Driving yesterday, the engine started running rough. It gets much worse over 2k RPM to the point that the engine may be coming loose from the car.

The mechanic checked it this morning and said the engine runs rough and is misfiring, but all 8 fuel injectors are good and all 8 spark plugs are firing. The codes recorded misfiring on 5 out of 8 cylinders(302, 303, 305, 306, 307).

their thinking is that the timing chain slipped, because jaguar V8's have a plastic chain tensioner that can fail.

they need to open the valve covers to check further.

before opening up the engine, what else can I ask them to feel more confident about their work so far?

how can I get a second opinion?

thanks in advance!

 

Sounds like a very logical opinion on the cause of the problem. There is a serious issue though. If the chain has jumped one tooth the engine runs rough and survives, jumping two teeth will bend valves and perhaps destroy the engine.

I would not start the car again even to take it for repairs.

You might ask for an estimate and also ask if they will use the Lincoln LS parts at considerable less expense than the same parts in a Jaguar box. Total cost at an independent, straight parts and replacement labor, no repairs should be less than $800 ($200 parts, 4 hours labor).

Ask what else they would recommend doing while under the hood. I would consider replacing the thermostat, thermostat tower and the short hose in front of the engine top if is it anywhere near time to flush the coolant. All that is going to be exposed by the the top end work anyway.

Please don't start the car again! Not even to move it around the shop.

 

Now the mechanic said that the tensioners are intact, but #2 cynlinder valve is stuck open. That will require the head to be removed to fix. 30hrs. of labor to get the head off and over to another shop to grind the valves.

The other option is to remove & replace with a used engine.

Need some serious advice!

 

Tough call, but with 145K on yours, a used engine with under 75K is probably a better bet.

 

And ... before installing the used engine ... replace the primary and secondary timing chains/tensioners unless they are *known* to be the 3rd gen.

 

Leaning towards replacing with good used engine, also was recommended by mechanic.

Anyone know of possibility of replacing with used 4.2L ?