Potential solution for coolant smell - Titan

[C-Kwik]

Some of you Titan owners may have run into this type of an issue. Broadly, many point to the radiator cap as the culprit and the solution as Nissan has a TSB that addresses a leak from the radiator cap. Mine had a very strong coolant odor that I would usually notice when I stopped after a drive. I've looked at the TSB and my Titan and decided to try it despite my doubts. I didn't feel there was an issue there and the titan's radiator cap is not a pressure release cap and no coolant was leaking passed the cap. As I had thought, replacing the radiator cap failed to solve the problem.

Coolant was definitely leaking from the radiator area. While I couldn't see exactly where it was coming from without tearing the car down some, it would appear to be coming from the lower radiator hose connection area. It would appear though that the leak was not a constant leak as my hoses would collapse when the engine cooled down. Parking it for several days would not allow air to bleed back into the system. My speculation was that coolant was forcing itself passed the hose connection under high pressure.

Evaluating the sytem further, I found the coolant catch tank was pressurized. The coolant catch tank cap actually had the pressure relief spring in it. I pulled the cap and tried pushing in the sprung portions of the cap. It would not budge under moderate force. Turns out it took a bit of force, but it actually "broke" free and after that, it was much easier to press in after I did that. I ordered me a new cap and replaced it. It's been some 3 months and not one bit of coolant smell is noticed. I still have the old cap and periodically push the center button in and it seems to sieze up over time as I have to break it free each time before I can push it in. I did compare the new cap's button and the old one and the newone was much smoother in operation.

So my theory at this point is that in some cases, the coolant catch can cap is the culprit in some coolant leaks. I am obviously only one case of this and I haven't had access to others with coolant leak issues, but I do wonder if the TSB is looking at the wrong problem. The Radiator cap's only job is to seal the top of the radiator filler neck and has little that can fail under normal coolant operating pressures. Overpressurizing the coolant system will show itself in the weakest link first. In my case, it was likely the lower radiator hose. Other's experiences may be that the radiator cap failed first. This is only speculation at this point, but if you have this issue, check out that coolant catch tank cap as well.