2006 grand prix gt overheating

[Trevor_L]

 I have searched and found some helpful info but i need help. 2006 grand prix gt 3.8 supercharged overheating never the the warning level but damn close. I have changed the belts, water pump, the thermostat, I flushed the radiator and refilled it purged the air. Car climbs up past the middle line at an idle but stays steady while driving..... on the flat ground and with my foot out of it. Going up a hill of and the temps rise. Have not gone up a big enough hill to see if it continues to rise. But once it flattens out or I start down hill the temp levels out again. Not much coolant loss maybe a cup full in a week.

Head gaskets? With a baby on the way im trying to figure this out asap.

[Schurkey]

Electric fans?  DO THEY WORK?  BOTH OF THEM?

[digitaloutsider]

Check those, and have the intake manifold gaskets been changed? There's no milkshake in the oil, right?

[Trevor_L]

Both fans kick on. They work with ac on or off. Have not checked the intake. And I know it still has the plastic elbows but they dont seem to be leaking.

[digitaloutsider]

Look in the oil and also make sure that there is no sludgy shit on the oil cap. These engines are prone to intake manifold gasket failure, and if you don't know if they were ever done, you should probably just go ahead and do them.

How long has the car been doing this?

[Trevor_L]

Oil is clean. No milk shake. It thas been going on a few months. We got the car from my wifes aunt and uncle. They never drove it much. Her uncles solution was to take out the thermostat.

[55trucker]

How did you have the rad *flushed*?

Most rad shops don't even have a hot caustic tank to *clean* a rad anymore, the cost is too high & the caustic solution is not *environmentally* friendly.

The only way one can see if the tubes are plugged is to pull the tanks off to get a look inside, (outside of having the rad flow tested), if they are then go out & get a replacement rad.

 

[Trevor_L]

I flushed it myself. I warmed up the car not fully but warm then opened the drain. When completely drained and cooled i refilled it with plain water and drained it. Pulled the upper hose and flushed the radiator till water came out clean. With no thermostat i filled the block till it ran clean as well.

[GTP091]

21 minutes ago, Trevor_L said:

I flushed it myself. I warmed up the car not fully but warm then opened the drain. When completely drained and cooled i refilled it with plain water and drained it. Pulled the upper hose and flushed the radiator till water came out clean. With no thermostat i filled the block till it ran clean as well.

That’s also how I do a flush. I’m with trucker on the rad being the culprit.   Rads are relatively cheap maybe the coolant went to long without being changed and he rad got nicely corroded up.

[Imp558]

And put a thermostat back in.

Your wife's uncle knows less than over half of a century of automotive engineers from every car manufacturer..

[Trevor_L]

8 hours ago, Imp558 said:

And put a thermostat back in.

Your wife's uncle knows less than over half of a century of automotive engineers from every car manufacturer..

 I did replace it. And yeah he's about three cans short of a six pack. 

[Imp558]

Psych0matt had the same problem with his, it may be worth it to wait for him to chime in.

I think he replaced the radiator on his 3rd Gen in the end.

[Trevor_L]

12 hours ago, GTP091 said:

That’s also how I do a flush. I’m with trucker on the rad being the culprit.   Rads are relatively cheap maybe the coolant went to long without being changed and he rad got nicely corroded up.

I'll look into the radiator. Would could explain the heating up. But I noticed the intake gasket should be replaced. Looks like a little leak.

[55trucker]

The rad will only last as long as the system is properly maintained, & I emphasize *properly*.

General coolant is good for 3 years max, (whether it be concentrated or 50/50) if one neglects the fluid changes the ph balance will go off, aluminum components will suffer, the coolant takes on an acid formulation.

Never use tap water when refilling the system, use only deionized water. Regular tap water is *hard* & will form lime deposits in the system. 

 

[Trevor_L]

Didn't know about the water. Is filtered water ok or should it be distilled?

[GTP091]

Distilled is ok. Deionized is what you should use.  It's a bout $2 at the store  for 4 litres.  My local auto store only has deionized water beside the coolant jugs.  I have not seen distilled there for years now..  If you get premixed this is already done but you can do cars for the same price if you mix it yourself.  Never use rad stop leak to fix a leak.

[Trevor_L]

No stop leak for me. No such thing as a mechanic in a can.

[Imp558]

If the intake gasket is leaking it would be a good idea to address that first.

There's no point in wasting new coolant and time.

[Trevor_L]

Ok looking into a radiator. Any aftermarket ones i should avoid?  Do i need one for the supercharged motor?I ask due to pricing,  anywhere from 70ish up a few hundred. I know you get what you pay for.

Edited August 20, 2018 by Trevor_L

[digitaloutsider]

L27/L32 are the same radiator. Looks like RockAuto has a Denso for $73, which seems incredibly reasonable given the brand.

May as well order the aluminum AC Delco intake gaskets while you're at it.

[Trevor_L]

Sounds like one hell of an idea. Thanks guys your all awesome 

[Trevor_L]

One more quick question. What are you doing to cool your tranny? External cooler only or keep it thtough the radiator? I noticed as engine temps go up to does the trannys.

[98gpgt]

Don't rule out low tranny fluid or tranny issues. My parents old 84 Grand Prix would heat up when pulling a small trailer. I don't know if anyone thought to check the tranny fluid. Years later I borrowed it for a trip, 7-800 miles round trip. When I got to where I was going, the car wouldn't back up. Not too long afterwards, the tranny died. Still not sure if anyone checked thenfluid. You said going up hill, I had a clogged cat once in an old Chrysler. I went up a steep hill, and temperature shot up.

Edited August 21, 2018 by 98gpgt

[Imp558]

I recycle Ford truck tranny coolers and make my own brackets. They're BIG like a good sized college text book and I get them cheap at PAP and flush them in my parts washer.

[digitaloutsider]

I agree, used OEM coolers are a good plan. No matter what you do, be sure you go with a stacked plate cooler, not some cheapo fin and tube POS.

I went with the Hayden 678 on mine because it was shitty out and I didn't feel like going to the junkyard. No matter which route you go, don't bypass the factory cooler, use it in line.