Hello everyone, I am currently in the process of replacing the timing chain tensioners on my 2000 VDP. I am having trouble locating the 'triangle' on the flywheel where the CPS is located. I have hand turned the engine four times, but can't seem to find it. I did notice that one of the squares cut into the flywheel was rounded on one side, is this for the Crank locking tool? I work with two mechanics and they suggest that if I get the #1 piston to the top of the cylinder on the compression stroke, I have located top dead center and can go from there. Is there any truth to this in relation to this engine? Thanks

 

Is the #1 cylinder the one closest to the front of the car on the passenger side?

 

Are you doing both the primary and secondary tensioners? Where are you starting from? Broken chain? Have the tensioner tools?

 

Jag has 85,000 miles on it and started to hesitate during acceleration. I checked the normal stuff, ignition, fuel. Everything appeared to be operational. Then I started reading about the timing chain tensioner problems on this site. I removed the cam covers and discovered that both secondary tensioners were cracked. Fearing that one of the chains had jumped a tooth, thus causing the hesitation while driving, I decided to change all the tensioners and various other parts that go along with this job. Parts are in the mail, just getting a head start on the tear down. I do have the tools needed for the job.

 

I'm assuming the slack in the secondary timing chains could be enough to make the car run rough, since the tensioners weren't doing their job. If this is the case, one of the timing chains jumping a tooth is probably not what happened. When I line up the flats on the camshafts, the drivers side is near perfect, but the passenger side exhaust cam is about 1-2 mm off on the low side.

 

Suspect that your 'rough' is due to some other reason other than tensioner/timing. The cam positions you describe are what should be expected. The right side flats are not parallel due to the valve spring pressure on the cam lobes.

But . . . since you have the parts, tools in route and the valve covers off it will not hurt to complete the update.

The tensioners operate on oil pressure and with the engine off there will be a little slack in the chains. While a crack is certainly something to be concerned about it is the missing 'slippers' on top of the tensioners that are the biggest problem.

 

Thanks test point, If I align and lock the flats on the camshafts, can I assume the crank is in the correct position, or could I be a rotation off? Also, while troubleshooting the hesitation, the only code that comes up on my OBDII was a P1646, O2 heater A bank. I figured it was running rich so I replaced both upstream sensors, but the code and the hesitation won't go away. Any Advice?

 

The cam/crank timing position for setting the chains has NOTHING TO DO WITH TOP DEAD CENTER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The engine is timed 45 degrees AFTER TOP DEAD CENTER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The reason is so that no piston is at TDC and valves cannot contact the pistons.
Lock the crank, Lock the cams and install the chains!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The engine is now timed!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I guess you could put the #1 piston at TDC and set the 'A' bank cams with a dial indicator (like the old Aston Martin V8s) and then do the same with the 'B' bank but WHY?????????????????????????????

I used to answer the shop phone at the Jag dealer and listen to the guy at another shop tell me how the pistons were set at TDC and the cams were set with the FLATS and now the engine "RUNS LIKE SH*T". I would tell him to forget about TDC, It has NOTHING TO DO WITH TIMING A JAGUAR V8. He now has an engine with pistons at TDC and cams at 45 degrees after TDC (I guess they don't contact the pistons with this setup but I don't know as I have never tried it)

bob gauff

 

Thanks for the info motorcarman, Like I said in my first thread, I'm having trouble locating the triangle indent on the drive plate so I can lock the crank. Is it obvious when looking through the access grommet? How big is it? Is there any chance it's not there? With the cam flats lined up, is it good, or could I be a rotation out?

 

You can't be a rotation off on the crank... the crank turns twice for every rotation of the cam. So being one rotation off would put the cam 180 off. if the cams are locked, the crank should be in the right place, assuming the timing chain hasn't slipped a tooth. Even then it would be close... (within twice the angle of a cam sprocket tooth). And to the best of my knowledge, if your'e MORE than one tooth off on the chain, you'd have a valve in a piston.

 

Thanks quadmaniac, great too know!

 

To answer your question: I couldn't find the triangle on my flywheel either. And YES, the rounded "window" is where the crank locking device fits. When I put the lock in, I made sure the camshaft flats were really close, that way, I knew the crank was at the correct location.

After I did the tensioners and took the camshaft and crankshaft locking devices off, I turned the engine over with a socket wrench to make sure no pistons would be coming into contact with valves - just to help me be secured in knowing that the timing was correct (you know, sort of like measuring twice and cutting once in carpentry).

 

Thanks ysgeye, I came to the same conclusion, but it puts my mind at ease knowing you went through the same thing.

 

Just an update, new tensioners in, timing set, all back together. Fired right up!

 

And yes, the "magic" hole is a subtle rounded looking side. As I remenmber, there was a revision that changed the triangle or eliminated it. The rounded hole should be under the ckps hole just as the cam flats become level on top

 

Here is an update on my XJ8: I bought the car, really, as only a body, as the engine didn't run and the prev. owner said the independent Jag mechanic said it had something to do with the tensioners. Other than that, I couldn't get any other information from him, theoretically because he got it from someone else while it wasn't running and after the Jag mech. told him that, he decided not to mess with it.

So, I put in the tensioners and buttoned it up. It started right up, but the motor was jumping like a frog on hot pavement, so I checked the compression of the cylinders. 4 of them had 150-155 psi, and 4 had 0 (not all on the same bank, mind you). It was as follows: Bank 1 (left side): 155, 155, 155, 0. Bank 2: 150, 0, 0, 0.

I put oil in the 4 cylinders with 0 psi and it still read 0. Now I am thinking that some valves in those cylinders are not seating correctly, though it did not look like the timing chains jumped any teeth on the sprockets. Could also be the valve guides are leaking, though I would think that there would be at least a brief showing of pressure in the cylinder if that were the case.

Looks like it might be time to pull the heads to see if the valves were trashed unless someone has an idea of what else it could be.

 

Sounds like this one might deserve a new post, so we can follow your efforts. There was no evidence that the timing chain had slipped a tooth or two?

Performing a leakdown test (a leakdown tester is relatively inexpensive from sources such as Harbor Freight Tools) would tell you whether you're seeing valve or piston/cylinder issues.

 

Thanks quadmaniac. For anyone interested, we're currently working on an O2 problem/condition on another post, appropriately named - Ignition Coil Multimeter Test. I'm hoping it is related to the problems in this thread.

 

With pressure of 0 a leak down test is not going to be very reviling.

 

If you set each piston at TDC compression, one at a time for the ones reading 0, and then with air tank still pressurizing the tester, you can listen for air flow (or feel pressure build up by plugging with your hand) at the throttle body, the exhaust and the oil fill hole to help determine whether the leak in that cylinder is intake valve, exhaust valve or piston/rings respectively.