FJ40 Radiator Extension (Reservoir Runs Out of H2O)

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@FES74

OEM coolant reservoirs started in January 1975. You can see from the illustration, below, no reservoir was in F engine FJ40's from 1969 through the end of 1974.

View attachment 2735853

You really need to post some pictures of the piping arrangement to your reservoir. If there is boiling water leaving the radiator and entering your reservoir, the coolant in the reservoir should act to quench the hot radiator water, collect it, and then let the coolant flow back into the radiator when the engine cools off, and the coolant contracts.

Note that is there is air in the engine cooling system, the heated air will force a lot more coolant out of the radiator than just expanding coolant.

The original radiator cap (non recovery system) is typically a single seal cap, whereas a recovery system cap is a double seal cap. Make certain you have the correct one.
Thanks a lot @73FJ40 . Appreciate your sound input. Am the 3rd owner of this FJ40. I guess the current cooling setup now is no longer original. I will check on its cap's type. Thanks again.
 
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*note The viscous fans still spin even when cool, but not aggressively. If you do have a viscous fan it will roar noticeably when hot.
Properly working viscous fans are very important. The truck WILL overheat if it's not working properly.
Thanks @pithicus . I'll double check on this too because unlike my modern cars, this truck does not roar noticeably even when it is hot.
 
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@FES74

OEM coolant reservoirs started in January 1975. You can see from the illustration, below, no reservoir was in F engine FJ40's from 1969 through the end of 1974.

View attachment 2735853

You really need to post some pictures of the piping arrangement to your reservoir. If there is boiling water leaving the radiator and entering your reservoir, the coolant in the reservoir should act to quench the hot radiator water, collect it, and then let the coolant flow back into the radiator when the engine cools off, and the coolant contracts.

Note that is there is air in the engine cooling system, the heated air will force a lot more coolant out of the radiator than just expanding coolant.

The original radiator cap (non recovery system) is typically a single seal cap, whereas a recovery system cap is a double seal cap. Make certain you have the correct one.

20210720_124240.jpg


20210720_124216.jpg
 
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@FES74

OEM coolant reservoirs started in January 1975. You can see from the illustration, below, no reservoir was in F engine FJ40's from 1969 through the end of 1974.

View attachment 2735853

You really need to post some pictures of the piping arrangement to your reservoir. If there is boiling water leaving the radiator and entering your reservoir, the coolant in the reservoir should act to quench the hot radiator water, collect it, and then let the coolant flow back into the radiator when the engine cools off, and the coolant contracts.

Note that is there is air in the engine cooling system, the heated air will force a lot more coolant out of the radiator than just expanding coolant.

The original radiator cap (non recovery system) is typically a single seal cap, whereas a recovery system cap is a double seal cap. Make certain you have the correct one.
@FES74

OEM coolant reservoirs started in January 1975. You can see from the illustration, below, no reservoir was in F engine FJ40's from 1969 through the end of 1974.

View attachment 2735853

You really need to post some pictures of the piping arrangement to your reservoir. If there is boiling water leaving the radiator and entering your reservoir, the coolant in the reservoir should act to quench the hot radiator water, collect it, and then let the coolant flow back into the radiator when the engine cools off, and the coolant contracts.

Note that is there is air in the engine cooling system, the heated air will force a lot more coolant out of the radiator than just expanding coolant.

The original radiator cap (non recovery system) is typically a single seal cap, whereas a recovery system cap is a double seal cap. Make certain you have the correct one.
@73FJ40 Hope you saw all those 3 pics i sent. That' the current cooling system i have. Thanks
 

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@73FJ40 Hope you saw all those 3 pics i sent. That' the current cooling system i have. Thanks


Here is a Option i offer , 100% TOYOTA Genuine NipponDenso Japan non usa parts ..............



eazy peezy to mount too







1626766543324.png






1626766572124.png

1626766605294.png






1626766638650.png
 
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Here is a Option i offer , 100% TOYOTA Genuine NipponDenso Japan non usa parts ..............



eazy peezy to mount too







View attachment 2736219





View attachment 2736220
View attachment 2736221





View attachment 2736222
Thanks @ToyotaMatt. How much is the cost?
 

flx

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Your reservoir seems small.
A lot of options of catastrophic issues have been proposed here, I would really start by checking benign things before to go on the hunt for a crack in your head.

If your cooling system has air it will push it out with time and so replaces it with coolant from the reservoir when cooling off and has yours is small it will basically empty it. Fill it up but this is actually a good thing as you get less air in your system.
And if you get really hot I'm pretty sure the expansion of the coolant is superior to the size of your reservoir so once cold the engine will suck everything back.
When your engine is hot and running it the reservoir full ?
 

flx

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The original radiator cap (non recovery system) is typically a single seal cap, whereas a recovery system cap is a double seal cap. Make certain you have the correct one.
I had noticed that between an old all metallic cap and a more modern one with the yellow sticker but not sure what will be the difference in operation ?
From my experience the one-seal type is capable to push coolant out and suck it back.
 

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I had noticed that between an old all metallic cap and a more modern one with the yellow sticker but not sure what will be the difference in operation ?
From my experience the one-seal type is capable to push coolant out and suck it back.


My overflow WILL handle a FJ60 2F size OIL COOLER Equipped system and the same exact capacity of there bottle too ..........


if it fails you in this regard capacity you can return it

i stand behind the Technical specifications of ALL my products
 

flx

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My overflow WILL handle a FJ60 2F size OIL COOLER Equipped system and the same exact capacity of there bottle too ..........


if it fails you in this regard capacity you can return it

i stand behind the Technical specifications of ALL my products
It does not fail me, just the maximum expansion of coolant on my engine represents the entire capacity of the reservoir. If I had not the reservoir (like before) all the liquid capacity of the reservoir will be on the ground and that much more air would be on my cooling system. It does exactly what I was expecting from an overflow bottle with a one bolt easy install. Fitting a bigger reservoir would mean moving things under my hood and making a bracket, etc.
 

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It does not fail me, just the maximum expansion of coolant on my engine represents the entire capacity of the reservoir. If I had not the reservoir (like before) all the liquid capacity of the reservoir will be on the ground and that much more air would be on my cooling system. It does exactly what I was expecting from an overflow bottle with a one bolt easy install. Fitting a bigger reservoir would mean moving things under my hood and making a bracket, etc.


do u know the exact capacity you need or want ?

i DO have larger options NOT listed online store ?
 

73FJ40

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I had noticed that between an old all metallic cap and a more modern one with the yellow sticker but not sure what will be the difference in operation ?
From my experience the one-seal type is capable to push coolant out and suck it back.
Your experience is contrary to what the auto radiator industry manufacturers say .

Possibly radiator caps in France have special characteristics not available here in the US?
 
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Often the little brass /silver 10mm spring loaded disc that allows fluid to return gets gunk under it. It's easy to clean out.
@FES74 . your cap will look something like below pic if it's a recovery style cap.
A bad sealing cap can cause boiling problems because the system won't pressurise.

cap.jpg
 
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73FJ40

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@FES74

Please confirm the routing of the tubes feeding and draining your reservoir.

Does the black hose from the radiator connecting to the reservoir feed an internal tube in the reservoir that is routed to the bottom of the reservoir?

Does the clear/reinforced hose hanging off the side of the reservoir connect to a vent just inside the cap, venting the very top of the reservoir?

If these hose connections are not routed as above, and are reversed, pressure leaving the radiator will blow coolant out of the reservoir, and there will be no recovery of coolant when the radiator cools off.
 
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@FES74


Please confirm the routing of the tubes feeding and draining your reservoir.

Does the black hose from the radiator connecting to the reservoir feed an internal tube in the reservoir that is routed to the bottom of the reservoir?

Does the clear/reinforced hose hanging off the side of the reservoir connect to a vent just inside the cap, venting the very top of the reservoir?

If these hose connections are not routed as above, and are reversed, pressure leaving the radiator will blow coolant out of the reservoir, and there will be no recovery of coolant when the radiator cools off.
@FES74

Thanks @73FJ40. Here's my reply below:

Please confirm the routing of the tubes feeding and draining your reservoir.

Does the black hose from the radiator connecting to the reservoir feed an internal tube in the reservoir that is routed to the bottom of the reservoir? - Yes.

Does the clear/reinforced hose hanging off the side of the reservoir connect to a vent just inside the cap, venting the very top of the reservoir? - Yes. Thanks again.

If these hose connections are not routed as above, and are reversed, pressure leaving the radiator will blow coolant out of the reservoir, and there will be no recovery of coolant when the radiator cools off.
 
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Often the little brass /silver 10mm spring loaded disc that allows fluid to return gets gunk under it. It's easy to clean out.
@FES74 . your cap will look something like below pic if it's a recovery style cap.
A bad sealing cap can cause boiling problems because the system won't pressurise.

View attachment 2736739

Thanks @pithicus . Yes, my rad cap is similar to that.
 
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Your reservoir seems small.
A lot of options of catastrophic issues have been proposed here, I would really start by checking benign things before to go on the hunt for a crack in your head.

If your cooling system has air it will push it out with time and so replaces it with coolant from the reservoir when cooling off and has yours is small it will basically empty it. Fill it up but this is actually a good thing as you get less air in your system.
And if you get really hot I'm pretty sure the expansion of the coolant is superior to the size of your reservoir so once cold the engine will suck everything back.
When your engine is hot and running it the reservoir full ?
Thanks @flx. Yes, you are correct. The Reservoir begins to get full when the engine gets hotter.
 

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