Hi all

As the title implies, I have a slight miss on B1... Now, I've eliminated the wiring loom and the injector, neither are at fault, I'm dreading a burnt valve, she's had this slight miss since I got her, A valve is within budget, not so with a cylinder head.

Any other possible causes? It isn't the "full" miss when an injector clip is pulled off, but the left-hand tail-pipe isn't smooth like the right-hand one, seems to die away as the revs climb, most noticeable on idle. I'll do a compression check ASAP and report back.

In the mean-time, any tips for going about pulling the head? Looks like the aircon has to come out...?

Thanks in advance.

 

Yes, compression test and if warranted, a cylinder leakage test. This will tell you whether is a burnt intake/exhaust valve or something entirely different (which would manifest, in addition to a miss, lots of smoke, loss of coolant / oil).

Did you switch injectors? Is this how you know it is not an injector/wiring loom issue?

 

pulling the head is not for the light hearted, some tools required.

some tools not in regular tool boxes

 

[QUOTE=NathanDD6;1406881]
Any other possible causes? [quote]


Have you considered the possible ignition culprits?

- spark plug
- spark plug wire
- distributor cap

Cheers
DD

 

Thanks for the responses, no loss of oil or coolant, and no smoking.

I swapped the injectors and also interchanged leads, no difference at all. Cylinders all "drop" a certain amount when the respective injector lead is pulled, but B1 "drops" less than all the others.

To be honest Doug, B1 is the only cylinder with a different lead (I fabricated a carbon lead from another car, checked the ohms, all seemed normal when compared to other leads) maybe I should swap B1 and A1's leads over... Worth the try, thanks. Spark plug and dizzy cap are good.

I've driven her about 1000 km's (620 miles) like this, and the problem hasn't gotten worse.

The engine also only has about 11000 km's (6900 miles) on her.

 

On the topic of tools, What would I need to source? What fancy/Jaguar specific tools will I need?

 

Swap that HT lead before anything else.

Then, if they will reach, swap B1 and B3 injector plugs. They are on the same sequence as each other, along with B5, which certainly wont reach. If the miss stays on B1, nothing new found.

The main concern with pulling the head/s is messing with that Plastic chain tensioner on the RH side. They have a very bad habit of snapping when messed with, and at $600 (last one I got), not funny.

Sliding the head all the way up the studs can be fun, not, and sometimes the engine needs to be tilted over to allow the head to clear the studs.

With such low mileage on a "newish" engine, I would not expect the heads to be "stuck" to the studs.

A huge task in any language, and as said, not for the feint hearted.

A "tight" valve clearance could also be causing it, and that is equally as big a task.

 

Just confirmed the HT leads are not at fault, and neither is the injector plug... So in for the big one???

Grant, you say "SOMETIMES" the engine needs to be tilted... This is something I won't be able to do... I assume this isn't always the case... You also make mention of the plastic chain tensioner being on the RH side, seeing as the left bank is the one in question, does this make life easier and safer?

I also hear of fancy tools etc used when taking the head off. Are these essential?

Thanks for the responses.

 

That tensioner must be released with either head and/or camshaft removal.

Some have been real lucky and managed to lift the sprockets off the camshaft snout and onto the metal rest arm supplied in there for that purpose, without the tensioner ratcheting outward, I have not had that luck. That tensioner spring is a STRONG sucker. If you do get that sprocket on that arm, place a circlip on its snout to keep it there, coz if it falls off that arm, that tensioner will ratchet to full out in less than a heartbeat.

No real special tools. There is a special tool to release that tensioner, but I have never used it, nor know where you would find one these days.

The engine jacking for clearance is something you wont know until the head is up on the top of the studs, and clobbers the shocker tower instead of coming clean off.

The setting up of the head with tappet clearances etc is a very time consuming task, and you will need an assortment of the Jaguar specific tappet shims, and a micrometer to complete.

There is a special tool for setting the camshafts in the TDC position PRIOR to dismantling anything, and are readily available on ?bay, and I would at least get that.

I reckon you will have to remove the RH camcover as well, but maybe not, that will depend on how you are going to address the tension issue with that chain tensioner.

When you do get into it, always remember to rotate that engine clockwise, and NEVER anti-clockwise, or backwards. Once the cam sprocket is undone that engine CANNOT be moved at all.

 

RH cam cover as well, well then I'll do that too, I've had cam covers off before, just never a head... I'll check the clearances while I'm at it. What is going to be the easiest? RH cam cover too, having a students budget, I'd like to do as much as possible on my own.

So it's just the tensioner to be careful of it seems?

Thanks for the advice plus anymore.

 

Before you dig in to this motor a proper diagnosis should be made. Consider pressurizing the suspect cylinder with compressed air to see where the gases are going. If out the exhaust or intake you've got a valve trane issue. If into the crankcase then you've for a piston, bore or rings issue. No point in taking the head off in situ of you've got a cracked piston. If the cylinder holds, then you've got a fueling, spark or perhaps intake leak. Once properly diagnosed you can disassemble whats necessary and see what opportunities present themself to effect a proper repair.

 

Agreed 100%. Also known as a cylinder leakage test. This should absolutely confirm that you have an issue and further justify you having to undergo this major undertaking.

 

I'll try the compressed air route, limited budget, don't really have the dough for diagnosing etc... But I've got a compressor

 

Compression tester comes tomorrow, will post the results.