Testarossa - tappet noise from engine

Low oil, dirty oil, wrong grade/type of oil, or clogged oil filter would be the typical culprits for the easy fixes.

 

Does the testarossa have hydraulic valve lifters??

 

No

While a change in lubricant along with a valve that was already on the "loose" side clearancewise can start clicking, the valve train on a TR has solid tappets with shims and doesn't "pump up" like the hydraulic lifters on a Chevy.

Excessive valve clearance that suddenly appears (especially if the noise comes and goes) can be a result of one or more loose valve seats.

This was (and still is) a problem with some 12 cylinder Jaguars. The steel valve seats did not have enough "interference" when pressed into the cylinder head and when the engines are overheated (not uncommon for a Jag) the seats would literally fall out (really bad).

 

What weight oil was put in ? That's the first place to start. If it wasn't 15w-50 or 20w-50 then I would get the oil changed with either of those weights pronto. I recommend Mobil 1 15w-50.

 

I agree with the above posted comments. Does the car burn any oil? '84-'89 Porsche 911 engines would have ticking sound when the valve guides were starting to go, and they would burn a bit more oil than a 100% healthy engine.

 

2na, the inline 6 jag also had problems on the exhaust side of the head where the guide for the tappet would
back out of the head and the cam lobe would interfere with it... use to make a distinct tapping noise.
Jaguar had a "hold down" kit that was retrofited to the exhaust side of the head as a precaution.

someone once told me that ferrari valve clearance usually tightens instead of loosens due to wear.
can anyone confirm that????
in 17k miles that seems highly unlikely but hey who knows.

can you verify it is a tappet by listening with a stethoscope???
I had that happen to my porsche once, I know they all tick.
but this tap was more prominent than normal with a definite change in performance.
Turned out to be a plug wire discharging to ground on the head through the extender.
burned a hole right through it.....
thought I'd check the rest of the wires by using a spray bottle of water on them while it was
running,,,,,, nice light light show in a dim garage.
needless to say all the wires were breaking down over time.

 

Valve clearances can tend to tighten up from wear and also sometimes from stretching valve stems. I've seen the heads pop right off of some valves (Maserati, VW).

 

Does the noise change when the engine is revved, or on overrun? (I obviously don't mean in frequency, but in character)
I like the plugwire suggestion, good thing to check, but also have a look at injector seals and manifold gaskets, or even a loose plug.
A dropped valve-seat can of course happen, a compression or leak-down test should tell the tale, but one would have to seriously overheat the engine for that to happen. Yes, the Jag V-12 has a propensity to drop valve-seats, but almost uniquely after overheating, and almost always on cars equipped with cat converters. The overheating is almost always due to lack of- or badly performed maintenance. I run mine hard, and it is problem-free, but well looked after.

If you suspect a dropped valve seat, don't run the car until it is cured in order to avoid expensive damage.

Good luck!

Jack.

 

A stethoscope can isolate the source of the noise (I have an electronic unit, it's amazing what sounds are going on inside a running engine when you isolate them from the exhaust sound).

 

Well, IMHO, I would park the car until the issue is resolved. There are several events that could be taking place with your engine, and until someone gets an eyeball on it there is not one soul here that can make an accurate diagnosis.

You have a noise that you describe as a valve tap as well as a noticable lack of power. This is not a good sign. It could simply be a sudden change in valve clearance, it is possible a shim wore through its hardface. This is quite unlikely but certainly possible. The cam could have suddenly had a lobe failure, again, rather unlikely but... You could have a loose valve seat ready to drop, an exhaust header leak, a piston gudgeon pin that suddenly loosened up, a cracked piston ready to break up, a bent valve ready to break off, a broken valve spring, its even possible your timing belt jumped. It could be almost anything. But if you notice, just about any one of these items could be downright catastrophic if allowed to fail completely.

A dropped valve seat can do incredible damage, as can a bent valve, a broken retainer, a broken piston. A bad cam can throw steel shavings into the aluminum cam journals and destroy the cylinder head. While a cracked piston, a loose valve seat, or a bent valve would be quite expensive, catching it before it actually destroys the entire engine would be a bit more economical.

I would suggest you absolutely do not run the engine for any reason until it has had a compression test, a leakdown test, and a thorough going over before you run it at all. You need to inspect the cams, the tappets, valve clearance, the timing belt, etc.. Sure, a warm engine would be best for checking the cylinders, but your looking for damage now, not wear. I would also suggest a borescope to peek around inside the cylinders. And I would disable the ignition so some fool mechanic dont try starting it either. There comes a point where we dont need to listen to it anymore, we need to inspect.

 

I'll second that.

 

I've never heard of spraying water on the wires. Interesting.

 

I had a bad plug wire zap me through a stethoscope once. That was NOT funny.

 

Can you hear me now?!

 

huh?

 

?????? Your playing russian roulette my friend, I wish you luck. If your mechanic thinks driving it some more might fix it, and you follow his advice, your as foolish as he is. The odds that changing oil and driving it will fix it are about zero, but not impossible.

I preached to my niece for years to check her oil, keep it topped up, she never listened. She once drove home over 10 miles, the last 6 of which were freeway, with no oil. The oil light was on steady BEFORE she got to work, and although a service station was across the street from her work, she chose to drive home. The car was overheating, smoking and squealing when she pulled in the driveway. It took all of 5 quarts to refill it. She drove that car almost another year before selling it. It should have blown up, but it broke the odds. And as far as my opinion about keeping oil in the engine goes, she laughs at me to this day and says I am full of crap. I hope I am equally full of crap in this instance.

 

At least in Russian Roulette there is only one round in the cylinder. This is like playing with five rounds in and only one empty.