Re-Filling Coolant, does the air relief plug work well??

[Pathofinder]

Myself and my husband put a new radiator in the pathfinder, aswell as replaced some heater hoses. Thing is when we tried to refill the coolant, I dont think we got near all the air out and Im not having any luck trying to get it out.

The is an air relief plug on the back at the top against the firewall, your supposed to take it off while its idling with the rad cap off, and if theres ANY air in the system, it would purge out that hole followed by a steady stream of coolant. My car doesnt do this

The only way I could get coolant out of that relief hole was after it was idling for about 20 minutes or so to rev it and it would spit and slightly splash out of the tube, but nothing significant. Has anyone tried this before and what were your results??

You can also see the coolant level surge up and down when its idling, you can really see it surge if you stick the funnel into the rad openning and fill it over the rad so the coolant stays in the funnel and you can watch for bubbles that way, but when I rev the engine with the funnell in like that, the coolant level raises white a bit.

I also couldnt tell when the overflow openned, how long should it take and how do I know its even openning? My husband thought there would be obviously coolant flow/movement/rushing through the radiator that we could see with the cap off, but the coolant seemed to not move or flow around at all.

Big pocket of trapped air?

[fueler]

you did better than me, i couldnt even find the relief valve when i did mine (slightly different engine than you)

if your car idles normal, warms up to operating temp, and drives normally, i wouldnt worry about it. If there was an air pocket, your engine would probably be idling funny.

[Scottnbarbi]

No no no! Air pockets in the cooling system are bad news. You can warp heads, blow gaskets, etc.

[Pathofinder]

Ya Id like to get them out, I figure the coolant NOT streaming out of that tube meant there was air in there, aswell as the coolant surging when revving while idling.

It also does not have the best heat output at idle, forgot to mention that, heats right up when you hit the peddle though

Id love to make sure somehow the water pump was doing its job or the thermostat is openning, like I said we thought coolant would flow/move visibly inside the rad

But maybe we didnt idle long enough...?

[AZhitman]

Lots to address here.

OK, first off, you're not going to be able to determine ANYTHING with the engine running. The coolant won't reach operating temp with the cap off, and even if it does, it's no longer a "sealed" system, so you;re gonna get 200* coolant all over yourself and the ground when the thermostat opens.

Coolant is NOT streaming out of the relief tube because it's not pressurized. Gravity and atmospheric pressure (14.7 psi) are kicking your butt. There's nothing to force the water UP and OUT of the relief tube. Relax.

You're not going to see coolant flow/movement/rushing through the radiator with the cap off, for one of two reasons: Your thermostat isn't opening (because the system's not pressurized by a cap) OR your thermostat is shot.

Last, heater temp at idle is irrelevant to your cooling system. That can be a bad heater core, a bad air mix door, a vacuum leak to the air mix door mechanism, etc. Separate issue. Skip it for now.

Here's what needs to happen: Replace the thermostat. Should be done every few years anyway, just do it. It's cheap. Replace the cap while you're at it. It's probably not operating optimally anyway.

Fill radiator to top of neck. Open the relief port, and top off radiator completely. Close relief port, squeeze upper hose with both hands to "burp" the radiator, top it off one more time and put the cap on. Fill the overflow to 1/4 full, and go drive. You're done. Any air in the system will be evacuated into the overflow and replaced by coolant (when the vehicle cools).

Welcome aboard - GREAT question!

[AZhitman]

No no no! Air pockets in the cooling system are bad news. You can warp heads, blow gaskets, etc.

No. See above.

[Pathofinder]

The thermostat is indeed brand new oem

The air relief method and having coolant come out of it in a fluent stream I believe came straight out of the manual, I thought I should be able to open it and have all the air come out followed by coolant.

[AZhitman]

I've never had a car that did that... and I've replaced a lot of coolant.

Seriously, if there's coolant at the top of the radiator neck, and your truck isn't parked "nose-down", and there's some coolant in your overflow, you're done. You did good.

[Pathofinder]

Im reading a few of these coolant fill up walkthroughs aswell, and they all mention idling with the rad cap off to relive air and a big amount should drop when the thermostat opens up, then top it off, top off resevoir, check the next day after a few cycles.... but you say it wont ever get up to temp with the cap off?

I figured my car just had an extra help with the air relief plug, and Id really love for coolant to stream out of that hole

Im curious if you can get the thermostat to open with the rad cap off now though, or ensure the water pump is flowing enough water, mine may be OEM I have no records for the truck for its first 100k miles.

[AZhitman]

You're gonna have a stroke...

Those walkthoughs are assuming that there's no water IN the block. If there is, there's no "big drop" when the t-stat opens. You have water in the block, trust me. And the heater core.

As much as you want coolant to stream out of the bleeder hole, it's unlikely to do so.

If your Pathy isn't overheating, you're done. Seriously. I wouldn't lie to you.

[Pathofinder]

No its not overheating but it doesnt have near as good heat output at idle and you can hear a slight gurgling (assuming from heater core) when I rev the engine

I bought a prestone rad cap, maybe I shoulda stuck with OEM on that aswell

[AZhitman]

The gurgling sound is air bubbles rushing through the heater core.

Like I said before: With the engine cold, check the overflow bottle - should be above the "low" mark on the bottle. If not, add coolant until the bottle is half full or at to slightly above the cold level mark.

GO DRIVE. When the coolant heats up, it expands and should burp some some trapped air into the bottle. Then, when the system cools and the coolant shrinks, it draws fluid from the bottle into the cooling system.

After about 3 thermal cycles, the system should have the air flushed out.Keep an eye on the coolant level in the bottle for the next 3 to 4 trips.

You can use distilled water to top off that bottle (no need for more coolant).

[Pathofinder]

Sorry if Im asking alot of questions but you give fast knowledgable answers lol

Im curious how coolant actually GOES to the overflow tank, being as the hose for it come right off the top of my radiator neck, right under the rad cap. When I put my radiator cap on, does it not seal out the hole that leads to the overflow hose??

I think Im actually having a problem with coolant getting pushed over to the overflow side, but this radiator was purchased from Ebay and the rad cap is a prestone version and was only $8 if that makes a difference. So I was unsure if maybe something was off seal wise... Hard to explain Im a mom not good at car questions haha

[Densetsu]

Simple answer: http://auto.howstuffworks.com/cooling-system7.htm

[Pathofinder]

Nice link thanks

I didnt know coolant was SUPPOSED to go into the overflow at operating temp and then be drawn back in. A better question for me might be then why does my coolant not get sucked back into the rad then. Would an air bubble in the system mess this up?

[Chuck Tribolet]

The 2001 PF FSM shows two cooling system vents. One is just in front of the firewall , top dead center, rubber cap on a
tube. My stickshift has that one. The other one is shown on a tube on the front of the engine, passenger's side of center line.
Mine does not have that one. Maybe the automatics do (somebody with a slushbox please chime in).

You vent cold, engine off. Fill the rad to the top, wait a bit, put the rad cap back on, put the vent cap back on. Make sure
the coolant in the overflow is between MIN and MAX. Done.

The radiator cap will let coolant into the overflow if pressure in the system exceeds the caps rating (typically 12-15 PSI).
It SHOULD suck back as things cool down. If you get hot enough to boil the coolant in the block, the suck back can be
rather rapid as it the vapor condenses back to liquid.

Chuck

[Pathofinder]

My automatic does not have the vent hose at the front either, only the one at the firewall

Coolant should not stream out of that hose while flushing?? I read different but they may be wrong

[AZhitman]

We're fixing something that's not broken...

Until you've followed the steps in the post of 25 Jan 2011 23:17 above, there's no reason to belabor the issue.

Seriously. My fear is you'll miss something REALLY important while obsessing over the cooling system.

[Pathofinder]

I have done those steps, but the truck may not have even hit operating temp this week as it was -10 or more everyday and my kids school is all I have on my agenda. So far for those 3 days or so, on these little drives, the rad coolant level stays PERFECT and doesnt push any coolant.

But I think if I got caught in traffic or something and the car really had a chance to heat up, it may push it.

I think Id like to purge the heater core no matter what though, its got quite a few miles on it, and I think rad stop leak had been used. Is there a best way to keep only distilled water in there instead of using a garden hose??

[Pathofinder]

Especially after reading this thread on google, and its fix for my exact car

http://x.nissanhelp.com/forums/pathfind ... ating.html

"Restricted/Obstructed Heater core was removed and cleaned of debris. Engine now runs cool as the otherside of the pillow"

[Chuck Tribolet]

An obstructed heater core is NOT going to cause it to run cold. About the only thing that will make it run cold is a thermostat
that's stuck open. And it should hit operating temp in a mile or so no matter how cold it is if the thermostat is functioning.

[Pathofinder]

Who said anything about the heater car causing it to run cold??

I just want to flush/reverse flush the damn thing and get ALL the air out of my system as efficiently as possible

[AZhitman]

I already told you how to do that. You're not listening.

Your vehicle DID hit "operating temperature". Ambient (outside) temperature is irrelevant.

I don't want to be rude, but you're looking for a problem that doesn't exist.

p.s. The idiots on that other site are talking about DEBRIS on the OUTSIDE of the heater core (probably around the squirrel cage, aka the blower fan). It should be cleaned periodically as well, but it's in the passenger footwell and unrelated to the cooling system.

[Chuck Tribolet]

The 2001 PF FSM shows two cooling system vents. One is just in front of the firewall , top dead center, rubber cap on a
tube. My stickshift has that one. The other one is shown on a tube on the front of the engine, passenger's side of center line.
Mine does not have that one. Maybe the automatics do (somebody with a slushbox please chime in).

Actually, that was a 2001.5 PF FSM. I got a look at a 2001 PF FSM, and that picture is different. It has another arrow pointing
to the plug on the tube, and says "Not all models are provided with plugs on the water pipe."

[ARKQX33V6]

Heaters, Air to air and air to liquid are parallel in a car from point of view of internal heating. So what happens to a car heater does not affect car engine unless the car's heater leaks and the engine coolant tries to make up the heater's losses.

Coolant jackets around an engine include the expansion tank because cool coolant expands when heated and contracts when cool. The coolant must have a pathway to from the expansion chamber.

Coolant gets hot from the engine, T stat must be bypassed when cold, when hot, T stat opens to allow greater flow across the heat exchanger, the rad, to cool coolant. When initially installed, coolant takes the place of any air in the enclosure and compresses this air, this air must be allowed to be removed. The easiest is to have a vent that is placed in a high position within the coolant housing. This vent must be open while coolant at room temperature in inserted into the jacket surrounding the engine.

Fill the vessel as much as you can, leave rad cap off and vent open, start engine, get it to temperature, the Tstat will open, the coolant will move around and drop as the air is pushed out by compression. No more air out but coolant starts coming out close the vent. Watch the open rad cap, as level drops while hot put a bit more in when it settles top off with cap. The expansion chamber is open, check the level while hot, do not overfill.

With the coolant system buttoned up operate vehicle at various speeds and load. Temp gauge should go to normal.

Stop let cool, check the overflow chamber for at least a level of coolant at the low or normal range, if too low add to that mark, stop.

If set to correct level you are good to go. Only time level may increase is on a very hot day but the over flow chamber is designed to accept any and all coolant for the system.

Warning, coolant that is not premixed with pure water or 100 % coolant is a no good coolant for removing heat. It must be mixed with pure water at a ratio between 50%-60%. At that rate of mixing it has rust inhibitors, freezing protection and cooling abilities. Pure coolant does not have the ability to move around in a close system. Pure coolant can not absorb heat---water is needed. Make sure to use pure water not tap water, tap water contains minerals that can precipitate out at above room temperature and your vehicle will get to 220 degrees under pressure of two atmospheres.

Precipitation of materials from being dissolved in tap water can and does regularly inhibit the radiator from cooling by coating the thin surfaces and stopping the air to liquid transference of BTU.

Coolant must be readily available to draw in heat then readily remove this heat, the coolant must be slipperier than water, it must easily flow everywhere, it must not freeze, it must not boil, it must lubricate, it must prevent rusting...it must be able to do its job under pressure, at no pressure, when very cold and when very hot. In all types of weather and conditions.

Do not take coolant for granted.

[Pathofinder]

I already told you how to do that. You're not listening.

I don't want to be rude, but you're looking for a problem that doesn't exist.

Not to be rude either, but we had a BIG heater core blockage. I made that decision based on after the car running for 15 minutes, the one heater core hose was still outside temperature, while the other was hot.

Sure enough when I pulled the upper hose off NO COOLANT came out, looked dry. Pulled the bottom hose off right after and coolant gushed out



Stuck the garden hose into the top barb, felt a bunch of little debris hitting my hand in the water, assuming they came from the core, stuck the hose in the bottom barb, and then back and forth to both a few times with the hose on full blast, a steady shooting stream was not coming out.

[Pathofinder]

BUT, today we also removed the stock radiator fan and clutch assembly as it was in poor condition and had some huge cracks in it and ordered a new one which wont be here until Tuesday since we didnt get the order in early enough today.

So we topped off the coolant (close to 50/50 mix) and idled the car with the cap off, didn't want to idle for to long as the fan was no longer attached. But I did notice that after 7-10 minutes of idling, the lower rad hose was still outside temperature, while the upper hose was HOT, to hot to hold for more than 1 second.

I didn't want to leave it idling without a fan cooling source, but I dont think the thermostat opened, as the coolant never started moving/flowing while looking in the neck of the rad, and like I said the lower hose stayed cold. Keep in mind the radiator/hoses/thermostat and rad cap are all brand new.

I also took a video of the coolant "surging" as the car idles with the rad cap off, because I dont think I explained it well, the coolant raises alot higher when you rev the engine.

http://img98.imageshack.us/i/5vt.mp4/

Hope Im getting somewhere with this!!

Currently waiting for the car to cool down so I can pop the rad cap off and check coolant level and go from there. Hope to hear some opinions!

[ARKQX33V6]

At operating temperature the 2 rad hoses are the same when it comes to touch, over 150 F we feel hot, remember coolant is over 200F at operating temp. Sounds like the by pass is working as the coolant level is up and down in your pix but the T stat is closed.

When cold open the bottom rad hose into a bucket and capture the coolant, enough should run out to open the T stat assembly, watch for gaskets and remove stat make sure it is installed correctly and place in boiling water and watch for it to open then replace if no good. But if good make sure it is in the correct way, refill, re vent and retry

[ARKQX33V6]

In re listening to your engine I find it extremely noisy, sounds like a minor exhaust leak with bad valve. Like a small diesel engine.
Is anything off the input or exhaust side?

[ARKQX33V6]

Sounds like your valve train is not getting oil