WOT Posted January 10, 2012 Share Posted January 10, 2012 So Ive been plagued for atleast a year now with a cooling system that just doesnt want to work. Mainly because Im the guy that wants to do EVERYTHING myself. No matter what I seem to try, I always end up with air in my cooling system. I recently bought the airlift system that puts your hoses and system under vacuum and fills by sucking coolant in. And it seemed to work, but after a week I began to hear gurling from behind the dash, and loss of heat from the system at idle. Is there a clear cut way to fill this system from empty and get all the bubbles out?? One thing that bugs me is I have this coolant/air vent coming up between the engine and firewall with a rubber cap on it. At any time I can pull that cap off (even after just refilling the coolant) and the level in the rad will drop as soon as I pull that vent cap off.... Im just really curious and frustrated I guess on how to do this system properly and keep my cooling system air free.... Its been a while.... Cheers Link to comment Share on other sites More sharing options...
devonianwalk Posted January 10, 2012 Share Posted January 10, 2012 This seems odd to me. I have had my radiator off at least three time this year and not once did I have any air bubbles in my cooling system. It is possible that you may have a clog somewhere in your radiator or heater core. This would explain why you can hear the "whooshing" sound under your dash. Link to comment Share on other sites More sharing options...
WOT Posted January 10, 2012 Author Share Posted January 10, 2012 Well the rad is 2 years old so I doubt its clogged. The heater core very well could be cloggged somehow I dont know much about that. I did take both hoses off about a year ago I guess and run the garden hose through it no problem with good flow Link to comment Share on other sites More sharing options...
Kingman Posted January 10, 2012 Share Posted January 10, 2012 Have you jacked the front of the truck up? That usually helps, sometimes VGs can trap air like no other. Link to comment Share on other sites More sharing options...
5523Pathfinder Posted January 10, 2012 Share Posted January 10, 2012 Yeah, get that front end up as high as you can! Well, about 3 feet up is the best. Place a funnel at the top of the radiator and fill. You need to let it run once you have the system filled. Its got to get to operating temp so the T-stat will open. You can rev the engine a few times to help it burp. Lower it down and keep watching for bubbles. Link to comment Share on other sites More sharing options...
Towncivilian Posted January 10, 2012 Share Posted January 10, 2012 Do you have an OEM radiator cap? Link to comment Share on other sites More sharing options...
silverton Posted January 10, 2012 Share Posted January 10, 2012 This is on an 01 so it has the VQ. But you definitely want the radiator fill spot being the highest point, parking on a slight incline usually does the trip. Also buying one of these really helps. Run the engine for awhile with the heater on blast, and just watch for the bubbles to flow. http://compare.ebay.com/like/190378966229?var=lv<yp=AllFixedPriceItemTypes&var=sbar Link to comment Share on other sites More sharing options...
WOT Posted January 10, 2012 Author Share Posted January 10, 2012 I do have an OEM nissan cap, bought new this summer. I have tried jacking the car up high, filling the system, turning on the engine til the tstat opens and the water starts visibly moving in the rad, then I rev it for a while til the bubbles stop coming out, top up to the neck of the rad, put the cap on and think Im done. Ive done that 5+ times now, and everytime I eventually lose heat at idle and when I take the cap off my rad is low and I have pushed some coolant into the overflow. At first I thought I had a bad headgasket, but then a guy I trust mechanics wise said that trapped air in the cooling system will cause it to blow coolant into the overflow. I just dont get how Im not getting the air out when I use this vacuum tool to fill, and then even run the engine for 20 min..... Does anyone have any insight on when to use / not to use that vent cap on the back firewall?? I really just want to do this one more time, and have it solid and reliable for the winter!! Thanks so far guys Link to comment Share on other sites More sharing options...
01burgundyQX4 Posted January 11, 2012 Share Posted January 11, 2012 I think you have to let the coolant system get rid of the last amount of air. Do the best you can to fill it up, and don't open it up again. When it gets hot the air will expand and will push out into the overflow tank. When it cools down again it will pull the coolant in the overflow tank into the radiator. The more this cycles the more air is purged and if you keep the coolant overflow full the coolant will replace the air. If you take off the radiator cap you let more air into the system. If you have a hole or leak in the hose that goes to the bottom of your overflow tank, it will pull air back in to the radiator. If the overflow is not the high point of the system, then you will have problems. You will need to jack up the front of the vehicle and let the temp/overflow cycle a few times, then don't open the system again. Link to comment Share on other sites More sharing options...
WOT Posted January 11, 2012 Author Share Posted January 11, 2012 If you have a hole or leak in the hose that goes to the bottom of your overflow tank, it will pull air back in to the radiator. This part stuck out to me. I wouldnt say my overflow hose is in "top" condition, especially since I have no idea which way it was originally routed, and I have since routed it myself thru easy to access spots I didnt know you were "allowed" to leave the overflow past the max line either, I didnt even know coolant got sucked back into the rad from the overflow. Maybe I should check and just change that hose, do you guys have a clamp on there the overflow hose connects to the rad neck? I dont Link to comment Share on other sites More sharing options...
devonianwalk Posted January 11, 2012 Share Posted January 11, 2012 Maybe I should check and just change that hose, do you guys have a clamp on there the overflow hose connects to the rad neck? I dont Yes, it is a weak little spring wire clamp that you can remove by pinching it with your fingers. Burgandy has an excellent idea! Link to comment Share on other sites More sharing options...
Towncivilian Posted January 11, 2012 Share Posted January 11, 2012 I have some puny clamp: I think my overflow hose is sweating, I need to replace it... Link to comment Share on other sites More sharing options...
WOT Posted January 11, 2012 Author Share Posted January 11, 2012 I really like OEM clamps so Ill probably buy a new overflow hose and clamp today on my way to work if they arent stupid expensive Anyone know the purpose of the vent cap on the back firewall and when it should be openned and closed during the refill process?? Link to comment Share on other sites More sharing options...
01burgundyQX4 Posted January 11, 2012 Share Posted January 11, 2012 Looks like the factory service manual is calling that the air relief plug. You can take that off when filling the radiator, and put it back on when coolant spills from it. This site has factory service manuals: http://www.nicoclub.com/FSM/ Link to comment Share on other sites More sharing options...
WOT Posted January 11, 2012 Author Share Posted January 11, 2012 I have never been able to make coolant spill from that relief plug Link to comment Share on other sites More sharing options...
Towncivilian Posted January 11, 2012 Share Posted January 11, 2012 I really like OEM clamps so Ill probably buy a new overflow hose and clamp today on my way to work if they arent stupid expensive The overflow hose is somewhere around 11 bucks, the clamp is about $6 from the dealer. Link to comment Share on other sites More sharing options...
devonianwalk Posted January 11, 2012 Share Posted January 11, 2012 Looks like the factory service manual is calling that the air relief plug. You can take that off when filling the radiator, and put it back on when coolant spills from it. This site has factory service manuals: I can't seem to find the air relief plug on mine? Here, maybe a close-up will help! Link to comment Share on other sites More sharing options...
Towncivilian Posted January 11, 2012 Share Posted January 11, 2012 (edited) But the OP's air relief plug is the black capped off tube in the center of this picture: Edited January 11, 2012 by Towncivilian Link to comment Share on other sites More sharing options...
shift_love Posted January 12, 2012 Share Posted January 12, 2012 get one of those funnel kits that fits inside the radiator where the cap goes, open that valve, and run the motor with coolant in the funnel and wait for it to suck it all down, itll relieve air through the valve on the motor and suck in more coolant...as soon as you dont have coolant being sucked in and nothing but coolant coming out of the relief you should be good to go, squeezing air pockets out of your upper and lower hose may help speed the process as well...youve just gotta get the motor up to op temp for this all to start working...if this still doesnt work and youre overheating you may have a clogged radiator as well. i had a 2001 vg33e frontier that did this, i know the vq is totally different but theyre working off of the same principles Link to comment Share on other sites More sharing options...
adamzan Posted January 12, 2012 Share Posted January 12, 2012 You can get one of those sweet funnels at princess auto since I see you are in canada. http://www.princessauto.com/pal/product/8225880/Funnels/pans/Spill-Free%22-Funnel Link to comment Share on other sites More sharing options...
WOT Posted January 12, 2012 Author Share Posted January 12, 2012 I was just there on the weekend to didnt see that Link to comment Share on other sites More sharing options...
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