Mysterious coolant

-

dukeboy440

FABO Gold Member
FABO Gold Member
Joined
Jan 19, 2007
Messages
56,751
Reaction score
33,881
Location
No
my 74 slant 6 225 has a mysterious coolant leak. I've topped the radiator off, only to see it disappear with in minutes while the car is warm. there's no coolant in the oil, there's no puddles under the car, no drips, no leaks in the hoses, or heater core. Nothing coming out of the exhausts. It's just disappearing. While I am building a 440 to swap in, I still like to be able to drive the slant while I'm gathering parts but I cannot seem to locate this dang coolant problem. It has to be going somewhere. Could it be leaking into the cylinders and simply burning off? No smoke or haze comes out of the tail pipe though. :violent1: :banghead:
 
Have you checked for coolant in the trans? The trans cooler could have a leak.
 
Have you checked for coolant in the trans? The trans cooler could have a leak.

There is no trans cooler attached to the radiator. Previous owner put a stand alone trans cooler on and the radiator itself doesnt even have the fittings or anything for the trans cooler, they are plugged off.
 
If it's not leaking externally, it HAS to be either going into the trans or the cylinders or oil pan

How fast is it "using?"
 
If it's not leaking externally, it HAS to be either going into the trans or the cylinders or oil pan

How fast is it "using?"

about a quart to half a gallon this morning when I let it run for about 30-45 minutes. This has been an ongoing thing, at first I attributed it to having air in the system when I put the new radiator in but it's still doing it, probably gone thru well over 2 gallons since I put the radiator in and topped it off.
 
I just wrote a long reply and lost it. Try Blue Devil [ame="http://www.ebay.com/itm/like/301028217027?lpid=82"]Head Gasket Sealant Blue Devil Permanent Sealer 16 Oz | eBay[/ame]. To seal up the leak. It will permanently seal any coolant leak, even head gaskets unless it is pouring out like a garden hose.

Good luck!
 
My money is on the heater core. The heater box just aint leakin. Yet.
 
Most likely is the heater core, as steam. But on a cold night you should see it fogging the windshield (my 69 Dart did). It might also be a pin-hole leak in a heater hose, like my sister had in her 65 Mustang on a trip. It kept boiling over every 50 miles on a long trip. One shop said "must be head gasket", so we kept driving. A second shop found the leak and fixed it for $5. It didn't start until the pressure was up and it didn't even leave a noticeable wet spot, but did lose significant water.

Whatever you do, don't approach it like a coworker did with his late 90's GM truck. He asked my opinion on a 1 gal/wk coolant loss. I asked if he had smelled coolant in the cabin last winter, he said yes and that the windshield had been fogging, so I told him must be the heater core. Instead, he listened to a dealer mechanic and started shopping for another LS engine, then ended up buying another used GM truck.
 
Put a pressure tester on the system while it is cold and check it out. What may be evaporating when it is hot might show up when the system when it is cold. I would also suspect the heater core.
 
My money is on the heater core. The heater box just aint leakin. Yet.

Ding ding we have a winner. I just got the heater core pulled and sure enough found the leak. Thanks all
 
Great but "Gee Whiz" I can't believe you could not SMELL that much leaking........and it usually doesn't take much to smell and to fog up the windows from the defroster.
 
Great but "Gee Whiz" I can't believe you could not SMELL that much leaking........and it usually doesn't take much to smell and to fog up the windows from the defroster.
Never smelled a thing and I've seen it fog the windows just never made the connection until you all mentioned it. That's why when you all mentioned it, I decided to yank it out and see. Found a box full of my coolant but somehow not leaking into the passenger compartment
 
If he's running the newly formulated antifreeze that's on the shelf most everywhere now, I am not surprised there was no smell.
 
I think it is SO cool that with the help of FABO he solved his problem is less than 3 hours. People helping people, for no personal gain. Helps to balance all the negative news you hear about people. Keep it up People!! Happy Holidays!
 
I think it is SO cool that with the help of FABO he solved his problem is less than 3 hours. People helping people, for no personal gain. Helps to balance all the negative news you hear about people. Keep it up People!! Happy Holidays!

Yep I was frustrated as all get out. I've had heater cores go bad before but they always dripped onto the carpet. This one didn't. So thanks guys.


Yes it was new antifreeze. Prestone 50/50 mix
 
I just put Evans Waterless Coolant in my 85 M-B, after seeing it on Wheel Dealers. Not only avoids corrosion, it builds no pressure to cause leaks. I wish I had put it in my C-body when I put in a new alum radiator and had the block drained 6 months ago. I'll start putting in all my old Mopars. Costs more initially, but less in the long run and no maintenance.
 
I just put Evans Waterless Coolant in my 85 M-B, after seeing it on Wheel Dealers. Not only avoids corrosion, it builds no pressure to cause leaks. I wish I had put it in my C-body when I put in a new alum radiator and had the block drained 6 months ago. I'll start putting in all my old Mopars. Costs more initially, but less in the long run and no maintenance.

Yep, what he said! I use it also!
 
-
Back
Top