# Ford 3500 lower radiator hose collapsing



## NateOakes (Nov 13, 2016)

the tractor had a mixing of several antifreezes in it and I thought it best to flush and replace it. 
There was a recent issue with a former water jacket repair on the block, JBW broke loose and I had to redo it, just letting you know.

I replaced the lower radiator hose a year ago, seems ok however it collapses when the tractor is running. There is no thermostat in this tractor water pumps throughout the system continuously.
Today I drained and refilled the system in preparation to draining it again and then refill it with new antifreeze. As the title notes the lower hose collapses after the tractor has been running for a few minutes. Doesn't happen immediately.
I am afraid the radiator may be plugged enough to prevent enough coolant to flow into the pump causing the hose to collapse - almost totally closed off. I can't think of any other thing that could cause this. The hose does not have a spring in it, new from New Holland a year or so ago.
I now plan to drain the system again and than fill it with a commercial flush, run it for some time and see it the problem continues. 
I don't run it long at any one time due to the hose collapsing.

Based on the symptoms does anyone have any other idea on what the problem could be?
If I do condemn the radiator I'm not sure a radiator shop could boil it clean economically, any thoughts on that?

A parting thought; if you are retired and need a hobby, buy an old tractor. You'll always have something to do.


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## NateOakes (Nov 13, 2016)

Forgot to mention. The radiator cap is not on during this running and the hose collapsing. System is open to the atmosphere. FWIW cap is also new.


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## Nic99 (Jul 1, 2021)

I'm certainly no expert, but I would tend to agree that there may be an obstruction in the radiator.
The water pump is pulling from the lower hose....if there is a restriction, it would make sense as to why the hose is collapsing.


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## Hacke (Feb 22, 2011)

Normally, most of the time the thermostat is closed and the pump circulates the coolant through two holes in the engine block. The circuit with radiator and hoses are isolated. When the temperature reaches the value were the thermostat opens, the radiator circuit is connected and hot coolant pushes through the upper hose, and is replaced by cooled coolant through the lower hose, to the pump. The pump's suction effect through the lower hose is normally very small.

If you remove the thermostat, things change. Coolant is continuously being pumped through the radiator circuit, which has a resistance. The pump is sucking through the lower hose all the time, the hose will eventually get hotter than normal (coolant is passing the radiator too fast to be cooled properly), which makes it softer, and it collapses.

Put back the thermostat (why was it removed?) and things will be normal.


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## Nic99 (Jul 1, 2021)

NateOakes said:


> Forgot to mention. The radiator cap is not on during this running and the hose collapsing. System is open to the atmosphere. FWIW cap is also new.


A collapsed radiator hose is the result of a vacuum condition. Usually, this is caused by a clog or constriction somewhere in the system.

The thermostat is housed in a location where the coolant has already passed through the engine block before entering the radiator to be cooled.
It remains closed until the coolant temp reaches the preset temp....say 168 to 203 degrees.

Once the thermostat opens, the coolant is allowed to free-flow through the system with little to no restrictions.

Complete removal of the thermostat does remove a minor restriction, but the results would tend to be overheating at normal operating rpm
and/or would fail to reach operating temp at idle.

It should not result in creating a vacuum.

The most common cause for radiator hose collapse is a vacuum issue caused by a faulty radiator cap...
additionally, it is possible that your radiator is clogged or dirty.


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## Ultradog (Feb 27, 2005)

I had the same problem on my Ford 4200.
Radiator was not blocked. Cooling system all good. But the lower hose is old and getting soft.
Only place to get a correct one is at the CNH Dealer and they want $80 for it..
I took some stiff wire and wrapped it around a piece of 1" electrical conduit I had in the shop.
Made a spring of sorts.
Then I screwed the spring into the hose.
Problem solved for a few more years.

PS Radiator cap on or off has nothing to do with it.


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## NateOakes (Nov 13, 2016)

Thank you all for your inputs,
All interesting thoughts on the matter. With no t-stat I believe that the fluid will run somewhat cooler. For a diesel this isn't desirable but the tractor should still run ok. How removing the t-stat could allow it to overheat I don't understand. The mass of coolant is still running through the radiator and exposed to the same air flow. The mass isn't running as slow as it would have with a t-stat however the cooling effect on the entire mass of coolant should be the same. Instead of the block containing a mass which is hotter than the rest of the coolant which is cooler; all of the coolant is cooler and very close to the same temperature in the block and elsewhere.

The tractor is old, radiator looks somewhat new. This tractor hasn't had the best of care over the years I've had to do a lot of work on it to get it this far. I find it amazing that anyone who would own a tractor (TLB or not) would simply use (abuse) it and not do much of anything to maintain it. Guess I found such a seller.
Had to replace the brakes, clutch, lift pump, have the loader frame (hydraulic fluid reservoir) welded, and put a 1-wire alternator on it so far. There was nothing to charge the battery when I got it, the battery had to be replaced due to excessive charge/discharge. This is just another element to make right.

I am believing it in my best interest long term to pull the radiator and have it checked for flow. Don't like the idea as the loader makes working on this a challenge. I don't want this to come back and bite me in the future. Worth something to lay this to rest.

A spring in the hose would prevent it from collapsing even if there were insufficient fluid present from the radiator (i.e. a partial vacuum condition) resulting in insufficient coolant flow. It would prevent a weak hose from collapsing in a normal running engine, but this hose is almost new. There will always be some degree of vacuum at the inlet to the pump, that's how they work. BTW the hose may be a year old and it totally collapses, and it collapses slowly! Takes a few minutes for it to totally collapse.


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## Hacke (Feb 22, 2011)

NateOakes said:


> .
> ..With no t-stat I believe that the fluid will run somewhat cooler. For a diesel this isn't desirable but the tractor should still run ok. How removing the t-stat could allow it to overheat I don't understand. The mass of coolant is still running through the radiator and exposed to the same air flow. The mass isn't running as slow as it would have with a t-stat however the cooling effect on the entire mass of coolant should be the same. Instead of the block containing a mass which is hotter than the rest of the coolant which is cooler; all of the coolant is cooler and very close to the same temperature in the block and elsewhere.
> ...


The radiator need still standing coolant in order to work properly. Hot coolant is introduced at the top in portions (by the thermostat) and in between the portions, the still standing coolant is cooled by the air. Coolant at a low temperature has a higher density than warmer coolant. The coldest coolant will therefore be at the bottom of the radiator, and goes into the engine when the thermostat opens and fills a new hot portion at the top.

The metal in the radiator will be gradually cooler from top to bottom and that helps the cooling when colder coolant sinks down and meets even colder metal. The heat that the metal sucks out of the coolant is transported away by the air.

If the thermostat is removed and the engine is cold, it will take longer time for the engine to reach working temperature, since there is a constant flow of cold coolant through the engine. After a while, the coolant is heated and there is no cold coolant to bring down the engine temperature with. The entire radiator is heated, the hot coolant runs constantly through it. There is not enough time for the air to bring down the temperature enough.


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## fuddy1952 (Mar 6, 2021)

"With no t-stat I believe that the fluid will run somewhat cooler."
Many years ago when my wife & I took automotive mechanics the one instructor said what happens is the radiators job is dissipating heat, coolant flowing too fast through it and it can't work properly. 
When we were drag racing we used a restrictor instead of thermostat. On older cars I would drill a 3/8" hole or two in thermostat. That way if it sticks shut you still have flow.
If you're good at fabrication you could make a radiator hose to garden hose adapter. Then water flow check radiator.

Sent from my SM-S205DL using Tapatalk


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## Bob Driver (Nov 1, 2017)

Radiators (Often called Heat Exchangers) plug from the bottom. Pull the lower hose and shove an inspection mirror in the opening to check for scaling and buildup. Most better quality lower end (suction) radiator hoses have a spring insert to keep them from collapsing, those springs are less than $10 at NAPA. The cost of pulling that radiator and having it cleaned at a professional radiator shop is a pittance compared to what the potential damage to your engine will cost to repair from overheating


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## NateOakes (Nov 13, 2016)

Pulled the radiator yesterday. It appears to be the original! Not many radiator repair shops around anymore but I located one. The cost of checking out the radiator and pulling the ends to clean is not all that far from a new radiator - and with the age of the radiator the capillaries are probably prone to cracking.
Best solution is to replace the radiator.
No on the radiator is C5NN-Z, then a 6FA1 probably a date code, parts catalog shows C7NN-8005-N. I'll have to ensure the unit I order is the proper configuration!


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## NateOakes (Nov 13, 2016)

I find no cross-reference to the C5nn-Z number!
I am finding a lot of C7NN-8005H radiators that say they fit but no cross-reference.
Does anyone know for sure what a correct present p/n will work in my 3500 TLB? The local NH dealer quoted me a price of over 1K, sounds high!


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## Ultradog (Feb 27, 2005)

Many years ago an old mechanic told me, "Jerry, you aren't a mechanic. You are just a parts changer."
That comment stung but was great advice.

You are making assumptions about this thing and being a parts changer. Not smart.
Learn to test things before you draw any conclusions and whizz away your money.
You may have a blocked radiator and you may not.
A simple test will tell you what you have.
With both hoses removed from the radiator stick a garden hose in the bottom hole and test the flow. Put the cap on for this.
Use a rag and your hand to make a half fast seal between the hose and radiator. That radiator should handle full flow of water from a hose through it. (Minus leakage where your hand is making the seal)
If you are getting full flow of water through it you sure don't have a blockage problem. If you get any crud coming out of it reverse the flow several times till you get clear water coming out.
Do not make a tight seal on the garden hose. A typical home water system will run about 80+ psi.
A typical radiator will handle about 30 psi.


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## NateOakes (Nov 13, 2016)

I did that. crud came out the top but I didn't have the cap on.
I will repeat the testing as you suggest.
FWIW: I've used the tractor with no issues, then this spring I noticed that it was overheating, steam from the radiator and all that. Tried the flushing chemicals, then noticed the bottom hose collapsing. 
Symptoms point to radiator but I will run the hose reverse flow through it to see how it goes.


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## NateOakes (Nov 13, 2016)

Ran water through the radiator with the hose as described. There is throughput with some leakage at the hose connection. I have a well with a pump on it and it is nowhere near 80 psi but water does flow through the radiator, can't say that the water output is the same as the hose puts out when it is not being routed through the radiator. Reversed it just to see what came out and some copper colored flakes did come out - nothing at all major, mostly clear water.
Does my hose have enough pressure and volume to prove the radiator is good, I don't know. 
I do know the present symptoms. Hose collapsing, no water flow through radiator due to hose collapse. 
Thermostat hasn't been in the tractor for a long time - before I got it. 
I know the radiator has had all kinds of liquids thrown into it, these include: both types of anti-freeze (red and green), 'universal anti-freeze', radiator flush solutions, anti-rust additives, even windshield washer fluid.

Maybe the hose has weak sides and can't take the pump's suction. But the new hose came from the NH dealer without a spring so one should not be necessary.
All I'm left with here is confusion and a tractor in pieces.

Removing the radiator with the loader attached took me several hours. Tight quarters in that area. I could reinstall it, try a new hose etc to see how it goes, a day of work will cost less than a new radiator - I'm retired. One thing I won't do until I'm sure the system is working as it should is to install new anti-freeze.
At least now with access fo the front of the engine I've had the opportunity to redo the upper bracket on the alternator I installed. Also notice that the u-joints in the crankshaft driven hydraulic pump appear worn out. Just something more to change.


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## Hacke (Feb 22, 2011)

NateOakes said:


> ...
> I know the radiator has had all kinds of liquids thrown into it, these include: both types of anti-freeze (red and green), 'universal anti-freeze', radiator flush solutions, anti-rust additives, even windshield washer fluid.
> ...


That can mean that you have clogged passages in the block/head. I would remove the pump and have look.


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## NateOakes (Nov 13, 2016)

I flushed the head/block with the radiator off the tractor, ran water from the thermostat opening through the system. Clear water came out of the water pump. Drain cock for the block was also open. 
A blocked passage in the head/block would cause an increase in head pressure at the pump output, how would this result in an increase in vacuum (suction pressure) at the inlet to the pump? The water pump is not a positive drive pump (must always pump) if it were it would have a bypass on it for when the thermostat is closed. 
The collapsing hose is my primary symptom.


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## Hacke (Feb 22, 2011)

NateOakes said:


> I flushed the head/block with the radiator off the tractor, ran water from the thermostat opening through the system. Clear water came out of the water pump. Drain cock for the block was also open.
> A blocked passage in the head/block would cause an increase in head pressure at the pump output, how would this result in an increase in vacuum (suction pressure) at the inlet to the pump? The water pump is not a positive drive pump (must always pump) if it were it would have a bypass on it for when the thermostat is closed.
> The collapsing hose is my primary symptom.


Since you have the radiator out of the way, and the coolant history, I suggested you to remove the pump and have a look. There may be restrictions in the pump as well. Even if clear water comes out when you flush, there may be harder deposits in the passages that are baked on to the surfaces. These deposits can give a restriction that makes the pump prioritize the radiator circuit (least resistance), which is open all the time (no thermostat) and boost the effect I described in post #4.

I do not understand what you mean by "bypass". The pump is always pumping around coolant through the engine. When the thermostat opens, some hot coolant is replaced by colder coolant. Since you do not have the thermostat in place, the system is not working as it should.


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## Ultradog (Feb 27, 2005)

Hacke said:


> That can mean that you have clogged passages in the block/head. I would remove the pump and have look.


Hacke,
I think you are a little off on this
If the head and/or block were plugged the pump wouldn't be drawing enough water from the radiator to collapse the lower hose because it couldn't push it anywhere .


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## Hacke (Feb 22, 2011)

Ultradog said:


> Hacke,
> I think you are a little off on this
> If the head and/or block were plugged the pump wouldn't be drawing enough water from the radiator to collapse the lower hose because it couldn't push it anywhere .


All sorts of additives and anti-freeze have been used. The radiator seems to have a good flow. That made me suggest removing the pump and examine the passages, since the radiator was removed.

If the "suction port" is clogged or the wrong gasket is used, all suction effect will be on the "radiator port". That together with choked passages inside the block/head could give an abnormal underpressure on the suction side of the pump (= collapsed lower radiator hose), just like a choked radiator would do.

It is a theory that may be wrong, but I think it is better to examine things as far as possible to try to find an explanation. You may also find other problems to fix while you are at it.


But, without a functioning thermostat, the system is not working as intended.



Passage seen in screenshots from:


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## Ultradog (Feb 27, 2005)

Hacke said:


> All sorts of additives and anti-freeze have been used. The radiator seems to have a good flow. That made me suggest removing the pump and examine the passages, since the radiator was removed.
> 
> If the "suction port" is clogged or the wrong gasket is used, all suction effect will be on the "radiator port". That together with choked passages inside the block/head could give an abnormal underpressure on the suction side of the pump (= collapsed lower radiator hose), just like a choked radiator would do.
> 
> ...


Just so we are on the same page:
The only suction in the entire system is on the suction side of the pump - ie, through that lower radiator hose. 
The rest of the system is under pressure.
The pump sucks water from the lower radiator and Pushes it through the water jacket then through the upper hose back to the radiator.


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## Hacke (Feb 22, 2011)

Ultradog said:


> The only suction in the entire system is on the suction side of the pump - ie, through that lower radiator hose.


On the suction side of the pump is also the passage that I marked with an arrow in my previous post. It goes to the snout were the lower hose connects. When the thermostat is closed, the pump circulates coolant from the upper part of the engine through that passage, to the bigger hole at the bottom, through the engine and back to the pump.

We do not have thermostat or radiator cap, so if the hole with the arrow is clogged and the passages in the engine are choked, the pump will have a hard time moving around the coolant and there could be an underpressure at the suction side of the pump that makes the lower hose collapse. It was just an advice to the owner to check his equipment since it is convenient when the radiator is removed.




Ultradog said:


> The rest of the system is under pressure.


It would have been if there was a radiator cap. If there was a proper thermostat and radiator cap, perhaps the lower hose never would have collapsed. It is impossible to solve a problem when vital parts are removed.



Ultradog said:


> The pump sucks water from the lower radiator and Pushes it through the water jacket then through the upper hose back to the radiator.


What happens when the thermostat (upper hose) is closed?


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## NateOakes (Nov 13, 2016)

OK, a lot of theories and suggestions.
I finally had the time and opportunity to look into his further. I did remove the water pump. Nothing clogged, no ports blocked. It is back on now.
The head bypass port, or shunt circuit, was ok, this is in place to also help in heating the head to assist the diesel action. Diesel's love heat and my removing the thermostat goes against that but the engine has always run ok.

Of course I find new things to work on whenever I do any work on this tractor. This time, among other things I cleaned out years of grease/dirt/etc from beneath the hydraulic pump. I believe my bushings for the front axle need replacing but that will have to wait.

I further looked at the radiator.I pushed water in from the bottom connection with a garden hose. I put the radiator on its front, filled the core with water, cap in place, and plugged the bottom connection, then pulled the draincock and put around 30 psi of air into it from the draincock. Top connection left open. Seemed to have loosened up 'stuff'. When I turned the radiator on its top and flushed it with water a lot of 'stuff' came out. Copper colored chunks of what appear to me to be solidified radiator sealant. Some of these chunks were well over a square inch, some approached 1/8th inch in thickness.
I think I resolved the clog issue. Walter flows through the radiator now with no interruption. 
Haven't put the radiator back in yet, still doing other things with it removed as I now have access to those areas. Don't forget I have a loader attached to the tractor.

BTW is there a special connector for the oil pressure sensor? I've tried to make a standard 1/4" push on connector work but it doesn't want to slide on. Would a 3/8" work or is there a unique connector I need? This is a circular connection not a flat tab.

There was no charging circuit on this tractor when I bought it, the gauges were all disconnected, wiring pulled. I am in the process of fixing that now. Put a one wire alternator on it which works fine. Debating on changing the oil filter to a spin on stye but wonder if it is worth it, convenience, less messy only as I see it.
I have some welding to get done on it before I get the radiator back in and I don't weld!


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## Ultradog (Feb 27, 2005)

Hacke said:


> On the suction side of the pump is also the passage that I marked with an arrow in my previous post. It goes to the snout were the lower hose connects. When the thermostat is closed, the pump circulates coolant from the upper part of the engine through that passage, to the bigger hole at the bottom, through the engine and back to the pump.
> 
> We do not have thermostat or radiator cap, so if the hole with the arrow is clogged and the passages in the engine are choked, the pump will have a hard time moving around the coolant and there could be an underpressure at the suction side of the pump that makes the lower hose collapse. It was just an advice to the owner to check his equipment since it is convenient when the radiator is removed.
> 
> ...


I haven't been on here for a while. You may be right Hacke. I don't know.


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## NateOakes (Nov 13, 2016)

Hacke is absolutely correct this is the shunt or bypass circuit that is most active when the thermostat if installed is closed. 
Nephew brought his welder to the tractor today and took care of some things I had to correct before installing the radiator. That welding is done but the radiator is still not reinstalled due to lack of time.
When he was here I found several more areas that require attention to the welds. Some of these are on the structural members of the loader bucket. Cracks and lack of penetration common! 
Aim is still to get the tractor running again before I go further into the weld issues.


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## Hacke (Feb 22, 2011)

Since you have the radiator removed, resolve 3-4 dishwasher tablets (or the same amount of powder) in boiling water, and fill the radiator with the solution. Leave the radiator standing upright for as long time as possible. If possible, heat the bottom now and then with a hot air blower.

When it is time to put the radiator back, keep it standing and empty it, flush with a hose from the top first, then backwards and forward again.


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## NateOakes (Nov 13, 2016)

Thanks for the advice, I'll do it.


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## NateOakes (Nov 13, 2016)

Final update.
Thank you UltraDog for your common sense suggestion.
Yes I should have cleaned the radiator before even suggesting buying a new one.
I reinstalled the radiator as well as other items last week. Started the tractor and water flowed as it should have, no lower hose collapse.
Probably a self inflicted wound on my part when I was trying to 'fix' the block water jacket leak. Didn't realize that stop leak material could mess things up as it did.
Haven't run the tractor a lot yet but initial indications are that the 'new' JBW is holding -- so far.
Wouldn't surprise me if I caused the failure of the earlier fix by plugging the water flow.

Even with the above should a used engine show up for a reasonable price in good condition I would consider investing in it even if it is only stored away for another day. And no, I don't expect this to happen, seems these are as common as Edsel's, maybe less so.


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