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Changing Coolant In 1994 348 Spider

Discussion in 'Technical Q&A' started by marbroman, Nov 15, 2022.

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  1. marbroman

    marbroman Rookie

    Jun 15, 2016
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    #1 marbroman, Nov 15, 2022
    I am wondering if it is possible to completely change the coolant in my '94 348 Spider without pulling the entire 'propulsion unit'? I have read several step by step procedures and most are somewhat confusing and most say that only a partial flush is possible.

    My 348 has two rads tucked up ahead of the rear wheels. The passenger side rad shares an oil cooler on the lower half of this small radiator which obscures the little slotted drain plug in that rad.

    The drivers side rad has a small slotted drain plug which is quite visible from underneath and can easily be removed. Does anyone know the size/thread of that small slotted drain plug?

    Some coolant change procedures say remove the drain pugs from both drivers and passenger side rads, other procedures just say remove the one drain plug from the drivers side (after removing the inner wheel covers). Which is the correct procedure? Removal of the passenger side drain plug will necessitate the removal of the oil cooler which appears bolted to the rad. That looks like a helluva job.

    Does anyone know the actual capacity of the cooling system? There are confusing posts of 10 litres or 20 litres. I have to check the owner's manual, but even this might not be accurate. Has anyone completely drained the cooling system and measured contents?

    Some procedures talk about drain plugs in the sides of the engine block, and these also need to be removed and replaced afterwards. Is that actually possible without removing the engine and other components such as exhaust headers.

    Finally, what is the BEST replacement antifreeze to use. I have seen so many suggestions. My local Ferrari guy uses the Zero brand. There are so many different types out there now. There appears to be Prestone in my 348 at present, at least it is green. the Zerex stuff appears to be orange. I have heard that organic acid technology (OAT) antifreeze is best and that it is generally orange in colour. But I have seen other OAT type antifreeze out there in yellow (hybrid OAT), or phosphate free hybrid OAT which is kind of a greenish blue colour and then there is also phosphate hybrid OAT, which I think is more of a pink colour. Or should I just use regular old Preston green?

    Finally, I have seen a YouTube video that appears to show a vacuum system sucking in new antifreeze. But the video does not show how to remove the coolant in the first place. Is vacuuming in the new coolant the best way?

    I would really appreciate any useful guidance here group.

    Thanks in advance.

    marboman
     
  2. greyboxer

    greyboxer F1 World Champ

    Dec 8, 2004
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    #2 greyboxer, Nov 15, 2022
    This question may well already be answered either in the 348 section or at my348.com - worth taking a look at both
     
  3. 348Jeff

    348Jeff Formula 3

    Oct 25, 2011
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    #3 348Jeff, Nov 15, 2022
    Last edited: Nov 15, 2022
    Why don't you just buy one as they are very cheap? part# 140149

    https://www.ferrariparts.co.uk/diagram/ferrari/348-gtb-gts-gtc-spider/022-cooling-system-radiators

    https://www.ferrariparts.co.uk/part/ferrari/140149

    There's a rubber O ring too which is worth replacing at the same time.

    Is it the fan oil cooler shroud that is obscuring it as this only 4 bolts to remove?


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  4. 348Jeff

    348Jeff Formula 3

    Oct 25, 2011
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    #4 348Jeff, Nov 15, 2022
    Last edited: Nov 15, 2022
    Pic in situ with the oil cooler fan shroud removed - you can see that the plug is accessible

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    Still a little confused though why it's not accessible - appears to be so here???
     

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  5. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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    #5 yelcab, Nov 16, 2022
    And drain the block.
     
  6. moysiuan

    moysiuan F1 Rookie
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    Nov 1, 2005
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    #6 moysiuan, Nov 20, 2022
    Zerex GO5 is the right type of coolant for the mixed metals (Al and Brass) in that era. It is a hoat formula, which allows for a 5 year change interval if you wanted to leave it that long, and was OEM for Mercedes etc. of the era. I used to use the actual Mercedes product, I recall the dealer telling me it was actually supplied by Zerex.

    It is getting slightly harder to find, late 90's Mercedes went with G48 (usually blue colour). No more brass or solders in the radiators by then.

    It is almost clear, amber in colour. It does mix with other conventional coolants.

    You will never fully drain the car, and I would not worry about it. The glycol does not wear out or get dirty (unless there is a head gasket leak), it is the additive package that degrades over time to protect the metals. Change every three years or so, and all will be fine. I would use a 60-40 blend if your climate allows for that - coolant is less effective than water for heat removal but the added additive content will serve the anti corrosion function better at higher concentration.
     
  7. johnk...

    johnk... F1 World Champ
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    #7 johnk..., Nov 21, 2022
    Here is what I do in my 355. The capacity is just under 3 gallons. I don't have a lift and I don't want to mess with the block drain plugs but I do want all fresh antifreeze. So I drain both radiators as much as possible. As I recall, about 1 1/2 gals comes out. Then I fill with new antifreeze. Now I have 50% old, 50% new. I run the car for a few minutes to let it all mix, let it cool, and then drain the radiators again. Then fill. Now I have 75% new, 25% old. Do the process once more and I'm at 87.5% new, 12.5% old. That's good enough for me.
     
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  8. Mike Morrissey

    Mike Morrissey Formula 3
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    #8 Mike Morrissey, Nov 21, 2022
    John, as always, you are one smart cookie! Great advice, plus I’ll bet your heat exchanger is in great shape!
     
  9. raemin

    raemin Formula 3

    Jan 16, 2007
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    #9 raemin, Nov 22, 2022
    A complete flush is not a silver bullet : I was amazed at the amount of debris that were left in the system after my last engine rebuild: the engine block and the cylinder head were dismantled and flushed in my machinist "washing machine", all hoses replaced, etc... Needless to say this was even more extensive than what we mean by a "complete flush". The filter still collected the equivalent of a teaspoon of debris.

    If you are as paranoid as I am, a Gano filter will make your life easier : this transparent filter will let you know instantaneously how the coolant is doing. You then just have to partially flush until you feel comfortable with what you see.

    I prefer to perform these flushing procedures with distilled water and water wetter: better for my wallet and better for the environment (water wetter is cheaper than coolant and no point in wasting 30liters of glycol). Also water wetter has a tendency to dislodge the crude, which makes the flush even more efficient.
     
  10. Sarc

    Sarc Formula Junior

    Nov 1, 2003
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    #10 Sarc, Jun 22, 2023
    Very clever @johnk… What are you using to extract the coolant?
     
  11. johnk...

    johnk... F1 World Champ
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    #11 johnk..., Jun 22, 2023
    Gravity. Remove the expansion tank cap and remove the drain plugs at the bottom of the radiators.
     
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