Since this has now turned personal and is a disservice to the OP, I will no longer participate in this thread.

Gus, if you cannot keep to the technical issues at least lets move this over to the psychology forum where we might better explore those issues. And you are in no position to question my character.

 

Steve,
Sorry you feel that way and I hope you get the help you need.

 

Now, now guys. The only reason I am bothering to respond is that I have respected and appreciated insight from both of you in the past, I, for one, enjoy a good TECHNICAL argument because I believe exploring all aspects of an issue by multiple sources is a great way to learn. And that was the argument I was trying to provoke. To be positive, Technical arguments need to stay Technical, even if contentious. I do not think that anyone here (even the so-called pros and "experts") cannot learn from someone else.

 

Well put Sparkie - Honestly guys, please lets agree to disagree and continue to try and help the OP who I'm assuming still has the issues as I haven't heard to the contrary!

 

Gentlemen, Sorry to cause such a fuss but I will admit that I'm having a good time with it... Trust me... I know how to run compression and I ran it three times on this engine. I was quite suprised to find zero compression zero compression on #8 but relieved at the same time to find what was no doubt the problem. There is some more to do before I begin to pull a head. I intend to plug in a scan tool to read trouble codes and will report such here when I do. Otherwise, I agree with the basic premise that zero compression is a major and catastrophic failure and is likely the cause of the "reduced performance". I also agree that the priority is to fix the catastrophic failure and go from there. BUT... this isn't a chevy and it is a major undertaking just to pull a head. So I will want to know all codes before I decide on the way ahead. This car isn't perfect... I need to work the ABS and the ATC but that will come after we are again road ready. Otherwise, this car ran great until it over heated. I don't want to go off on the "overheating problem" again. There is no overheating problem. The car ran hot and I know why. The car is skipping now but will run at idle and on the road... just runs very badly. I would expect nothing else from an 8 cylinder running on 7 cylinders.
Now... all ya'll kiss and make up.

r/
Mike

 

good to know Mike

I'd like to thank all the guys who jumped in one over another to try and offer advice for you in the first place......Man this is a great forum

Come back with the updates

 

Mike,

Let me say that I am sorry for the way things turned out on your post and I will try to be a better person the next time. The good thing is that you did not let it affect your troubleshooting the problem or your coming back to the forum. I would still like to help.

Gus

 

This is great and I really appreciate talking to everyone. As I said in my intro, i think, forums like this aren't new to me and I am just pleased to be here and dialogue with like minded folks. Thermo turns out is a neighbor. I will hook up with him some time soon and plug in his scan tool. Will let all know the results. I also need to pull all coils and plugs to run compression again with some oil in #8. Take care all and you gotta love it.

R/
Mike

 

I broke the same plastic vent line this week working on the heater. I repaired the break with a fuel line hose secured with fuel line clips. The vent line was very brittle, probably wise to replace after 100k mi. The repair held for one day before I replaced the line. Got a new one at San Jose Jaguar for $22. Put it onto the existing ports very carefully so as not to break them!

I know you are long past this problem now but I hope you get the old girl up and running soon.

P.S. I do not see a strong connection between the overheating and the loss of compression in one cylinder. You did detect overheating and shut the engine down. Could you have caught it in time? Could the loss of compression be a fluke coincidence?

Good luck,

Dan

 

Ladies and Gents,

Back on line here. Thanks to Thermo for letting me use his code reader. Per previous post, I have no compression in #8. Below are the trouble codes that were stored. First reading is just that... Second reading is after deleting first and running the engine for a few minutes in park. I have been to this web site to read the codes: http://www.engine-light-help.com/jag...ine-light.html so I know that they say but I don't know what they ALL mean. I do however understand from previous experience with other vehicles that a catastrophic event such as NO COMPRESSION in a cylinder will cause all kinds of things to read with no rhym or reason. Here we go!
FIRST READ:
P0303, P1313, P1316, P0102, P0112, P1111, MIL ON, MONITRS, 0 INC, 7 READY, MISFIRE, FUEL, COMP, CATALYST, EVAP, 02 SNSR, 02 HTR.

DELETE FIRST READ, RUN ENGINE:
SECOND READ:
P0301, P0302, P0303, P0304, P0305, P0306, P0307, P1313, P1316, P1000, MIL OFF, MONITRS, 6 INC, MISFIRE, FUEL, COMP, CATALYST, EVAP, 02 SNSR, 1 READY, 02 HTR.

That's all. I will run compression once again and test with air for leaks in #8 via valves or through cooling system. All opinions and expertise are welcome.

Thanks to everyone for your help and recommendations thus far.
R/
MikeC

 

P0303 – Misfire cylinder #3 = See P0300
P1313 – Misfire rate catalyst damage “A” bank(1) = Cylinder compression low
P1316 – Misfire excess emissions = (this flag only when accompanied by an individual cylinder misfire P0300 to P0308)
P0102 – MAFS Sensing circuit low voltage = Blocked air filter or failure
P0112 – IATS sensing circuit high voltage = Wiring open or high resistance

After the second try
P0301, P0302, P0303, P0304, P0305, P0306 and P0307 are all cylinder misfire.

My suggestion is to look at your timing chains.

 

Well, I guess the codes are neat from an academic perspective, but DUDE, you got a dead cylinder. Althoug the cains are possible, I must bet against the diagnosois of one whom I usually agree with. I say it is a valve, a head gasket (my bet), a hole in the piston, or a cosmic pressure warp (maybe I would bet on that instead). Pull the head and figure it out. BTW, I might go futher out on the limb and bet the plug from that cylinder was clean as a whistle while the others had some crud. Keep us posted

 

Hello everyone,
I am reading all posts, with great interest, since almost the exact same thing just happened to my ’99 XJ8L! The car overheated, stopped, and now is running rough (one cylinder is not working) etc, etc. Almost exactly the same symptoms as mike’s so…. most likely the head gasket is blown. Now, the question that I have is what else could it be? Is it worth it to spend money on replacing the head gasket to find out later that there is another problem with the rod, pistons, valves etc? Is this a possibility?
Thanks for your help,
Gregor

 

Well, to fix the head gasket, you will have the head off and can inspect the valves and check warpage. Rods don't drop compression and the rings in one cylinder are unlikely to drop to zero compression without visable cylinder wall damage.

 

SEEN THIS A LOT THROUGH THE YEARS!

When an engine with aluminum heads overheads, pray to GOD that the head(s) don't warp, because that happens like the Sun rise in the morning. You or somebody will have to pull the head and have it surfaced.

TESTS: 1. You can buy or rent a radiator pressure tester. Put it on and pump it up to the cap pressure rating. Water will come out where the head gasket is blown if that is the case. Watch this one! You may push water into the cylinder. Also, look for bubbles coming out of the radiator.

2. I modified my compression tester by temp. removing the valve cores at the engine end and the pressure release port. Get that cylinder up to TDC on the compression cycle and feed compressed air into the cylinder. You will hear the air coming out of the intake or exhaust if a valve is bad. It will bubble in the radiator if the head gasket is blown, or hiss out the joint between the head and the block.

3. Watch your oil for water. It gets like a thick cream and light in color when water gets into it and heated up. Hard to get it all out.

 

I want to thank everyone for their post. I am not a jag expert but I am a car guy. I think I agree with SPARKENZAP and GLENDORAMIKE. I will run compression again but I am confident I know what I will find and that is no compression in #8. I will also go TDC on #8 and put some air in it to see what happens. I will come back again and post these next test results. Thanks again everyone.
R/
MikeC

 

You could also run a leak down test! and that should tell you where you are loosing compression intake, exhaust, piston or cooling system? Then make your decision on rebuilding or replacing. Some times the parts cost alone will determine the outcome for you. Paul

 

Well I'll try to add my tupennyworth, politely, I hope !

WIth no compresson on No 8 cylinder it is clear that you either have: -

1. a bent valve thus not closing, and preventing compression
2. a hole in the piston (very unlikely, in my view)
3. a seriously blown head gasket

Forget all these funny codes you have seen, and concentrate on the mechanicals; you are going to have to lift the head to see which of the above three it is, and then you can start fixing it. A bent valve or blown gasket will be fairly straightforward to fix, but a hole in the piston is an engine out and dismantle job so probably not worth the effort.

For what its worth, I had a bent valve on my old XJ6 4.2, and was back on the road after a day.

 

How did the valve get bent?