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6th Gen ('00-'05): 3.8 upper intake leaks

  #1  
Old 11-21-2014, 03:38 PM
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Default 3.8 upper intake leaks

So I am sure this has been done to death, but I cant find it.
My used 02 Monte has been plagued with overheating trouble and leaks from day one.
I first replaced the leaking radiator and thermostat, I am pretty sure the PO tried some of that Stop leak crap and clogged stuff up. Now the only time it overheats is when the cooling fans don't kick on- that's another story!
There seems to be antifreeze running down the right side(front) of the engine, it's dripping underneath while the car is running. There looks like a new water pump, and the water is circulating fine. Looking at it I couldn't locate the right side leak, but noticed coolant dripping on the left side, behind the EGR valve. Looks like it's coming from the crack between the upper and lower intakes.
So I would like your opinion- when I do the upper intake gaskets should I do the lower ones? I also have leaky valve cover gaskets, would it be easier to do them at the same time, or is that irrelevant? Would a standard lower set suffice, or is the "improved" Felpro set that much better? I believe something has been worked on here since the stove pipe from the EGR seems skinny and a good distance from the upper plenum.
This car is otherwise very well kept, I am thinking someone thought it had bad head gaskets and unloaded it. There is either Radiator Stop leak or H2O on the rad cap. It is however a higher mileage car I just want to be reliable for awhile.
 
  #2  
Old 11-21-2014, 07:37 PM
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If doing vc gaskets and uim gaskets do the lim gaskets as well along with the coolant elbows. And only use the revised aluminum lim gaskets and aluminum coolant elbows.
 
  #3  
Old 11-21-2014, 08:45 PM
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One Thing For Certain YOU Can Do To Find Out What Is leaking Is To Do A Pressure test. It will show you exactly where and what is leaking
 
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Old 11-22-2014, 11:31 AM
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Coolant pressure test? Not sure if I can get the tester kit out here where we are. Is there a way to do it myself?
 
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Old 11-22-2014, 03:45 PM
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You would need the tool. I'm not sure if there is a way to do it without. I kno most chain auto parts stores have it for rent tho
 
  #6  
Old 11-23-2014, 12:43 PM
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https://montecarloforum.com/forum/en...rt-done-50420/

Could use this for reference if you would like to.
 
  #7  
Old 11-24-2014, 08:32 AM
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Yesterday I stoked up the Flame Princess and took it apart. I bought all the gaskets, and later the elbows (forgot).
The car is pretty clean, except along the top of the lower intake, it was greasy. Everything came apart nicely. The VC gaskets on the front were pretty flat and gooey, it was leaking pretty good on the exhaust, the rear one not so bad. The upper intake didn't look too bad, throttle body had minimal black goo, where the stovepipe for the egr comes through looked fine, as did the gasket in that area, had a black plastic and orange rubber gasket on it, the lower intake looked untouched. I pulled it and cleaned it up really well, the old gasket only had one suspicious spot where the rubber was misshaped, no real evidence it was leaking yet. It was black plastic with grey-ish rubber. The forward cooland elbow broke at the o ring and was full of black rtv this must have been the leak, there was a rust trail running under it. Replaced both elbows. The water pump was new.
I have no idea where the coolant leaking from between the ui and li behind the egr was from, but it seems to be resolved.
The only problems I had were draining the coolant- had to pull the lower hose off the water pump, and the "special" clamp was rolled under where it was fun to get to, replaced it with a real clamp. I broke that really nice plastic thingy holding the pcv valve in, gotta run to the u-pull-it , and I wasn't sure which way to overlap the lower gaskets, tried both ways, got the best fit and rtv'd it. It was getting cold!
Started right up and ran pretty good for having a vacuum leak at the pcv. Will run it today and check for leaks again. Will drop the oil today, too.
I just was wanting to make it reliable for a winter car (I have a 'vette, a 92 Camaro, and a sweet 87 T/A GTA) so I didn't go for any performance mods- just don't want to add fluids all winter!
Now to tackle the cooling fan issues...
 
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Old 11-25-2014, 08:54 AM
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So I changed the oil and warmed up the car- still have a coolant leak. There is a slight "bubbling" sort of, between the ui and li at the bolt with a stud top behind the egr-not quite leaking, but like a small air leak you can see. I attached a pic. I also attached a pic of my li gaskets.
The coolant is running down the front of the block somewhere- I cant determine where because of nasty oil build up (leaks and the oil filter was less than hand tight). It finally drips under the car from the aluminum plate , or cradle, under the front of the motor. I felt under the water pump and the forward water pump bolts, they were all dry- that was all I could reach. I cannot reach the rearward water pump bolts or rearward elbow. The heater hoses are all dry, also. Would it be likely the person that installed the water pump missed something?
Other than the drip the car is running great.
https://www.dropbox.com/s/3wlxha9oj0...50748.jpg?dl=0
 

Last edited by VIIISecondRide; 11-25-2014 at 09:02 AM. Reason: fixed link
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