help you isolate any leaks in almost every portion of the car .

 

Did you check the o-ring on the dipstick and the oil seals on both top and bottom of the oil filler?

 

When I was working at the dealership we used to replace the exhaust manifolds on the early S-types for cracks they would tick when first started but it would go away when hot. Never saw any smoke but if tyhe crack is bad enough there may be smoke.

 

About the only oil leak causing the smoke can come from a few places. 1. spilled during repairs. 2. The oil pour tube (o ring or broken at connection point) on the cam cover is leaking. 3. Your new gasket on the cam cover is twisted or installed incorrectly. Coils. Coils and plugs should always be replaced together. Amazon sells and coil set Evan-Fisher EVA13872065006. I've had these on the engine for 40,000 miles with no issues. The whole set was a hundred bucks.

Finally, get those zip ties off the connectors to the coils. If you've broken a clip, it is better to use electric grease (very sparingly), make the connection, and then carefully tape it to the coil. The zip tie pressure could pull the wires out of the connector or break them.

Sorry your oil leak is on the driver's side. That is about the worst place to work on this engine. Terrible engineering with access and placement. Good luck.

 

My friends, it was a very long day, I am very tired and I come with very bad news.

There is oil in the exhaust manifolds. It starts burning as soon as the engine starts warming up and the amount of smoke rises substantially when you increase the RPMs. There is no oil coming out directly from anywhere, it is going into the exhaust manifolds directly and leaking outside. This means major internal problems and I have to say I am very saddened by this.

Do any of you know exactly what is causing this? At this point I don't even know if it's even worth to get someone to take the engine apart and rebuild it.

Here are pictures from both the exhaust manifolds from the bottom where you can see the oil leaking. There is no oil at the top at all.

 

Step back from the ledge! Don't jump!

Unless you are a climate change researcher, don't aim for a predetermined conclusion. Go where the troubleshooting actually leads you, not where you fear it might go.

The conclusion you have reached is HIGHLY unlikely. To have oil leak out like you're thinking, you'd have to have two major issues active at one time. You'd have to have severely worn piston rings and/or valve seals to dump that much oil into the exhaust. And then you'd have to simultaneously have a major exhaust leak to let that oil escape.

Now it does appear you have an exhaust leak. But I'd be willing to bet your reputation that the oil you're seeing is the remnant of what you have previously added to the cylinders. To fully clear it out, It might take some hard driving for 50-100 miles. (If using the metric system, that 50-100 miles) If you've only been running at idle or putzing around the neighborhood, you've still got plenty of excess oil in there. Don't scare yourself of some major internal damage.

Some steps to take:

Fix the exhaust leak. This can affect what the O2 sensor sees and contribute to rough running.

Review all previous vacuum leaks that were repaired. If you insist there are no leaks because you replaced those suspect gaskets, I shall force you to watch "Beaches: The Director's Cut" until you beg for mercy.


There are no guarantees a new gasket is sealing properly. Maybe you've got a warped casting or a gasket didn't fit properly. Retest to be sure.

Consider replacing the coils. This has been previously discussed.

Check the fuel pressure at the injector rail with a mechanical gauge. This was suggested in your other thread, with no mention that it was accomplished. Do not rely solely on the scanner reading. The poor computer will happily regulate fuel pump output inaccurately to match a bad sensor and never set a fault code.

 

Once again, the leak is above the manifold in 99.9% of the cases. When the engine is COLD run your finger along the bottom of the cam cover just above the manifold. I bet you find a bit of wet oil there. Next, start the engine and run it for 10 seconds and repeat the process. One of the best ways to see it is with an inspection mirror but you should be able to feel it first. That cam cover can leak for several reason. Crooked gasket, the gasket not under the bolt, bolt bushing not right. Good luck.

 

Your theory makes a lot more sense than mine. To have that much oil collect externally, it should be fairly easy to isolate the source.

If the “white glove” test doesn’t find the source, consider doing a smoke test. I had an oil leak on my pickup that was hard to isolate. Thirty seconds with a smoke machine and the exact spot was plain as day.

 

Hey there everyone.

So, first of all, thank you so much for your post kr98664! It did cheer me up!

Now, I must make something very clear. There is ZERO oil coming out from anywhere in the engine. No, I did not reach that conclusion out of thin air or just by a vague look around the engine. I used a borescope on all areas of the engine and saw clear as day that the seals are perfect, everything is bone dry and there is no oil at all on top of the exhaust manifolds. I even cleaned thoroughly the oily areas in the exhaust manifold with a ton of brake clean and a rag and they came back exactly the same way as before. I repeat, there is no oil coming out of anywhere and the top of the exhaust manifold is completely dry.

With that said, I will do what is left for me to do in regards to the recommendations I got here. I will:

• Change all coils
• Check the cylinder compression
• Check the fuel pressure on the rail
• If doable without removing the engine, take out the exhaust manifolds and replace the gaskets

With that said, I am not optimistic.

As mentioned, I used a borescope and I have some images some of you may find interesting. I don't think they will help reach a diagnosis but I'll leave them here.

All valves kind of looked like this. Tons of nasty carbon (and this one was taken after cleaning it).



7 of the 8 cylinders looked "normal" in terms of carbon build up, just like this one.



One of the cylinders is caked in carbon however. Any idea why? Really nasty amounts of build up.



This last one was after I got the car running again (after everything that was done in the first post) and it has some sort of residue on the sides? Fresh gas/oil?



Thank you all for the help so far!

 

How much have you driven this engine since trying to bring it back to life? Over the years, I have revived several dormant engines. In nearly all cases, they ran somewhat poorly at first. I think the main culprit is piston rings getting stuck in their grooves, various seals losing flexibility, and other things like that. It took some spirited driving to help free up whatever wasn't seating properly. I would be very hesitant to condemn an engine like yours without first working it hard and seeing if that helps. Running at idle just isn't enough.

After that, examine the case for your boroscope. Does it have provisions for a padlock? If so, put the boroscope in the case, lock it up, and then have somebody else hide the key. Give them strict instructions not to give you the key, no matter how you might beg or plead. I say this because at this stage in troubleshooting, the boroscope is mostly scaring you silly, versus offering any useful information. Carbon inside an engine is normal. How much is normal? I can't say. Unless you're interpreting such results on a regular basis (such as a mechanic in a busy shop), it would be very easy to reach the wrong conclusion and convince yourself of doom and gloom. This is especially true if the engine has only been run at low speed with no load, and not actually worked hard out on the road. Larger engines, such as a V8, are more prone to carbon buildup because they spend most of their time just loafing along. A small 4 cylinder, on the the other hand, tends to be cleaner inside because that poor engine is working harder most of its life.

The carbon you see on the back of the valves? Does it affect compression? If not, it may not be a big deal. If may be a simple byproduct of cheap fuel and the engine rarely having to work hard. I would suggest a compression test and if that is good, try running a cleaning fuel additive. Over here in the States, I am very partial to Chevron brand fuel as it contains their proprietary cleaning additive Techron. Can't tell you if it is the best stuff on the market, but I run it almost exclusively in all my vehicles (a wide range) and have had zero fuel issues. I see no reason to change.

Not sure what to suggest for that oil leak. A smoke test may be your best bet, even if the cam cover appears to be oil tight. Be super careful about jumping to the worst conclusion. So far all we've seen is a bunch of PanickedPartsChanging™ and very little actual troubleshooting or diagnosis. Remember, keep your boroscope locked away for now to avoid scaring yourself.

None of what you're experiencing is unusual for an engine that sat dormant for several years. Remember that the fuel pump is a known problem area if inactive for an extended period. This doesn't mean rush out and replace it, but do physically check the fuel pressure with a mechanical gauge and compare it to your scanner reading.

Do a compression test. Myself, I wouldn't even bother until I had driven the car at least 100 miles and worked it hard. If you want to run the test first and it passes, you're good there. But if the results are low or uneven, go work the poor engine hard on the highway and see if it improves. Most likely it will.

 

I have the same year, model, and engine. If those cam cover gaskets aren't on right or the bolt housings are on right you get a nice cool down drip. It looks like the lower side of the cover or just at the back. from teh photo. Mine leaked when i got too and I have the scars on my arms to prove it. lol