Coolant smell + no leak = confused me. Help please

Hey hey,

So I noticed a few days ago that I could smell coolant after the truck got to temp. At a stop light one morning a was able to see a bit of "smoke" coming from the hood, but haven't seen it since. The temp gauge doesn't show it is over-heating, and i have the proper amount of coolant. I don't see any leaks, and the truck runs fine other than that. When stopped, I can smell it through the vents when the heat is on, but once I get going, no smell.

Any ideas where to start?

 

pressure test it

 

what engine, what year, and how many miles?
If you can smell it, it is leaking somewhere.
Water pump can lead very slowly for many miles, as can radiator.
It will get worse, and I would pressure test as suggested. Keep an eye on it, and I would NOT use any type of stop leak.

 

My radiator did this until it became noticeable that it was leaking. Like said above I would have the system pressure tested to rule out the coolant system. Next would be a compression test to rule out the head gasket.

 

check the heater core

 

X2 on heater core and x3 on pressure test

 

Another suggestion to check the heater core. Turn the defroster on (hot and defroster vents, no AC) and see if you get steam on the windshield. A tiny leak could cause a coolant smell yet otherwise be undetectable. You could also check for coolant dripping from the AC condensate drain.

 

mine did the same thing, it end up being the heater control valve on the firewall replace and no more coolant smell/white smoke coming from hood.

 

Check on the plastic topper of the radiator even under the hose on top . My leaked very slowly to the point of were I would only need a cup of coolant every 3 or so months and wasnt noticeable at first but they are probably right on what to do.

 

1999 v6
201,000 miles

I got a pressure test kit on the way home, but none of the adapters fit - will be returning it today.

I checked the coolant and there wasn't any oil mixed in, but haven't dropped the oil.

I did notice that while digging around, I found one of the metal brackets that holds my battery cables together rubbed through the plastic shielding and was starting to rub through the rubber. Glad I caught that now!

Thanks for all the suggestions, will check all those things today.

 

might want to check the heater control valve. thats what was leaking on mine. actually a pretty easy fix.

 

X2^^^

My first gen had a hairline crack on the plastic radiator topper, hardly noticeable until I was looking for it. Check the bottom as well

 

Common causes have been mentioned for small leaks with no visible signs of coolant loss. These are the ones I have seen over the years:
Heater core
Heater control valve
Lower radiator hose
Water pump
Intake manifold gasket

What you can do is look around those areas for an orange "fuzz" that looks similar to battery corrosion on the battery post, but it will be typically orange in color (Unless you are using green coolant, then it could be green fuzz) It is easy to remove the top cover from the timing belt so that you can look into the timing belt area and inspect for the water pump leak, and front of the intake manifold gasket area as well.

 

One more semi common leak spot not yet mentioned is the "bypass pipe" under the lower intake manifold. Unfortunately it is not visible. Most folks initially detect it when it gets bad enough that enough coolant collects in the space under the intake (the valley). It then starts to seep out at the rear of the engine. There is a metal plate closing off this area where the wetness is seen. It will take a mirror to inspect this area. Look for the plate with a 5/8" or so tube coming out of it. This leak can get on the exhaust crossover pipe and/or be "baked" by it.
The actual leak comes from failed FIPG on a 2 bolt flange where the pipe mates to the block near the front of the engine (under the intake). These can leak for years undetected other than a very slow loss of coolant.

Should bypass pipe be the culprit, while the intake is off, replacing the "knock sensor wiring harness" would be prudent. They tend to get very brittle and are usually just waiting for the opportunity to fail.

 

I have the same problem and I found that the heater control valve is leaking coolant... does anyone know how to fix this.

 

Replace the valve.

 

I will... I was just wondering if I had to replace the cord that delivers the coolant to the valve too

 

This may sound a bit weird, but I had the same issue and it ended up being a leaking battery. I was getting a antifreeze smell, looked through the whole system and no leaks. The coolant level never dropped and my engine temp was normal. After about a month, my battery died. When I pulled the battery out, it had been leaking from the back. After I replaced it, I haven't had the smell. It's been 5+ months and no antifreeze smell.

 

When you get your replacement don't make the same mistake I made.. That screw in the center don't tighten it!! It doesn't need to be tight it's just holding that little metal plate on. I had to replace that thing 2 times because the first time I installed the new one I tightened that screw..

 

I did replace the leaking valve and im still getting the foggy windows and coolant smell. Im guessing its the heater core but im having trouble locating it.