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328Thermostat

Discussion in 'Technical Q&A' started by RussF, Jul 3, 2005.

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  1. RussF

    RussF Karting

    Nov 1, 2003
    222
    Washington
    #1 RussF, Jul 3, 2005
    While replacing my water pump I bought a thermostat from NAPA that would fit the housing. I appeared to be the same as the Ferrari thermostat but when I got home I can tell that some of the metal parts are not as robust. I installed the NAPA part and am going to order a new Ferrari TS. Here is the problem.

    When I start the car the temp goes up to 195, the TS opens and then the Temp drops way back. Then it climbs again which is normal but as soon as it comes close to 195 the temp drops way back. Does this about three or four times before the temp stabilizes at between 195 and the line to its left. This porpoising does not seem normal although I don't believe it hurts anything.

    Ant thoughts?
     
  2. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,350
    UK
    #2 Iain, Jul 3, 2005
    Might not be doing too much good either - could be a big airlock is causing the problem. A big airlock in the engine is bad because you get localised overheating which can play hell with expansion rates & cause headgaskets to pop if you let it go on too long.

    Jack up the back left corner (drive it up onto a block of wood or something), run the engine & bleed from the top of the T-stat & also the radiator.

    The Ferrari T-stat also does some kind of diversion thing so if the Stat you bought isn't the right size it might not be working properly. I got a replacement for mine from Daniel at Ricambi (Jack Russel Racing) & after some initial concerns I've decided its working just fine. The only issues with it were that it has no air bleed hole in the surround (easily fixed) & I found it a very tight fit so I eased the edge of it a tiny bit - after which it fitted fine.

    I got thrown off the scent a bit because after replacing the Stat because the thing was running much warmer = more pressure in the system & it started tossing coolant out the overflow. Replacement cap has now fixed that

    The Ferrari Stat from FUK is about £75 -over $125 which is a bit hellish for a T'stat.

    I.
     
  3. RussF

    RussF Karting

    Nov 1, 2003
    222
    Washington
    #3 RussF, Jul 4, 2005
    Thanks Iain. Your post was helpful. However here is the latest. Drove the car for about 30 highway miles last week and the temp stayed below 195 degrees. Went to start it up this morning and the tempwent above 200 without the thermostat opening. I shut the car off and the coolant leak from just forward of the passenger rear wheel was back. It does not seem to be coming from the rebuilt water pump. When I popped the radiator cap there was a lot of pressure buidup. Could it be the expansion tank overflow> Not sure where the overflow dumps onto the ground. Any thoughts anyone?
     
  4. Ricambi America

    Ricambi America F1 World Champ
    Sponsor Owner

    Dec 7, 2003
    16,465
    Winston Salem, NC
    #4 Ricambi America, Jul 4, 2005
    Are you using an old .9 BAR or a newer 1.1 BAR radiator cap?
     
  5. RussF

    RussF Karting

    Nov 1, 2003
    222
    Washington
    #5 RussF, Jul 4, 2005
    Jack. I am using the 1.1 cap but I think that I sorted out the problem and there is a lesson here. If you read my earlier posts after a 25 mile drive last month I noticed a large puddle of coolant coming from the passenger side just forward of the rear wheel. All indications pointed to the water pump including 34 k miles on the original pump. After three weeks of frustration I finally got the pump changed and the problem seemed to be cured. Well this morning I started the engine and the temp went up and past 195 without the thermostat opening up. I shut down the engine and the coolant puddle reappeared just as it had before I replaced the WP.

    I searched the archives, leearned a few thing and then checked to coolant level. It was way down near the bottom of the holding tank-almost dry. I filled it up to 6cm below the neck and took the car for a 25 mile drive at highway speeds. The temp stayed level on the highway at below 195 degrees and would only creep up to 195 in town. Everything worked perfectly.

    The lesson. Don't assume the worst-in my case having to replace the WP. I am now convinced that my problem was just low coolant. Even so I still do not understand how low coolant can cause the coolant to rise to the level of the overflow pipe on the coolant holding tank.
     
  6. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,350
    UK
    #6 Iain, Jul 4, 2005
    The Coolant tank overflow dumps out pretty much directly underneath the tank - so if the leak you get is on the other side of the car I'd be doubtfull that that's the problem.

    I just had to replace my 1.1 Bar cap that was only about 5 yrs old because it was no longer holding 1.1 bar. Most garages have a tester that they can use to check it (mine was only holding about 0.8 bar)

    From what you describe I'd guess you do have a leak somewhere that only really shows itself when the engine is warm (i.e when there is pressure in the system). Your best bet would be to get the thing up on a lift and pressure test the system. Most competetent shops should be able to do this for you.

    Having an Airlock in the system will cause the pressure to be higher (because air expands more than coolant) & also having a lack of coolant will cause the temperature to yo-yo around the place from what I've seen.

    If you fix the leak & get the air out the system I think you should find that the temperatures settle down to normal. For my car that means running pretty consistently at the mark below 195 & only climbing to 195 in traffic at which point the fans will come on & the temp will drop back again.

    On the coolant level thing, if you look at it doesn't leak just because of the level in the tank, it takes pressure for coolant to open the cap & then escape out the overflow. If you had an airlock you will get more pressure in the system which might cause coolant to come out the overflow - the expansion tank can appear to be completely full when there is air in the system.


    rgds

    Iain
     

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