Coolant tank emitting faint smell?

[billschroeder5842]

Hey all, I have a question on my '91 with 93k on it. The car runs great and I'm very good about maintenance. This is a question about a faint (faint) coolant smell.

A bit of "base line:" The radiator is 18 months old with 3k miles on it. The hoses are Jerry Gasket black silicone with the OE factory clamps. I did a coolant flush/fill about 2 months ago-- about 300 miles.

After a run today, I popped the hood in my garage and smelled a faint coolant odor coming from the passenger side near the front of the car. I really never get coolant odor so I thought I'd do an inspection.

I found nothing, nada, no bueno for leaks. I inspected each hose clamp/junction, tightened any screw clamp (only one was a bit loose on the tube that takes coolant to the throttle body) and crawled under the car and checked the water pump, therostat housing and drain plug. I event went to the inside and checked the passenger side footwell for a heater core leak. No leaks, drips or anything. I checked after about 6 hours and there was no smell at all,

However, I did check the coolant overflow tank up near the front of the car. There was some coolant in the tank but it did not register on the dip stick. There had been some evaporation as I had filled the coolant to spec-- just barely covering the dip stick bottom. (I'll fill tomorrow)

So, could the faint coolant smell be coming from the coolant dip stick vented cap as the collant went push-pull after the engine was shut off and cooled down? Could the low coolant caused some air to be sucked up, then spit back and then get vented?

Thanks fo reading and any advice- I'm puzzled on this one.

[RSLyrick]

Hi Bill,

you've done a thorough inspection of the car and found nothing, that's the most important thing.

However, when it starts to leak only a little bit (droplets), depending on the location, it sometimes instantly vaporize making it difficult to localize the actual leak...but it "could" smell.

I had a tiny leak at the left coolant arm junction with injector housing that I could only identify because I started seeing green stains there but no puddle. So maybe look for stains as well.

Have you also inspected the junction between the white recovery tank itself and the hose connected to it and eventually slip your hand under the tank to check if it's "soaked" ?

Naturally, as pressure build up within the cooling system, coolant/vapor will automatically flow to the white recovery tank. The small vent on the recovery tank cap prevents pressure from building up there and allows coolant displacement from the surge tank to the recovery, so it's possible that coolant chemicals evaporate a bit and you a get a light coolant smell...but coolant boils at around 265 ?F...

I would simply refill the recovery tank and check regularly. You can also check when you go for a run, engine running at operating temperature (quick stop, pop the hood with engine running and inspect, and try to smell coolant).

I don't use the dip stick for checking the coolant level. I prefer to use a small mirror and a bright light and look at the side of the tank directly at the "HOT and "COLD" marking. That allows me to accurately check for coolant loss.

[DRM500RUBYZR-1]

Purchase a coolant pressure tester and bring it up to 14 or 15 pounds no higher as you do not want to stress the old heater core and observe how it holds up for awhile.
Sounds like a minor leak as previous poster stated.
Keep us posted.

Marty

[billschroeder5842]

Thanks guys- I'll pick one up and see what happens. I'll report back.

[billschroeder5842]

Originally Posted by DRM500RUBYZR-1

Purchase a coolant pressure tester and bring it up to 14 or 15 pounds no higher as you do not want to stress the old heater core and observe how it holds up for awhile.


Marty

Marty- as you suggested, I took my kit and brought the pressure up to 14 and let it sit for 30 minutes. No, pressure drop and no leaks.

Good news, but it is still baffeling.

Thanks for the suggestions.

[DRM500RUBYZR-1]

Bill,
Great!
That at least confirms that the cap can and does hold pressure and there is no leak of any significance when cold.
Re-reading your initial post, I would agree with your thoughts about having little to no coolant in the overflow tank being a possible cause.
If the coolant level in the engine was a bit low it would try to draw back in and if nothing were there, would have ingested some air, which could have then escaped when next shutdown. That could have created a coolant odor which being hot, may have escaped through the vent hole.
Very possible.
My next suggestion would be to run the car with the pressure tester, bringing it up to operating temperature.
Again, observe the pressure while running.
Then shut it down and observe what happens during heat soak to see if pressure holds.
Of course I would add coolant to bring the level in the overflow to the proper level and cycle it through a few running cycles to see if it draws coolant back into the system, ensuring all is full.
If after all of that the faint odor is still there, then more investigation is needed.
Although the pressure held during your initial test that cannot rule out something happening when temperature rises.
While I always love the look of black silicone hoses, at the shop we often encountered very minor leaks as they cycle over time which you also know, requiring routine tightening periodically, more so that OEM.
Lastly, what radiator did you install? OEM type or upgrade?
Perhaps the problem has resolved itself, but if it has not lets keep checking things.
Thanks for posting your progress. Others find these threads useful in the future upon encountering similar situations.
Merry Christmas!

Marty