So some of you may be aware that I have been trying to solve a no-start problem with my 2007 XJ6 for some months now. I drove the car from NE Ohio in early December and parked it at an off-airport parking lot where they keep your keys and car. Two days later I returned to the parking lot from the Pittsburgh airport only to find that the lot personal could not get the car started. So since driving the car to the Pittsburgh airport in early December, the car has not started since then. Prior to this the car ran and started just fine every time.

I have been trying to diagnose the no-start problem ever since. Looking at fuel and spark issues to no avail.

So finally on Tuesday evening in preparation for changing the spark plugs, while I had the coils off and the plugs out, I decided to do a quick compression test just to verify what I thought would be normal motor condition. The results were dismal and very depressing.

Cyl dry compression wet compression

1 0 30
2 78
3 15
4 65
5 90
6 22

I did cylinder one first and thought the compression tester was not working. But then I moved onto cylinder 2 and got a reading. After I was done with the other I went back and retested cylinder 1 but still absolutely NOTHING on the tester. So I squirted some marvel mystery oil into the cylinder and tried again. This time I got a reading of 30psi.

What I don't understand is how a normally running AND normally starting car could go from totally operational and reliable to this absolutely terrible engine problem in the space of two days while sitting supposedly idle in a parking lot. This makes zero sense to me.

I am totally depressed by this result as it means the car will be off the road for a long time and I really miss driving it.

 

Once I discovered the issue with the dismal engine compression I decided to remove the cam cover to see if by chance the timing chain had broken. I know when I bought the car that the previous owners were terrible about changing the oil in a timely manner and as a result I knew there was some sludge build up but even I was surprised by the amount.

BTW, the timing chain was fine.

 

I don't have any idea why this would happen suddenly either, but will be interested to hear what you discover. I'm sure it is very disappointing.

It sounds very suspicious that all 6 cylinders would lose compression unless there indeed is a cam timing issue.

Any chance someone abused it while it was at the airport?

.

 

So is it solved or not?

 

That is my theory but I cannot prove anything. They had the car and the keys for two days. However I still have a hard time imaging what exactly someone could do to cause something like this. A friend suggested over-reving like crazy in neutral or park but I have no clue why someone would do anything like that.

One suspicious thing is I found a large clump of dirt embedded into the driver's side exhaust outlet that I know I did not do.

 

The reason for not starting has been discovered. So my months of digging into the fuel system or ignition system are over and done with.

 

That engine is really gunked up!

 

That is some terrible gunk. Seems like it would take a long time and a lot of neglect to accumulate that much. But the AJ16 is so tough that it is probably mostly unaffected by it!

From the beginning of the crank-but-no-start issue, knowing now that fuel has been flowing, the cylinders have been washed down with a lot of fuel, leading to loss of compression. You added oil to all cylinders, correct? I don't have first-hand experience doing this but others here have. Maybe with multiple oil injections, compression will continue to improve?

Of course this does not address the first issue of not firing during cranking, which then leads to cylinder wash. But, one thing at a time.

 

So a bit like I suggested a couple of weeks ago? https://www.jaguarforums.com/forum/x...9/#post1840613

 

Sorry about the P.M. but I hit the send icon before entering text . I'm with SleekJag12 on that it may be a bore wash scenario . With the excessive blowpass gasses cooking the oil as the crankcase vapor swirling around and then getting separated back out into a liquid as a way of explaining the gunk . The unburnt fuel being pushed past the rings into the crankcase into the oil pan diluting it is certainly not good as well .

I would recommend changing out the oil with probably 2 oil changes ( cheapest is fine for the flushing ) to get this compromised oil out before it compromises your main bearings and crankshaft / piston rod journals . After the first oil change I recommend using a product call Reslone to remove any possible blocked oil passages and varnishes in critical areas like the journals .

As to the borewash / compression use the same Rislone on the top of each cylinder and turn the engine through to force it into the area of interest which is the rings as well as coating the cylinder walls and let it sit for a day or so .

I can be completely wrong .

Have you every had someone ring your door and say they just bought a car ( Ford ) for $ 400 and need it fixed for the next days inspection ? 10 things wrong

 

Ummm, Sorry, I don't understand this last sentence.

 

No , it's someone else as I have more important things to do including this . Spent 9 hours on a junk Ford yesterday .

 

No.
But I bought a 1996 X300 VDP for $300, renewed 2 light bulbs, and it passed inspection!

Steve, I don't suppose you made a note of the odometer mileage before turning it over to the off-airport valet? (not judging....not something I'd think to do, either, but if you did, you'd have some idea whether or not they messed with it)

Over-Revving in park/neutral is not possible, I don't believe - but I may be wrong. Andy (XJR Engineer) posted recently in another thread that it is rev-limited to 5950 but there may've been caveats regarding that info that I didn't notice. Also, back during the knuckleheaded "Cash for Clunkers" days, there was a video - I think youtube, but a link posted somewhere here in the forums, of an X300 4.0L with a crankcase full of the specified poison elixir being run to failure. Hard to watch, but the takeaway was the AJ16 will go at high-revs for awhile with it's engine oil replaced by an engine-killing agent. On the other hand, there is a TSB - revving in Park/Neutral will do in the transmission. Stay below 2000, if I recall correctly.

 

Did I miss your explanation of the cause of the no-start? It wasn't low battery voltage, was it?

Cheers,

Don

 

Don:
Something internal to this engine with only 140K indicated miles has gone south and the cylinders have such low compression, that the engine will no longer start. This is why the first post I did in this thread enumerated the actual compression readings I got from this motor.

I know some folks here will disagree with this but this is the second Jaguar engine where I have had this problem after purchasing a high mileage or unknown mileage car. The previous time it was with a 3.6L AJ6 motor in a 1985 XJS. In that case I pulled the motor and replaced it with a 4.0L AJ16 motor from a 1995-1997 XJ6. When I installed the 4.0L AJ16 motor into the XJS I kept ALL of the old intake and engine management system and exhaust system from the 3.6L setup. When I was done installing the replacement 4.0L AJ16 long block, it started and ran just fine which a night and day change from the old worn out 3.6L that would not start at all. I gave the old worn out 3.6L engine to someone else and when he tore it down he discovered a lot of broken rings and other nasty stuff that was causing the low compression. In that case most of the cylinders were in the 30 psi range for compression.

I am now shopping around for a replacement 4.0L AJ16 motor for this car so I can yank the junk one and replace with a good used one. When I get to the point where I tear the old non-starting 4.0L AJ16 motor down from this 1997 XJ6 I will post another thread here with details of what I find inside the motor.