I have this from a local friend who is helping me too so I think I will give it a try. If it does not work I can always still do what Greg suggested-

Erik,

Sound like a valve is stuck open; I imagine you tried both testers and checked that it was sealing well. Probably explains why we would get a backfire some times when trying to start.

To see if a valve is stuck open, one will need to pull off the valve cover. Pretty easy to take on and off so don't let that slow you down, however, you will need new valve cover gaskets when putting it back on and a torque wrench to torque the bolts correctly (you'll need one of these anyway for most of the different bolts throughout the car.) It is possible that the valve is stuck in the valve guide and that running the engine may free it up when it gets heat applied to it. So, I recommend to still put primary effort into getting the gas into the cylinders through the injectors a higher priority. Once that is going, it may solve the stuck valve problem on its own.

 

Agreed. But 'pulling off the valve cover' on the Jaguar V12 comprises the steps I mentioned.

If you get it all back together and start it, I agree there is a good chance the valve will unstick once it gets running, so why not try it? However, let's see what the others say (Where are you Grant?) before doing anything. Meanwhile get the fuel system checked and the injectors, maybe?

Greg

 

Greg- do you have any sense of what the little yellow part I mentioned a couple of posts back is? I want to repair/ replace it but I'm really not sure even what system it belongs in to try to look up parts.

 

The little yellow part looks like the oil pressure sending unit for the light, not the gauge. The one that operates the gauge is standing up, and much bigger.

I hate to say it, but 0 compression isn't good at all. I cannot imagine what would cause a valve to "stick" open. As much as I hate to say it, I would more venture a cracked or dropped valve seat. Its at this time, I wish there were some sort of little camera that you could put in the spark plug hole, and get it to "look" back up at the valve pockets.

As far a removing the valve cover, we are talking a V12 here, not a 6 cylinder. The intakes have to come off to get the valve covers off. If this engine were able to be started, as soon as it did, you would hear the sound of excessive valve clearance. IF its a dropped valve seat. Could be a burnt valve. A very outside chance of a valve stuck open.

This 6.0 I got running, had uneven compression across the board. I put PLENTY of PB Blaster down on top of the cylinders, in hopes that the poor fuel quality of ethanol had caused some of the rings to stick. After sitting overnight, I spun the engine over to get the excess fluid out of the cylinders, and then did another compression test. It was dramatically better. My lowest cylinder was 190, and the rest were around 235. I haven't pulled my 5.3 yet, as I am having a hard time explaining to myself why I would go through all the trouble to change the engine without tearing it down, to find out why that one cylinder is low.

On another thread, one fellow took his engine apart, tried to CC the heads, and just about ALL had leaking valves, and/or seats.

I have no further advice for you here I don't think. In my opinion, you have bigger problems. As much as I hate to say it, this engine most likely needs the heads off, to find out why there is no compression on that one cylinder. Its bad if it has a dropped seat, or burnt valve, but I have also heard of these engines getting a injector running so lean, that one cylinder can actually develop a piston problem from that one cylinder running so lean.

This is one of those times you find yourself at a fork in the road......

 

about this- " I wish there were some sort of little camera that you could put in the spark plug hole, and get it to "look" back up at the valve pockets."

Do you mean like a boroscope or endoscope? What kind of space to work with are we talking about here in that little hole?

 

If you rotate the engine to where the piston is at the bottom of the stroke, You have plenty of room so to speak. About the size of a empty soup can. To even consider something like this, seems it would really help if those on this list might have pics to share, so you would know what you're looking for. I have a set of early heads I could send you pics of, but they are an entirely different animal than the HE heads. On my 71 V12, the valve seat didn't drop, but was cracked. This caused it to "****" in the valve seat pocket. With that, the valve couldn't close all the way, so I had the same sound as a dropped valve seat. It still required that the seat be removed, a larger seat opening machined, a custom valve seat, all new exhaust valves, 1 intake valve (bent), guides knurled, new Teflon seats. Seems about 700.00 for all that alone. That was on a XKE convertible. The problem with the XJS, is it "may" be more economically viable, to get another one, rather than fix this one.

 

I looked back at the posts, and Greg may be onto something. I really doubt it is a stuck valve, but in the grand scheme of things, this is another "free" thing you can do. In my opinion, if the valves were moving, you then would need a dial indicater to measure valve travel on every valve, or maybe even check valve clearance. If the valves on the dead cylinder are moving, but one of them has really excessive clearance, (over .020) then something is holding that valve open.

The thing to keep in mind on our V12s, they tend to have less valve noise over time, as the valve seat wears, valve face wears, and valve clearance closes up.

 

For better or for worse I have time and I have effort. And within reason I have money I can spend on the car as well.

The most I have ever done on a car up till now is change the oil and the oil filter. So over the last few weeks I have learned a ton more than that just accessing and changing the plugs and wires and doing a compression test.

I bought this car to be a learning experience and it looks like a learning experience it shall be!

If removing the fuel rail and checking the injectors does not require the same things required to access the vee then I think I am going to put everything back that I have apart right now and proceed to try to learn to remove the fuel rail and injectors.

This may not be the most efficient or direct method but I am ok with that- I just want to learn about cars so everything I do is something new.

If I make sure the injectors and rail are working properly and get it him started and cylinder 1b does not magically fix itself then I will try to learn how to take off the valve cover/ check the valve.

The car does not have to run by any certain date so there is no hurry either.

So if anyone is still willing I can use all the help I can get.

I will begin going through the Kirby book, my Haines manual, my auto repair for dummies book (not kidding), and my Jagewer ROM manual to try to tackle the injector rail/ injector thing.

Greg in France had mentioned taking an injector and checking to see that it was spraying fuel so that seems like a reasonable place to start.

 

and thank you about the thoughts about using a scope. I have a couple of old endoscopes up at work but you are right Supecharged- I would have to know normal first to know what abnormal looked like!

 

Just subscribed to this thread.

Keep the good work going, dorschman, amazing what you are willing to do , considering the 'limited' experience.

Take it easy, learn before you do, and you will be fine.
Your satisfaction at the end will be paying for everything.

 

On the 6.0, I actually removed the whole fuel rail, injectors and all. I then took a jug, and a EFI pump, and hooked up a supply line to the rail, and a return. I pumped carb cleaner through the rail. Using a 1.5V AA battery, and a spare injector electrical connector, I "pulsed" the injectors one at a time. It was a eye opener! The injectors that didn't work at all, I used a 9V battery, and after shocking them a couple or three times, the worked! Then going back to the 1.5V AA, I flowed them. Some of them went from shooting a straight stream, to fine cone shaped spray in a matter of a second or two. Some had to be flowed much more. But none of them over 10 seconds, to be spraying beautifully. I have seen hope work out. And I am a optimist. I just like the odds to be in my favor . Check the injectors. Start it up, as a V12 Jag has been known to run on 6 cylinders. Check out YouTube for what a dropped valve seat sounds like. And remember, if you have any intention of repairing this engine, a dropped valve seat has been known to break, and then scatter in the cylinder, doing much damage.

 

I think, repeat think, it is the oil pressure warning light sender. If it is screwed into the aluminium fitting that also has the camshaft oil pipe feeds on it, then that is what it is. Cheap to replace, BUT make sure you counter-torque the ally fitting when unscrewing it or the fitting will snap off!

But WHAT is that huge brass thing with the red flexible pipes on it ? Has someone fitted a non-standard water valve for the heater?

Greg

 

That looks like the check valve and other parts of the air injection system found on some engines depending on market.

 

If you look closely, it has a wire connected. The A.I.R. system doesn't have anything like that. I still feel that is the oil warning light sending unit

 

I think this course of action is a very good idea. If you undo the little horizontal metal piece holding down each injector to the manifold, and undo the connections to the rail from the fuel pipes, then the rail and injectors can be pulled out as a unit. Then you can buy a set of new fuel flexibles (rail to injector) and test each injector and clean it as SC6 indicated and put the lot back. MAKE SURE you stuff some rag down each injector hole as soon as they are out.

As SC6 has been proved correct, he may well be right about the valve. But it could easily be that the engine stood for long enough with the exhaust valve happening to be wide open on the cam, and it just got corroded there enough to stick. So starting the car and hoping is a good plan I believe. If it does not free up, then you know what is working and you can dive into the head removal knowing that when that is done, the engine will run for sure.

If you post a photo of the front of your engien where the belts are, someone will know if you have the air injection on nit still. If so, this can be removed easily and discarded.

A scope can look into a cylinder, the problem you have is that the exhaust valve is in a vertical pocket into the side of which pokes the plug, so the scope has to be able to look upwards from its end, not just downwards.

Greg

 

SC6, I and I think Baxtor, was referring to the brass thing with the big red pipes attached to it behind the sender.

Greg

 

I should be able to get to work on removing the injectors/ rail this weekend. And I will get a pic of the front of the engine too.

 

I can hope too. Its just hard for me to see a valve getting stuck open. Maybe it can, but its a bronze guide, with a steel valve. Maybe? Just maybe?? there was enough moisture in the air, to somehow rust that one valve, enough to not allow it to return? And if there were that much moisture, why only one valve? There are at least 4 valves open at any one given time. Lets cross our fingers, and hope....really

 

As I began to try to figure out how to depressurize the fuel system I found these in the right side of the trunk not attached to anything. Anybody recognize them and should they be attached to something?

 

To depressurize the fuel system do you just pull the silver box off the red box? Or can you just undo the connector that comes from it?

I wimped out and tripped the motion/ inertia sensor switch in the driver side door area and ran the pump a couple of times and had no fuel pressure when I began to start the rail removal.

But I would like to know how to do it properly.