1989 XJS 5.3 Terrible Engine Noise

Bill,

Glad to hear that it was not a dropped valve seat. You don't even want to imagine what that would have meant. Don't be put off by the comparative difficulty of working in the valley on the XJS. Be patient and you'll be able to do it.

Based on one of the plugs being broken, I'd strongly suggest that you change all of the plugs before you go any further. I changed mine a few months ago. As long as you have several different length ratchet extensions and a universal joint, you can do it. Just try to get the extension as close to the angle of the plug as possible. If any of the plugs are stuck, don't force them. And before pulling a plug, be sure to clean the area around the plug with compressed air as a LOT of debrise builds up in the plug wells. And be sure to put anti-seize on the threads before reinserting. If you're having problems treading the plugs, try a piece of gas hose. Slip it over the plug and you can insert them more easily.

I used NGK plugs and like the performance. Some people like the Champions, but I found the performance a bit better with the NGK's. Others seem to like the Bosch Platinum +4's, but at $6 ea., vs. less than $2 for the NGK's, I found it hard to justify the extra money.

Other things you should check. Make sure that the vent lines to the distributor are in place. The filter (a small plastic fuel filter attached to a hose near the driver's side fender) should be clean. And the vacuum hose should be attached to the top of the distributor and run to the manifold on the driver's side. This circulates air throught the distributor to prevent a buildup of vapors that can cause the distributor to explode.

Check the main fan. If it has a yellowish/orangy colored hub, check it VERY CAREFULLY for cracks. If it is cracked, replace it immediately. Those hubs are notorious for catastrophic failure that car rip a lot of things up. Better yet, remove the mechanical fan and replace it with an electric fan. And be sure the auxiliary fan is working properly and cycling on and off.

Check your cooling system, especially the hoses. If you're not sure when the last time the system was flushed and coolant replaced, do it now. Use a 50/50 mix of coolant to water, and add a bottle of Red Line Water Wetter (NAYYY). Keeping your big cat from overheating is a major priority. And don't forget to check the lower hoses down below. Suction from the water pump can cause them to collapse and cut off flow. Also, the radiators are notorious for clogging. Flushing and flow testing is not enough. Visual inspection is suggested. Recore or replace with an upgraded radiator to keep it cool. And while you're at it, make sure that there is not crud that's built up in the fins of the radiator, and between the radiator and condensor and transmission cooler that can cut off air flow. Check to be sure that there are no gaps around the radiator that will allow air to bypass the radiator.

A little preventive maintenance will go a long way to your enjoyment of the car. Older cars like ours need a thorough going over at the beginning of every driving year. Don't forget the normal stuff (belts, air cleaners, oil change, filter, lube, etc.), but these are a few of the special considerations you should be looking at with our car.

I took my XJS for a drive on Sat. Beautiful day here in NJ. Carol was driving our XKE. We had them up to about 120 mph on the Interstate, then took them on some back road touring. We'll be slaloming them in a couple of weeks too. Then up to Lime Rock for a run on the track then end of May. They are great cars. Enjoy!!

Steve Weinstein, JTC-NJ
JCNA Slalom Committee Chairman
JTC Slalom Chair
'72 E-type 2+2
'89 XJS Coupe

Steve, a special "Thank You" for the heads up on the potential for damage if, I was not very careful and very lucky! I did NOT start the engine any more after your comments. :)
---------------------------------------------------------------------------
Update on 89 XJS Terrible Engine Noise

A special "Thank You" to all you that have responded to my problems with engine noise.

Well, I hope that I have finally discovered the sloution. After a lot of ideas, suggestions, and prodding from some to keep looking. I discovered that the insulator and center electrode had separated from one of the spark plugs. The wire and the insulator with the center electrode were just laying there in the V. I did not ever recognize what it was for a long time. Did not look its part.

I really should have found this sooner but, I am really intimidated by the V-12 and was very reluctant to probe around in an engine that I know nothing about! No room to move your fingers around in and especially when it is missing, and making all kinds of NOISE... Remember, I have had the XJS a little under two months.

This is a good time to say "Thank You Lord" because the chances for an engine fire were greater that I had any idea of. The fuel had to be pouring out of the little hole in the base of the spark plug, spraying every where, and the electrode was still connected to the plug wire and just laying there in the V waiting for a good connection and some hot sparks.... :) Kinda scary when you think about it.

Scott Watts, AKA ThunderCat1984, lives within 30 miles of me and is coming in the AM to help me find where the plug goes and replace it. Just hoping that no other damage was done as a result of the "plug"

Again, Thank you for all interest and suggestions that so many of you did show.

Bill Giardina, 1989 XJS Covt. Raymond, MS
Bill Giardina 89XJS

Bill,

I hate to be the bearer of bad tiddings, but there is one very bad sound that can come from these engines, and you best hope it is not it. It sounds to me like you might have dropped a valve seat. Have you had a problem at all with overheating? If you have, a big problem is that the head are made of aluminum and the valve seats are iron. Different metals, different expansion and contraction. The valve seats are pressed into the head. If you overheat, and the head cools too quickly, the valve seat can literally drop out of the head. When it does, it shatters inside the piston chamber and makes a horrid noise. Part of the problem, being that you've only had the car for 2 months is that you don't know if the PO had problems with it overheating.

Unless you can see something obvious from the outside of the engine that would cause the noise, I would strongly urge you NOT to start the engine again and get it to an experienced, qualified mechanic who is very familiar with Jaguar V-12 engines. I'm not talking about the dealer -- most don't want to have anything to do with engines as old as ours, and you'll pay a premium for it. And don't take it to your local garage, unless he is a bona fide Jaguar mechanic with V-12 experience. They don't know what they are looking at.

If you don't know a good mechanic, contact your local Jaguar club and ask around. But I would not start the engine to try to diagnose the problem. If it does turn out to be a dropped valve seat, you can only make the problem worse, not better, by running the engine. And if there is a fuel leak in the valley, you run the risk of an engine fire (keep an extinguisher handy).

In terms of checking things in the valley, you're right. It is a tangled mess and hard to get in there. But with a good drop light and a little determination, you can poke your way around and check things out. Most of the plugs are very hard to get to and require at least a long extension and a universal joint on the ratchet. 1A and 1B are almost impossible to get to without unbolting the A/C compressor and moving it (ask me how I know).

Good luck and let us know what you turn up. BTW, spark plugs don't just come out, unless they weren't in to begin with. This seems unlikely, as you were driving the car for a while with no problem.

Steve Weinstein, JTC-NJ
JCNA Slalom Committee Chairman
JTC Slalom Chair
'72 E-type 2+2 (V-12)
'89 XJS Coupe (V-12)