Losing coolant (1 Viewer)

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I've had this perpetual issue of coolant loss for the past couple of months in my 87 fj60. All indications are telling me I have a cracked head with no visible leaks and definite milk shake residue in the engine. I've brought it to to a pretty knowelagable cruiser mechanic who has told me he's pretty sure it's not the head. How he came to that conclusion I'm not sure. What we have done is replace the lower radiator hose, engine oil cooler seal and replaced the thermostat. The problem has gotten a bit better, at least the truck is not overheating any longer and the coolant loss is not as great. On average I would burn through the reserve coolant tank on a 30 mile commute at freeway speeds. Now I'm down to about a quarter to half of the reserve coolant on a 30 mile drive. The mechanic had mentioned installing an oil cooler seperator, but that seems like applying a bandaid to a much larger problem. Being that I am a weekend warrior mechanic, has anyone run into this issue and the outcome was not a cracked head?
 
Not a similar issue, but why does he think it's not the head? Are you seeing oil in your radiator? Have you changed the oil recently, and if so, how did it look?
 
Seems like a smart mechanic... he's getting to charge you for all sorts of little things and multiple bouts of labor instead of looking at the bigger issue. There are ways to diagnose a cracked head right? @Output Shaft, @beno, @orangefj45.... many others who could chime in I am sure.
 
Sounds similar to my issue that I was having this time last year. Head to your LAPS and grab one of those Engine Exhaust Gas Coolant testers that tests to see if there is exhaust gases in your engine coolant. It could be that there is a small break between two of the Siamese cylinders and thus you are just getting the coolant burned off.

Also, do you know the age of the water pump? It has a small weep hole that will slowly drip out coolant when it is on its last leg (similar to the fuel pump). Mine was doing something similar where I seemed to be burning through coolant quickly, not really over heating though. Then I remember one cold day hearing a really nasty cold bearing as I drove away from work but it went away. Then spent about 3wks trying to figure out why it would spike in temp to about 3/4 the way up and sit there. Ended up my HG was gone inbetween two cylinders and what I heard was my water pump failing. Redid the entire topend and everything is kopasetic now!

Oh and by the way I am a weekend warrior mechanic too (we like shadetree mechanics!!!LOL) and I was able to do it in a couple weeks by using my friends barn and working on it a few hours at a time at night 4 days a week. If you had a dedicated couple days you could pull everything in one day, get it all machined and then replace everything in another day or two.
 
It could be a crack or it could just be a blown head gasket. Or maybe something else less sinister.

Take a look at all the spark plugs. See if one of them looks a lot different than the others (because of coolant getting into the combustion chamber).

When the engine is stone cold in the morning, remove the radiator cap and make sure the coolant is filled to the very brim in the radiator. Replace the cap. Make sure it's a good cap.

Fill the coolant overflow tank to between the min & Max Mark on the tank & mark that level with a piece of tape.

Squeeze the radiator inlet hose a few times with your hand to get a feel for what an unpressurized cooling system feels like.

Drive the car for your 30 mile commute and then park & keep the engine idling & squeeze the radiator inlet hose (with a gloved hand). It should feel hard and you shouldn't be able to compress the hose (pressurized system).

Examine the coolant level in the overflow tank. It should be at the Max line.

If the inlet hose is squishy again (not hard) the cooling system is leaking coolant somewhere.

Shoot an infrared temperature gun at the front of the radiator directly across from the inlet hose. The temps should be under 210°.

Take a close look at all the cooling hoses to see if there is a leak.

If everything looks good, but you're still burning coolant, get a coolant exhaust contamination test kit. I think @gregnash will have details about that.

It is possible that the oil cooler has developed a leak inside it. But that's very rare.

If the engine oil is milky, then coolant is getting into the crankcase somehow. Change the oil immediately. The coolant in the oil will damage the crank bearings. Buy cheap oil & change frequently until you get this fixed.

If everything is pointing to coolant getting into the combustion chamber, the head will need to come off & checked out.

If you have to smog test the car, burning coolant will eventually wreck the catalytic converter.
 
Just to add to Output Shaft's recommendations, you can also test cooling system pressure with the system cold. I've used a kit similar to this many times to find small leaks, typically just a hose clamp that needed to be tightened. It's simple, just replace the cap with one of the adapters, pressurize the system to about 15 psi and go looking for seeping coolant. A well sealed system should hold 15psi for 10+ minutes. In your case, since you know you're losing coolant, if the system holds pressure that would point to a bad cap. Maybe it could be used find a leak into one of the combustion chambers, but I've never had to dig that deep.

Radiator Pressure Tester Kit
 
was a pressure test done on the cooling system, are there any indications of contaminated coolant or oil?
 
check the water pump weep hole, you may not not even see it dripping when parked and at freway speeds it will get blown away(to the rear) If its leaking it should be crusty around the hole
 
check the water pump weep hole, you may not not even see it dripping when parked and at freway speeds it will get blown away(to the rear) If its leaking it should be crusty around the hole
And if you replace the water pump you should replace the fan clutch as well as belts at the same time. There is one small hose that goes from the water pump to the outlet pipe of the radiator and the oil cooler. Replace as many hoses as you can as they are a PITA to get to once things are back together.

Oh and Fan Shroud Mod too if you haven't!
 
He's in deep now. That friggen rabbit hole we all don't look forward to. GL!
 
Really appreciate the advice. We pressure tested the cooling system and everything checked out. Another issue which occurs is if the truck is idling at a light or stopped the engine temp will pin at hot briefly and then slowly back down. I assume this could be possibly air in the cooling system?
 
I know my radiator has a pinhole at the neck, or a bunk lip. not enough to fail a pressure test, but enough to weep enough coolant to stain the rim of the upper tank, and loose about a half gallon a week or so from the catch can. the temp gauge could be the fuel gauge current limiter going south.....do you notice the fuel spike as well?
 

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