Not sure if my car has a leak somewhere, but Im going to get under it tonight once I get home. Ive had to refill the coolant about a quart during the 100 plus degree months recently. So not sure with what is leaking yet. I do know that I dont have a working heater at the moment, Ive only had the car for about 7 months or so. So just curious about what may be normal. My 86 is a daily driver and I put about 80 miles on it every week.

 

You didn't specifically say the last time you topped-off. A quart every, let's say, few weeks doesn't seem like anything to worry about IMO. A quart each week, well, that's a different matter.

Loose hose clamps can cause a minor loss of coolant. Give all of them a snugging-up

If you don't see a leak (or evidence of a leak) then your head gasket might be leaking a wee bit.

Cheers
DD

 

1. Good point.
   
2. Last fill up was about 8 weeks ago.
   
3. thanks Doug! Im going to start going through the system in order to get the heater working. But I wanted to get a feel. Will start to check it weekly now. 20 years ago my first S3 was checked before every drive. Since I also own an equally reliable XJS, I tend go check things once every month. The XJ6 shouldve have a closer eye on it.

 

My gap between remembering to even look at coolant levels is a few weeks. Actually having to do anything would be every few months.

Coolant loss can be tricky. If its very slow it will evaporate off as it leaks and you may only notice if you notice residue staining. My last episode of this was with my daily driver truck. I was steadily loosing fluid at a slow rate with no obvious leaks and feared a head gasket issue as mentioned by Doug. While doing something else I noticed what appeared to be small runs of "mud" building up on the back of the radiator. I was the residue from tiny leaks. Replace radiator and all good.

 

I learned ear;y on that a phillips screw driver is inadequate to get a hose claomp tight enough to avoid seeping. a socket doew it much better. Rachet or break over drive. leverage needed.

Now adays, a drik driver, pro styles

 

An '86 S3 will have the "slotted block", which was a final spatchcock by Jaguar to sort out the block cracking between the bores. It succeeded in doing this, but even so, the head gaskets are known to be liable to fail once the engine gets up to about 85-90k miles although not all engines suffer. Main thing to check is to wait until the engine is totally cold and then remove the coolant pressure cap There should be no residual pressure. If there is, then the head gasket is suspect. You can test the coolant for combustion products to confirm, many garages have the test equipment to do this. Of course it could just be a leak somewhere else. One very mysterious leak on a car was tracked to the heater valve at the back of the engine compartment ! This is operated by vacuum, and if the internal seal goes, the coolant escapes into the vacuum system, and then into the inlet tract, so no external leak is ever seen. I have also seen a corroded timing chain cover that allowed coolant to pass from the coolant passage into the timing chain compartment; not good !

 

Thanks for the insight on the slotted block. I did remove the cap a couple of times today, and there was no pressure so that’s a relief. Im not familiar with the timing chain cover design, Im curious to know more about that. Im tempted to replace the heater valve with a manual valve I have sitting on my work bench, just to get rid of anything any issues that could arise from it. I havent found any obvious leaks as of now. I am wondering about how and why my currently not functioning. Over the weekend I did kinda get hint of coolant smell inside the cabin, but its not really there. I know coolant when I smell it quite well.

 

Minor coolant leaks can be hard to trace. Sometimes the only evidence is a stain.

Among other things look at the underside of the water pump

Cheers
DD

 

This morning I slowly opened the coolant cap and there was very light residual pressure. Now Im thinking the gasket is suspect…. Oh joy! What a pain this is gonna be.

 

I made an appointment with my local Indy to pressure test the system to find any leaks first. Then proceed to check for headgasket leaks if any are present.

 

to properly fill the cooling system, you need to remove the expansion tank cap, start and warm the engine, setting the Heater to maximum heat with expansion tank cap OFF. Run the engine about 20+ minutes until thermostat opens and closes through several cycles and stabilizes. All the time with Heat ON at maximum temp and cap off.

you will see coolant being "burped" out through expansion tank as engine warms up and this will bleed system of air. Keep adding coolant until no more burping.

replace cap on tank and drive the car a while, all the time with Heat ON at maximum temp.

park the car, turn heater OFF, shut engine and allow to cool overnight. Next morning check coolant level and add as needed.

If there are no leaks, level should remain where you last checked it.

 

Another symptom of HGF is one can usually smell the coolant in the exhaust after the engine is warmed-up. My 1980 XJ6 had a cracked block which was only finally cured by rebuilding the engine around an uncracked one. Yes, there were a few, a very few, that never cracked !

 

knock knock knock on wood! my '84 is coolant leak free and uncracked.

 

I havent smelled that yet. Im going to drive it all week and see if I notice any changes. I mentioned the residual pressure to my mechanic and he wasnt too sure that I should be worried about that. He did insist on replacing all of the coolant hoses, so I will go that route once he has the car in a bay. Thanks for the great input. I dont know what Id do if the block needs to be replaced.

 

I would not expect a slotted block to need replacement, but the deck may require a very light machining pass to clean it up, although even this may not be needed, and a clean-up without machining will suffice. Of course there is then the other mating face, on the cylinder head, that could well need a skim, but you won't know until the head is off.

Even the non-slotted blocks that have cracks are not scrap, because lipped liners can be fitted in place of the non-lipped ones. The lips cover the cracks. Of course this requires a full engine strip-down, so would be done as part of a full overhaul, which could include replacing the ghastly rope rear main crank seal with a modern lipped type.

 

Great advice Jose, for those of us that check our coolant routinely, but don't really know what we are doing (like me!)

 

Its been a few days with about 80 miles on it since I refilled it, and the level is still the same. Weather has been nice. So I believe that when the temps go up, it starts to leak somewhere in the coolant hoses. Will be getting tested on Tuesday, will most likely proceed with all new coolant hoses and clamps.

 

if the water pump is not weeping through its weep hole, then the suspect hose will be the one you can't see, the one connected at the bottom left side of radiator.

 

Don't do anything except drive it a few more days and then recheck.

How full have you been filling the brown tank? More than about half way?

A million years ago, with my 87 XJ6, I kept having to add coolant. Someohow I discovered that anything past about half full in the brown tank just....disappears. I stopped adding coolant and the coolant seemed to find its own level and stay there.

I really can't explain it as anything pushed out of the brown tank should go into the overflow tank.....and then get sucked back into the brown tank as it cools down.

But there you have it

Cheers
DD

 

not in my '84, the brown tank is full up to the bottom of the filler neck and it does not go down.
Maybe the '87 was different.