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  1. #1
    Join Date
    Dec 2008
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    Plumbing a 1UZ into a Sumo

    Hi,

    Still working on solving the various connection issues and have a query concerning the cooling system.

    The attached diagram is based on the plumbing that was use for the RV8 installation. However the 1UZ has a small 8mm pipe (circled on the picture below) that, according to the Toyota manual, is connected to the "Reservoir Tank".

    I should declare at this point to being confused by the difference between "Header Tank" and "Expansion Tank". My understanding was that "modern" cars used a sealed cooling system including an expansion tank that filled when the coolant expanded & drained back into system when it cooled back down. A header tank, as I understood it, was used on older cars and was used to top up the coolant. Excessive expansion was vented to atmosphere via the pressurised cap meaning that the header tank needed occasional topping up. Into which category does a "Reservoir Tank" fit?

    The plumbing to the radiator, see attached diagram, worked fine for the Rover installation with only the need for occasional top ups after spirited driving on track days. My query is how to connect the pipe which, on the Soarer, went to the Reservoir Tank"?



    Regards,
    Ian













    Pilgrim Sumo Mk3; IVA Apr. 2014; RV8 3.9 EFi ; Cosworth T5; Granada Donor
    Phase Two underway - Conversion to Japanese

  2. #2
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    841
    Hi Ian,

    The pipe to an reservoir tank allows the coolant to expand from the engine block on warm up as the thermostat is closed at this stage. You need to have a level of coolant in the reservoir tank so no air can be sucked back .The reservoir tank will fill further and save the expanded coolant until cool down . The thermostat closes on cool down and draws the coolant back from the reservoir tank not causing a vacuum in the engine block. Any expansion in the radiator and hoses on the other side of the closed thermostat will feed to the header tank. There are two different pressures on warm up either side of the thermostat until it opens . Not having the bypass hose could mean the pressure build up in the head and block.

  3. #3
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    Jon,

    Thanks for the response but puzzled how it appeared to work with the Rover V8.

    What you say makes sense, so would your advice be to connect the pipe in question to the header tank, where Hose D is shown, and blank of the inlet on the radiator where Hose D was connected? Or would you T off Hose D to the 1UZ pipe?

    Regards,
    Ian
    Pilgrim Sumo Mk3; IVA Apr. 2014; RV8 3.9 EFi ; Cosworth T5; Granada Donor
    Phase Two underway - Conversion to Japanese

  4. #4
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    Location
    Chelmsford Essex
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    841
    Hi Ian,

    You want a volume of water head to always be present . The "D" pipe will not have any water until water expands. You need to tee into Hose C and below the top hose level . Water can then expand and you will have a continuous head of water. You never want any air to be able to be sucked into you small pipe outlet.

    Also I understand that the system can be a pig to bleed down and eradicate the air. Hence the nut on the thermostat housing and a modification to the top hose to the radiator having a in-line hose filling point.

    https://www.youtube.com/watch?v=dGGwyjv36OU

  5. #5
    Join Date
    Nov 2003
    Location
    West Midlands UK.
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    On the LS400 the pipe you have circled in the photo goes down to the water/ oil cooler assembly on the oil filter housing.

    If you are running without the oil/ water cooling assembly (that the oil filter screws into) I would suggest that you have that feed circled in the piccie going into the expansion tank/ reservoir ( with a pressure cap fitted) and that you have a bleed feed coming from the top of the radiator going into the expansion/ reservoir tank also.

    It is imperative that the water level in the expansion tank/ reservoir is higher than the level of the water in the bridge between the two heads ie higher than the Lexus fill point which is the large bolt on the front water bridge. If the water level in the tank is below this you will have zero chance of bleeding the air out of the system.

    We use a small Volvo expansion tank mounted on the top of the footwell to achieve this . It has two feeds into it, one for the circled tube on the thermostat and one from the top of the radiator. Heater can be fed from the two connectors located on the water bridge between the heads on the back of the engine as is done as OEM Lexus.

    hth,

    Cheers,

    Tony
    Supply by blagging, engineering by bodge......

  6. #6
    Join Date
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    Quote Originally Posted by jon1d View Post
    Hi Ian,

    You want a volume of water head to always be present . The "D" pipe will not have any water until water expands. You need to tee into Hose C and below the top hose level . Water can then expand and you will have a continuous head of water. You never want any air to be able to be sucked into you small pipe outlet.

    Also I understand that the system can be a pig to bleed down and eradicate the air. Hence the nut on the thermostat housing and a modification to the top hose to the radiator having a in-line hose filling point.

    https://www.youtube.com/watch?v=dGGwyjv36OU


    Jon,

    Thanks for the response and the link. Noted that there were a couple of comments, below the video, questioning the need for the additional filling point.




    Quote Originally Posted by TonyD View Post
    On the LS400 the pipe you have circled in the photo goes down to the water/ oil cooler assembly on the oil filter housing.

    If you are running without the oil/ water cooling assembly (that the oil filter screws into) I would suggest that you have that feed circled in the piccie going into the expansion tank/ reservoir ( with a pressure cap fitted) and that you have a bleed feed coming from the top of the radiator going into the expansion/ reservoir tank also.

    It is imperative that the water level in the expansion tank/ reservoir is higher than the level of the water in the bridge between the two heads ie higher than the Lexus fill point which is the large bolt on the front water bridge. If the water level in the tank is below this you will have zero chance of bleeding the air out of the system.

    We use a small Volvo expansion tank mounted on the top of the footwell to achieve this . It has two feeds into it, one for the circled tube on the thermostat and one from the top of the radiator. Heater can be fed from the two connectors located on the water bridge between the heads on the back of the engine as is done as OEM Lexus.

    hth,

    Cheers,

    Tony


    Tony,

    I am, as you mentioned, running without the oil/water cooling assembly. I will need to check the level of the water in the header tank relative to the fill point. The position was OK for the RV8 installation but may be marginal with the 1UZ.






    Many thanks for all the replies.

    Regards,
    Ian
    Last edited by Ian C; 20-06-19 at 12:10 AM. Reason: 2nd thoughts
    Pilgrim Sumo Mk3; IVA Apr. 2014; RV8 3.9 EFi ; Cosworth T5; Granada Donor
    Phase Two underway - Conversion to Japanese

  7. #7
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    A header tank is part of the pressurised system and should be the highest point. An expansion tank is not pressurised and simply catches any coolant that has been expelled from the pressurised system and then allows it to flow back when things cool down. (Doesn’t need to be high up) With the volume of coolant in a big. V8 you probably need both.

  8. #8
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    You can get thermostats with a small hole 2-3mm to allow equalisation of pressure either side while it’s closed.
    https://i29-photobucket-com.cdn.ampp...Thermostat.jpg
    Like that

  9. #9
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    Quote Originally Posted by 1dayiwill View Post
    You can get thermostats with a small hole 2-3mm to allow equalisation of pressure either side while it’s closed.
    https://i29-photobucket-com.cdn.ampp...Thermostat.jpg
    Like that
    Photo not opening file of the attached thermostat.

  10. #10
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    Colin
    Dax Standard Chassis. Ford 302, AOD auto, DB s/s sidepipes, 2017 T reg.

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