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Tips
Tips

'85 XJ6 Losing Anti-Freeze

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tony barnhill

tony barnhill

Great Pumpkin - R.I.P
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Don't know where its going - nothing in oil, no smoke out tailpipe, no evident leaks, no puddles on ground underneath....but going through quite a bit - a half gallon over the last week.

Any ideas?

Oh, radiator was recently rebuilt & fan was replaced with new plastic unit.
 
Tony, I once had a pinhole leak in my Mini that didn't drip or leave a trail, there was nothing anywhere it shouldn't be, etc. Apparently while driving, the pressure would build and an un-noticable spray would mist out and dissipate. The only way I ever found it was a slightly cleaner area near the leak - this case was the lower radiator hose clamp and I had to be upside down and backwards under the car to see it. It baffled me for a while.
 
Coolant recovery bottle?
Can and do get cracked when you swap radiators.
Have you pressure-checked the cooling system?
Sometimes just the cap will do it.
If the seal under the top is bad (not the one that seals in the coolant), when heat expansion pushed coolant into the bottle, the suction required to pull it back in when it cools can't work if that top seal is broken.
Push enough into the tank, there is an overflow.

Is the tank going empty or the radiator itself?
Important troubleshooting information.
 
Best solution is a pressure test. The cap should be a 15 pounder. There are a lot of places to leak on one of these. It is not unheard of for the headgasket to leak, but usually it will seep down the sides of the block. I think there is a freeze plug behind the starter, but that may only be earlier engines. The heater valves also leak a bit, look for white crusties on the operating portion. The tanks can leak at the seams, and the water hoses near the throttle body sometimes leak too. Be very careful about proactive repairs like re torqueing the head. The studs go all the way down to the main bearings, and they are known to corrode. They sometimes snap, and you can bet that it snaps flush at the bottom.
 
New correct cap....am gonna pressure test tomorrow...when refilling, I can hear it gurgling down into the radiator....ran it 100 miles tonight at between 80 & 90 mph & temp was hovering just below 90 (beginning of the green line on the guage).
 
Gurgling isn't a problem.
So, you're telling me the reservoir is not where you have to fill it, rather the radiator itself?
 
No, I'm filling the reservoir.
 
I hear it gurgling somewhere - like its running into the radiator...'course there are those baffles or whatever in the reservoir it could be gurgling through.
 
I once ran into one of these that had been given a dose of "bars leaks" and it almost totally clogged the fill hose. Check for some kind of obstruction. Fill to the top of the little tab, and squeeze the top hose a few times to force it to bleed out any air. Then top up as required.
 
Tony: 5 places to look while under pressure 15lbs. Watch the reservoir for leaks, look around the thermostat housing, aluminum corrodes, look with mechanics mirror for the weephole under water pump, pull both knee pads from both sides of console and look at heater core and pipes.
 
Leaking head gasket!!
 
internal or external?? If you are going to pull the head and fix it properly, I have a suggestion for you. Make a flat fairly thick steel plate that will fit between the cam covers. Drill and tap holes at each head stud location. Obtain long bolts for these. Drill holes above each spark plug hole. Cut off some scrap plugs, and well some all thread to those.Screw the plugs into the plug holes, and secure the plate with nuts and washers as required. When you are absolutely positive all attaching bolts are off, thread the long bolt thru, and have them push on the head studs. Screw the long bolts evenly and the head will rise up like you planned it that way.This sounds like a lot of work, but it is NOTHING like trying to get a stuck head off of a 4.2. Also, the intake manifold is extremely difficult to get loose from the head. The easy way is to just bring it off with the head, and deal with it on the floor. Good luck!!.
 
Gotta be internal - nothing showing externally....when I initially start the car, it seems to miss for just a bit before it smoothes out...today for the 1st time, a little backfire......if I get real close to the tailpipe while its idling, I can see a few drops of mist out the left pipe.

My plan tomorrow morning is to pressurize the system...then I'm gonna pull the plugs, take a look at them & then spin the engine over to see if there's any anti-freeze mist coming from any of the spark plug holes.

Checked & I have a head gasket set on the shelf....so, head'll come off....thanks for the tip - I'll use it.
 
Same experience as Silverghost, above, on my Mk2. I had a very small leak from a core plug, could never see it (it was the rear plug behind the manifold). Spent a hole year topping up coolant (and looking and worrying!). Eventually got a pressure tester and coolant dribbled out so finally I could find it. One word of caution; after the test it leaked much faster! I tried some radweld as a short term solution, that stopped the drip, but it still lost coolant until I changed it.
 
I'll know tomorrow if its internal to the head....I've removed the plugs & am keeping the system pressurized at 16psi (& its slowly losing pressure)....figure after church tomorrow, I'll turn the engine over & see how much anti freeze shoots out which spark plug hole!
 
Tony;

I had the exact same problem with my 87.

Perform a compression test using a leak down tester. I suspect you will find a head gasket leak. Take the cap off the expansion tank before you start.You will know for sure if when testing one of the cylinders the coolant rises up out of the tank and overflows. That is the compressed air finding its way into the coolant system.
 
Yep, think so...I'm taking it to the garage later this week...I'll tackle any MG head - not gonna chance a Jag though! We'll see what their leak-down test shows.
 
Richard, I am reading this before I finish my first cuppa coffee. Hopefully you wrote it the same way. Think you made a misstatement when you said do a "compression test" using a cylinder leak down tester. Huh? Probably mean something like check for combustion leakage, using a leak down tester.

Two related, but different kinda tests. One is using the engine pumping action, to see how much pressure develops. The other is with the engine static, outside pressure introduced into the combustion chamber to see where it escapes...

Just in case there are any novices here, learning..

Kinda like going to the doctor for an EKG and a GI....
 
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