Air in cooling system
Thread Starter
|
Senior User
Joined: Jul 2001
Posts: 119
Likes: 0
Air in cooling system
I have a 1991 F150 with a 302 C6 tranny. I have replaced the water pump, Radiator, thermostat (160 degree) and cap. What happens is after a 15, 20 min drive my over flow tank startes to fill up and when I stop and idle the temp starts to go up. When I shut it down I can bubbles coming from the over flow tank.
Not sure where to go from here. I changed everything I could think of, any ideas??
Thanks again
Not sure where to go from here. I changed everything I could think of, any ideas??
Thanks again
Senior User
Joined: Aug 1999
Posts: 343
Likes: 0
Air in cooling system
The bubbles are your coolant boiling. You are overheating. Replace the thermostadt again and verify you installed the correct water pump and rad cap.
From what I can tell, your cooling system is not working properly. You need to re-check your work.
Randy
From what I can tell, your cooling system is not working properly. You need to re-check your work.
Randy
Senior User
Joined: Jan 2001
Posts: 416
Likes: 0
Air in cooling system
Why did you change the system? was there an over heating problem before? Perhaps ther is a blown head gasket of a cracked head allowing exhaust to get into the cooling system. I agree that you should check the thermostat to see if it is install the right way around. Also see if there is a small hole around the outsid perimiter if the thermostat. It should be at the top when installed. Sometimes drilling a small(1/16 in) hole in the thermostat and placing the hole up will let the air that is trapped in the system when filling escape.Perhaps you could get a service station to do a pressure check on the system to see if it hold pressure. I haave heard that Ford engines can have head cracks around the exhaust valves that are hard to diagnose. Good luck! SR.
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
Air in cooling system
How long since you changed all these parts? It could just be the cooling system bleeding the air out of it.
How much fluid is in the overflow tank when the engine is cold. There is a line that says something like "fluid cold level". Make sure the antifreeze is at this line when cold.
How much is there when the engine is hot, I believe there is also a line "fluid level hot".
The bubbles you hear could just be air being purged from the system. As the engine heats up the fluid expands and the "extra" goes into the overflow tank. The air is also pushed out into the tank, the bubbling you hear. As the engine cools the fluid is drawn back into the system. If there isn't fluid in the tank it could draw in air.
As for temp going up when idling. How high? What is outside air temp? How long at idle before temp starts to rise?
Sparky
How much fluid is in the overflow tank when the engine is cold. There is a line that says something like "fluid cold level". Make sure the antifreeze is at this line when cold.
How much is there when the engine is hot, I believe there is also a line "fluid level hot".
The bubbles you hear could just be air being purged from the system. As the engine heats up the fluid expands and the "extra" goes into the overflow tank. The air is also pushed out into the tank, the bubbling you hear. As the engine cools the fluid is drawn back into the system. If there isn't fluid in the tank it could draw in air.
As for temp going up when idling. How high? What is outside air temp? How long at idle before temp starts to rise?
Sparky
Thread Starter
|
Senior User
Joined: Jul 2001
Posts: 119
Likes: 0
Air in cooling system
Well the reason for changing the parts is due to an engine and tranny swap I did. I removed the old tired 302 for a new 302, 10:1 compression, mild cam (484 lift 290 degrees duration), and 1965 289 hipo heads reworked ported and polished. I also swapped from a 5 speed stick to the C6. With that a new radiator was needed and I didn't want to use the old water pump. I have 600 miles on this motor and this is the only problem that I have.
The system holds pressure and the temp on the gauge reads alittle below the N in NORMAL. After a 20 min drive at 65 mph (2700 RPM) and I stop at a stop sign and take off again the temp goes up ¾ of the way. Then it starts to drop off as I drive again. But the over flow tank fills up and over flows and when I turn it off I can see bubbles going into the over flow tank. If I pull off the hose I can feel pressure coming out of the radiator where the overflow hose goes.
That's where I am, pulling my hair out right about now. All the plugs look great, no smoke from exhaust, no fluid puddling anywhere, I will try just about anything right now. The only thing I have left is the intake gasket and or a head gasket but I would think I would see something somewhere.
Thanks for the help
The system holds pressure and the temp on the gauge reads alittle below the N in NORMAL. After a 20 min drive at 65 mph (2700 RPM) and I stop at a stop sign and take off again the temp goes up ¾ of the way. Then it starts to drop off as I drive again. But the over flow tank fills up and over flows and when I turn it off I can see bubbles going into the over flow tank. If I pull off the hose I can feel pressure coming out of the radiator where the overflow hose goes.
That's where I am, pulling my hair out right about now. All the plugs look great, no smoke from exhaust, no fluid puddling anywhere, I will try just about anything right now. The only thing I have left is the intake gasket and or a head gasket but I would think I would see something somewhere.
Thanks for the help
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 7,298
Likes: 45
From: Southern California
Air in cooling system
It does sound like it could be a leaky head gasket. I had a blown head gasket on a car once, and it had the same symtoms you describe. As someone already suggested, you should have the cooling system pressure checked to confirm this. A cylinder leak-down test might confirm if your head gasket is blown too.
Thread Starter
|
Senior User
Joined: Jul 2001
Posts: 119
Likes: 0
Air in cooling system
I am going to check the plugs again tonight and see what I get. I have another EFI intake that I have been porting, almost done, and when I swap that over I might just say screw it and do the head gaskets. A shame to rip a new motor with 600 miles on it down but it that works then it will be worth it.
This problem just has me stumped. Any more ideas are welcome. Thanks for the help already.
This problem just has me stumped. Any more ideas are welcome. Thanks for the help already.
Trending Topics
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
Air in cooling system
I don't know if they will physically interchange, but do you have the correct water pump? The newer serpentine belt pumps are designed to run backwards. The fans also. I don't know if you are mixing parts from year to year and may have the wrong one in, depending on the belt set-up you decided to use. One other thing I would check, is to make sure a spring is installed in the lower radiator hose. If not, it can be sucked shut by the water pump when going down the highway.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Senior User
Joined: Mar 2000
Posts: 360
Likes: 0
Air in cooling system
I'll throw my $.02 in, I think you have a marginal cooling issue. That's why it cools down at high speed with a lot of air being rammed through the radiator. And why the temp goes way up when you stop with engine running. And why it barfs after you shut it off. A near-overheating engine overheats when it is turned off, as there is no more pumped water flow, and no more cooling other than direct radiation from the block. So the water in the water jacket gets even hotter for a while.
Thread Starter
|
Senior User
Joined: Jul 2001
Posts: 119
Likes: 0
Air in cooling system
Well is fill the over flow tank when I am driving not when I shut it down. When I turn it off I can see bubbles coming into and out of the tank. I made sure the water pump was correct last night. The assc. bracks and equipment are all the same stock stuff for a 1991 truck. The swap was a direct swap so nothing special was done or needed. The motor pulls nice and hard form 1500 to 5000 rpm. The cam is good until 5700 but I don't want to rev it any higher until the motor is broken in alittle more. And I know the stat is in the correct way.
I have to finih porting this new intake I have and swap it in next week. I hope I see something when I pulling the old one off. or the problem just disappers.
ANy other ideas and help are welcome thanks for the great advice.
Corey
I have to finih porting this new intake I have and swap it in next week. I hope I see something when I pulling the old one off. or the problem just disappers.
ANy other ideas and help are welcome thanks for the great advice.
Corey
Senior User
Joined: Jan 2001
Posts: 416
Likes: 0
Air in cooling system
Hi again. I think that for the time it taked befor you start riping the heads off you should do a compression check and a pressure test on the cooling system. You have run the truck long onough tfo purge the air that may have been trapped in the system whe filling. If you are getting bubbles in the tank after this long there is another problem, possibly a warped head or a crack in the block/head or a blown head gasket. The tests should give you some idea where to start looking. I mentioned before that a crack can occure around the valve seat and are very hard to detect. Quite often they will allow compression pressure to escape into the cooling system but won't allow coolant into the cylinder(s)so the engine will run fine,ie: no miss from wet plug(s)etc. You could also check the plugs first thing in the day before running to see if there is any wetness from coolant on them. Good luck, SR.
Thread Starter
|
Senior User
Joined: Jul 2001
Posts: 119
Likes: 0
Air in cooling system
I will check all the plugs this weekend after letting it set for a day or two. I will also do a compression check for each cylinder also while I am at it. I find it hard to believe it is the heads since they have all new components, hardened seats, valves, guides, springs, retainers, studs and guideplates.
I will let you guys know what turns up from this weekend on Monday. Thanks fir all the help!
I will let you guys know what turns up from this weekend on Monday. Thanks fir all the help!
Senior User
Joined: Jan 2001
Posts: 416
Likes: 0
Air in cooling system
Hello again. Just a thought, have you checked the actual temp of the engine when it is doing this? The stock guage is not accurate for this. Use a propoer temp guage. It is possible that the thermostat is in backwards or is hooped(even if new,VOE) One other thing to check, is there a spring in the bottom rad hose. There shoud be one there to keep it from collapsing from the suction of the water pump. I have seen this happen before and it is real hard to diagnose, the vehicle will idle fine and keep cool at a low speed but when higher speeds or hill climbing come into play it will over heat and boil the rad fluid. Just a thought. SR.
Thread Starter
|
Senior User
Joined: Jul 2001
Posts: 119
Likes: 0
Air in cooling system
Well Installed a new instake last night and I looked at the stat and lower hose. Everything looks good and works correctly.
I still get the same problem. Drive for 20 or more min. and the over flow tank starts to fill up. Even to the point of over flowing. The temp runs real cold but I still get this problem. I I lookat the tank when it is idling after a long drive it looks normal up filled with fluid. But after I shut the ening off I can see air bubbles going in to the tank. If I pull the over flow hose off and block the radiator port with my finger I can fear and hear the pressure it is releasing.
I installed a new cap, check plugs (light brown/white), and a compression check the other night and everythign looks good so this still blows my mind to what is causing this.
Any other ideas people? Would a bad mixture of Antifreeze/Water cause this? (to much water)
Thanks again
I still get the same problem. Drive for 20 or more min. and the over flow tank starts to fill up. Even to the point of over flowing. The temp runs real cold but I still get this problem. I I lookat the tank when it is idling after a long drive it looks normal up filled with fluid. But after I shut the ening off I can see air bubbles going in to the tank. If I pull the over flow hose off and block the radiator port with my finger I can fear and hear the pressure it is releasing.
I installed a new cap, check plugs (light brown/white), and a compression check the other night and everythign looks good so this still blows my mind to what is causing this.
Any other ideas people? Would a bad mixture of Antifreeze/Water cause this? (to much water)
Thanks again