newworld

87s4 aut. coolant temps are normal, no issues, no visble leaks. new water pump etc. coolant reservoir is always empty. each time i fill halfway. have an alum reservoir tank.

a bit perplexed. oil dipstick clear. coolant clear. it is possible coolant drain plugs maybe weeping but nothing on floor of evidence. i recently did an engine pull.

i put in rad switch new and it leaked for awhile kept tightening it till stopped leaking. main upper hose leaked a bit tightened that, and i thought that was it but still reservoir is empty when cold. when i squeeze upper hose i can hear gurgling in reservoir.

GlenL

Well, it's going somewhere. My experience is that "mystery leaks" are usually into the cylinder. Check for steam from tailpipe on start-up.

If it's a leak in the engine bay from a plug or hose it'll smell of coolant. If you're lucky it'll show a wisp of steam.

A good test for coolant in the cylinders is to pull the plugs and crank it over. Observe the engine while someone else turns the key. The coolant will fly out. Also, the plugs will show which hole has the leak. The coolant tends to clean the ceramic part.

Best of luck

FLYVMO

Remove the spark plugs and see if there is any coolant in the cylinders, most likely in the rear. Happened to me when I removed a bolt that goes through one of the water jackets in the rear. Ended up with coolant leaking into the cylinder.

Cheers!
Carl

rgs944

Sometimes a leak will be small enough to not steam or show any dampness. Look for green dry deposits on the radiator and elsewhere.

Hilton

Check the ATF level before you run the car any more. If you haven't done it, now would be a great time to do a fluid replacement on the auto box while you're checking for coolant in there.

Hopefully its not going into the ATF cooler in the radiator (its not under pressure like the engine oil side - so coolant tends to go there without ATF coming out). A local had it happen - and spent $$$ on a transmission rebuild afterwards.

davek9

Does your heater work? If the heater core is leaking, it will drain under the car over the bell housing near the TT onto the exhaust or if a heater line into the Firewall drain down the front of the Firewall out the Flap.

newworld

several thoughts....

--start up all my cars i get white smoke on startup, there is a lot of condensation in exhaust system and sometimes drips of water from exhaust. that is normal around here in baltimore due to humidity etc. so that is inconclusive and smoke goes away after warm.

--no coolant smell in engine bay or exhaust.

--i do see on oil filler cap some brown sludge, most likely due to cooler temps in oil filler plastic neck, oil dipstick clear.

--heater core is good, heat works

--no trans leakage. rad seems fine as it partitions oil and tranny fluid.recently changed all tranny and it was red bright color

--i did have a leak on alum reservoir on oring where sensor level is. i fix that and no more leak.

--the car used to spill out a good 3 cups of coolant on the floor due to that oring failure, i thought this was the problem

--now i find no more leaks on ground, but reservoir is empty.

davek9

I would Pressure Test the system, and see how it holds.

Avar928

I had that same problem, it was the heater feeder line. The hose was so old and fragile that under pressure it would spray coolant out from the seams where it connected to the heater valve despite the clamps super tight. By far the worst thing I've ever had to change on the car.

dr bob

Old cars with old hoses will leak. Got one?

The coolant hoses (ALL of them) should be on your PM schedule sometime around every other timing belt/ water pump service. This would include the hoses between the head and the heater valve, the valve to the heater core, the heater core to the steel Y pipe under the reservoir, the hose from the bottom of the reservoir to the Y pipe, the hose from the front of the Y pipe to the water bridge. Then there are two vent hoses, one of which includes the coolant pressure sensor so there's a stub hose to the reservoir. Plus the two big radiator hoses of course. May not be a bad idea to pop a new heater valve in there at the same time. And a new reservoir cap.

As Devek9 suggests, you should pressure-test the system with evrything cold to find the leak. Chain parts places will loan you a pressure tester (just leave a CC deposit), and the initial procedure takes minutes. Pump it up to 14 PSI and start looking for dribbles. With the car cold, the escaping coolant won't be evaporating, so you will be able to find external leaks a lot more conveniently. Check the reservoir cap too while you have the tester.

Besides the hoses and connections, look at the heater valve, the drain valve/stop on the radiator, the hose nozzles in the radiator tanks, the core, the tanks themselves, and the seals between the tanks and the radiator core. If the heater core is leaking, you'll see coolant from the evap drain onto the floor under the car, and may also see coolant in the carpet.

Others have already discussed the issues of internal engine leakage.

Bilal928S4

I would do as Dr. Bob has recommended and also try and wiggle each connection. I had a problem on my 91 GT. could not fond the leak even after pressure testing but was losing coolant while driving. Ended up being the short hose from the block to the heater valve. Only leaked when disturbed.

newworld

ill chase this down, the problem is when i lift up the car, i like to go under when cold, if i go under hot, i got issues.

definitely not hose to heater, i changed all the hoses and even double clamped that one specifically.

that short one heater valve i will recheck, but i dont think it leaks.

ill try to find the culprit, as i mentioned i thought i had it in the oring on the coolant sensor.

but no joy.

there is a hose at front that clamps to side metal tube on passenger side, under 14 point connection, it was always a bear to put on.

i wish that whole right side front was reorganized on this car.

the left side is great, the right side is a pain. hard to change coil, hard to get ac, hard to put hose on, etc etc

Barry Chan

Low pressure reservoir cap? Coolant released while driving then when it cools down you will have low or no coolant left in reservoir!

fraggle

I'd do a compression check to rule that out. Mine lost a lot of coolant in mystery mode when the headgaskets were on their way out.

newworld

I think i found the sneaky little leak. It finally puked a cup on right front under rad. I felt under clamp upper hose and wet. I put antiseize on these clamps i t works loose over time.....i hope thats it......