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Slow Leaks and Additives

My 1982 Ford Granada has a slow, external antifreeze leak that I can’t seem to pinpoint. It happens only whemn the car is runn9ing and warmed up (pressure in the system). It dosen’t leak when cold and sitting. Are leak stopper additives any good? Or, will such additives clog my radiator (fairly new) or ruin the water pump or thermostat?

How old is the water pump?
If it’s over 5 years / 50k miles I would just change it and cross my fingers.

Next time you are driving someplace far enough to warm up the car, and it is dry outside, take a couple of sheets of cardboard with you. When you park, leave the engine running and slide the cardboard under the engine. Let it run until you see coolant on the cardboard. Shut off the engine and see if it is under the waterpump. Be careful, an electric fan can start up after the car had been turned off.

With a mirror like this”-diameter-magnifying-inspection-mirror-p-101686.html?osCsid=gafov88oc0pl3eo12sjuhdk382

and a small light you can look behind the water pump pulley and likely see the yellow residue of leaking coolant at the weep hole.

Additives are not a solution. You need to find the leak.
I’d recommend you get a UV sensitive dye and a blacklight. Run the motor 'til warm with the dye in the cooling system, then put the car up on ramps (engine off) and look under the hood and under the car with the blacklight. The leak will light up before your eyes.

I prefer NOT to use stop leak unless you wish to run the car for only a few more months. I get the feeling you like this older car and want to keep it around so fix it CORRECTLY and not Band-Aid it with stop leak of some kind. One of my friends who used to work as a mechanic feels that stop leak should be outlawed unless the car is just about ready for the scrap yard and this buys the owner a few more months/few more miles of use.

Look at the thermostat housing, hoses/hose connections, water pump, new radiator, etc. for signs of the leak. Also consider that you might have a cracked head/head gasket or block if it has been overheated. It is likely not something serious like this but you should consider this too.

I prefer NOT to use stop leak unless you wish to run the car for only a few more months. - See more at:

I think I found the leak. It looks like it’s coming from the base of a sensor screwed onto the side of the engine. I’d like to tighten it slightly, but it dosen’t look like a standard hex nut. Also, I don’t have enough clearance for any wrench movement. Does anyone have any ideas or solutions?

Sounds like possibly a coolant temp sensor, but usually they have a hex fitting.
Can you take a photo?

Wrench movement can usually be obtained by using either a
stubby wrench,
ratcheting box-end wrench,

or socket with a ratheting “thumb drive”.

or sometimes an angle drive

I’ve had cases where I had to modify an existing tool.

If you have the 3.8L V-6, it is notorious for failures in the heads and head gaskets and all the subsequent failures from combustion gasses escaping into the cooling system. But I would be amazed if a 3,8L lasted 30 years. Which engine is in the car?

@Rod Knox In 1982 I believe the Granada came with a straight 6, or a V8, 302 or 351. I don’t recall any of those cars using the V6 engine. Ours had a 351 Windsor V8, a real thirsty brute with lots of torque. The straight 6 models were easy to work on, while the V8 was a brute due to small clearances.

The engine is the 3.8L attached is a photo of the sensor

@jmarc I stand corrected if the engine is the 3.8V6.

It’s been many years, Docnick. And the Granadas, Fairmonts, LTD IIs et al, seem to get lumped into a slurry and it is difficult after all the years to separate the models and engines but the 3.8L engine was so prone to overheating failures and my recollection was that it made its debut in 1980 so I shot from the hip. The 200 I6 was a much more reliable engine in my opinion. And the photo looks like a temperature warning light switch but it looks like oil leaking around it. Can someone recall where the oil switch was? I seem to recall it was in the timing cover like the old Buick 3.8L. And I thought all Ford temperature switches were near the thermostat.

FWIW that switch looks like an oil temperature switch. I know you guys were talking about antifreeze. I just looked on

@db4690, do you mean the oil pressure switch? An oil temp switch would be unusual for an 80’s Ford. But, I agree, i also think that is the oil pressure switch. The temp switch is usually near the thermostat housing. If the leak is near there, it would be easier to reach with that power steering pump out of the way.

@BustedKnuckles my mistake. It is an oil pressure switch.

I’m just trying to give OP an idea what part he may need to replace. The switch in OP’s picture might be something else, but it looks like the switch in the rockauto picture.

The sensor in the picture looks similar to the first generation GM knock sensor. Most Ford sensors of that era used a threaded stud as the connector.

No. a closer look seems to show that there is a blade on the sensor.