New(to me) engine running hotter than the one it replaced?

Discussion in 'KJ General Discussion' started by GitEmSteveDave, Sep 10, 2019.

  1. GitEmSteveDave

    GitEmSteveDave Full Access Member

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    So I had a used 3.7 engine with 51k on it installed in my Jeep after I lost compression in Cylinder 6 and causing a litany of problems.

    Since I didn't like the idiot gauge on the engine temp(my old dodge had an actual gauge with numbers on it), I bought a bluetooth OBDII reader and a tablet to monitor my coolant temp and a variety of other things.

    Since the new engines been installed, the temps are running about 10 degrees F hotter than the old engine and creep up a lot faster when stopped at light or for a train. Where I used to run 195-199F while actually driving and getting air moving past the radiator, it's now around the 206F range. When stopped, it will creep up to about 221 before the fan kicks on and it drops.

    The only difference I know of, besides the engine, is the mechanic insisted on putting green crap in the engine when refilled instead of HOAT, and I'm gonna resolve that soon with a flush at a dealer. Would using a different coolant, or perhaps one not ratioed properly cause a difference in the thermal load it carries?
     
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  2. Aceofspades

    Aceofspades Full Access Member

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    How was the new engine stored? Water jackets could be loaded with rust and debris and now it’s circulation though your system is causing build up
    Same thing with the water pump and thermostat. Those could be in worse shape then your original ones.

    I personally always flush engines before they go into vechicles. You’d be surprised what I’ve seen come out
     
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  3. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    The dealer has a recirculating machine and can install the hoat.
    A new mopar thermostat would be a good idea before flush.
    Fan normally does not kick on until around 224 aprox.
     
  4. JasonJ

    JasonJ Full Access Member

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    A mechanic who insisted on green coolant in my Jeep/Chrysler would have been fired on the spot; and I would have hauled my busted down vehicle and all my parts to someone with a brain in their head.
     
  5. jeeptorino68

    jeeptorino68 Full Access Member

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    And yes the wrong coolant ratio can cause temp issues. Water is more efficient at cooling tin hoat. But you need hoat to prevent freeze and corrosion. So if it was 100% hoat I could see it running hotter...
     
  6. GitEmSteveDave

    GitEmSteveDave Full Access Member

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    I've got a 6 month warranty on the used engine, so I'm kind of stuck with this guy for 6 months for any issues. So far they had to put my old throttle body on, because the throttle was getting stuck when driving.

    I think they are confusing HOAT with OAT because one of the arguments they gave me was that there were no silicates in HOAT and that's bad for a hybrid metal engine.
     
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  7. Aceofspades

    Aceofspades Full Access Member

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    HOAT = Hybrid OAT - Hybrid metal engine
    If that helps to remember
     
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  8. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    I do not understand why any shop would not use Hoat or Zerez G-05.
    The owners manual clearly states the requirement.
     
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  9. Aceofspades

    Aceofspades Full Access Member

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    Honestly because shops who are a jack of all trades (car manufacturers) don’t specialize in anything. Unless it’s a dealer

    To them they use whatever they bought in bulk aka universal.
     
  10. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    Yup and they also don't know that the plastic water pump impeller on these jeeps can be damaged by the wrong coolant.
    Also hoat and oat don't mix well.
     
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  11. GitEmSteveDave

    GitEmSteveDave Full Access Member

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    I don't want to say that I didn't say it before they swapped the engine, but I'm sure if I went back and checked the recording(yes, I try to record all LARGE financial transactions I take part in, like the sale of the vehicle and also me paying for the engine, due to it being all in cash) I reminded them that the engine takes HOAT. Also the manual was in the glove box, so checking it would have been easy.

    I also did the same when I had the radiator and water pump/thermo replaced. That's my normal mechanic though, and he's used to jeeps, so he knew exactly what I was talking about.

    I will admit I have no backbone when it comes to mechanics, because I fear that they can do something to the engine that will cause it to grenade in 1500 miles and never be traced back to them.
     
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  12. Aceofspades

    Aceofspades Full Access Member

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    Myself included. I’ve turned every nut bolt on my vehicles myself. Shops do my alignments and balancing.
    I had a place recently do some work while we just had our first baby and I swear they sabotaged it. All these random Mickey Mouse shit keeps popping up since then. Go figure
     
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  13. JasonJ

    JasonJ Full Access Member

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    That does happen.. although I doubt to the extent many think. It takes a lot of effort and intelligence to time-delay sabotage a vehicle, enough that many shops are going to do just one or two things and leave it at that, if at all. Purposely leaving a critical fastener loose is a common one. Incorrect fluids and "hoping" it causes an issue later when it's nor their problem anymore is another.

    I think by and large, most all service techs are honest enough not to do such things. But I know it happens regardless.
     
  14. GitEmSteveDave

    GitEmSteveDave Full Access Member

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    I don't think all mechanics do it, I just swear that if I anger or upset the mechanic, they will put a tube of something in the oil, or clip a retainer that will lead to failure when it's not on there for more than 500 miles.
     
  15. Aceofspades

    Aceofspades Full Access Member

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    It’s mostly evap tricks if ya know what I mean. Then charge $350 to blow some smoke ;)
     
  16. JasonJ

    JasonJ Full Access Member

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    Perhaps... I think this is also a bit of apprehension on your part. I understand it though. I think the real trick to resolving that fear of retribution is to try and find "the one mechanic" who not only treats you good, but that you trust and can become a friend, or at the very least an ally.

    I know for me, I got one guy I could go to, he did a crap load of work on my FIL's vehicles for decades, and was a friend of his dad before that, this mech did the work I could not on my then girlfriend, now wife's car years back. He's older now, and the newer high tech cars aren't worth his trouble. So he specializes in classics and antiques now (and is damn good at it- has some amazingly valuable and precious vehicles in his shop).

    But Perry, and Perry's dad before him have served our family for about 50 years. I can still go to him for more basic mechanical work when needed- like when I couldn't get the abs brakes in a 2001 tahoe to fully bleed.

    You need a guy like that.
     
  17. GitEmSteveDave

    GitEmSteveDave Full Access Member

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    I have a guy like that, my normal mechanic. The only thing I "hate" about him is his habit of replacing spring clamps with screw clamps. Other than that, he's great, knows Jeeps, and gives you a discount if you pay in cash. But he's also sooooo busy that he doesn't take on big projects.