I'm trying to help a friend get his XJS back on the road. I'll spare you what we've done already changing sensors and vacuum stuff, it now runs fine. But...it has a loud tick. Just getting near it, listening, my guess would be a valve thing, or, less likely IMO, bearing. So it sounds like it has to be taken apart, even come out. But here's what is strange to me. Usually when an engine has a ticking sound, when I have put a stetoscope on it, e.g. on the valve covers, I hear a much louder tick, logical since the noise is created inside the motor. But this one is different, the tick is quite loud just standing by the car with hood open, but the tick can't be heard with the stetoscope anywhere on the left part of the engine, only place I can hear it is on right side valve cover, but the tick is very weak.

So is there a possibilty this tick comes from something on the outside of the engine? Good to know before I start taking it apart? Or am I clutching at straws here?

Any advice will be appreciated.

 

My car makes this noise too. I did a bit of poking around online and found a thread, I think it was on here, that identified that noise as the injectors behaving normally. There were several comments to the affect that the injectors are very noisy. But lets wait for Greg, Grant, or Doug to be sure...

 

Hi No Quarter

I also had a Strange Ticking Sound on Start Up some years ago, which made me so Paranoid, that I filmed a couple of Back to Back Videos which you can see and listen to in the YouTube Link below

Where the general consensus of opinion was that I was in fact Paranoid and had nothing to worry about but just because you're Paranoid doesn't mean that they're not out to get you, so when I delved a bit deeper

I found out that the noise was almost certainly caused by some Ignition leads that were shorting together, as a result of getting some of those leads wet which was self inflicted when I very carefully tried to WASH THE ENGINE!

Which was not only a massive mistake of really epic proportions! but also something You must Never do!

Though having said that the Engine noise you are getting, seems to be a whole new different Ball Game that could be a cause for concern

Greg and Grant and Doug would probably know the answer, so wait and see what they say

Strange Noise from my Engine caused a bout of Paranoia down at 'Orange Blossom Towers'

 

The audio on such videos never seems to come out quite right, IMO.

Anyhow, your engine sounds just like mine always has. Based on the video clip and your written description, my advice is "For the love of god, don't take anything apart!"

Cheers
DD

 

Can you isolate the ticking? Either with a mechanics stethoscope or long screwdriver. You should be able to locate the sound.

 

That's what I've been trying. Never found it hard on other engines, but on this one, very hard. The only place I can hear the ticking through a stetoscope is on right valve cover, and the sound is very weak. Which again makes me doubt the source is internal...

 

Noisy Injectors, caused by lack of use.

30ltrs of GOOD gasoline, full bottle of Injector cleaner, Esky full of beer, ROAD TRIP.
Obviously top up the gasoline as needed, but no more Injector cleaner for about 2000kms.

However far you can with the border fiasco, not far down here.

If they are exactly the same when you return home, take a SMALL hammer, and I mean a SMALL hammer, and with the engine running, go along each Injector and GENTLY "tap, tap, tap" each one. That has revived 100% of all mine over too many years. Never had Injectors professionally cleaned as of typing this scribe.

As said, lack of use, major PAIN for any Injected engine.

 

A development, and not a good one. After trying most of what's suggested above, I bit the apple as we say, 12 plugs out, compression test. Not good. 11.5-12.5 on 10 cylinders, 0(zero!) compression on 5A and 2B, yes both banks!
So I today removed fuel rail, left intake and left valve cover. I was going to look for strange things and to check valve gaps, I've read in the manual 0.30-0.35mm. Strangely 5 cylinders had well below that (is 0.30-0.35mm correct?) and the zero compression cylinder had, wait for it, a gap above 3mm. Yes both cups are just about 3mm further down in the head when cam is not pressing on them. Have anybody ever heard about anything like it?

Of course the obvious thing now is to remove the head. But doing that, and on both sides, takes time and money, and I'm not sure the owner thinks this car or engine is worth saving. That's why I'm trying to find out what's wrong before I dismantle more...

Any experience like it?

 

Zero? Ok ok, hold on a sec. Zero? 11?

Brother, check your tester. I'm trying to imagine what would need to be taking place for ALL of those to be so off. I mean, if there was valve damage, or ring damage on one or 2 I could see. But all 12? How would the car even be close to moving under its own power?

 

Jay, you got it wrong. I have 10 cylinders with normal compression and 2 cylinders with zero compression. Maybe I wasn't clear....

 

(smiling) I git it wrong quite a bit... Honestly, in many places, I'm just getting the courage to post on issues, especially like this one.

​​​​Still, Help me. What's 11.5-12.5 (you'd written something like that - I can't reference back on my phone) in the other 10 cylinders?

 

Sorry, used the EU scale, in PSI it would show around 170 on 10 of the cylinders=OK

 

The valve gaps should be 0.254-0.305mm for a HE engine. 0.305-0.356mm is correct for Pre-HE engines.

Can you put a bore scope in the spark plug hole and look at the tops of the pistons? Zero compression will be caused by either the valve being open or the piston not sealing. If the engine sat for a while stuck rings are a definite possibility. Soaking them in oil should loosen them eventually.

The other possibility that comes to mind is that the engine was overheated and dropped a couple valve seats. 5A and 2B fire right after each other, so it is conceivable that they were both open when the engine stopped, allowing the valve seat to fall out of the head. That would hold the valve open, eliminating any compression from those cylinders, and make a ticking sound as the valve seat bounces around on the valve destroying the head. Its a widely reported result of overheating, but actual cases seem to be pretty rare.

 

Might be less common now than in the past. I think proper service and care of the cooling system is better understood now than it was 25-30-40 years ago.

Cheers
DD

 

My thoughts.

Dropped valve seats, YES, MAYBE, but the ones I have heard, NOT many, are CLACK,CLACK, and audible across the street. 5 & 6B being the main culprits.

Broken valve springs/s. possible, and that would hold the valves open. A valve seat is about?10mm thick. and then jamming sideways, would be more than that.

Bore scope is a good suggestion, and cheaper, and easier than heads off.

170PSI on a HE is LOW, usually around the 240 mark on the dry run.

As mentioned, if it is deemed to be caused from overheating, then a s/hand engine, if you can find one, is looking viable.

 

Hi No Quarter

This might help!

I've found a Video of a running XJS V12 with a suspected dropped Valve Seat, which 'Big Pants' Posted on my Blog, so that I could compare it to the noise I was getting from mine, where everyone was in agreement that the noise I was getting was nothing to worry about and anyway now its disappeared completely

Unlike in the Video you are about to see, where you will also be able to hear what a possible Drop Seat Valve might sound like!

And I'm not gonna Sugar Coat it, as this is very clearly the stuff of Nightmares!

What A Drop Seat Valve Might Sound Like! This is the Stuff of Nightmares!

Keep Scrolling down past my Videos and you will very easily be able to find it about 1/3 down Page 54 of My 'Cherry Blossom' Restoration Thread

 

Found 3 valves with seat dropped 3 mm. Yes, and valve lash above 3mm in those 3. So both heads must off, working on that.

 

When you get the heads off post some pictures. I want to see what it looks like and how much damage has occurred.

 

Working slowly to get heads off. While doing that, coolant has to come out, strange thing, loosened lower radiator hose, less than one liter came out! So it's been running without any coolant almost. Incredible. What a history this poor car has. And overheating is likely the reason for the valve seat problems. But what caused the water to disappear? I've seen no leaks (but not much liquid left to actually leak). I had convinced myself the water pump was ok since a failing water pump drips water. But maybe that's what happened.

I guess my question is more, can something more serious cause the water to disappear? I've noted no strange exhaust fumes (but again, not much water left since I got it here). And oil is perfect, no sludge in it.

My thoughts right now are new water pump and thermostats and that should cover it. But am I missing something?

 

You are missing the very high probability that an engine so overheated as yours must have been to cause his level of damage is very likely to no longer be true. I would find a replacement PDQ.