help with overheating 79' 308 USA | Page 3 | FerrariChat

help with overheating 79' 308 USA

Discussion in '308/328' started by Minoru, Oct 11, 2021.

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  1. mike996

    mike996 F1 Veteran

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    #51 mike996, Oct 19, 2021
    Last edited: Oct 19, 2021
    Air will be sucked into the expansion tank whether you remove the cap or not as the engine cools. That's a normal function of a radiator cap - seal against pressure; open with vacuum.

    You can do as suggested - fill the expansion tank and vent it to a catch tank. That is what most cars do - they maintain a full coolant system and the catch tank receives the overflow as the coolant expands and then the engine sucks that overflow back in as the engine cools.

    This was a common modification back in the days before cars came with overflow tanks/bottles for that purpose. By the time frame of 3x8's most cars had them. Ferrari obviously felt that if the coolant level in the expansion tank was correct, there was sufficient space in the tank for coolant expansion/air compression and that no catch tank was necessary.

    Based on my '89 328, I'd agree; can't speak for other models.
     
  2. tuttebenne

    tuttebenne F1 Rookie

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    Are you sure the standard 308 cap is designed to open with vacuum?
     
  3. mike996

    mike996 F1 Veteran

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    The little valve on the bottom of the correct 3x8 cap IS lightly spring loaded shut but a bit of vacuum will open it.
     
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  4. smg2

    smg2 F1 World Champ
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    I have to say I think the direction the conversation is going is distracting to the OP. He really really needs to sort out why his engine is running hot and why excess air is getting into his cooling system. It's not due to the expansion tank. In all the yrs of hot rodding these engines, once properly bled, the system runs as designed. No over boiling etc.. esp with Evans as it simply can not do that, it's a literal ZERO pressure system.

    Adding over flow tanks will not solve the problem, it only masks something else going on.

    Please diagnose and find the reason for the overheating. It doesn't take much to warp the cylinder heads on these engines... Seen it many times. Quick check list..
    Is it running proper AFR?
    Pressure test the cooling system
    Combustion leak detector is a quick test and inexpensive tool for checking the air in the cooling system... If it shows combustion gas... Time to replace the head gaskets.

    The only goofy thing with the 308 cooling system is the dual heater cores sitting high... Otherwise the system works with little issue. I believe the 328 shifted the cores down a touch and tilted the radiator to improve air purging. But over time the system will self bleed, hence the air gap in the expansion tank.
     
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  5. tuttebenne

    tuttebenne F1 Rookie

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    Thanks Mike. Gotta check that next time I'm in the garage.
     
  6. Minoru

    Minoru Rookie

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    Today, I tried a radiator leak test using the tool shown in the photo.
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    After the pressure into the system, I left it more than one hour, but the gauge level was not changed.

    Image Unavailable, Please Login
    So, I think that there is no leak in the system for the time being.

    Next, I made the following tool and started the engine. the level of the coolant was around 6cm below the neck of the filler.
    Image Unavailable, Please Login

    After the engine was getting hot....

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    Wow!!!!
    It should mean there is still air pocket somewhere in the system. I tried to bleed from the both the radiator bleed bolt and the thermostat bleed bolt several times, But the situation was not so changed.
    As someone mentioned, I suppose that there is big air pocket in the heater system because the heater core is located at the higher position.

    Is there anyone who knows how to remove air pocket in the heater system effectively?
    (This time I also flushed the line of the heater line and heater cores, I think there is no clog in the system.)
     

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  7. mike996

    mike996 F1 Veteran

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    "It should mean there is still air pocket somewhere in the system."

    Nice tool! BUT I'm not confident that "air pocket" is the only possible source of the overflow.

    The amount of coolant in the bottle is not really very much - looks like a lot due to the height but the shape of the bottle means there is probably not much more than a (coffee) cup of coolant. Within the expansion tank, given it's surface area and associated volume, I'd think that's probably not much more than 2.5-3 cm of height within the tank.

    I know you said you set the cold level at 6cm below the neck of the filler. Do you mean below the base of the neck, where it is attached to the tank, or below the top of the neck?

    I guess what I'm saying is that if you lowered the cold coolant level to, say, 3cm below where you originally set it, there might not be any overflow at all. I think that due to the very lengthy cooling system in these cars, there's enough variation in total coolant capacity that could easily be a few cm difference in "correct" expansion tank coolant level from car to car.

    Just some thoughts...
     
  8. johnk...

    johnk... F1 World Champ
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    Another thing is that if the air is trapped in the heater core it has no effect on cooling unless it prevents the system pressure from increasing enough, when hot, to prevent cavitation and/or boiling. But this isn't a problem with Evans. So if the car is over heating and no coolant is expelled when the cap in on the tank, air in the heater isn't the cause of running hot.
     
  9. tuttebenne

    tuttebenne F1 Rookie

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    #59 tuttebenne, Oct 20, 2021
    Last edited: Oct 20, 2021
    Was the car hot (thermostat open) when you observed the rising coolant level in the "tool"?

    Using the concept of your tool and if you wanted to dispel your concern for the heater cores (I agree with John's comment) if you had a large vessel filled with coolant in the filler neck, your heater cores are no longer the highest point in the system. You could open the heater valve and any air trapped in the heater cores should shift into a position where it can be released through a bleeder.

    PS: is that some sort of check valve you have in the small hose from the thermostat housing to the reservoir?
     
  10. Minoru

    Minoru Rookie

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    Thanks for your comments. As it is very difficult for me to explain in English correctly, please see this picture. I filled the coolant up to this level.
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    But, when I checked the Ferrari 308 manual, I found;
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    If so, my level is lower than the level shown in the manual??
     
  11. kcabpilot

    kcabpilot Formula 3

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    Heater cores are not the problem, they have their own circuit which bypasses the radiator and, unlike the radiator, do not have a top to bottom flow path. Inlet and outlet are both at the top so they do not trap air as does the radiator. Furthermore the high point on the coolant manifold on top of the block is where the bleed line connects to the top of the expansion tank so the engine will self bleed. The only place where air can get trapped is the top of the radiator.

    The system contains about 5 gallons (18 liters) of coolant. Pressurizing the top of the expansion tank to 1 bar doesn't tell you anything, the system runs at 1.1 bar (or 0.9 bar if you still have the original cap) so if there were a leak, you'd see it and you'd be constantly losing coolant. When you put the inverted bottle on the filler neck you were running at no pressure so what you are seeing is not how the system will behave with cap sealed and pressurized.

    If you want to check the head gaskets you need to do the cylinder leak-down checks. To do that you'll need to get access to the crank pulley so you can rotate each cylinder to TDC then pressurize and listen for leaks into the coolant system. You can start by aligning the PM 1-4 mark on the flywheel then look through the oil filler cap. If you can see the timing mark on the intake cam then you are at #1 TDC, if not then you are at #4 TDC. Start with that cylinder then each 90 degrees of rotation will put the next cylinder in the firing order at TDC. The firing order is 1-5-3-7-4-8-2-6.
     
  12. Minoru

    Minoru Rookie

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    tuttebenne, thanks for your comments.

    This time, the temp was at 195F stably.
    No.

    In any cases, I will check the clog of the heater cores again . Last time I checked the both at the same time. I needed to check one by one... Because I think that the situation got worse when I replaced heater hoses.
     
  13. Minoru

    Minoru Rookie

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    Thank for your comment. I see... It means that my test is not enough to conclude that there was no problem with the cylinder gasket?
    So, should I do as you mentioned in https://www.ferrarichat.com/forum/posts/148146184/?
    I also prepared a tool for this sake, I will try it later. Thank you very much for your detail instruction.
     
  14. RodC328gts

    RodC328gts Formula Junior

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    Im sorry I can’t help with this and I wish you best luck to solve your problem.

    It would drive me crazy to experience something similar.
     
  15. johnk...

    johnk... F1 World Champ
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    Agreed.

    If there is trapped air in the system, when the cap is on the volume of that air would be approximately 1/2 that with the cap off. Based on your pictures it would suggest that such a reduction in air volumes would actually leave the coolant level in the expansion tank below the cap level, thus there would be additional air in the expansion tank under pressure. The fact that Evans doesn't boil when hot allows you to slowly remove the cap when hot, reducing the system pressure by venting the air in the coolant tank, then allowing any air trapped elsewhere to expand and push coolant out of the tank. With regular coolant such a reduction in pressure results in flash boiling and the explosive discharge you see when taking the cap off a hot system. The reality is that while coolant temperature at the gauge sensor point may be 180 - 195*F, internally there are areas where coolant temperatures are well above above the boiling point for normal coolant at atmospheric pressure, but apparently not above that of Evans.

    That said a little research shows a couple of thing. 1) While Evans doesn't boil, it does expand, and more than the typical 50/50 mix coolant. 2) Evans coolant has poorer thermal and heat transfer properties than normal coolant. Thus I would expect that when filling with Evans you might need to slightly under fill the system to allow for the additional expansion and I would suspect that the engine would run a little hotter.

    All that said, it doesn't resolve the problem that you felt the car was running hot before you made all the mods and switch to Evans. But what isn't clear to me (I haven't read all the posts carefully) is if you are just running hotter than you think you should or actually over heating to the point where 50/50 coolant boils over which would imply temperatures above 250-260*F when the system is pressurized.
     
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  16. tuttebenne

    tuttebenne F1 Rookie

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    Maybe I'm not getting a good enough view but it sure looks like the fuel return check valve is in your coolant hose.
     
  17. smg2

    smg2 F1 World Champ
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    Oh boy ....
    Evans is a PITA coolant to setup... Seriously it's the one thing I don't like about it, however it's fantastic at what it does and keeps the big bore engines we build from melting down. Critical that the system is flushed and bone dry, including heater system.

    Evans recommends in their literature a brix scale reading of 56 or higher as I recall. You don't say what the pictures of the scale are, I'm assuming one is the coolant from a bottle and the other is what's in the engine? The second refractometer reading shows water...a fair amount.. 47.5 is something like 20% water...

    You mentioned it holds at a steady 195*.. if so, here's what I'd do. Remove approx 1qt of Evans from the system. Run engine.. and note where the level rises to. Is there bubbles forming in the coolant? Does it go cloudy?

    I think you're dealing with excess water in the coolant. Unless you've got bubbles and exhaust gas puffing out of the expansion tank that you didn't mention.

    Here's the reality, Evans will have the engine run a bit hotter then a 50/50 mix. I see on our engines a steady fluctuation from open/close of T-stat 175-195*F. The benefit of Evans isn't colder running, it's corrosion protection, stopping the galvanic process and flash boiling cavitation that occurs in the hot spots between the liners in the engine, esp on our big bore builds. (We also use an increased capacity radiator).
     
  18. kcabpilot

    kcabpilot Formula 3

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    Just an FYI - I did have a blown head gasket and I did have combustion leakage into the cooling system however I used the Block-Tester at least half a dozen times and always got negative results, the fluid never changed color. I even tested it at the tailpipe to confirm it was working and it was but it never caught a trace of combustion gas at the expansion tank. I finally confirmed my head gasket leak at #4 cylinder with the leak-down tester.
     
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  19. Minoru

    Minoru Rookie

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    Thanks. Well I already noticed my Evans include water... In order to avoid excess argument I tried to delete those photos, but it seems that they were not deleted. Thus, I tried the last operation to vapor out included water. But, as you mentioned, if it contains 20% water, it would be better to replace by new Evans. However,,, I also noticed that the balance of the system is not so good. I changed a fan switch to the new one which starts to work at lower temp around 80C. If the temp of Evans is higher than the normal water base coolant, this is not good. If so, I think that I need to replace it to the water base one.
    Anyway, I will try leak test again. Thank you for your help.
    This time, I changed a lot at the same time, so it is more difficult to figure out what is the cause.
     
  20. smg2

    smg2 F1 World Champ
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    Even with the increased temp of Evans and we're only talking about an increase of maybe 10*F it's the better coolant due to even temperatures inside the engine, corrosion is no longer an issue.
    195*F coolant temperature is perfectly fine BTW.

    What is the running temp of the engine? Is it stable?
     
  21. Minoru

    Minoru Rookie

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    Thanks for the all commented for this issue. After that I tried several things, but the situation is not so good.
    What I did are;
    - Head gasket leak test as kcabpilot instructed -> No leak.
    - I changed the coolant from Evans to Normal water base coolant.
    - I re-flushed the all system.
    - I checked the thermostat with hot water. -> The thermostat works without any problems...
    - I checked the system leak test. -> No leak.
    - I did bleed the air several times...and several times. I also jacked up the front of the car.
    - This time I used a coolant changer. (funnel type.)
    - I used auto air bleeding valves. https://clarkandclarkinc.com/catalog/detail/automatic-bleeder-valve-for-308328-engine
    I think that I did the all what I can do.

    When the water temp was cold and the thermostat was closed, it was OK. Once the thermostat was opened and fans started (around 180F) , for a while the water temp was stable, but it did not go down. After that, the temp increased gradually. Though I drove at general traffic, the water temp increased over 195F and more... I feel that It looks like that the capacity of the radiator is not so enough. So, I called the radiator professional who re-cored the radiator. But he said that he did the work as much as he can. (He have ever re-cored many Ferrari radiator including 308. )

    I think that the only method which I can do would be replacement the radiator by better one.
    Nick Forza's radiator is one of the candidates. If there is someone who installed the Nick's one, It is helpful if you can give me your comments

    Or, do you have another idea to sort out this issue?
     
  22. morcal

    morcal Formula Junior
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    Minoru-san, it looks like there is a restriction in the water flow circuit. Would check if for whatever reason a rubber pipe is pinched somewhere and/or if the water pump is functional
     
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  23. Minoru

    Minoru Rookie

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    morcal-san, thanks for your comments. I also thought as you think. I supposed that there should be clogs or some restrictions in the system. So, I rechecked the all aluminum pipes, rubber pipes, but I found that no issues. (I used a blush type pipe cleaner to check them.) Furthermore, I did flushed all the system using water flush gun.
    But the situation is not improved.
     
  24. morcal

    morcal Formula Junior
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    Please make sure that the air flow is correct: some time the fans may be connected in the wrong way and the air is pushed forward and not in the direction of the driver
     

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