mark 5 coolant leak. need some help troubleshooting

carfreak

New member
my 78 mark 5 has a coolant leak. under the front of the engine block. all of the hoses are fine. but when i put coolant in it just starts leaking. and is all empty in like 5 days. could it be the freeze plug or head gasket? any help would be great! thanks.
 

tixer

Lincoln Evangelist
Hey Carfreak!

The very first thing I'd check is the weep holes on your water pump. When the pump fails, it will coolant will leak out of these holes, top and bottom. It should be fairly easy to spot.

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Take my word for it. If you have to replace this, step 1) is to pull the radiator. when I did the job on my '86, I was young and stupid. I tried to work around it. I succeeded, but the job took two days.. :D

Alternatively, I'd inspect the various frost plugs. I've seen those fail before as well.
 

Lvnmarks

quandoomniflunkusmoritati
The very first thing I'd check is the weep holes on your water pump. When the pump fails, it will coolant will leak out of these holes, top and bottom. It should be fairly easy to spot.

Agreed, there designed to leak there so you know to replace them.

I don't know the set up on a Mark V but I'm guessing you will need a fan clutch tool as well when replacing and if your going as far as removing the radiator and have the extra cash just go ahead and install a new one with new hoses and thermostat. Just one of those things I like to replace in pairs then you know you have a good standing cooling system for years to come.
 

opalescent 96

New member
I don't think you need a fan clutch tool for a Mark V should just be 4 1/2" bolts. If you want to wake it up replace the timing chain with a straight up pre 1971 non retarded chain while you're at it. Smog motor years have an 8 degree camshaft retard built into the timing chain that makes them pigs and kills horsepower...
 

billcu

Head Moderator
Do you mean the sprocket is different? I don't think you can change that timing with a different chain?

Moving this to the Mark Series section. :wave:
 
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