I have a 2012 DGC 2.6L VVT Flex van, 173k. I am having an issue with trying to figure out where I am leaking coolant. The reservoir is full, there are no puddles under the van in the morning (not even a drip, except for where I spilled coolant while replacing it). I am losing about 1 quart every other day, or so. Today (3/19/21), I smelt coolant on the passenger side, while I was cleaning out the passenger seat (I am an Uber and Lyft driver, so the front passenger seat is kept full of stuff). I am assuming that it's either the thermostat or the water pump, but can't be sure.
Back in September, I had the heater core hoses keep popping off, so I replaced them, then did a cooling system flush, so those hoses are new, and I know are not leaking.
Any guidance would be appreciated.

 

If you’re smelling coolant in the cabin then either the heater core is leaking or it’s burning it. Given the quantity being used I think the latter is the most likely cause but best not to rule anything out.

Things to check:

1) Check the engine oil color and condition - white, foamy residue indicates coolant contamination. Most likely cause is the engine oil cooler/oil filter housing as they are common failures. Even without signs of contamination, the cooler may be leaking externally and the coolant is evaporating before it can pool and run off the engine.

2) Look for white smoke from tail pipe, especially when starting hot.

3) Rent a pressure tester from your local parts store and perform pressure testing with the engine cold and hot.

4) Use a short length of coat hanger or pipe cleaner to check the case drain for the evaporator - if this is plugged up then coolant leaking from the heater core may not be draining out.

 

I am experiencing a similar issue. I recently had the oil changed and the smell started shortly after. I'm not losing a lot of coolant, but I can smell it.

 

With my van, it turned out to be the Oil Filter & Cooler Housing was shot, since it's cheap plastic.

 

I lost about a quart give or take over the course of 400 miles/ 3 weeks since o noticed the smell. The oil level is fine. The oil filter housing is dry. I don't see any thing on the ground. So annoying.

 

Depending on the size and location of the leak, coolant can evaporate quickly enough that it won’t collect and drip to the ground. I’ve seen this occur with at least a few of the oil filter housings, and several radiators of different makes.

Many auto parts stores rent cooling system pressure testers - perform a pressure test with the engine cold. The pressure should hold for at least 5 minutes.

Also don’t forget to inspect the coolant lines that supply the rear heater core - it’s common for rocks and debris to damage them.

 

The reason I think it's the housing is because it started after an oil change. If it is the housing, can become a catastrophic leak? Or is it a slow leak?

 

The size of the leak depends on how bad the housing is damaged; but Yes, it can become catastrophic.

Not that you should panic about it, but time is not on your side if the housing is to blame. The longer you wait to repair it, the worse it will get - how long it takes depends on several factors.

Try to get a look at the oil filter housing/cooler from the driver side of the engine. If you shine a light under the intake and position your head close to the battery, you can kind of see it. What you’re actually looking for is coolant that’s pooling in the valley around/underneath the housing. Any coolant present in the valley indicates the housing is leaking.

The good news is Dorman offers a replacement housing made out of cast aluminum (part# 926-876) - you have to transfer the oil cooler and sensors but it eliminates the worry of a plastic replacement cracking again (which does happen).

 

Just FYI - I was looking at Dorman’s website and found that they’re now offering a nearly complete replacement housing with a cooler as well - part# 926-959. It looks like the sensors still have to be swapped, but it has everything else.

 

I finally saw it dripping on the ground and the leak was becoming more apparent. I dropped it off at the mechanic yesterday. He will figure it out.