I have a 1999 jaguar xk8 with 49k on the clock that would not start due to bore wash. I pulled the plugs and put a teaspoon go oil in each cylinder and got it started. However, it started making a loud knocking and would not stay running. I'shut it off and now I suspect the tentioner(s) are an issue. I have not torn it down yet but I'm worried the noise was pistons and valves coming in contact but not sure. The dealer quoted me $4,200 to just replace the chains and tentioners.

Is there a way for me to tell if I have valve damage without pulling the heads off? I would suspect if the thing skipped a tooth on the sprocket I could tell when I pull it apart. If it has not skipped a tooth should I be ok? If it has skipped a tooth how bad could it be if it only ran under a minute?

 

Craig, unfortunately, time running with a jumped timing is not a deciding factor on the bent valves. That sure was a high number on the chain quote. The gurus here may be able to give you some good news, I hope so.
Sounds like you are able to get it fixed by yourself, but give all the DIY a read.


Wayne

 

That is out of the park quote the DEALER is giving you. Do you have any shops around you that work on European cars, not a dealer or any sort but a one off shop that works our types of cars?

 

Was it running before the bore wash with no issue? If you just got it started and ran it for a few moments you may have not done any hardcaore damage. I know when my 97 went south I started it a few times and it ran like crap for the minute or so I let it run but did no damage pistons or the like. I think the damage part comes in when it is run for too long at idle or while you are driving down the road be it at 25 mph or 70 mph.

 

If you can remove the valve covers you can the see if the flat areas near the front of the cams line up when you rotate the engine clockwise from the front using a socket on the crankshaft pulley.
Do not attempt to start the engine again until the alignment is confirmed.

 

.

 

I did read/watch a lot of DIY stuff and it is nothing I don't think I can't handle. It is just a pain and I need to purchase a Harmonic balancer extractor and install tool along with the cam locking tools. The one thing I'm not to sure about is how the crank is locked at TDC. Also, I'll need to figure out how to lock the crank so I can remove and install the harmonic balancer.

On the stuff I watched I saw they removed the radiator fan and radiator. Is this needed? I know it would be tight but I don't have a way to capture the A/C gas.

Cheers,
Craig

 

Most folks do not replace the primary tensioners and shoes as they have a history of a 100k miles or more. It is the heat of the heads that do in the secondary plastic. If you are only going to do the secondary tensioners there is no need to remove the harmonic balancer, radiator, AC condenser, et. al.

You do not align the crank at top dead center. In fact it is 20 degrees ATDC where the cams align if I remember correctly. Crank to cam alignment is determined by the ground flats on the cams and with a plug in the flex plate alignment hole but it is not TDC. Since you suspect that the chains have skipped a tooth you need to go for the cam hold down bar alignment as the zip tie only works with known good alignment.

You can visually inspect the cam alignment with the valve covers off. The right side cam flats will be slightly turned down, a couple degrees, to the center due to valve spring pressure. The left flats will be just about dead parallel. If they match this description you do not have a cam timing/bent valve issue.

If they do not align as described then you may well have a bent valve. Look for a valve bucket shim that has not returned to the top of the bucket. Worst case you may have to do the tensioner replacement and cam alignment and then do a compression test.

 

Thank you so much. That is very good information and will go a long way in properly sorting the engine out.
-Craig

 

I'm pretty good at "turning a wrench" but I have no idea where to find the " flex plate alignment hole ".
Thanks again,
Craig

 

Have a read through this thread, particularly Norri's post #14.
https://www.jaguarforums.com/forum/x...-center-80142/

The thing I found difficult to get my head around when I first got my XK8 was that setting the timing is totally different from that of any other car I have owned. The crankshaft position sensor is removed at the rear of the engine (see thread above) and the "special tool" inserted in it's place. This puts the crankshaft at a position where none of the pistons are at the top of the bore.
The four camshafts are then set, and locked with the two other "special tools" so that the machined flats near the front of each cam are all horizontal and in line.
The crankshaft and camshaft sprockets have no dots, arrows, marks, or slots etc, nor are they "locked" on to the camshaft with a keyway. They are irrelevant to setting the timing and are **only** held on by the tight fit of the taper join and correct torque of the bolts. Similarly, TDC has no relevance or significance in timing this engine.
If, when the crankshaft is in the correct position, the four "flats" are horizontal and line up, your timing is OK. If they don't line up, then you can use the tools to hold the cams in position while you undo the relevant sprocket and move it to the right place. If the three tools (one holding the crank and two holding the cams) are in place, you can do what you like with the sprockets without upsetting the timing in any way.

Please note - the crankshaft tool must NOT be used to hold the crankshaft while you undo the harmonic damper bolt - neither the tool nor the flexplate will take the torque required. There's another couple of special tools for that purpose, but you would only need them if you are replacing the primary tensioners as well as the secondaries.

 

Unless you are going to replace the primary tensioners you do not need to worry about the crankshaft alignment, which is done through the crankshaft sensor hole on the bellhousing.
Just turn the crankshaft clockwise as seen from the front, and observe the flats on the camshafts. If they line up, your timing is good.

 

'Timing' on almost every car has always been ignition timing. That is now handled electronically. This discussion about cam/valve timing was new to me when I bought the XK8 and has no obvious logical relationship to piston/crank position. I guess Jaguar engineers understood it as it seems to work.

 

Replaced timng chain, fits well into the crankshaft sprocket, but the chain will not fit tightly into the cam actuator sprocket. The engine is a 2003 XK8 with 4.2 engine. Do the earlier 4.0 engines have different sprockets on the cam actuator?

 

The 4.0 engine comes in two different versions. The early engines have roller style chains Primary and Secondary.

The later 4.0 uses the Morse style Primary with roller secondary and the sprockets are DIFFERENT.

 

Are the sprockets for the 4.0 engine different than on the 4.2 engine?