Swollen Coolant Hose - Strange Symptoms

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I changed out my alternator about a week ago and momentarily disconnected my lower rad hose where it goes into the T-stat housing to do so. Don't ask why, it didn't help. I burped the system until I saw no bubbles, topped up, and thought nothing of it. Since then, I've noticed my coolant reservoir has been bone dry, even after driving, and my upper rad hose has been swelling a lot and far hotter than I ever recall. I figured there must be more air in the system or my T-stat is stuck (new OEM T-stat last year), but I performed another burping session today and only had a negligible amount of bubbles come up. I ran the truck this morning for 40 minutes (parked) with the heat on full and turned the interior into a sauna, so it is blowing hot air. I don't have a scangauge or IR gun so I was not able to get engine or coolant temps, but my temp needle never wavered from halfway. Lower rad hose never got past "kinda warm" to the touch, likely from ambient temps, upper rad hose could have melted my skin off. I ran the truck with the rad cap off, no funnel at first to observe if coolant was flowing into the reservoir when it reached the small hole, and it was, so a faulty rad cap could maybe explain why my coolant reservoir is empty, and maybe even the swelling hose due to not releasing pressure, but what about the T-stat? The coolant was damn near boiling when I finally shut the truck off and I really don't think the T-stat ever opened as the coolant just kept rising in the funnel.
 
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94SRUNNER

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It sounds like you may still have air in the system. When I did some work last month on my coolant system I first bled the system without the radiator cap and the front end elevated, but was not able to get all of the air out of the system. The following morning I used the coolant system bleeding funnel (purchased on Amazon and pictured below) that attaches to the radiator to bleed the system. This allowed me to get the large majority of the air out of the system. One other note, when you installed the thermostat, was the jiggle valve oriented in the correct position, i.e. at 12 o'clock?

new_tstat_06112021.jpg
 
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It sounds like you may still have air in the system. When I did some work last month on my coolant system I first bled the system without the radiator cap and the front end elevated, but was not able to get all of the air out of the system. The following morning I used the coolant system bleeding funnel (purchased on Amazon and pictured below) that attaches to the radiator to bleed the system. This allowed me to get the large majority of the air out of the system. One other note, when you installed the thermostat, was the jiggle valve oriented in the correct position, i.e. at 12 o'clock?

View attachment 2746463
I did the poor-man's versions of that - big funnel with duct tape. It was water tight and allowed a large amount of coolant to rise into the funnel without leaking. I should probably invest in one of those though. I did not pay any attention to the orientation of the jiggle valve when I installed last year but have since learned that it should be at 12-o'clock. Could an out if place jiggle valve be enough to keep a thermostat shut?
 

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It shouldn't keep the thermostat shut, but it would keep air from bleeding out properly. It would be worthwhile to remove and doublecheck your work. While the thermostat is out, you could test it per the FSM to insure the thermostat is functioning properly.
 
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It shouldn't keep the thermostat shut, but it would keep air from bleeding out properly. It would be worthwhile to remove and doublecheck your work. While the thermostat is out, you could test it per the FSM to insure the thermostat is functioning properly.
That makes sense. I'll have to wait until Tuesday to get a new Thermostat gasket but I'll give that a shot then. Is the fact that my lower rad hose did not really heat up a good indicator that the thermostat never opened?
 

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That does indicate that warm/hot coolant is not flowing through the system as designed. That said the lower hose will be cooler than the upper hose. Also you may want to consider replacing your coolant hoses and clamps if yours are swelling, that could be an indication that they are failing. Are they original OEM or have the been replaced (either with OEM or aftermarket) at some point?
 
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I replaced the lower with OEM last year, the upper (which is swelling now) is also OEM but did not warrant replacement when I did the T-stat last. I will get on that this week. Thanks for the info!
 
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Best way to burp. Drive until operating temp reached and RPM around 2,500 for 5 minutes or more with both heaters to max hot (you can turn fans off, after setting temp to hot). Park on a hill, front end higher than rear. Let cool down overnight (8 hr or more). Before starting and sun-up (before OAT begins to climb). Take radiator cap off, and top with coolant to very top. The fill reservoir to hot mark (low if -20 OAT). If you added any coolant, repeat again next day.
 
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Best way to burp. Drive until operating temp reached and RPM around 2,500 for 5 minutes or more with both heaters to max hot (you can turn fans off, after setting temp to hot). Park on a hill, front end higher than rear. Let cool down overnight (8 hr or more). Before starting and sun-up (before OAT begins to climb). Take radiator cap off, and top with coolant to very top. The fill reservoir to hot mark (low if -20 OAT). If you added any coolant, repeat again next day.
Awesome write up, I'll certainly do that. I'm all buttoned up now with a new upper rad hose and a thermostat in the right position (I tested it in boiling water per the FSM), but after another half hour of running the truck with the heat on, there was no evidence that the thermostat ever did open. I did about 3 stints of holding my RPM above 2000 for a couple minutes, and that got plenty of air out but still no thermostat action. Is this abnormal?
 

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Awesome write up, I'll certainly do that. I'm all buttoned up now with a new upper rad hose and a thermostat in the right position (I tested it in boiling water per the FSM), but after another half hour of running the truck with the heat on, there was no evidence that the thermostat ever did open. I did about 3 stints of holding my RPM above 2000 for a couple minutes, and that got plenty of air out but still no thermostat action. Is this abnormal?

How do you know the thermostat did not open once it was installed?
 

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The coolant level won't necessarily drop in the funnel when the thermostat opens. When the thermostat opens, it allows the coolant in the system to completely circulate through the system and push air out, if air is in the system.

How long did you let the engine run while bleeding the system? I assume at least until the factory gauge was at the normal operating level?
 
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The coolant level won't necessarily drop in the funnel when the thermostat opens. When the thermostat opens, it allows the coolant in the system to completely circulate through the system and push air out, if air is in the system.

How long did you let the engine run while bleeding the system? I assume at least until the factory gauge was at the normal operating level?
Yes, and for about 20 minutes past that. Went until squeezing the upper rad hose stopped producing bubbles. I'm going to drive it later on today and park it uphill as per @2001LC 's suggestion and just monitor things
 

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Sounds like a good plan.

As a point of reference, I am able to see when my thermostat opens using my ScanGaugeII. The coolant temps will rise as the engine comes up to temp and it typically peaks at some temp, then falls a few degrees as the thermostat opens and allows cooler coolant to flow through. .
 
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Forget the fancy funnels or any fill tool.

The cool down and check level method, is only true method to insure proper level. Even the makers of these fill and bleed "tools", instruct say: "must check level manually" Very import: Do not take radiator cap off until complet cool down (~8hr's)

Notes:

Sometimes air bubble gets traped, mostly in a heater core(s). Driving and hitting brakes hard, helps free the air bubble(s). You'll know there's an air bubble in a core or coolant low. When engine hot, yet no (not very hot) cabin heat.

Coolant hoses swell for only one reason I've seen, over heating!

Extreme and prolonged overheating, rubber hoses like those of power steering, will turn brown.

Make very sure:
Radiator cap good.

Reservoir hose free of obstruction and hose goes straight to the bottom of reservoir. Don't get the hose stuck on shelve in reservoir. If it gets stuck on reservoir shelf, it will curl upward and suck air.
 
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Forget the fancy funnels or any fill tool.

The cool down and check level method, is only true method to insure proper level. Even the makers of these fill and bleed "tools", instruct say: "must check level manually" Very import: Do not take radiator cap off until complet cool down (~8hr's)

Notes:

Sometimes air bubble gets traped, mostly in a heater core(s). Driving and hitting brakes hard, helps free the air bubble(s). You'll know there's an air bubble in a core or coolant low. When engine hot, yet no (not very hot) cabin heat.

Coolant hoses swell for only one reason I've seen, over heating!

Extreme and prolonged overheating, rubber hoses like those of power steering, will turn brown.

Make very sure:
Radiator cap good.

Reservoir hose free of obstruction and hose goes straight to the bottom of reservoir. Don't get the hose stuck on shelve in reservoir. If it gets stuck on reservoir shelf, it will curl upward and suck air.

I've seen you share this method on more posts than I can count and I certainly trust your knowledge of the 100 series cooling system....

So you are saying that if you follow this method and keep doing it every day until you can't add any more coolant that the system is 100% air-free and I don't need to focus any more attention on that aspect of the cooling system?
 
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Correct! Just as I've post many of times. It works, and is only sure method!

Provided no air bubble blockage. Which I've only seen bubble blockage in heater core(s). Which you can easily tell as Water temp gauge reads normal (3 o'clock), but cabin heater does not blow very hot as it should. I hit the brakes hard at ~30 MPH and I hear gurgling sound as bubble dislodged, than heater blows hot. May need to top rad again.. This only happens sometime, when I blow out heater cores. But low coolant will not reach heater cores at all, or until very hot (expansion). This too result in no or low cabin heat.

I can't say you don't have other issue that may needing attention. But over night cool down, is best way to top and remove air in a properly serviced coolant system.

What happens is, by parking front end high. The radiator top become high point. Air bubble will form at high point as coolant cools and contracts. But if you open the cap before full cool down, you loose vacuum of contraction. The contraction vacuum sucks coolant from reservoir. But fail to do so efficiently if air bubble at top of radiator (goose neck of cap). Fails if reservoir hose clogged. Fails if reservoir hose end is not submerged in coolant (sucks air)

A stuck closed thermostat, will result in overheating.
A weak thermostat will result in not reaching operating temp.
A very low coolant system will result in overheating and blowing engine.
Weak cap will result in runn cool.
Stuck cap will result in over pressurizing and likely overheating.
Clogged radiator fins (washe the fins( result in running hot even overheating.

 

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