2001 XJ8 4.0L "Jolene" 150K miles
Noticed the smoke today coming up and out of the left front wheel arch today. She has had the smell of burning oil since I bought her a couple of months ago; like most of my Tahoes do after they reach the high mileage marks, 100K miles or more. Usually, on a Tahoe you can clean the engines with Engine Brite and a good firm hose spray. I did that on Oxana my 2004 Vanden Plas...she really didn't like that! She showed me by blowing three coil packs! Now I'm gun shy.

I've only had her four months. So back to the subject, Jolene was smelling oil engine-like stronger than normal as I was stopped at a light, really like oil spilled on exhaust manifolds and I though it was the ute in front of us. You know the smell? Smoke but no flame thank the gods. You know, after an oil change some spills over onto the manifolds, it smokes rather than catches fire. So when I got to where I needed to go, I lifted the bonnet carefully quite frightened that it might flash. , yet it didn't. On opening the bonnet the smoke appeared to be coming from the left side rear of engine compartment. Is that to be expected, do I have some gaskets somewhere to renew?

I don't know what oil was used in it before, but my oil change place used 5w-30 synthetic last week. Like I posted previously, I just got the car back from her transmission surgery last week so only now got around to oil change, I hear bad things and good things about using synth light weight oils. I don't want to go down that rabbit burrow at the moment, but I could use advice of what I should take care of and where to look...and with everything hidden in the bay, what shields to take off and how to do it.

Does this engine have valve cover gaskets like my Chevy s? How do you get to them? I really don't know, sorry if it sounds silly.
Is the synth 5W-30 too light for the 4.0L with 150K miles? On my Chevy s, I still use that weight and have no worries at all...no burning or leaking.

r/
Rick

 

Yes they have valve cover gaskets that leak straight onto the exhaust, each bolt holding it down also has its own little rubber isolator and there are 4 spark plug tube seals.

https://www.ebay.com/itm/232803737265

Check the condition of your secondary cam chain tensioners while you’re in there.

 

It is possible that you have a leaking valve cover gasket, but first maybe the best thing to do is get it on an overhead lift and see if you can see for sure where the leak is coming from.

If it is a leaking valve cover gasket they are relatively easy to replace. It is a fitted rubber gasket, and also you should replace the spark plug seals and retaining bolt seals while you are there.

Basically remover the coil cover, remove the coils, remove the valve cover, assembly is reverse of disassembly.

There are two types of valve cover gaskets/spark plug seals etc., as yours is a 2001 A27 motor you would need a gasket set containing items 2, 3 & 4 in the diagram above. (items 15 & 16 are for the earlier A26 motor)


.

 

My '03 VDP (30k miles) has a slight oil weep on one of the banks, spotted by the guy who did the independent look at the car before I bought it a couple of months ago. My local gas station where I have basic maintenance done said I should be prepared to replace the valve cover itself as well as their experience is that even with new gaskets the old cover will leak. Their guess was about $500 parts and labor. The guy who does the work for me has a Lincoln with an almost identical engine on which he said he had to replace the covers on both sides. It would be delightful if one did not have to replace the cover as well.

 

There should be no reason to replace the actual valve cover (especially on such a "virgin" low mileage example like yours eliotb). Age can make the rubber gaskets less flexible and new ones should cure the problem. Some people recommend using genuine Jaguar gaskets, others have found that aftermarket examples work fine. Some people recommend adding some silicone gasket sealer such as JB weld, Permatex, etc, other find that this is not necessary. The most important thing is to purchase a complete valve cover gasket set which includes the actual valve cover gasket, all of the spark plug o-rings, as well as o-rings for all of the valve cover bolts. It is a relatively simple job and shouldn't take more than an hour or so to do.

The VVT oil seal can also be replaced at the same time, although it is easy to replace this with the valve cover in place if needed.


.

 

The biggest cause for cam cover gasket failure is a dirty/plugged part load breather. It fails to release the cylinder blow by back pressure from the block.A quick check of the intake air filter will reveal oil staining from the full load breather since the part load isn't breathing.
The part load uses the engines vacuum at lower rpms to vent the crankcase.
Another problem causing leaks is over torquing the cam covers and causing cracks in the cover.

 

Personally I prefer the earlier red and grey gaskets for the pre VVT cam covers. They are a bit more hearty and have never leaked on me, you just need to go light on the torque (7-8 nm). I once used the thinner black gaskets and they leaked after 5K (a shop put them on so they may have been crap to begin with). Don't forget the VVT seals while you are at it.

On the matter of a cracked or worn out valve cover, it can happen, especially if the engine has overheated before. I encountered one case where new gaskets weren't doing the job and upon closer inspection cracks had developed around the lip holding the gasket and the bolt holes. I wouldn't use a sealant that may flake off into the oil so I ordered a used cover off ebay and it solved the problem.

 

Felpro Lincoln LS set on the sc motor, cheap and nice snug fit needs no sealant. Does the long part fit on the NA 27 and 28 motor because it costs less 1 mahle long gasket.

 

The red and gray gaskets for the AJ26 will fit the AJ 27 and 28. It does requires some slight trimming at the tabs where the timing cover meets the block but the shape is the same. Also on the gaskets that go around the spark plug wells you may have to trim the tabs off the top. The key as mentioned is going light on the torque. The later gaskets called for 9 nm, these only need 7 - 8 nm.

 

I have recently been fighting this issue myself. I developed a small oil drip leak at the rear of the driver's side cam cover after completed redoing the front timing chains / guides / primary and secondary tensioners. I used all new OEM gaskets on the valve cover, including the spark plug / valve cover bolt o-rings. I removed the cover and did not see any cracks, so I reinstalled it using the recommended torque and sequence:



I drove it around and still had the leak with significant smoking after each drive. I verified the partial load breather was ok so I was left thinking I may just have a small crack or warp in the cover itself. I ordered a new OEM cover from SNG Barratt however I ordered the wrong part and this one had to be modified to fit the VVT solenoid. I was able to modify it fairly easily and the VVT gasket fit perfectly.



Now I also used new OEM gaskets on this one as well. Reinstalled everything and have been driving around. The initial drive still had minimal smoke, however it has since dissipated with each drive. I think it may be the old oil on the header heat shield burning off. Fingers crossed that I've fixed the problem

 

Seems like a lot of effort. I didn’t even know those covers existed until I saw the huge orange and grey gaskets on a junked car.

My 11/98 VDPS is a 26 motor but has valve covers with the thin grey gaskets you‘d usually find on AJ27/28 SC and 3.2 motors. The factory probably ran out of the early valve covers somewhere around this point.

 

The red and grey gaskets would fit your 26 with no modifications. Its only about 30 minutes of work to modify them for later engines and they have double seals where they meet the heads instead of single on the later designs. I'm not sure why they were changed besides cost, the later ones are inferior IMO. Last I checked they are still available.

 

Looked into this more, the valve covers changed as soon as the first 27 rolled off the line and carried over to the 26S until end of production right before MY2000. Mine came from the factory with the first of 3 revisions to the later design, the early big gasket ones are long obsolete parts only available used.


No top mount VVT:

LH: AJ83272 (original design) -> C2A1513 (final)

RH: AJ82553 (original design) -> C2A1515 (final)


Top mount VVT:

LH: C2A1514

RH: C2A1516

 

Thanks for the help. I ordered the gasket set as xalty suggested.

 

Maybe we are talking two different gaskets but a quick Google search shows red and grey gaskets for sale. Only new as far as I can see, a used gasket is worthless as they often stretch and tear during removal.

 

How would I know what to look for ? Cracks only? I've only seen a couple of photos on the forum. I'm getting mixed signals on whether Jolene has the 26 or 27 engine, yet the presumption is that the gaskets are the same, no matter which?

 

What is the recommended torque for the different bolts? I see the sequence is the normal spiral for heads. Thanks for the diagram; it eases the anxiety of the job. These cars scare me.

 

Around 90in/lb

The 26 engine was only on the 1998 regular and the 98-99 supercharged cars. You have a 27 and that gasket set will work.

If they’re still the red plastic type they will fail shortly and you’re in for some trouble. They’re located where the shiny piece of metal with two bolts is.






The gaskets are available, I’m talking about the covers themselves that have been long discontinued and superseded.

 

Ah, I see, makes total sense. Any valve covers I have bought have been used anyway. I do wish they had a magnesium cover upgrade like the AJ16 straight six had, more metal the better in the engine compartment.

 

Thanks for the photos! I can see clearly now So, on the tensioners, must one remove the timing chains to remove and replace the tensioners?