Why do I smell coolant?

I've noticed a coolant smell the last few times I've driven my deuce. No signs of leaks anywhere. Temps in the 180-190 range per the gauge. There is a 2 x 2 in hole in the radiator that was patched by Uncle Sam and is holding well - again no leaks. I checked the coolant level after it had sat for about ten days not running. The level was full AND when I took the cap off it sounded like I was cracking open a fresh soda - so the system is holding pressure.

Is it just a multifuel design thing or is something bad about to happen? I've looked everywhere and there isn't a drop of coolant outside of the system.

DUG You got a leak somewhere. It may be very small ,causing the coolant to evaporate, but the smell will be there. In time you will find it .

Look very good between the heads. Good luck whatever you find.

Also look for traces of a white-ish powdery residue, at the heads, water pump, hoses, etc. That is the sign of evaporated AF. You should probably do a pressure test, just going by the cap isn't going to tell you if you have a small pressure drop.
Is the smell under the hood? I learned many years ago that mold that grows on heater cores smells just like an AF leak.

I had the same with mine, turned out to be a bad radiator cap. I hope yours is as simple also.

I also have a slight coolant smell in my Deuce cab once in a while, usually when the weather is cold. Once the engine warms up the smell goes away. I always check the coolant level and never have to add fluid, but the smell is there. Always makes me uncomfortable, but I will live with it until I find some problem.

Do you have a pressure tester with the correct attachment for the Deuce radiator neck? I had to buy an additional attachment for my tester to work on my Deuce rad.

No pressure tester - I'll have to pick one up. I just noticed a pressure release when I removed the cap after ten days sitting.

The truck has no heater.

I'll pick up a new cap since they're cheap.

Ours smelled like that once too. It tested great and no leaks. We found that once driving it a few drops did make it out of the over flow tube. So we replaced the cap and it solved the problem. A new cap is like $7-$13 try a new one and look around everything again.

Mine burps out some antifreeze when I was driving it in the 80's and 90's. Just enough to irritate my because my overflow tube is plugged. Still full.

Make sure yours isn't too full, especially since you drive it when the weather is rather warm.

Well.............I loaned my truck out this weekend for a friend to take on a "date".
When she came home I smelled antifreeze. So I have followed some of the flushing threads and thought I would flush her this morning. I opened the drain valve....then closed it and cleaned out the dirt in it. Then opened it again......antifreeze looked like it had come out of the jug. So I thought, let's heat her up and try. It was a hard start for her....must remember I burn monkey pee in her. On the 4th try she stayed there. So I went around the front and smelled antifreeze. I took off the mushroom and saw dripage (not a word) at the oil pan. So I traced it to the top.
Looks like I now have a blown head gasket. To my luck...it only leaks when cold.
So I thought I had Murphy tied up on the Mercedes trany, but now he has moved to the Deuce.
Good News.....You all are safe...I will have Murphy here at least until Wed of next week.
Good Luck All

You say that you have some pressure in the cooling sytem even when it is cold. That to my opinion indicates a problem with the cylinder head gasket. The problem is still small, but with time going by, it might increase. Check with a warm engine the radiator. Open very carefull. If bubles come up the head gasket is blown. Replace it. If you are lucky, it is only the gasket. Else the head has a very litle crack, so the head must be replaced by a better one.
Wolf

I was getting brief smell of anti freeze but no real heavy amounts and loss of coolant. The system is very clean and was just and flushed and new coolant and the radiator is clean and no sign of excess rust/corrosion. I noticed a slight drip and wetness at the very rear passenger side and thought the cursed head gasket. But on closer exam it was the small hoses to the cooler that were deteriorated and slightly leaking. The coolant was reacting with the air and causing corrosion and the rubber on the hose was rotten and flaking away. An afternoon of removing and replacing the hoses and clean up the coolers and no more smell. The leakage was ever so slight that you would not notice any loss of coolant I suspect.

Quit eating pancakes in your trucks.

When it's cold, as in sitting overnite or longer..mostly in the early AM while the ambient temps are down, raise the hood and look for cold water leaks. The leaks appear depending on temps and the torque on the hose clamps and seal up once the engine builds a bit of heat. As stated prior, the leaks that seal up will have a white streak comming from them when not leaking and after the engine has warmed enough to dry the leaking coolant.

Mine did this after I topped off the radiator cause it was down slightly. On the next couple rides it puked out the amount I put in. It's not done it since and I stopped trying to top it off

Water expands when it gets hot. Remember this when topping off the radiator.

Has anyone thought of adapting an expansion tank to a M35? It would be easy to solder in a tube but you would need a proper pressure cap with the outer seal. By forcing the overflow into the bottom of an expansion tank, all fumes of ethylene glycol are condensed. Plus air is then excluded from the system, preventing corrosion.

WillWagner said:

When it's cold, as in sitting overnite or longer..mostly in the early AM while the ambient temps are down, raise the hood and look for cold water leaks. The leaks appear depending on temps and the torque on the hose clamps and seal up once the engine builds a bit of heat. As stated prior, the leaks that seal up will have a white streak comming from them when not leaking and after the engine has warmed enough to dry the leaking coolant.

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my truck didnt start getting coolant leaks until the temps dropped below 20*.....I hate seeing that green fluid leaking it makes me die a little inside

Check your hose clamps....They may need to be tightened. That is not something one often checks when servicing a deuce and the lower rad hose is a pain in the rear to get at.

RL

Turned out to be a tiny leak on the upper radiator hose. It was hard to see until I installed two fresh and clean alternators. The leak didn't show up on the old alt. Installed a new hose but haven't put many miles on the truck since then. Planning on replacing all the hoses, the water pump and having the radiator clean out before summer.