'93 245 w/ 212k miles.
Replaced timing belt, water pump, radiator at 200k miles.

The coolant is disappearing and the engine temperature gauge gets hot. After replenishing the coolant, the temperature is fine; however, I can NOT find a leak. I've looked all under and over with the engine running (belly pan off) and don't see anything.

There are two really bad places the water could be going> 1) engine and 2) transmission. The other possibilities are hoses, water pump, radiator, etc. Since I've recently replaced the water pump (Volvo) and radiator about 12k miles ago, I don't think it's those components. IF the coolant is making its way into the engine (like a blown head gasket or something??) how will I know?

This car has been regularly maintained and has never been modified or anything. It's puzzling because I can't find the coolant leak. The cabin doesn't smell like anti-freeze so..I don't think it's the heater core...but how do I check for that?

Thanks for any help.
Cabbie

I took off both of the heater hoses at the back firewall. The top one had a hole in it. I may have made it slightly bigger when I pulled on the hose to get it to come off the engine...but it definately had a hole in it. I'm so glad the unexplained coolant loss wasn't the head gasket. I went ahead and replaced both hoses (very tight quarters there!).
The only thing that sorta went wrong was that I broke off the little nipple on the flame trap. I think the bottom hose was easier than that darn top one.
Thanks for all the help. We'll see if the coolant loss stops now.
Cabbie

I would look for white smoke coming out of the exhaust, mayonnaise under the oil filler cap, one or more parkingly clean spark plugs and an oily film on the coolant in the expansion tank for the easiest ways to check for a head gasket failure. If none of these indications are present it's still not conclusive though.
I would also lift the carpets and check if they are wet near the heater core and hoses.


Erling.
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No white smoke, oil filler cap is not mayo, .. what did you mean about "parkingly clean" spark plug??? The coolant expansion tank gets empty all the time (have to keep filling up with water). I'm worried that no anti-freeze in summer heat may make engine run hotter...but I can't find the leak and anti-freeze gets expensive. Next step is to lift carpets and replace both heater hoses on the firewall. Got my fingers crossed that it's not a head gasket.

You may not smell antifreeze if you have diluted it with lots of water.

If the heater core is leaking it may be draining out through the evaporator drain pan rubber tube for the A/C. It maybe dripping on the trans and evaporating. Look around for trails or stains.

There is a test kit for checking the radiator for head gasket leakage. You can get it at NAPA that sucks the gases out of the water and through a detector fluid. It very accurate but I think they cost about $40 plus?

Next thing is to have the engine cold and apply air pressure to the cooling system. Just 5 pounds pressure will work. I use a Mity Vac tool that switches to pressure and their adapter for the coolant bottle.

A good radiator shop may have both tools for troubleshooting, if your desperate.

Phil

Thanks...
I'm gonna put anti-freeze back into the system to help me "smell" it again. I pulled up the carpets tonight...the driver's side floor board was a little moist. Kind of strange. but... doesn't account for the amount of coolant. Maybe the heater core is draining out of the A/C evaporator drain....cause there is always the sound of moisture hitting the muffler and transmission. I'm gonna put the anti-freeze back into the system and the next thing is to get a pressure test I think. I'll check on the NAPA hydrocarbon test thingy too.
This is getting frustrating....
Thanks
cabbie

It sounds like you might be getting warmer!

Interesting that you can hear a sizzle and the carpet was moist. The carpet may be getting damp from some spillage out of the pan when turning corners.

A passenger can sometimes get doused on the toes from A/C condensate. The drain can get plugged with leaf debris, that enters from the cowl vent, at the very back of the console.

By any chance, have you rubbed the insides of your windshield and noticed that it smears like it is oily. The antifreeze mix, will migrate just like any other moisture in the car, to a cold windshield. The difference is the water vapor leaves, the glycol doesn't.

If you are losing such a great amount of fluid. I doubt it is a head gasket. You would have a rough running engine and the oil would eventually reflect a milky look.

How long have you ran without antifreeze or without changing it?

Either of those can cause a premature failure of the heater core due to the fluid changing its chemistry. Acidity/electrolysis. Take your pick.

If your are a little lazy about doing maintenance, like most everyone, then I recommend getting Valvoline/Zerex G05 antifreeze. It the was the first, 5 year extended use and patented product. It is hard to find but it is worth it, for a lot more reasons to numerous to explain now.

I have found one place that stocks it because commerical customers order it! It is the straight stuff that I mix with distilled water. That helps keep those little crusty rocks out of the radiator!
Avoid any of the premixed brands like the plaque. Who knows what they use, plus your buying their water with shipping to boot!

Don't use DEX Cool. It is like the other Dexron's of 3,4,5 now 6 I think. I question the number of revisions within their famed transmission fluid products. They have been experimenting for quite some time to get both those products to be compatible.

If you find out it is your heater core. You may want to remove the hoses from the firewall and couple them to back to each other. You could try the bypass idea, above the core, inside behind the vents too. It is the highest point in the system.

You can do this until to get around to replacing the core. It is summer and you can pass on having it for a while.

If the loss of coolant goes away this will confirm it too!

Warning! It is a tight fit down there under the manifold but wait until you have to get down into that console. I have, had to change or oil fan motors, which are fun enough and dread the day for a heater core. Especially, since there is a A/C coil in the housing on mine.

I'm Loving that antifreeze
Phil

Typo, sorry. Read "sparklingly clean". If you have coolant leaking into a combustion chamber the result will not only be white smoke but also a steam cleaned spark plug.

Over-diluting the coolant is not good even in summer, as it contains anti-corrosive ingredients.

When I once suspected a leaking head gasket the well-reputed guys at the Automobile Association's garage measured for HC above the coolant in the expansion tank. As they found none they told me it was a conclusive test and that the gasket was fine.

Erling.
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I'm gonna lift the carpets near the heater core next.

I feel your pain. In addition to what you have done, look now for the very small things like the heater hoses at the back on the engine near the fire wall. It's a real pain to do this, but it is an option to rule out.

Also, I have experience the top radiator hose at the plastic connection dripping ever so slightly because the top hose was not a perfect fit. It was just a little drip but very annoying.

Finally, feel under your water pump. Once I did not get all the gasket material off and the new water pump would not go in smoothly. Also check the orange metal heater hose that goes into the water pump and the weep hole on top of the water pump.

Others can chime in on telltale signs of head gasket failure.

The weep hole on top of the water pump doesn't have water dripping when the engine is running. Funny though... I always thought that the weep hole was on the bottom of the water pump, which would allow the drip to fall easier....

I thought it might be the pipe coming off the water pump.....or even the water pump...but I dropped the belly pan and went over the whole area with a light while the engine was running ( I know... dangerous)... no leak. I think it might be the back heater hose(s) or heater core inside the car. no sighns of head gasket leak.

The small heater hoses can develop pin hole leaks that are hard to find. Check the hose that is likely touching the oil filler tube, I had one leak and it was hard to find.
Dan

How fast was the coolant lowering with your pinhole leak in the heater hose that touches the oil dip stick?

It was a slow leak. Check with the engine up to temp and then flex the hose. Can you smell antifreeze?
Dan