Radiator issues - Nissan gurus?

"Chairman Kaga" (mike-mckinnon)
01/30/2017 at 10:42 • Filed to: None

I was bleeding some air from my M35's cooling system this weekend to improve my heater output, when the engine-side inlet of the air relief valve (image below - something Nissans have that I’ve never encountered before) broke off inside the hose. After much swearing, when I tried removing the remains it literally crumbled inside the hose . So a good hour later, mostly spent swearing, after buying a spring hose clamp tool and removing the debris from the hose , I had a 3/4" solid metal coupler in its place. None of the !!!error: Indecipherable SUB-paragraph formatting!!! or Nissan dealers have the part in stock except one, conveniently around the corner from my office, but the parts manager refused to sell me the part because it’s for an Infiniti (!!!). Infiniti could have it by Wednesday.

However, this morning the temp gauge was bouncing all over the place, so I assume I didn’t get all of the air out of the system. I’d prefer to not drive it in Austin traffic like this, although my project car is less reliable. It’s Italian...

So, if I can adequately burp the system through the radiator with an airtight funnel - !!!error: Indecipherable SUB-paragraph formatting!!! - is the valve even necessary? I feel more confident with a metal coupler in there than a plastic part. My real question is, is the valve more of a convenience for maintenance, or is it required for proper running?

92500U below.

DISCUSSION (4)

merged-5876237249235911857-hrw8uc > Chairman Kaga
01/30/2017 at 15:34

I would think if the system can be bled of air, you’d be good to go, but they installed the part for a reason. Maybe it’s a trouble spot for air to collect and that was the best option.

Have you searched a Nissan/Infiniti specific forum? I assume you’re not the first person to encounter this.

I’ve used a vacuum extractor/filler for my audi, and now other cars as well, with great success. It puts the entire cooling system in vacuum and then you flip a valve and the vacuum in the system pulls fluid from a bottle to fill the system. It is supposed to eliminate the air pockets and all that. So far, I’d say it works as described. But that’s for next time, or if you find you need to try something else to get the air out of the system. Not too helpful this time around, but maybe for next time.

Can you just crack the joint where you installed the spool piece? That would burp the air out of that location, then see what happens with the temps.

Chairman Kaga > merged-5876237249235911857-hrw8uc
01/30/2017 at 16:13

Well, I got the Lisle airtight funnel, jacked up the front, and spent a couple of hours cycling the car between idle and revving to 3k and holding for a minute, refilling, etc etc etc. About 90 minutes in, during a rev cycle, the heater literally went blast furnace in my face. I was monitoring actual temp on my OBD scanner and it dropped pretty quickly from 220 to 194 and held. It continued to “fart in the bath” a few more times before stabilizing.

I’m guessing there was a huge air bubble somewhere around the junction where the valve broke, which is right by the heater core inlet, and revving the engine put enough pressure in the system to blow it out. The funnel drained almost to the base, maybe a half liter , so it must have displaced a LOT of air.

A mechanic on the Infiniti forums said using the metal coupler won’t present any issues, although it does make life easier when it comes time to flush the system. I’ll replace it when that time comes again.

merged-5876237249235911857-hrw8uc > Chairman Kaga
01/30/2017 at 21:33

Excellent news. Sounds like that was the issue. I’ve never heard about that funnel, sounds like a nice simple way to refill the system.

Chairman Kaga > merged-5876237249235911857-hrw8uc
01/31/2017 at 09:35

It’s great. It comes with adapters to create an airtight seal against the radiator inlet, and it raises the fill higher than the highest point in the engine, so gravity will force displacement of air throughout. This is going to make my flush and fill for all three cars this summer MUCH easier.