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udidwht's avatar
udidwht
Explorer
May 11, 2018

Coolant capacity

Looking at the following manual for the 1994 Chevy P30 manual I'm not seeing anywhere 'Coolant capacity'...

https://www.gmcmi.com/wp-content/uploads/2014/05/P30-Chassis-Manual.pdf


I'm getting ready to replace all the coolant hoses, Heater core hoses, T-stat and possibly the coolant temp switch (lower coroner of radiator) as well as the one near the T-stat.

I've in the annual the fluid capacity for oil, Trans and Differential fluid but nothing for Radiator/engine coolant capacity. Anyone know how much I should purchase? I'm thinking the capacity is in the ballpark of 20-25qts total.

This is for 7.4L 454 TBI w/4L80E (94 Fleetwood Southwind Storm 28ft)VIN#1GBJP37N4R3314754

Any other suggestions/tips before I dig into this would be great.
Class A
  • enblethen's avatar
    enblethen
    Nomad
    May 11, 2018
    My 1993 Chev Owner's manual says 22.5 quarts. This may not include the recovery tank.
  • udidwht's avatar
    udidwht
    Explorer
    May 11, 2018
    enblethen wrote:
    My 1993 Chev Owner's manual says 22.5 quarts. This may not include the recovery tank.


    I take it you have a 454?

    I guess I was pretty close. I was thinking of getting 6 gallons and that should cover it and give me some to spare.
  • udidwht's avatar
    udidwht
    Explorer
    May 11, 2018
    enblethen wrote:
    7.4 TBI
    Yes, 6 gallons of premixed.


    I see the Prestone has (2) the 50/50 (265 boil over) and Concentrated.

    The concentrated shows it's a mix of 70/30 with a higher boiling point 276F with 15lb cap. Concentrated it is.
  • 77rollalong's avatar
    77rollalong
    Explorer
    May 11, 2018
    5.0L (VIN H) 18q 17L
    5.7L (VIN K) 17q 16L
    6.5 Diesel
    VIN F,P&S 26.5q 25L
    VIN Y 24q 23 l
    7.4L VIN N 23.0 q 22 L
    On vehicles with rear heater add extra 3 quarts (2.8L) of coolant.
    (from Mitchels ON-demand)

    After I do a flush of a system, i just add half my capacity of pure coolant then top off with water, since the system is never completely empty after flushing.
  • udidwht's avatar
    udidwht
    Explorer
    May 11, 2018
    77rollalong wrote:
    5.0L (VIN H) 18q 17L
    5.7L (VIN K) 17q 16L
    6.5 Diesel
    VIN F,P&S 26.5q 25L
    VIN Y 24q 23 l
    7.4L VIN N 23.0 q 22 L
    On vehicles with rear heater add extra 3 quarts (2.8L) of coolant.
    (from Mitchels ON-demand)

    After I do a flush of a system, i just add half my capacity of pure coolant then top off with water, since the system is never completely empty after flushing.


    Curious....why add the water if the coolant is already pre-mixed (either 50/50 or 70/30 concentrated)?
  • 77rollalong's avatar
    77rollalong
    Explorer
    May 11, 2018
    I don't use pre mix when filling a flushed system, as the remaining water in the system will dilute the premix, even if you pull the lower rad hose there will still be water left in the block, and heater core. so i measure out how much pure antifreeze i need , then top off with water and will give the proper antifreeze to water mix.
  • wolfe10's avatar
    wolfe10
    Explorer
    May 11, 2018
    I agree:

    Final rinse with distilled water.

    Pour in 50% of system capacity with coolant concentrate.

    Top off with distilled water.
  • udidwht's avatar
    udidwht
    Explorer
    May 11, 2018
    77rollalong wrote:
    I don't use pre mix when filling a flushed system, as the remaining water in the system will dilute the premix, even if you pull the lower rad hose there will still be water left in the block, and heater core. so i measure out how much pure antifreeze i need , then top off with water and will give the proper antifreeze to water mix.


    You have a rough guess as to how much coolant is removed after pulling the lower hose vs what's remaining in the block (total capacity).

    If I'm not mistaken coolant even in the concentrated form still comes at a 70/30 ratio. Not sure if one can even purchase 100% pure coolant at a local FLAPS.

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