Northstar 4.6 Overheating
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Northstar Engines and System Technical Discussion Discussion, Northstar 4.6 Overheating in Cadillac Engine Technical Discussion; Ok I hope I am in the the right forum. As I have been reading about the Northstar 4.6 it ...
  1. #1
    gtoman1970 is offline Cadillac Owners Member
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    Northstar 4.6 Overheating

    Ok I hope I am in the the right forum. As I have been reading about the Northstar 4.6 it has a history of overheating while driving down the hwy. My problem is mine overheats while at idle or low rpms. When driving down the hwy it seems to run fine. I have had it in the shop, run a car fax on it, called other dealers that have
    recorded repairs on it. It looks like water pump, sending unit, thermostat, radiator cap have been all replaced. My GM shop is not set up to test for exhaust gases in
    the coolant.

    I have been reading about some solutions for head gasket repairs, have even called a company that sells steel-seal. When telling him about how my overheats while
    at low rpms he wondered for sure if mine was actually head gasket. So now I'am at a stand still. I have found a 96 Cadillac Deville with hail damage and trany
    problem and thought about pulling that engine, but would I end up with same problem. Then I thought of replacing the engine and have found a GM engine for 4800.00. Will I still have the same problem after a few years. Is it worth putting that kind of money in a 1998 Cadillac Seville with 127000 miles on it. The car is probably a
    8 on a scale of 1-10, 10 being great. I just bought the car and the dealer won't stand behind it. I may have 300 miles on it since Dec 28 2011.
    gtoman1970

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    vincentm's Avatar
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    1. There's no history of the Northstar overheating while on the hwy.

    2. You can test the for exhaust in your coolant by doing a block test, rent the kit from.any auto parts store, if your dealer/mechanic says they're not equippedbto do so, they suck..period, its a simple test


    3. Only way to fix the HG is to remove the engine, snake oils will render your engine to the grimm reaper


    Have a good day

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    maeng9981's Avatar
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    re: Northstar 4.6 Overheating

    It is too early to diagnose it as a HG problem. You have done no tests.

    Are your fans running when the temp reaches 222-224? (between 4/8 and 5/8 tick mark)

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    Submariner409's Avatar
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    re: Northstar 4.6 Overheating

    This thread is a duplicate of one I have seen somewhere else in CF.

    gtoman 1970, You are misinformed on the Northstar - You NEED to do some homework: Go up to the black bar ^^^ and study the entire Cadillac Technical Archive. Then go down to Discussions, Item Specific and wade through the pages of Cadillac Tech Tips, skimming threads of interest. Then, try to surf through Seville pages............Yes, it's a lot of reading, but without some real knowledge base you'll be flying blind.

    Overheating at idle or low rpm is either fans, dirty A/C condenser fins (front of radiator assembly), or poor coolant flow..........all can be diagnosed and repaired with some basic knowledge of the engine and systems.

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    re: Northstar 4.6 Overheating

    Have you checked the purge line to be sure it is clear?

  7. #6
    gtoman1970 is offline Cadillac Owners Member
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    re: Northstar 4.6 Overheating

    Yes we have done testing. I have had it in a GM dealership, they tested to see if fans were kicking in as per GM specs, test showed sending unit recorded same as cluster. When idling you can feel coolant pulsating, when rps were increased up flow increased in top radiator hose and temp dropped. Tech talked with GM tech and told him to check cross over hose for blockage which he did. When temp increased left fan would blow cold air. Vehicle has been in several shops to figure out the problem, least 1 Cadillac dealer. GM is advising head gaskets.
    gtoman1970

    ----------

    Quote Originally Posted by vincentm View Post
    1. There's no history of the Northstar overheating while on the hwy.

    2. You can test the for exhaust in your coolant by doing a block test, rent the kit from.any auto parts store, if your dealer/mechanic says they're not equippedbto do so, they suck..period, its a simple test


    3. Only way to fix the HG is to remove the engine, snake oils will render your engine to the grimm reaper


    Have a good day
    I am about to turn the vehicle over to the grimm reaper, Maybe just add enough snake oil to unload it to another dealer since a dealer sold it to me and won't stand behind it. Hate to pass on the problem.
    gtoman1970

    ----------

    Quote Originally Posted by submariner409 View Post
    This thread is a duplicate of one I have seen somewhere else in CF
    .
    Yes I posted in in the wrong spot according to you so I re-posted it here. Will do some reading up above.
    gtoman1970

    gtoman 1970, You are misinformed on the Northstar - You NEED to do some homework: Go up to the black bar ^^^ and study the entire Cadillac Technical Archive. Then go down to Discussions, Item Specific and wade through the pages of Cadillac Tech Tips, skimming threads of interest. Then, try to surf through Seville pages............Yes, it's a lot of reading, but without some real knowledge base you'll be flying blind.

    Overheating at idle or low rpm is either fans, dirty A/C condenser fins (front of radiator assembly), or poor coolant flow..........all can be diagnosed and repaired with some basic knowledge of the engine and systems.
    Yes I posted in in the wrong spot according to you so I re-posted it here. Will do some reading up above.
    gtoman1970

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    re: Northstar 4.6 Overheating

    [QUOTE=gtoman1970;2832242]
    gtoman1970

    ----------



    I am about to turn the vehicle over to the grimm reaper, Maybe just add enough snake oil to unload it to another dealer since a dealer sold it to me and won't stand behind it. Hate to pass on the problem.
    gtoman1970

    ----------

    /QUOTE]


    If you want to do the not so nice thing and pass it to the next dealer without be honest and disclosing the issue then so be it
    its your Karma that will come back 10 fold lol

    if you bought it as is no warranty at all then thats what happend
    dealer probably new it was bad and just wanted to unload it

    if they can't do a block test then they are full of BS and know what the problem is but don't want to admit they sold you a car that they already new was baad

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    Re: Northstar 4.6 Overheating

    I edited your title to make it more descriptive.

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    Re: Northstar 4.6 Overheating

    This is not a HG - N* overheating at idle is almost unheard of. I am 100% with Sub - if water pump is good and coolant is flowing, either the fans are not coming on or you have a clogged radiator or blocked/obstructed radiator or condenser...and these are not common problems. I think you should suspect your radiator is clogged (internally)

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    How bad is it over heating past the middle mark on the gauge.my temp gauge will move maybe a half a centimeter pass the middle mark some times only in idle but goes back to normal range by its self but my gas gauge jumps around sometimes too so I don't know if my temp gauge is acting up like my gas gauge or is it really running hot.

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    maeng9981's Avatar
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    Re: Northstar 4.6 Overheating

    Quote Originally Posted by sts 03 View Post
    How bad is it over heating past the middle mark on the gauge.my temp gauge will move maybe a half a centimeter pass the middle mark some times only in idle but goes back to normal range by its self but my gas gauge jumps around sometimes too so I don't know if my temp gauge is acting up like my gas gauge or is it really running hot.
    Yours is working normally.

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    Re: Northstar 4.6 Overheating

    Quote Originally Posted by sts 03 View Post
    How bad is it over heating past the middle mark on the gauge.my temp gauge will move maybe a half a centimeter pass the middle mark some times only in idle but goes back to normal range by its self but my gas gauge jumps around sometimes too so I don't know if my temp gauge is acting up like my gas gauge or is it really running hot.
    it perfectly normal for it to get up to 230 on hot days at idle
    even though i still panic when mine gets to the 1:00 and 2:00 Oclock mark every now and that when its in the 90s and idling
    with ac on
    but ones i start moving again it goes back down
    and i know its normal but i still panic about it

  14. #13
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    Re: Northstar 4.6 Overheating

    so thats normal for it to jump a little pass the half way mark.

    ----------

    i was thinking something was starting to fail.

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    Re: Northstar 4.6 Overheating

    Quote Originally Posted by sts 03 View Post
    so thats normal for it to jump a little pass the half way mark.
    yup
    look in Sub's Profile Picture ALbums i think there is a graph there that shows temp rangs what is normal fine ok and then the Oh Shit factory LOL

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    Quote Originally Posted by gtoman1970 View Post
    Yes we have done testing. I have had it in a GM dealership, they tested to see if fans were kicking in as per GM specs, test showed sending unit recorded same as cluster. When idling you can feel coolant pulsating, when rps were increased up flow increased in top radiator hose and temp dropped. Tech talked with GM tech and told him to check cross over hose for blockage which he did. When temp increased left fan would blow cold air. Vehicle has been in several shops to figure out the problem, least 1 Cadillac dealer. GM is advising head gaskets.
    gtoman1970[COLOR="Silver"]
    They didn't do a block test?

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