300tdi expansion tank question

[volvotgb]

Hello, I am fitting a 300tdi and autobox from a Discovery into a Volvo 6x6 military vehicle. I have a big radiator out of a Ford 7610 tractor, and ideally I would like to run it without an expansion tank. Has anyone done this with a Tdi engine ? I presume that you would put the heater return into the bottom hose and the little vent pipe from the thermostat housing into the top hose ? 

Any reason not to do this ?

Thanks for your help

[Ed Poore]

If I understand what you want to do instead is get rid of the expansion tank by closing the loop on the cooling circuitry?

The clue is in the name of the part - it's there for a purpose - to allow the coolant to expand. You need that ability either via a recovery tank (which needs a suitable radiator) or by using the expansion tank setup.

Useful description here: http://blog.cantonracingproducts.com/blog/setting_up_your_cooling_system_expansion_vs_recovery

[reb78]

Go back a few years though Ed and cars used to fill via the rad so didnt have expansion tanks. I dont know if the radiator had some capacity to allow what the expanson tank does on modern vehicles though?

[Bowie69]

Looks like the Ford radiator has the overflow :

https://www.qtponline.com/products/radiator_41627.html

So, with a recovery tank, you just need to work out the other bits. It sounds, to me, like you have it right.

https://workshop-manuals.com/landrover/defender300tdi/cooling_system/engine_cooling_system/

This shows the heater return going to bottom hose.

Relocating the bleeder hose to top hose.... Hmmm... Not so sure, putting it on the pump outlet may cause some odd things to happen. I would take your radiator to a radiator building and get them to solder in a new nib to the top tank of the radiator to be safe. Make sure top of radiator is above the thermostat.

 

[volvotgb]

Thanks for the replies. The radiator is well above the thermostat, so thats no problem. The problem I have is I dont have anywhere high enough up to put the expansion tank for it to be higher than the rad and the thermostat housing. All tractors I have worked on just have the radiator, no expansion tank, thats why I was considering it. I presume that as you dont fill the radiator until it is coming out of the cap, then it allows for some expansion. The radiator is considerably bigger than the standard tdi radiator, maybe bigger than the rad and expansion tank combined, so I think it will probably be OK

On the tractor, the overflow pipe just goes to the floor, no recovery tank. Do you think I need the recovery tank ?

[Daan]

Does the Volvo not have an expansion tank you can use?

[cackshifter]

The old minis used to have the expansion tank on the radiator, but on mine for various reasons that used to overflow and lose coolant. The fix was to fit a flat radiator cap (ie no valve) and extend the rad overflow to an 1100 expansion tank, which had the original pressure cap. There was no circulation through it, it was just there to extend the expansion volume . You could always just try the rad as is but keep an eye on levels - if it starts to lose volume, you could add an expansion tank (mine was much lower than the rad, the coolant just syphons, as long as the connecting pipe goes to near the bottom of the tank)