I took my 1988 Jaguar XJS in for some work. I had them install spark plugs, wires, distributor cap and rotor, oil change, etc. And when I got my car back it ran like an old tank. I couldn't figure out what was wrong with my car.
So I took it to a Jag mechanic, and found out that they never gapped the plugs to 25, they were at 40, they broke my distributor cap and glued it back together without telling me or their boss who owns the shop, they did not check the mechanical advance-it was seized solid and needed two days in varsol, it knocked when it started, they had the advance set at 23 degrees instead of 18. They set the timing to 18 after I took it back and insisted, but it still did not run right and still knocked when I started it and when it was warm it was real difficult to start. I mean my car was a nightmare when I got it back, I thought there was something else wrong with the car that had nothing to do with the work.
So the Jag mechanic gapped the plugs, installed a new distributor cap, rebuilt the throttle tower, repaired the engine vacuum system, replaced the two micro switches, freed up the mechanical advance, the throttle linkage was seized so he fixed that too. Then it ran quite nice, but I started to notice that it was starting to blow blue smoke. After all all I had been through I was real upset with the blue smoke thing, and found out by checking the dip stick a half a dozen times that they put too much oil in my car and the used SEMI-SYNTHETIC without asking me or paying attention to the repair manual I always have in my car.
So now I have a question, first I will say that I am having the synthetic taken out of my car, and having good old regular oil or put in oil for diesel engine (rotella). Now....the blue smoke thing....is it from too much oil or because of the synthetic or BOTH? And how is this going to effect my engine? Is my engine finished or will it be okay with new oil and the right amount. Did I damage some seals or something else? I am freaking out right now....and pissed off too.
Can you help me sort this out? The engine has decent compression on all 12 cylinders-between 160-170 psi., I heard it was supposed to be between 190-210 psi.
What is the normal oil pressure for this car? My gauge is in k-pascals not psi.

thread title is supposed to read:
mechanics screwed UP BIG TIME, I missed the "up"....

 

jetlag, as for the mechanic that did the initial work, I'm thinking a "stern" talking to and possible legal action would be in order (based on response to what you mention).

As for the oil that was put into the car, keep in mind that synthetic oil (they put in a blend of some standard oil with some full synthetic oil) acts differently than standard dino oil. It protects the critical surfaces just the same, but the oil molecule for synthetic is smaller, therefore it can reach more places. Hence you blue smoke (more than likely getting past the rings or valve seals). PUt in the dino oil and see what things look like then. I bet your blue smoke will go away. As for the rest of the engine, no crime, no foul.

As for your oil pressure question. The pressure that you see is relative to the engine RPM and the temperature of the oil. All the measurements I know of are based on standard motors, but the values should be fairly close. These are also based on an engine up at temp unless otherwise mentioned.

At idle, the pressure should be about 140 k-pascal (20 psi). Getting the engine rev'ed up to around 5,000 RPM, you will be up around 550 k-pascal (80 psi). Every motor is different, so, your values may be slightly different. The big thing that you want to see is that at idle the pressure is a fairly low value and is constant and as the engine RPM picks up, the oil pressure rises at about the same rate. If you see the oil pressure spike up, then you have an issue with blockage inside the engine. If the pressure plateaus out, then you have a bearing that is shifting and allowing too much oil to flow to it, starving something else of oil.

If you have any more questions, just ask.

 

How far over-filled was the engine oil? A quart, let's say, probably wouldn't make any difference...but 2 or 3 quarts overfilled certainly could.

Under what conditions do you see the blue smoke? At all times? Just on the first engine start of the day? On on hard acceleration? Since your compression is well below optimum spec I'd be leaning more towards an engine wear problem.

Yeah, go ahead and change the oil using a conventional oil and see what happens. It won't fix a worn engine (nor will synthetic oil cause a worn engine) but it might mask the symptoms. The V12s like 20/50 weight oil but if it's below freezing in your neck of the woods you might have to go with something lighter...like 10/40.

Don't be alarmed if the oil pressure at idle drops quite low when the engine if fully warmed up. This is quite typical for the 5.3 V12.

Cheers
DD

 

By the way the oil pressure spec on the V12 is 40psi at 3000 rpm, warm. It may well go higher (and will certainly go lower!) but that's how Jaguar spec's it.

Cheers
DD

 

Just a quick note, I got run out the door.
There is different compression rates for export to different countries from what I have read, right?
The car did not smoke before the oil change, and the timing was at 9 degrees. It was like that when I bought it over a year ago. It only started to smoke after the oil change.
I'll check your response later. thank Doug

 

Yeah they are refunding 1200 dollars for some of the work and I took it to a Jag mechanic who is also a mechanical engineer, he fixed everything.

 

I am going to have some of the oil drained out and see if that helps til I get the oil changed. I also heard that it can smoke if the engine breather filter needs cleaning, and that the pcv could be plugged as well.
I have been keeping my eye on replacement engines because it is always good to have an extra engine when owning these cars, especially if a head gasket goes.
I'll check your reply again later.

 

I have to say that for a 22-year old car, a bit of oil smoke with the modern "thin" oils is not unusual, I get a bit with my little 1977 MG Midget on start-up ! Once car has warmed through it seems to disappear.

Seizure of the distributor advance mechanism is quite common on these cars, so its good you have got it loosened off now; the car should run a whole lot better.

I would not worry about a bit of smoke on start-up, unless it starts to get really bad - its an old car and entitled to a little smoke now and again.

 

If the smoke is on startup then it could be a valve guide/seal that is leaking and an easy fix could be upping the oil viscosity. What is the oil that they installed and the rating 5w-30w or 10w-30w and what is the mileage on the car?

 

Gus is right about the viscosity being important- much more important than the synthetic or not synthetic. I believe the stories of synthetic being more likely to leak, or leak by for that matter is the stuff of urban legend. I have never seen a technical report supporting that position.