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Air in Cooling System


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cs2kplus
Novice

Oct 23, 2017, 3:59 AM

Post #1 of 16 (162 views)
Air in Cooling System Sign In

Hello all,
Vehicle: 1996 Ford F-250 XLT w/460 (8 cylinder) engine.
Issue: Cooling System
I have had ongoing issues with my F-250. It's a long story. Suffice it to say...I have replaced many cooling system components.
After resolving actual leak problems and having it checked for head gasket....I suspect I have air in the system. This causes the gage to fluctuate when hot. One thing my cousin found was that my upper radiator hose was installed above my radiator cap allowing air to be trapped. I rotated the hose so it was below the radiator. The fluctuation problem went away. But returned after driving the truck for some time. My assumption is that there was still air in the system and I needed to add more fluid. There are no visible leaks. I filled the reserve. Then removed the radiator cap, turned the heater on full, for a half an hour. This supposedly lets the air out. However, I've seen other methods involving a large funnel. It's a kit - or you can do a makeshift one of your own.
I guess my question is...what is the best way to make sure the air is out!
By the way...I was wondering if I should replace the upper radiator hose. The one that I rotated. When I got it from Pep Boys the guy said it was a close enough match. Well....I am starting to think this is critical. I see prices online from 13 bucks to 50+. There is also a special one that attaches somehow to the thermostat at like 60+. It may be special for my particular engine? Of course after I do this...I will have to burp it. Should I go with higher priced ones? Go with genuine Motorcraft?
WayneUnsure


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 23, 2017, 4:48 AM

Post #2 of 16 (153 views)
Re: Air in Cooling System Sign In

Your problem isn't going to be as simple as a radiator hose. Just because you had it checked for a bad head gasket doesn't mean it doesn't have one. There are very few tests that can conclusively exclude the head gasket. Most tests are inconclusive. Using an exhaust analyzer at the radiator to sniff for HCsis about the only accurate test I know.
I highly suspect the engine is pumping exhaust gases into the cooling system over time.

The method we use to remove all air from the system is to use a vacuum fill tool.





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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Oct 23, 2017, 4:49 AM)


cs2kplus
Novice

Oct 23, 2017, 5:30 AM

Post #3 of 16 (143 views)
Re: Air in Cooling System Sign In

Agreed. I do not know what test was performed.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 23, 2017, 8:02 AM

Post #4 of 16 (131 views)
Re: Air in Cooling System Sign In

Yup - you may have to perform more than one as IMO these engines are not hard to purge air out of hose not exact or not just has to be tight and sealed.
Check everything. Make sure cap is correct and hose to recovery tank is good or just toss it for new dirt cheap it's old enough unless just done. Just that would suck back air actually ignoring the recovery tank at all if so.


Other tricks for filling is tilt the vehicle making the radiator cap the highest spot and use a thermostat with a "jiggle valve" may be hard to find allowed air to pass thru but not liquid slow but a sure fill if equipped.


No rocket science with these actually and don't know of them for head gasket issues - actually none at all.
Check, check, check everything it's either exhaust gasses getting in perhaps intermittent by engine temp or sucking air in anywhere but can hold liquid pressure the bizzare and super rare is water pump might suck air but hold pressure near impossible to catch it do that!




T



cs2kplus
Novice

Oct 23, 2017, 8:22 AM

Post #5 of 16 (125 views)
Re: Air in Cooling System Sign In

Thanks for your reply!
There is probably not much you can name that has been replaced. Yes...much money thrown at it. I truly think there is air in there. I did the easy one I've seen on the internet where you simply open cap cold, run engine, turn on heat (no revving) for 15 minutes (I did like 45).
One thing I did not mention...I pull a camper. This is usually when it happens. But not always just the camper. I ran the other day with absolutely no issues by itself. Then the gauge acted up again when pulling the camper. This was BEFORE I did the burp trick above.
So...I will be pulling again Thursday. I think I may have gotten the air out. But I am on the fence with replacing the hose. Only reason for that...is it may just be the wrong hose...and may have been compromised by all the fluctuations its been thru???
I thought I had this licked when I rotated the hose a month ago and it pulled like a champ. But I am thinking there was still air.
It's been thru 4 mechanics....its just dang frustrating as heck. They think I'm crazy. They do not see what I see. I don't think they take it on the road. It does not have an issue parked.
Oh....one other reason I fell its air....is when I gas it....the needle goes down. I feel it's pushing it thru.
By the way..yeah I did read about inclining it. I may try that next.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 23, 2017, 8:39 AM

Post #6 of 16 (123 views)
Re: Air in Cooling System Sign In

Really, all your symptoms are pointing to a head gasket issue. You said you had it all out once and then it came back. You said the problem shows itself at highway speeds mostly. You have already tried all the methods that usually work on this vehicle.

All these things are leaning toward a mild head gasket issue.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



cs2kplus
Novice

Oct 23, 2017, 10:27 AM

Post #7 of 16 (107 views)
Re: Air in Cooling System Sign In

No. Shows it at any speeds. Just not idle.
What is complicating this is the fact that we did have several actual leaks.....including the water pump. Every time the system is opened...there is another potential for air to get in. I don't think anyone has bled it properly with each issue. Therefore there can still exist some air.
If it were the head gasket, would it lose fluid into thin air? I am not seeing any irregularities in the oil or any other typical performance issues. Runs great otherwise.
What really make no sense to me is last time I pulled the camper there were zero issues.
Even so...I may want the test done again as you suggest.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 23, 2017, 10:34 AM

Post #8 of 16 (105 views)
Re: Air in Cooling System Sign In

Of course it would vanish into thin air. It would be burned out the exhaust and no, there would be no other performance symptoms.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Oct 23, 2017, 10:50 AM

Post #9 of 16 (101 views)
Re: Air in Cooling System Sign In

Wayne - let's swap the word "air" for vapor - neither transfer the heat. What's catching my eye is you hit the gas (RPMs up) and temp gauge goes down. I too agree with Hammer Time (HT) that it's most likely a "mild" head gasket maybe from using too much or only water somewhere along the way for too long.


Said and mean it you have to rule out all other possible things including the rare stuff. It's old now so be it lots younger than many doing fine. When you say "all" or many cooling system parts there are the ones the really count - fan clutch can be lousy new out of box so can thermostats and other things. There's supposed to be a spring inside lower hose so strong a water pump (may not be soo good) it can suck one shut tight don't come with new hoses you put it in the new one from the old one maybe long missing? That happens to stop flow if missing with high RPMs so not consistent with the problems.
Temp gauge should achieve the one spot for temp and stay there below zero or over 100F outside exceptions would be with heavy load, steep climbs and just too hot out.


Fan clutches - been thru many lousy out of box. Should roar when radiator is warm annoyingly so or it's NLG (no longer good.)


You have a problem no question just nailing it is being elusive to you and some techs didn't find it. Vapor as mentioned is likely - either exhaust, spot boiling inside would re-condense to liquid causing hair loss to find, water pumps and thermostats as said this should either have a jiggle valve or a small "V" notch has to be up top or new vapor will not fly thru and out easily or at all.
A lot of test may be inconclusive but try this of assorted tricks when not clear:
Stone cold squeeze upper rad hose and feel the pressure which is none then. Start the engine just sitting there and see how long it takes vs the temp outside to build up pressure. If much or any really noted within a minute or two it's leaking exhaust spits into cooling system and may quit when warmed up fool anyone.


It's got to leave a clue somewhere just eluding finding it. Plugs may show which cylinder if a head gasket isn't the same as the others always should be,


Tom



cs2kplus
Novice

Oct 23, 2017, 11:55 AM

Post #10 of 16 (93 views)
Re: Air in Cooling System Sign In

Yeah. Not ruling out the head gasket issue.
By the way - I've never used water.
Replaced: 2 Fan Clutches (one mechanic said the others was junk) , radiator, water pump, sensors, expansion tank, many hoses, several thermostats, etc?
Ok...let me understand this squeeze test. You squeeze it cold, then start up, then if it can not be squeezed in 2 minutes there is a problem? Or the opposite?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 23, 2017, 12:13 PM

Post #11 of 16 (91 views)
Re: Air in Cooling System Sign In

"Squeeze hose test" = You are feeling for pressure before expansion of heat has increased volume of coolant to make pressure so is evidence of combustion gasses (vapor is vapor) is displacing liquid coolant. That's too early 1-2 minutes. Pressure is limited to the rating of the pressure cap no matter what which can be tested itself isn't the point but can't be too high, say more than 18 PSI is getting close enough to push seals in water pump backwards are directional. You could leave a pressure tester on it and watch rather than feel it but if ignored or pressure not released if it went up too high harm a good part most likely the water pump's seals.
You could "vacuum" fill the system eliminate all air/vapor and fill and vapor returning will get caught up by the thermostat or some. Any isn't going to work out well and has evidence of call it what you will vapor/air just not liquid.
This stuff is the elusive stuff. Antifreeze - the lie is the more the better so never use more than 50/50 max. Some applications will lower the percent to increase heat exchange capability generally not a truck of any sort.


I just hate to see you go thru a head gasket job and this still be the problem as said earlier this engine not known for head gasket issues but anything possible,


Tom



cs2kplus
Novice

Oct 31, 2017, 8:41 AM

Post #12 of 16 (59 views)
Re: Air in Cooling System Sign In

Ok....I have an update. Truck was taken to recheck head gasket possibly being bad. They did extensive tests that turned up negative. They were puzzled why I was seeing this. I told them, it is prevalent under load. So - they went all out and hooked up a 4000 lb trailer. Low and behold....it happened. Finally I had a witness!


The answer? They'd have to take it apart. May be head gasket, but more like cracked block. They agree the coolant is burning. Estimate: $2800.


But....my cousin recommended I just get a rebuilt. I see 460's for like 2K. I'm thinking this is a better way to spend a lot of cash?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 31, 2017, 9:59 AM

Post #13 of 16 (52 views)
Re: Air in Cooling System Sign In

I wouldn't trust that estimate either. They have no idea what they are going to find when they get in there.

The rebuilt long block is a good idea. Just plan on spending a lot more on the extras like ignition components, water pump, T-stat, filters, gaskets, etc.

You want to start new with all those things to protect your new engine. You will also likely have to replace the Cats.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



cs2kplus
Novice

Oct 31, 2017, 10:41 AM

Post #14 of 16 (43 views)
Re: Air in Cooling System Sign In

Yeah....there is no telling what happens when she's opened. I am leery of that choice.
Yes I definitely had in mind that there would be this that and the other thing to add on.
My cousin recommends Jasper. Any thoughts on them?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 31, 2017, 10:53 AM

Post #15 of 16 (38 views)
Re: Air in Cooling System Sign In

Jasper is definitely the best and by far the most expensive.

Personally, I think they are overpriced but they do give a good guarantee.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



cs2kplus
Novice

Oct 31, 2017, 10:56 AM

Post #16 of 16 (34 views)
Re: Air in Cooling System Sign In

Cool. I will have time to get lots of prices. Thanks!






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