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Pontiac Montana Engine Problems



  • Hi, Beowulf,

    Just a quick update - I went down and did my own check on the van, which is parked outside the mech's garage....oil is "clean", and rad isn't splashing back coolant when engine is warm. Intakes were "done" (dealership done - before I got van).

    Do you know anything you can "share" about fans and fan relay or the piece that attaches to waterpump -- could this be causing the symptoms for overheating?

    Talked to mechanic today -- same shop / other sr. guy - he doesn't think it is the water pump...(but he's guessing).

    Plans to do htdrocarbon test and pressure test Monday.

    I keep feeling like it is maybe one of the fans not kicking in properly -- but I don't know if this is they relay(?) or the fan...? It seems one fan definitely runs, as it blows cold air. Then suddenly something seems to "kick in" (like an engine "cough") - perhaps the other fan????


  • Don't worry, Tiger, I won't pick on you for not knowing what something is. I do like how you pick on yourself though. Anyway..

    If your mechanic says they were done, I guess it's a matter of how much you trust him. From just pointing it out won't do much since the seals are sandwiched between the valve covers and the head. Hopefully whoever replaced them did NOT use the anti-freeze that GM used. It is believed this contributes to the wear down of the seals.

    No, I don't know how to run a hydrocarbon test. My guess is plugging a code reader in will tell if their are any emissions issues. They are quite easy to use and if you have a book, which I do, it will tell you what the problem is and what is needed.

    Hope this helps.
  • Sure, a bad fan can cause overheating. Electric fans run on a relay that turns them on when the water temp reaches a certain temperature hence the warning near them that says, "fans may turn on at any time." If you have a bad relay to them, it's the same effect. If it fails, it may not turn your fan on at all. You have two fans, one is the cooling fan which is automatic, based on engine temperature, and the other works when you use your air conditioning.

    The water pump is it's own part and is mounted into the engine block. It does just what it says, pumps the fluid around the engine. A fan won't affect it, at least, it shouldn't.
  • hello, my belt has been slipping from the harmonic pulley, Now i have had the car for 4 years and replaced the belts a few times, i changed the belt tensioner and that did not fix the slipping. im wondering if the original owner but the pulley on backward what do you think?

  • i have a 2001 and it runs good but wont idle.I replaced the throtle position sensor and idle air control valve
  • We have changed pulley after pulley the water pump has been changed the power steering pump has also it just got changed the other day and after it got changed it is sluggish to start up and it still squeals really bad i was told that it might be the alternator, i really don't know what it could be could someone please help? thanks for your time.
  • wont idle ive changed the throtle postion sensor and the idle air control valve.please help i dont have any thing to drive. :cry: :confuse: :cry:
  • You need a new harmonic balancer. The pulley is slowly slipping, pulling away from the balancer (rubber). It's not align with the other pulleys, which is causing the belt to slip.
  • havnfun2havnfun2 Posts: 2
    My Moms Montana did the same thing....go and get a Throttle Positioning Sensor for about $35... they tried to tell her it was the intake gaskets leaking and wanted her to pay $1800....she called me and I told her it was the TPS and since we replaced it she has had no more problems with her van speeding up on it's own...hope this helps if you haven't already figured it out.
  • Thank you for your posting. This would have been an interesting thing to look into. After mechanics were split as to what was causing the problem, it was recommended by "all" to trade in my much-beloved van. So, after it overheated on the freeway - during a test drive related to the trade in (!!!) I really had to trade it if possible and did. The GM dealership gave me full value and a good price on a Chevrolet Uplander 2006 w/ low miles. It is NOT the van the Montana was - so miss the Montana! An almost loaded Uplander is a bad joke compared to the Montana - so many things missing, lower power, just everything. But for now, will hang on to the van, for timing of other things in life issues. Bigger picture - if the used car economy was a stronger market, I would get rid of it for a Montana - even an older one. Got the Uplander in December. It is going into the dealership for more repair work - for I think this is the 5th (!!!) time. Problems with gear shift getting stuck, horn still doesn't work, had a nearly broken tie rod that dealership didn't fix before selling the van, and the list goes on. Thankfully, other than wasting time, it has a happy ending since I bought the most extensive full five year extended warranty. For anyone listening to this - get the warranty. At $2000 it is a bargain! Less than six months into this - if I had had to pay for all these repairs out of pocket, I would have been out of pocket at least another $500 by now. The warranty covers first dollar - so I have had no additional money paid out. Meanwhile, Pontiac Montana - the model I had - wonderful van. Should have just put the $3-4000 out and fixed it, hindsight.
  • hi! i've had 2000 montana the problem is when i'm driving it all the guages shuts off and when i move the steering wheels it goes back! and my fuel gauge is unstable int goes up and down and most of the time is always full even though it's not! need help!
  • kenniekennie Posts: 38
    Re the fuel gauge... this is very common in montanas... mine has done it for 3 years and it's a 2000. Just use the odometer to indicate how many Kms you've gone and then fill up... the cost to fix just is not worth it unless you have warranty. I believe the "LOW FUEL" light is indiependant of the gauge problem so when it comes on you are definately low in the tank on fuel... this is the way mine works. You would have to have the fuel sending unit replaced and it is located in your gas tank very likely... they can test that is is failing by testing the wires.. if certain voltages are read they can tell it's gummed up. Cleaner can be poured in the gas tank to attempt to clean it but i'm not sure if it is worth of the risk of plugging something or running such cleaner through your engine if you don't absolutely have to.. the cleaner I think is called sea-foam I think. Cheers.
  • ray80ray80 Posts: 1,643
    Also for the fuel gauge (I believe its applicable for a 2000), it may be an issue with the c-305 connector.
  • kenniekennie Posts: 38
    What is the c-305 connector and what does it do??
  • ray80ray80 Posts: 1,643
    Its a pass-thru connection for wiring (from inside cabin to outside/underneath). It connects various wires for things in rear of vehicle(including connection to fuel pump/sensor). While its weatherproof on bottom (underneath) it is not inside cabin, spills/ various leaks inside can cause water intrusion and subsequent corrosion of wires. Google ' gm c305 connector' and you will find lots of stuff.
    The connector should be under carpet to the rear of drivers seat (you may be able to see exactly where by looking under vehicle for a bundle of wires that come out from cabin)
  • So what does it mean when your "service engine soon" light stays on? I am having a new issue with my van and it is staying on.
  • I was driving home and my van all of a sudden lost power and kinda sputtered. It almost felt like I was running out of gas. I knew that was not true since I just got gas. There was no loud bang or anything. So I pulled into the next driveway and my check engine light came on. So I turned the van off. I got out and checked the water and oil and everything was fine maybe 1/2 quart low on oil. Engine was not overheated and no leaking oil or anything. I turned my van on and there is a clicking noise coming from the engine and it has loss of power for sure. So I am going to have to have it towed. Does anyone have any idea? Has this happened to anyone? It is a 2003 Pontiac Montana with 115000 miles and has been taken care off well. so I am a little confused. I hope someone may have some answer? Thanks
  • spike99spike99 Posts: 239

    From your statement of "there is a clicking noise coming from the engine", your high miles van (for a 3.4L engine) could have anything from blown main bearings, to broken cam to blown pistons. It all depends on the exact sound of the "clicking" and its sounds location under its hood. Best is to get a certified mechanic to investigate and confirm what could be broken.

    Also... "Do trust your gut" as well. If your van has NO rust, its tranny is still good, its steering is still firm and overall, it's still a sound vehicle, then it might be worth fixing. Fix with new engine parts (on existing engine), or perhaps fix with a new re-built engine block. But if your vehicle is near its "end of life" and engine repair/replacement is too expensive, then simply "write her off". One of those "Humpy Dumpty fell off the wall" things....

    Hope this helps....

  • My wife just had the same problem happen to her 2003 Montana on the way home from work last week. :cry: We have 98,000 on the van and we have done all of the regular service to it. Now we are trying to figure out what to do? Does anyone have any recomendations? :confuse:
  • have your fuel filter checked, mine was almost completely clogged
  • You do not need to roll anything just test it by pulling one wire at a time and crank it you will know if there is spark there are two screws per pack replace bad one
  • kgb92kgb92 Posts: 2

    The vent fan for the interior has started to intermittently stop working, I was in a drive-thru line last week and it started then. No problems until this morning as I started going to work, it would stop I would turn it off, and after 10 minutes turn it back on. My engine has also been overheating so I do use this to help cool off the engine in traffic on the way home. I drive 70 miles to and from work daily, the way home is usually rather muggy and stop and go traffic. Any thoughts? I have to replace my A/C condenser again next week, I had the blower motor and water pump replaced last year, and the serpentine belt.
  • ray80ray80 Posts: 1,643
    I would guess (because it comes and goes) it may be an issue with HVAC cluster (loose conections maybe, you could try whacking it with your hand when it goes off to see if it starts again). For the overheating you might want to check coolant level in radiator as well as overflow bottle
  • kgb92kgb92 Posts: 2
    Thank you - I will try that this evening on the way home. I pretty much check the radiator and reservoir daily, this has been happening since last summer. I think I need to replace the intake manifold again or it might be as simple as the thermostat. I have bumped up my repair schedule to Monday - I just need to make sure I get home today, so I will be working late to make sure traffic is low.
  • I have an 03 montana. the temp guage never goes below half and as soon as i slow down it goes up to where the overheat light comes on. It doesnt sputter so i dont think its actually overheating though. could it be the temperature sensor maybe? help.....">
  • ray80ray80 Posts: 1,643
    First thing I would check is coolant level in both overflow bottle and radiater If you have been adding coolant on a regular basis there may be air in the system that might require bleeding after filling with coolant to maintain proper level.
  • armesarmes Posts: 32
    Engine may not sputter until you have blown the head gaskets. Do not use this as criteria as to weather it is over heating. I know this from experience with my 02. The temperature gage would go up and down like that even after the air was burped from the system. Then, wham the head gaskets blew and that is when the engine started to stumble. :sick:
  • The gas gauge going up and down is the fuel sending unit in the gas tank. It's a $34. part on ebay, and is a moderate to easy fix.
  • pajar0913pajar0913 Omaha NebraskaPosts: 1
    I have a 2002 Pontiac Montana and just recently it started to overheat at stop lights or anytime the van is on and not moving. So today went out down town. And on the way home the van over heated so bad the red light on the dash come on and I could hardly get the van to go past 30mph. Any one have this problem before. Thanks. Read hope it's something simple. Please feel free to email me directly
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