Mysterious coolant leak...I think...

[bebyb]

And the wreck didn't involve the m35. It was an 80s F250 in case you all were wondering.

 

[rustystud]

The reason I was asking about the year and model is if this is a dual brake system deuce it would have the front brake booster on that side where it's leaking. Old DOT 5 brake fluid is amber in color and when spilled on concrete it can look like water.

 

[porkysplace]

The reason I was asking about the year and model is if this is a dual brake system deuce it would have the front brake booster on that side where it's leaking. Old DOT 5 brake fluid is amber in color and when spilled on concrete it can look like water.

From post #1 of this thread;
[h=1]Front Axle Engagement[/h] Hello all, I have a 1980 M35A2C
So no dual brake circut there.

 

[bebyb]

From post #1 of this thread;
[h=1]Front Axle Engagement[/h] Hello all, I have a 1980 M35A2C
So no dual brake circut there.

Yes, single brakes according to my research. And the puddle is still there.

 

[porkysplace]

Yes, single brakes according to my research. And the puddle is still there.

Have you checked all the fluids to see if any are low ?
Is the puddle getting bigger ?
Maybe clean the spot on the floor then place clean cardboard on the floor and try and narrow down where exactly it is coming from. If you can determine where it's coming from you can then put a small catch pan under it to determine what kind of fluid it is.

 

[Lust4GreenSteel]

Dab something white in the fluid. What color is it? That can be a clue. I know a guy who tastes fluid that leaks from his truck to see what it is (I wouldn't do it myself, and don't recommend it as good practice).

 

[frank8003]

Yes, single brakes according to my research. ~ ~

So You have not ever looked under the truck seeking fluid or air leaks or have actually seen the air Pak(s) ?
Interesting. It is sitting on a cement driveway.
Get a creeper and a flashlight and go look at it all.

 

[bebyb]

So You have not ever looked under the truck seeking fluid or air leaks or have actually seen the air Pak(s) ?
Interesting. It is sitting on a cement driveway.
Get a creeper and a flashlight and go look at it all.

Yes, only one air pack. I take it the dual circuit brakes have two? I also read dual circuit trucks have an extra light or something on the dash. I have a peice of cardboard under it so when I go check it today I'll see if anything changed.

 

[porkysplace]

Well if you do decide to take it , I would recommend taking spare fuel filters.

 

[bebyb]

Well if you do decide to take it , I would recommend taking spare fuel filters.

Yes absolutely. I have an emergency pack of things I take along on all trips. Jury is still out if I want to risk it or not. I certainly don't want to damage anything.

 

[bebyb]

Okay so I checked the cardboard. Only a small drop of whatever it was on it, but the puddle is exactly where it was. Hasn't moved. Strange...

 

[cattlerepairman]

So the master cylinder is still full, so is the rad? Any leaks when running?

On an aside, I really recommend the master cylinder external reservoir mod. It is inexpensive but adds tremendous peace of mind when you can monitor the brake fluid level from the cab.

 

[bebyb]

Found it. Is that the coolant temp sensor?

 

[doghead]

That is your oil pressure sensor.

 

[bebyb]

It is coming from that general area and what is coming out is certainly not oil. Maybe it is somewhere near that. Checked the cooling system and it is definitely still under pressure.

 

[bebyb]

GTA-9-1-1851-8.pdf M35 complete diagram of with descriptions of all components.

LO9-2320-209-12-1.pdf
LO9-2320-209-12-1 Lubrication Order for the M35 series.

TM9-2320-209-10-1.pdf
TM9-2320-209-10-1 Operation, Installation and Reference data for the M35 series, Operator Level.

TM9-2320-209-10-2.pdf
TM9-2320-209-10-2 Scheduled Maintenance Operator level M35 Multifuel.

TM9-2320-209-10-3.pdf
TM9-2320-209-10-3 Troubleshooting Operator level M35 Multifuel.

TM9-2320-209-10-4.pdf
TM9-2320-209-10-4 Maintenance Operator Level M35 Multifuel.

Also, thank you for these links. I am going through them right now.

 

[bebyb]

I am starting to fear that it is a head gasket. Maybe a freeze plug, would be great if it was but is not looking promising.

 

[doghead]

It looks to have coolant dried up on the rear of the head in the picture.

Head gasket maybe,

Each head has a small freeze plug front and back.

The intake manifold is water-jacketed as well. Small hoses and gaskets to check there.

 

[bebyb]

It looks to have coolant dried up on the rear of the head in the picture.

Head gasket maybe,

Each head has a small freeze plug front and back.

The intake manifold is water-jacketed as well. Small hoses and gaskets to check there.

Alright thank you! That will be the next place I check.

 

[cattlerepairman]

I am starting to fear that it is a head gasket. Maybe a freeze plug, would be great if it was but is not looking promising.

Unless there is classic, complete head gasket failure (oil pouring out, compression leak, milk coffee coolant) I would recommend to do a cold re-torque of the head nuts first, then to run it and re-evaluate. Torque values have changed over the years, no guarantee it was torqued correctly in the first place and it can be surprising to see how much looser the nuts get after endless heating/cooling cycles.
If your block is a thick-deck casting (look for the letters "TD" cast near where the data plate is) you can torque to 157 ft-lbs. If not, it is 130 ft-lbs.