Hey guys,..

I've never had good heat in my Maxi,.. I've been through 2 motors and it's always been luke warm at best,.. I've always suspected the "valve" that's inline on the heater core inlet hose to be the culprit,.. so I decided to bypass that the other day as tempatures were dipping down into the 20's around here..

Anyway,.. now I've got the most heat that I've ever had blowing out of that thing,.. BUT,.. my temp gauge keeps dipping down to cold and the air turns cool at the same time,... I'm guessing that I've got some air pockets in the system (?).. but I'm not sure of the best way to "bleed" them out ??

Any suggestions ?

Thanks in advance
Rick

 

no bleeding needed with heating and a/c, sounds like youre having an issue with your thermostat

 

doubt it. 3rd gens are NOTORIOUS for being tricky to bleed, mainly the more common VG engine. You have to get the front way way way way way way up in the air then bleed it, cuz the heater core is higher up than the rad cap so air gets trapped there unless you are parked up a steep hill. and when bleeding of course always have the heat running so the heater core valve will be open.

 

Right on!..

Uhm.. will it "Self Bleed" with just the engine running/reving and the heat on, or is there some place specific to release the trapped air?

Thanks again!
Rick

 

well start with the engine cold, and have the rad cap off.. then once the coolant burps out some bubbles and has expanded enough to rise up to the top of the radiator then squeeze the top hose a time or two to help with any remaining bubbles then put the cap on so you won't leak coolant everywhere. then let it run until the radiator fans cycle once or twice. after that you should be good.

 

Cool!,.. and thanks!,..

I'll give that all a whirl today and see how it all works out

Thanks again!
Rick

 

these motors dont have a bleeder screw ?

 

yea that's just to help coolant go in easier when you are doing a full refill after draining it. it doesn't really do **** to actually get all the air out, due to aforementioned heater core height issues.

 

I installed a prestone flush into the top heater hose. no need to park up hill, on jack stands. burped the car great, and the vents burn my hands if I leave them in front too long.
http://www.amazon.com/Prestone-Flush.../dp/B002TZSUZ6

 

I had one of those kits on the upper heater hose as well,... that was with the control valve and all,.. but I took it all off and replaced it with a single length of 5/8" straight from the engine to the core.. ... guess I should have re-installed that "T" in there huh!?!

Well I parked it "uphill" in our drive way that's pretty darn steep,.. then jacked the front of the car up about a foot or so,.. the wheels were about 8" off the ground.. let er warm up,... which seemed to take like forever (?)... Finally the fans came on and I let them cycle twice,.. then took it for a spin... it was pretty hot for a while,.. but I did notice it dip down a few times here and there (gauge and physical temp..) ..

Picked up a new Rad. cap too just to be sure..

well see...

Rick

 

sure the core is not clogged at all? and sure the valve thingy is all the way open?

 

The Valve thingy is GONE ... I took it out to eliminate any restriction ...

And yes,.. the clogged thing has been on my mind a lot lately too.. ... the top hose (top from motor and into the core - That's correct yes?) ... but it always gets nice and hot,... but the outlet hose always seems much colder... Now I know that since the fan is blowing air past the core fins, that the exiting water/fluid will be cooler due to that,.. but I don't think it'd be THAT much cooler,..

I did hook the hoses up backwards the other day to sort of "Backflush" the core,.. but I don't know if it did any good or not (??) ..

I was out driving it around again,.. and I'm still getting dips in the temp,.. both on the gauge and in what I'm feeling blowing out the vents...

 

The heater blowing cool air at idle is one of two things - low coolant in the radiator/engine or the thermostat is stuck open.

As far as bleeding goes, service bulletin NTB90-079 describes the proceedure and says to jack up the front of the car so that the bottom of the bumper facia is 39" off the ground! It also states (and this is a 'no s**t') to check that you don't damage the muffler when you jack it up.

you can get service bulletins here:
http://maxima.theowensfamily.com/tsb...Years&tsb=none

 

the heater core often gets clogged with crapola after 20 years. pull the hoses off and remove the valve thingy (you already have), then give the heater core the business end of a wide open water hose from both directions for a minute or so in each direction. then reverse. and again. and again. ad nauseum. long as you cna stand to force yourself to keep flushing.

Then put it all back together and see what happens.

 

What the hell man - that's insane, 39" ? I have no idea how I can get it that high, unless like he said you do it on a hill WITH jackstands, but isn't that a bit dangerous, like the car could roll right over the wheel chocks? I guess a steep hill is the safest way.

Come to think of it, after filling the whole engine with new coolant last month, I never bled the thing really, but the air seems REALLY hot coming out the vent.

 

RE: When does the circuit OPEN

I was dong the coolant change on my Honda Civic last night, and it was taking FOREVER for the fan to come on, in fact it didn't even after 20 min. So, when I'm draining the old coolant out, and I can't get the block plug out, so I need to do the method of filling it with water, then running it (I don't have that prestone thing), is it the actual turning on of the fan that signals the cooling path is OPEN and the remaining old coolant is now mixed with the new tap water?

Or can I ignore the fan, and just look at the temp gauge. When the gauge moves to the normal operating position, does this confirm the path is OPEN.

 

Typically the coolant inside the engine is only circulating through the block and heater core until the engine temp starts to rise and heats up the thermostat,... then as the thermostat opens up from the heated coolant inside the engine, the remaining coolant in the radiator is mixed in / circulated with the already heated coolant in the engine -

The fans won't typically come on until the engine coolant temp reaches a pre-determened deg. which triggers a signal from a relay or similar device to turn on the fans to bring the temp back down to "normal" ..

Something like that anyway

Rick

 

When the car is just idling, the fans may not come on, especially in cooler weather. The thermostat may open up to let water flow through the radiator without the fans coming on. You can grab on to the radiator hose and it will be warm/hot if the thermostat is open, otherwise it will be cool.

 

OK thanks guys. Hose test is good. Makes sense - the fans were NEVER turining on for my Honda Civic the other night when doing the coolant. I'm just sitting there wasting gas. And the service manual says "run the engine with rad cap loosely on until fan comes on at least TWICE", I would be a very old man by the time that happens.

 

In your cold weather, that may not happen just because it never gets hot enough.

on a Maxima, the thermostat opens about 180 deg, which is when the coolant actually flows out to the radiator to be cooled. below 180 deg, the thermostat stays closed and the coolant just circulates through the engine and heater core until the egine gets up to proper operating temp (about 180-190 deg).

Once the thermostat is open and it's flowing through the radiator, the thermostat will probably open and close several times as the engine sucks in cold water from the radiator. eventually it will all get warmed up.

The electric fans come on at low speed once the coolant reaches above 205 on the Maxima. At 210 or 215, they go to high speed.

Since all of this is based on coolant temperature, the stuff may simply not happen if it's 30 deg outside and the engine never gets that hot. (That's also a good thing since that means your cooling system is working fairly well. I'd quit screwing with it and put it back together and drive).

 

i had the same thing on my civic.. fsm says to cycle fans 2x then idle for 10 minutes to "learn idle" after reconnecting the battery.. even in 60 degree temps the stupid thing won't get hot enough. i let it run for like 15-20 minutes then gave up and turned it off. but if i go drive it and then idle at a red light the fans will cycle on and off.. just not from a cold start w/o driving anywhere.

but my 3g would always cycle the fans, even when cold outside

 

Different cars, different cooling system capabilities.

 

Caped were you able to get the drain plug off the block - is it a D16Y8, that's mine. I couldn't the access is retarted, axle is right in the way. No impact wrench for me to get at it, and the bolt itself is crap, it's very shallow head and not a normal 17mm hex head.

So I just ditched the idea and did that fill and drain 4X method to get the old crap out. I was surprised, 6 yr old coolant in that honda and it didn't have a spec of dirt or discoloration in it, it looked brand new. This was not the case a few yrs ago when I drained the VG. It was pretty gross and smelled even worse.

 

i didn't drain the block, i had the battery cable off and the FSM says to idle it for 2x fans + 10min to "re-learn the idle". i wasn't bleeding the system, just idling the car. d-series ftgdmfl tho.. mine is a d17 something pseudo-vtec POS.. i HATE HATE HATE HATE HATE that car, selling it the moment it's paid off.

 

this is why you buy older cars. we plan on putting an h22 into my brother's 93 'lude, along with a 5-speed. stupid jdm f22-non-vtak-pos... of course he got spoiled, driving his sister's 98 'lude.

 

I've got the vg30de motor and I can't even get a bit of heat in the dam cabin. It's winter now and I need me some heat!!! Haha so how do I get to the heater core to check for these problems? I just bought this car and I'm putting some effort to fix the lil things. I need help, what are some of the different symptoms for making it blow cold air thru the vents??

 

did you bleed the system yet?

 

Ok i have a problem with a wierd battery drain. i did the whole test with a tester light hooked up to the neg side of the battery and then touch the neg battery terminal... dim light came on. which means i have something draing the battery while the key if off and the car is off... i started to pull fuses from the inside of the car and i found it. it was the (ELECTRON BATT) fuse i pulled it out the light would go out on the tester ligt. can someone help me finding this drain. also unplugged my stereo and disconnected the trunk light. thank you

 

I've had the weird battery drain as well turns out it was my security system was not shutting off and it was draining my battery. If you lock the doors and shut them does the security light still blink? There are little switches all over the car that could trip the security system. They are for your trunk hood and even in the driver door. You may think it's a battery or alt issue but it's not. Maybe something to look In to....

 

ill see if it is, not sure if my sercuity light even comes on

 

OK my VE doesnt seem to have heat, but comes in later when crusing. Im not sure if i bleeded it right, i lifted the nose off the ground till almost the exhaust tip touchs the ground and i had the radi cap and the bleed screw loose and let that run for a good 30 mins. The fan didnt really come on until i flipped th A/C switch while it was on full blast heat. So the questions are did i bleed it right? cause i saw no more bubbles then i tighted everything, and Should i take out the dash this summer and flush the heater core? or is it possible a leaky 15yr old radiator be a cause of this?

 

i bled my VEs on flat ground w/o using the bleeder screw, just the rad cap and my hand.
open the cap, start the car, add coolant til full, wait until coolant level drops, add more coolant, squeeze upper hose lightly to help remove air bubbles several times, wait until fans come on with the A/C OFF (a/c on causes fans to come on ) top off again as needed
this process does take time. took me an hour one time I recall.

 

alright thanks! but is it a possibility that the heater core be clogged a bit?

 

possible, but not likely unless you have used a radiator stop leak

 

quick question, is the stock radiator top copper? cause mines was replaced by the previous owner before and has a plug near the top radiator hose.

 

I would fill it up with coolant with the cap off and open the bleeder valve. Some people say that it works better if you jack up the front of the car.

 

Just fixed this issue today on my 2004 Maxima, 221,000 miles. Check from the thermostat line that goes to your heating system at idle (most complain cold air blows at idle). It may be hot on the top radiator hose, as it should....but after the thermostat the lines are cold (abnormal) with the heat on. This line is clogged! Mine was with metal type shavings, probably from the radiator my mechanic told me. Heater core was fine, many said it was an air pocket. They were all wrong, including a dealer mechanic!

 

Congratulations then! - how many frigging cooling systems do you know of that has metal shavings in them?

Without stripping down the thing nobody would rightly even think of that possibility ............ and fwiw metal shavings in the cooling system is bound to cause other issues too.

Just about 100% of people with heat problems on these vehicles DO find their bleeding technique to be responsible

 

Let me explain so all can better understand. I had this clown working on the bleeding of my system, and he followed all the methods including AllData repair instructions and what a Maxima "specialist" from the dealer told him. God only knows what else he did. He attempted this about 3 times and accomplished nothing. Then my new and actually "competent" mechanic who knew how to diagnose performance issues found the problem right away and surmised the following. He suspected the old mechanic dumped a metallic sealant into my radiator, no doubt thinking there was a leak somewhere bringing all those air pockets into the heating system. It clogged the hose area right after the Thermostat leading to the heater area on the firewall. I too searched the internet for answers and only found the one solution (air pockets). But my 45 years of car tinkering experience (I have rebuilt 2 engines), and open mind suggested there could be multiple possibilities. Glad I found a real mechanic who knew how to diagnose issues.

 

So in the end the net result is that the original issue was indeed a bleeding issue ....................... no?

The fact that an incompetent couldn't follow instructions properly and possibly buggered around with sealers or whatever in the coolant created a 2nd problem.