Hello everyone,
The car in question was burning oil quite a bit, so I've begun taking it apart to find where the oil was coming from. I found a small puddle inside of the exhaust manifolds so I figure the head gasket needs to be replaced. The head bolts seem to be nearly impossible to remove. I've managed to take off two, but the rest won't budge. Any suggestions? Such as what exact size to use?

 

Hi jaguarguy13,

The most common cause of oil pooling on the exhaust manifold would be failure of the cam cover gasket. Is that what you are trying to remove, or are you really removing the cylinder head? If so, please give us some more information and let us agree with you that you are pursuing the best course.

Here's a diagram of the camshaft cover (or "valve cover" on overhead valve engines by other manufacturers). The cover is Part 1. The main gasket is Part 3, there are six spark plug well seals, Part 4, and two half-moon-shaped plugs to seal the recesses left in the rear edge of the head when the camshaft bearing seats were machined, Part 7:


Failure of the main cam cover gasket, Part 3, is the most common cause of oil leaking on the right side of the engine. The gasket hardens with age and loses its ability to seal, and the tilt of the engine causes the oil to leak down the right side.

On our '93, the cam cover screws require a Phillips screwdriver, ideally a No. 2 or larger size to prevent galling the screws. The screws should not be too tight since the torque specification is in the inch-pound range, but baked-on oil can make them a little difficult to turn out, especially if they have not been removed in years.

The cylinder head, on the other hand, looks like this (shown without the camshafts):






There are 14 cylinder head bolts, Part 2. They take a 17mm 6-point socket (the heads can be rounded by a 12-point socket). You really, really do not want to remove any more of them unless you truly need to replace the head gasket. The most common point of oil leaking due to a problem with the head gasket seal is right above the distributor. Most owners just live with that until the head gasket fails in a more serious way, such as between a combustion chamber and a coolant jacket. When that happens, you may get clouds of white steam from the exhaust tail pipes and a very noticeable loss in power. You might notice coolant in the oil and oil in the coolant, and bubbles in the coolant reservoir tank.

Replacing the head gasket is an involved procedure that requires disconnection of the intake and exhaust manifolds, careful indexing of the camshafts and removal of the timing chain sprockets, etc. It's a job you must study and prepare for and have all the parts on hand before you begin, including things you might not think of, like JB Weld epoxy to repair erosion in the head and engine block gasket surfaces, a new oil pressure sender, and for the '93/'94 cars, a new heater water control valve (it will never be easier to replace them).

The cylinder head bolts are tightened in a two-step process that stretches the bolt. If you have removed two of them, you will need to check Jaguar's most recent recommendation on the reuse of the bolts. At least initially, they stated that the bolts must be replaced with new ones, but for some models they decided the bolts could be reused one time, I think. And removing two bolts without equally loosening all the bolts in a spiral pattern could possibly lead to the head gasket leaking even after you've reinstalled and properly torqued the bolts.

Please let us know which screws or bolts you are trying to remove and we'll be here to help!

Cheers,

Don

 

Hi Don thanks a lot for you in depth reply

I've already replaced the cam cover gasket, it wasn't even bendable anymore and just about shattered when I tried to bend it. The main reason i suspect the head gasket is because when I removed the exhaust manifolds, I found (mostly in cylinder one) quite a bit of oil inside of the head exhaust. Last time I tried starting the car, I couldn't see half of my garage (white smoke). The car also has 120k miles (if that's any help).
Edit: Though upon removing the exhaust manifolds, the original gasket on both sides were in three pieces only just attached together by a small area.

 

Hi jaguarguy13,

Can you please review the sequence of events that led up to your diagnosis of possible head gasket failure? I don't want to slow you down if you're convinced the head gasket is the problem, but if it's not, it would be great to figure that out now.

How recenlty did you replace the cam cover gasket? By any chance, were the spark plug wells full of oil?

Were there signs of oil on the outside of the exhaust manifold that could have come from the cam cover gasket leak?

How many miles on the engine?

Cheers,

Don

 

When I replaced the cam cover gasket there was quite a bit of oil where the spark plugs were. The main reason i'm assuming the head gasket is because of the excess amounts of oil residue that has coated the exhaust chambers on the heads, though I could easily be wrong. I think there may have been oil around there, I don't quite remember. The car has 120k miles on it, though it has been taken care of (regular oil changes, etc.).

 

If the engine is not running rough or overheating, and if it does not run continuously with substantial amounts of white steam coming from the exhaust, if you do not have signs of oil in the coolant or coolant in the oil, or bubbles in the coolant reservoir, then my hope would be that your head gasket has not failed. Do some research on the kinds of tests that can be done to test for a failed head gasket (cylinder leakdown, coolant hydrocarbons, etc.).

One very common source of oil in the combustion chambers is perished valve stem seals. Oil that lubricates the camshafts leaks down the valve stems onto the backs of the exhaust valves. When the engine is not running, the oil drips into the cylinders, causing the "blue smoke" at startup. But when the engine is running, the oil is blown into the exhaust manifold.

Another possibility is that one or more of the exhaust manifold studs intersects with an oil passage in the head, and that instead of sealing the hole, the stud is allowing oil to flow out along its threads. I have never heard of this happening on an XJ40, but I've read about it happening on some engines.

I'm going to PM Larry to see if he noticed any oil in his exhaust ports when he had his manifolds off recently.

Cheers,

Don

 

Can't say I noticed any oil in the exhaust ports or manifolds, just a bit of carbon.

I certainly wouldn't be pulling off the head unless I was sure there was a problem like Don describes above ..smoke on startup, well that's just XJ40's and those pesky exhaust valve seals!!

 

Thanks, you've both been a good amount of help. I feel as if my best bet would be to clean out everything as best I can, and try starting the car to see if there's a lack of power or if smoke is endlessly streaming out of the exhaust. I couldn't really tell before because there was so much smoke coming out of the exhaust I wouldn't be surprised if the neighbors thought the garage was on fire.
I drained the coolant a bit ago because I wanted to clean out the chambers, and I didn't notice any sludge/oily substance in it. Quick question, what's the size of the oil drain plug? The car wasn't started in quite some time before the initial cloud of smoke. Do either of you believe that, over time, that much oil could accumulate?

 

When I was shopping for my car I drove several on the way to finding mine.

One in particular had belonged to the chairman of the local Jaguar club at one time and had a full service record, but the present owners were a couple who just drove occasionally over the summer and AFAIK on Sundays only (yes really!!)

Anyway the car had too much of a rear end whine for my liking so I passed on it, but anyway the point of the story is this ...

The car was immaculate. When we fired it up, literally billows upon billows of smoke poured out of that exhaust for a good 5 minutes.

Huge clouds that eventually cleared up. When I did the test drive, she didn't smoke at all and ran like a bird.

As I was the seller's neighborhood it didn't bother me - however if I'd been at my own place I think MY neighbors would have had a petition together banning me for life.

What I'm saying, albeit rather long-windedly, is that yes - cars that have sat or get only occasional usage CAN and DO smoke like hell when they get going especially these old Jags as they also have the engine-tilt/exhaust seal issues.

good luck

Larry

 

Just do your homework on reinstalling the two head bolts you removed and don't start the engine until they have been properly reinstalled.


In my notes I show the oil sump drain plug on our '93 is 30mm. That seems really large to me, but I haven't changed the oil on that car in awhile.


Given that the engine sat without running for so long, and given that its valve stem seals are almost certainly perished, then all the oil that pools on top of the cylinder head at a sufficient level would have drained down the valve stems into the cylinders. That alone would cause a great amount of smoke at startup, as well as wet oil in the exhaust ports. I am hopeful that if you button things up, start the engine and let it run for a few minutes, the smoke may dissipate and the engine may smooth out.

Please keep us informed!

Cheers,

Don

 

With the bolts that I removed i'll just use a torque wrench and get them back to spec. An update on my progress: I took a fine wire brush and cleaned the carbon build up inside of head as best I could. I used 600 grit sandpaper and a sander to smooth out the surfaces of the exhaust gasket (I was amazed just how uneven and corroded the surface was). I coated the surfaces in just a bit of oil (spread with finger) just to avoid rust until the gaskets arrive. I still need to find a way to vacuum out some of the oil still left in the very back of the exhaust ports (was thinking a shop vac attached to a straw, with a few coffee filters in between to not ruin the vacuum). Would gasket sealer be a good idea on the exhaust seal? And any suggestions on the "best" oil to use? Currently i'm using conventional 10w-30.

 

Do you have the Jaguar Workshop Manual so you can torque the bolts properly? Have you checked to be sure that on your model Jaguar determined the head bolts could be reused one time, or not reused at all? As I may have mentioned before, torquing the bolts is a two-step process (torque to yield) that stretches the bolts.


The Owner's Manual has the oil recommendations, but if your car didn't come with a copy, you may be able to get one from Jaguar through their TOPIx website (https://topix.jaguar.jlrext.com/topi...cle/lookupForm).

Our '93 Owner's Manual specifies the use of 20W-50 for most climates, but in the winter I use 10W-40 for easier cold-temp starting. 10W-40 or 10W-50 would probably work for you year-round in Michigan. I use Castrol GTX "High-Mileage" conventional oil, but any major brand will work, and you don't have to use synthetic oil unless you really want to.

Cheers,

Don

 

Yeah with the torque i'm going to do some research before doing anything. I'm most likely going to go with 10w-40 over the 10w-30 I now have. The weather here fluctuates a surreal amount.

I found a link to the haynes book that should be really helpful to anyone that reads this forum.
http://wilfredfoto.nl/XJ6%20Series%2...8Haynes%29.pdf

 

Thanks for posting that link to the Haynes manual. It is also available in the large file download area of this forum at this link:

https://www.mediafire.com/?hx8bttsy4kxxr

The file at both links is the same and unfortunately it is missing Chapters 7 and 8, which are for the Automatic Transmission and the Driveline.

The last time I checked, the printed versions of the manual were no longer available new.

It is well worth buying the JDHT DVD-ROMs that contain the original Jaguar Workshop Manuals. The Supplementary Information DVD contains the Electrical Guides and other very useful info. Find them at jaguarheritage.com

By the way, the Cylinder Head bolt torque specs are shown on page 2A-2:

Step 1: Tighten the bolts to 44 ft. lbs. (60 Nm) (see the bolt tightening sequence on page 2A-14)
Step 2: Tighten an additional 90 degrees (1/4 turn)

Since you only removed two bolts, the bolt tightening sequence may not be of much value, but you may as well tighten them as though they were being done in the proper sequence.

Cheers,

Don

 

Just in case you are still determined to take that head off.

Get a hose that fits tightly over the head of the bolt, 2 inches high should do. Spray your favorite catalyst in the tube, it should fill up. Wait as many hours as you can, overnight is great.

Use a 1/2in quality breaker bar and socket. Ease counterclockwise, then back clockwise, back and forth. You may have success.

If you do it the way I've explained, if it breaks it should break above being flush with the head. Weakest point on those bolts are where the threads begin. My experience only.