The mystery of the disappearing coolant!

[5t341tH]

Hey guys. Been driving my 620 daily now since I totaled my daily. I have a mysterious issue with coolant disappearing. I have a brand new radiator. I fill the radiator up, plus I fill the overflow to the max line.

Every so often, I check the coolant overflow and it's empty. If I leave the overflow empty long enough, the radiator goes empty as well.

I don't see any leaks in the engine bay, no pools of coolant wherever I park, no coolant in the oil. The only leak I see is small droplets or so of green coolant underneath the engine. Usually hanging off of the transmission bellhousing.

Where can all my coolant be going? I see no puddles of coolant where I park at work or at home. Could it be leaking while I drive? What possible areas can I check to see where coolant might leak from? Like I said, nothing visible can be seen from the engine bay. Your thoughts?

[GRpufnstuf]

my GUESS,

Either you have a leak that only happens when the system gets hot and pressurizes.  Which means that it will mostly blow back under and away from the truck.  Explaining the transmission coolant drip.

 

OR

 

you're burning it in the combustion chambers via a crack or head gasket leak and are just lucky it isn't mixing into the oil

[5t341tH]

And since you guys like pictures.

Here's one spot of coolant I noticed

 

Plus, does anyone know what this is? Goes between the carbs vacuum advance and the distributor. Appears to be a one way check valve, but to me seems the work the wrong way.

[datzenmike]

Check the hoses for softness, bulging or rot. If not sure replace.

 

The hoses are....

 

One heater hose from the rear right of head into the cab heater.

One heater return hose to the lower water pump return fitting above the alternator.

 

One top rad hose from thermostat housing to rad.

One lower rad return hos to water pump fitting

 

One short 3/8" hose from intake just below front of carb to Y shaped metal tube.

One short 3/8" hose from thermostat by pass fitting to Y shaped metal tube.

 

The metal tube goes down the front of the engine to just above the alternator where it is connected also by a 3/8" hose to the the lower rad hose and heater return inlet to the water pump.

 

Check all hose clamps are secure and tight.

 

 

 

 

Other leak areas...

 

Intake manifold is water cooled/heated  It is sealed to the head with a gasket that may have failed.

 

The water pump has a weeping hole to allow water out should the seal fain inside. This prevents the water destroying the water pump bearing and seizing it. Presumably the owner will notice the leak and replace the pump befor this happens.

 

The thermostat housing to head or thermostat gasket has failed.

 

The rad has a leak.

 

The head gasket has failed. This can use water anywhere from slow to fast. If fast the exhaust may smell sweet from the antifreeze and it may visibly steam excessively out thew tail pipe when warmed up. Cylinder compression can push into the cooling system and displace the coolant out the over flow pipe to the recovery container, and spill. When idling with the rad cap off you may see bubbles. You may smell gasoline. The head gasket may also fail directly to the outside between block and head and NOT into a cylinder. 

[flatcat19]

Take a mirror and look at the freeze plug on the back of the head/block.

[Elkie]

My guess would be headgasket, mine went and it would lose coolant out the back of the head over the transmission.

[5t341tH]

Thanks guys for all tips on the possible spots. I will look at it tomorrow. But if it were to leak in those areas mentioned, shouldn't I have pool/puddle of coolant on the floor?

[Middle man]

In my case,I got underneath with a flash lite and noticed the weep hole was wet on the wtr. pump. No big deal I Thought looks easy enough to change.When ever I drove the fan blew coolant on the engine,in small areas.When I stoped so did the leak.The bitch was I had to change it twice cause the first new one was worst than the old one.The guy at autozone said no problem it has a life time warranty...wonder why? I don't go there anymore.

[Elkie]

All parts stores have a lifetime warranty. And all their parts are made by the same manufacturer in China and stuck in a different box. I used to work for autozone and would say very few pumps ever got returned, now starters and alternators are a diff story always have them benchtest before you leave, even though they are supposed to be "factory tested" when the are reman'd.

As far as the coolant, it might only leak when under pressure, and not that much. So you'll lose it while driving and maybe ten-fifteen minutes after you shut it off, leaving little trace of the leak while sitting. Mine eventually started leaking into cylinder 4 which made it clear at that point. I'd recommend getting a mirror and checking the back of the head, there's a freeze plug back there as well that a tendency to rust out.

[Middle man]

Mine was remaned in mexico,the guys had a basket full of returned wtr. pumps and said they were tired of there having to deal with returns. If they bench tested there water pumps I would of had them do it. The impeller on the second one was the same as the original. Just sayin this is not my first issue with there parts,not nearly! I'am done.especially with o'reilly's across the street.The top repair shops in town also stopped goin to autozone. That's sealed the deal for me.

[flatcat19]

their*

[banzai510(hainz)]

theres no bolt in the alternator

[datzenmike]

there's

 

 

 oops, sorry Mr. Perry. Continue.

[flatcat19]

I saw that. Decided to leave it alone because Hainz.

[5t341tH]

theres no bolt in the alternator

lol I just noticed that.

[datzenmike]

I saw that. Decided to leave it alone because Hainz.

 

You always we're faster than me.

 

 

Take a mirror and look at the freeze plug on the back of the head/block.

 

The one on the back of the block is hidden by the transmission.

 

[Middle man]

Thanks I did'nt even know there was a freeze plug back there.So do you have to pull the trany to inspect it?

[datzenmike]

I would only suspect it, if all other causes are checked and eliminated, and there is coolant definitely dripping from between the engine and transmission.

 

They are not really 'freeze plugs' but core plugs. Openings for the removal of casting sand after the mold is poured and the block has cooled. They don't work by the way. When a block freezes it almost always cracks even if the core plug pops out.

 

If the proper mix of antifreeze/coolant is used the core plugs very seldom are any problem.

[banzai510(hainz)]

I think my core plugs are leaky also.

 

They got rubber sqeeze type plugs with a nut to expand the runnber , if you cant get the 40mm brass ones to seal.. Look up on Rockauto.

[Middle man]

Educated again,I really do appreciate your patience.Thank you

[5t341tH]

hello fellas. Been super long since I had this problem and finally had some days off to pull the transmission.

It appears to be leaking from the heater hose going into the cabin. It wasn't visible before because it was on the bottom.

There it is.

 

How does this "freeze plug" look?

 

Also, since I am here I want to replace the rear main seal as well. Will oil pour out of the seal if I pull it out? Or should I drain the oil first?

[datzenmike]

It's a core plug, and it looks just fine. That's so the core sand can be removed from a hollow casting. I don't know why they are often referred to as freeze plugs as they sure don't work.

 

All the oil will have drained back down into the bottom of the oil pan well below the oil seal. The crank seal only has to keep splashed oil in. Drive two or more wood screws onto the seal and use them to pull the old one out.

[5t341tH]

Thanks Mike. So I just need to screw some screws and use them to pull off? Someone on the FB page told me its held in place with 2 bolts

Does it matter where I screw the screws?

[G-Duax]

Someone on FB doesn't know their ass from a drain plug...

 

Small screws, far enough away from the crank so they don't contact it at all.

If the screw auger themselves along the seal surface of the crank, you will lose the new seal quite quickly.

 

I use a very sharp punch to pierce the metal core of the seal, so that the screw doesn't wander off to towards the crank

[sebpv]

maybe he was referring to the rear main bearings caps? Anyhow those arent accessible until you remove the head. And also not needed for this task. As mentioned: screws and pull on them with a vice grip and it should come out.