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2003 Montana -Overheat Spike (occasional so far]


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nygent
Novice

Nov 22, 2011, 8:19 AM

Post #1 of 13 (3935 views)
2003 Montana -Overheat Spike (occasional so far] Sign In

2003 Pontiac Montana AWD
3.4L
102k miles

Over past two weeks have had two occasions where engine temp gauge quickly spiked. 2nd time dashboard warning message of Hot Coolant Temp.

My guess is faltering thermostat. Did briefly get a P0134 and P0135 Engine Code (O2 Sensor?) But no other codes.

Plan to drain and replace coolant and replace thermostat. Should I replace water pump while doing all of this? Any other thoughts? Should I replace with same temp thermostat or use different temp stat?

Will need to remove crossover pipe which passes in front of thermostat housing. Any suggestions or thoughts on its removal.
[EDIT-old post suggested using box wrenches and not removing crossover as back bolts had to reach. Anyone know housing bolt head size, 7..10mm? Thx]

Also. I would likely need to pull engine forward to replace water pump. And I am also going to replace plugs and wireset at same time.

Anyone have procedure needed to pull engine forward? Any diagrams appreciated. Or tips, tricks or suggestions. And what pound strength strap should I purchase to hold engine forward while working on it?

1. Thermostat and/or Water Pump replacement?
2. Engine forward procedure (strap needed)
3. Crossover pipe removal.
4. Water pump diagram, procedure.
5. Any other tips, tricks or suggestions appreciated.

Thanks.


(This post was edited by nygent on Nov 22, 2011, 8:34 AM)


Hammer Time
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Nov 22, 2011, 8:36 AM

Post #2 of 13 (3917 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

I really doubt your issue is with the thermostat. It sounds like it has air pockets due to a leak. That engine is notorious for intake gasket leaks. I would fill and pressure test the system first.



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nygent
Novice

Nov 22, 2011, 9:46 AM

Post #3 of 13 (3903 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

Thanks. Will topoff coolant. After reading about all the problems and class_action suits on gasket issues....

What's the difficulty level in a DIY job if I needed to replace upper intake gasket


Hammer Time
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Nov 22, 2011, 10:20 AM

Post #4 of 13 (3899 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

It's probably about a 6 out of 10



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Nov 22, 2011, 11:03 AM

Post #5 of 13 (3892 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

It turns into a 10/10 if you leave a rag under the intake or get the push rods switched.





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Sidom
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Nov 22, 2011, 2:01 PM

Post #6 of 13 (3878 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

Over if you overtorque the rocker arm bolts so the threads crack & the bolts pull out ( a good reason to not even take the rockers off)


nygent
Novice

Nov 25, 2011, 3:58 PM

Post #7 of 13 (3845 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

(Back to cooling problem)

Filled reservoir....ran heat full blast with reservoir open...got some air out]

(Dumb question)...how do I 'pressure test' system?

Its now to where while drivng temp is fine but once stopped and idling temp rises to redline.....still not always but happening bit more it seems.

No leaks observed...thanks


Hammer Time
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Nov 25, 2011, 4:00 PM

Post #8 of 13 (3843 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

It may be harder than that to get the air out of that engine. We use vacuum to do it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



nygent
Novice

Nov 25, 2011, 4:25 PM

Post #9 of 13 (3837 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

Ah....drat...so sounds as if its still likely an air in system issue causing overheat......and yeah....we just put heat on full blast (including rear heat) and let it run with reservoir cap open.....without any type of vacuum to do otherwise.....only option for now is to keep doing as we have...unless someone has an idea....thanks

(Or if ultimately we need to replace intake gaskets......am contemplaying signup to allldatadiy for procedure)


Hammer Time
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Nov 25, 2011, 4:30 PM

Post #10 of 13 (3834 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

It tends to pocket in the back head right near the temp gauge sender and it's hard to get out. You can't really leave the cap off because it relies on the pressure to raise the boiling point. What you might try is to fill it all the way, put the cap on and drive it a couple miles, then park it until totally cold and then top off the coolant again. keep repeating this until it doesn't take any more.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



nygent
Novice

Nov 25, 2011, 6:58 PM

Post #11 of 13 (3824 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

Thanks....is there some type of bleeder valve? Read on another forum about earlier model montana where it had bleeder somewhere near water pump.

Another suggestion was raising front of van then bleeding it with cap off using funnel in radiator filled with coolant. Apparently running heat while doing this and using bleeder to ciphon off any air. Repeating once or twice making sure funnel remains filled with enough coolant.


Hammer Time
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Nov 25, 2011, 7:03 PM

Post #12 of 13 (3821 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

That stuff isn't going to do it on this one. The bleeders will help if it has them but they aren't in the right place to get it all.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
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Nov 25, 2011, 8:09 PM

Post #13 of 13 (3813 views)
Re: 2003 Montana -Overheat Spike (occasional so far] Sign In

Have you checked to make sure the fans or coming on?






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