I work for a bus company and we experience coolant leaks in very cold temperatures(Detroit series 60).

I've been experiencing the same thing with my D2 the past week. It kinda makes my paranoia reach new heights, especially after completing a HG job 600 miles ago.

Anybody else experience this issue? It's never any real amount of coolant, just enough to make a wet spot on the pavement.

 

A leak of any kind isn't good, but "from where?" is the important question.

Any idea where it's coming from? If all else fails, but some UV dye in it.

 

The common leak for cold temperatures I can think of is at the bulkhead fitting for the engine oil heat exchanger. There's a hard line that goes in to a bulkhead fitting that's brazed or soldered onto the radiator. There's several actually. In cold temps, the metal can contract enough to crack the joint and it will weep. Once it warms up, it often won't leak any more and will hold pressure just fine. The solution is to rebraze or solder the fitting(s).

Another possible cause is where a hose has cold flowed under a static-tension hose clamp that just needs to be tightened, or the hose replaced if it's hardened or deformed enough. Last possible cause I have is from the water pump seal, through the weep hole.

 

Thanks for the responses guys.

The leak I see is coming from the plastic "Y" that connects to the Tstat and WP. The static clamps are still in place. Time to replace them I guess. Lol. Only happens when it gets stupidly cold, as it has been here in jersey.

I really just wanted to see if anybody else has been experiencing this same thing. I'm sure it is colder elsewhere though.

 

pressure test your cooling system

 

It holds pressure fine. Only leaks when is extremely cold. And it isn't much at all. I know where it is, I'm blaming the old hose clamps.

 

It holds pressure fine. Only leaks when is extremely cold. kind of an oxymoron there.
thats like saying it only overheats when its hot

 

It's really the old hoses. They cold flow out from under the old hose clamps so that the clamps that were once tight aren't tight anymore. It happens to all hoses over time. The spring-tension clamps can help prevent that from happening for a few years longer, and that's why they were invented, but if the hoses are really old they may be too deformed at this point. You could potentially resolve the issue for another year or two by cinching the hoses down with a bit of excess pressure using screw-type clamps, but that may crack the thermostat housing. The best solution would be new hoses and clamps.

 

Its time to replace that plastic junction, I had the same problem and the plastic fitting broke. It comes with the hoses already attached.

 

Didn't think of replacing that. Here goes another coolant flush for Rover... lol