I have a 1987 Jaguar XJ-SC with 77k V12. It is leaking radiator fluid and has been blowing white smoke. The smoke comes and goes but has not smoked in a while. I filled the radiator with just water to try to see where it was leaking and it has started to blow white smoke again plus now has a tapping coming from the engine and speeds up when I rev the engine. I have not seen where the leaking is coming from yet,(should be able to this Friday). This has now got me really worried. I now see a little milky look in the oil when I checked it too. May be the head but will have to check that too. Give me some ideals on where to start.

 

I think this is going to be mucho "Uh-oh!"

The tapping noise has me worried, as it's one sign that you have a dropped valve. Does it sounds like someone striking a side of the engine with the head of a hard plastic screwdriver?

Milky oil is often a sign that radiator fluid is leaking into the oil system. In this case, you may be correct and could be a head gasket. Would also be an explanation for steam being produced, as you both have a bad head gasket and radiator fluid was never meant to get as hot as engine oil.

As to where to start, well, I'd see where the steam is coming from. It may not be visible, though, as superheated steam is both dangerous and invisible (please don't just stick your head over the engine if it's hot). Do you happen to have a temperature gun? How quickly are you losing coolant?

Out of curiosity, did your car overheat recently? Give us a little history about the car, it may be useful.

 

White smoke is steam, is it only coming from 1 bank?

You say the radiator has a leak is it a leaking on the floor or is the coolant just disappearing?

Milky oil is not a good sign - this is indicative of a blown head gasket or at least water getting into the oil.

It the tapping a very loud clattering type noise that is isolated in one part of the engine, was it there before?

 

I got the car from a friend who had it regularly maintained and had owned it for 15 years. He said he was driving one day and it heated up and lost the radiator fluid. He never drove it after that. That was about a year back.I got it from him and have been starting it up trying to find where the leak was coming from only moving it from the driveway to the street. When I put the water in it I could see it coming out the bottom around the front drivers side but back from the radiator so I don't know if it's actually coming from the rad or something else like a hose. It has not heated up while I have started and let it run. I can get a temperature gun to check it. The white smoke was coming from the right tail pipe sometimes before this. It has never tapped before this either.

 

Forgot to add the tapping sound sounds more like not enough oil but checked the oil and it shows up to full line. I am preparing myself of this fix so can I get some roundabout pricing for a fix like this.

 

Two questions come to mind. First, does it start steaming right away, maybe a few minutes after you start your car and it's still in the cool range? Or only once it gets to around normal operating temperature? If it's the first, then the coolant is getting in the vicinity of the piston chambers, meaning that it might be a blown head gasket, as the piston chambers get hot right away. If it's the second, maybe it's just a loose or broken hose somewhere. There's at LEAST five hoses around the driver's side area, and the steam isn't coming out until the coolant itself starts getting hot from normal operating temp. Not sure what the white smoke from the right side might be. Perhaps a secondary water leak hitting the catalytic converter?

Now, as for your friend having driven the car overheated, well, it can only take one time to get a dropped valve. If it turns out to be a broken head gasket anyway, you need to get the head fixed anyway, right?

On the subject of finding a mechanic: most seasoned mechanics will avoid working on Jaguars like they avoid the plague. Parts are usually hard to come by locally, they (the Jags, not the mechanics) are not built like the cars that they are typically used to, and for the XJSs, there's usually little information for them to find on their computer databases on how to do something. Having this car is more akin to having inherited an old waffle iron. You need to find a specialist to fix it, otherwise you'll get an inexperienced person claiming they know how, only to get your waffle iron back, still broken (or worse), and cleaned with an SOS pad (you DON'T clean old waffle irons!).

If you want to save yourself a ton of money, do some of the jobs yourself. We're here to help!

 

If the white smoke is there right from start it can be an injector stuck open. It will not burn that fuel and some of it will find its way into the oil. If a drop collects at the exhaust pipe wipe it off with your finget and smell it. Also if fuel it will quickly evaporaye leaving your finger dry. If coolant the finger will feel sticky. It is quite usual for injectors to stick open or closed if the car sits for a long time, in particular pre HE 12s. Run a compression test wheb stone cold. If the head needs to come off you probably need a head puller. Search for threads started by me and you will find a pdf drawing and instructions on how to make and use.

 

You need to fix the water leak first, from what you said it sounds like water is leaking from the bottom before the car is started, this would indicate either a hole in a radiator or hose, easiest is to replace the radiator hoses, may as well do all of them while you are there.

Get this fixed before you start chasing and other issues.

 

It steams right away then would go away, now that it taps I have not let it run to temp. My friend stopped as soon as the car started to overheat and and saw steam from what he thought was a radiator leak then had it towed. I know these cars are crazy to fix just like my Porsche 928 so I would like to try to do some of the fix myself not only to save money but to know more about the mechanics of both of these cars. Plus I want to know some of what anyone is doing to my cars. I will try the finger swipe at the tail pipe. I am going to have a compression test done this Friday and I am looking for the leak first before anything else and I am hoping it's a lower hose. I do already have a radiator for it just in case. Thank everyone for their input and I will let you know what the outcome is with Fridays look/see.

 

Well found out it's the head gasket area so I will be having it done. I already have 2 foreign
garages that I know can do it and have worked on the car before for my friend who I got it from so I hope to have it done very soon. The radiator is still a question because the pressure check was done and that was alright so it has to be a hose or may need a real good flush and cleaned on the outside too. I know it will cost but it is well worth it being a XJ-SC which not many were made.