Intermittent coolant leak?

[bebyb]

Hello all, my m35a2 has a very intermittent coolant leak coming from the rear of the engine somewhere. Some days I'll run it and it doesn't leak a drop, other days there is a big puddle underneath it. There is no coolant in the oil so I assume it probably isn't a head gasket...but I guess there is always the possibility. Any ideas?

 

[frank8003]

Clean it, run + drive it, park it, examine it.
Find the leak.

After running up to normal operating temperature,
which of all the fluid systems remains
at the highest pressure after shutdown?

Clean it, run it, park it, examine it.
Where is pictures?

 

[gimpyrobb]

I hate to say it but, many have had the freeze plugs leak between the head and firewall. Got a inspection camera or mirror?

 

[bebyb]

I hate to say it but, many have had the freeze plugs leak between the head and firewall. Got a inspection camera or mirror?

I do have a mirror and have been looking for it. Might be a lose coolant temp sensor. If it was the head gasket the oil and coolant would be mixing right?

 

[gimpyrobb]

Not always, some of the gaskets have weep lines designed to leak.

 

[bebyb]

Not always, some of the gaskets have weep lines designed to leak.

In that case is it still safe to drive?

 

[gimpyrobb]

Without knowing the size of the leak, I would say yes, but only you can judge how bad it truly is. I would plan on the motor needing work very soon and drive it cautiously till you figure it out.

 

[bebyb]

Without knowing the size of the leak, I would say yes, but only you can judge how bad it truly is. I would plan on the motor needing work very soon and drive it cautiously till you figure it out.

It only leaks occasionally. You never see it leak when it runs, only when it is parked and has sat overnight, and most mornings you never see it. I don't know what it is. It might not even be a head gasket, could be that temp sensor or maybe a freeze plug. I certainly am unlikely to be a happy camper if it is the head gasket. Haha.

 

[gimpyrobb]

You have to BE CAREFUL to do this, but


Try opening the radiator cap after driving it and let it sit overnight. See if it leaks then.

 

[bebyb]

You have to BE CAREFUL to do this, but


Try opening the radiator cap after driving it and let it sit overnight. See if it leaks then.

Okay will do! If I do that and it doesn't leak, what does that mean?

 

[WillWagner]

Most all of the leaks will end up at the bottom/rear, gravity. Sounds like a cold water leak, meaning, it will only leak when cold, after coolant gets to temp, parts swell and the leak stops. Get a pressure tester and put 10 psi on it cold, before it is started. Look at all hose connections and between the heads. If the h gasket is the culprit, the leak will start on the exhaust side just under onr of the exhaust ports...if it has old style head gaskets.