Coolant Issues

[Dagriffi]

Hi guys, I tried to search for this but couldn't find an answer specifically to my issue, so i apologize in advance for asking something that's probably been answered already..

I have a 2004 Pontiac Grand Prix GT with 100k miles. The coolant has never been changed (my bad), so I am assuming it still has DexCool in it. I am slowly losing coolant, and the heat intermittently stops working. It also intermittently overheats. It also needs a little throttle some mornings to start, but otherwise runs fine. Is there a way to distinguish between a head gasket leak or an intake manifold leak? It seems like LIM issues are way more common than head gasket issues, but the heater issue leads me to believe that there is air in the system. Is it possible for air to get into the coolant system VIA the LIM, without the car running like absolute garbage and throwing codes? Also, how would you recommend thoroughly flushing the DexCool out of my system to switch to Green?

Many Thanks!
Dan

[Fivefingerdeathpunch]

From the sounds of it, its slowly eating coolant through the LIM gaskets.

The hard starting is likely a very dirty MAF sensor and Throttle body blade, both of those should be taken off the car and cleaned with the correct cleaner, its a very simple job that should fix that issue.

Also being that, that coolant has 100k miles on it, I'm sure its had a chance to get all sludgy and brown and disrupt coolant flow to the heatercore and preventing you from getting heat at times.

If I was you, I would replace the intake gaskets, back flush the heater core and flush the coolant system, then if you wish switch to green coolant. A flush can be done with a garden hose and some know how.

[Scottydoggs]

flushing coolant is easy. take the t stat out, put the housing back on, leave the hose on the t stat housing, now take it off the upper rad, push it down to the ground.

open the rad, put a hose in the rad, turn it on, then fire up the engine, all the coolant will pump out the upper hose to a bucket or the ground, as your filling the rad with fresh water, run it like this for a few minutes, usually till clear water comes out. then take the hose out, turn it off, then run the car till no more coolant comes out the upper hose, then turn the car off.

put a new t stat back in hook up the hose to the rad, then dump 1 gallon of straight antifreeze in the rad, not the 50/50 crap. start the car, fill the rad with the hose.

let the car idle, rad cap open till the fans come on, then open the bleeder screw on the t stat housing till a stream of coolant comes out. then shut it. top off the rad if need be, cap it, your done.

waiting for the fans to come on lets you know the engine is hot enough for the t stat to open, some times you will see the rad level drop as well. that would be the time to bleed the air as well. because it opened and took coolant from the rad to fill the engine with more coolant.



and it sounds like you need to do your lim and upper plenum gaskets. look for warping and cracks in the plastic upper manifold as well.


check these 2 threads out as well.

http://www.grandprixforums.net/97-03...ure-60667.html

http://www.grandprixforums.net/how-mod-lim-46931.html

[Dagriffi]

Thanks guys!

[Dagriffi]

Alright, I started tearing her apart tonight and have a few questions --


Just throttle body cleaner on the butterfly? This, as well as a dirty MAF will cause starting issues?



Upper gasket leaking?



The lower intake manifold.. what should I pry on to get that off? There doesn't seem to be a beefy spot to pry at that isn't a gasket surface..


The stovepipe I've heard so much about. Anything I should look for with this while it's torn down?





Thanks!
Dan

[Scottydoggs]

if you think you have all the lim bolts out and it wont come off, you missed 2 bolts, inside the runner in the oil theres a bolt, one in each corner, front right, and back left, or the other way around.

dont forget the egr tube is still bolted on in your pic. and if the plastic elbow is still there break it. then take then two last bolts out, and it should pop right up.

how was the top of the lim? dry? or wet. it dont look to bad in the pic. but you could have dried it up.


the TB. take the maf out, and clean all that carbon off, ( carb and choke cleaner works well) the whole thing both sides. and the edges of the flap/butterfly.

clean the maf with maf cleaner only.

[Dagriffi]

Top of the lim was dry, did nothing to it before the pic. I would have never found those two other bolts, thanks man.

[Scottydoggs]

you got it.

[Dagriffi]

So I removed the other two bolts you mentioned, for a total of 12 bolts removed from the intake manifold. EGR tube is unbolted, and I removed the two sets of plastic tubes. The whole thing wiggles slightly, but then there is a very solid thunk and it does not go any further. I've tried a pry bar under the thermostat housing, and under the bosses on the other side as well, and it does not budge! What am I missing??? The only bolts that seem to still be in, in that area, are the engine mount bolts.

[dsmuts]

take out the engine mount bolts.

[Scottydoggs]

did you pull the egr tube out of the manifold as well?

there shouldn't be anything else to remove. mine, i just pulled up it broke free, then i lifted it off.

[dsmuts]

I've had some stick slightly but with a good yank they came out.

[Dagriffi]

Thanks dsmuts, so the newer grand prix needs the passenger side engine mount removed, and the two other bracket bolts (towards the top of the picture) removed as well, and the manifold pulls off real easy.


The whiteish yellow stuff... DexCool cheese?


Well this doesn't look good..

[dsmuts]

Yeah that looks yummy lol. Clean her up and slap it back together with some teflon paste on the lim bolts.

[Scottydoggs]

if you split any coolant when the lim came off, make sure you wash down the lifter valley with a quart of oil, then change the oil. and filter.

i had some buggers in the cooling ports as well, just clean that crap out, clean the heads real good where the gaskets go, and the manifold, and slap her back together.


ive yet to see a set of old plastic gaskets that looked good, more proof this job should be done on general principals.

[Dagriffi]

yeah ill definitely wash the lifter valley down with oil. A couple more questions guys.. haha.

My Felpro LIM gasket kit came with a few o rings and seals that I'm not sure where they go. I'm assuming the gasket is for the thermostat, but what about the blue pieces and the orings?? To the side are the black rubber pieces that go on the sides of the lifter valley, so I don't believe the blue ones are for that..


What's behind this bolted cover? I wanted to give the manifold a scrubdown in degreaser before I reassembled, but don't want to get water trapped anywhere. Leave this on or take it off for the scrub/rinse?? Thanks!

[Scottydoggs]

under that cover is the coolant passage that you can hog out to open it up more for better flow. how to mod a lim post.

the 2 larger O rings maybe for the cast elbow or elbow. 04+ would used the large O ring for the t stat, older models use the gasket.

the orange ones should fit the manifold coolant ports. if you plug the holes you no longer need them. how to mod a lim thread again.

http://www.grandprixforums.net/how-mod-lim-46931.html

[dsmuts]

Long light blue ones are for a different style lim on the sides. Big black one is for thermostat. The other bigger black one is for the NA map sensor and so is the little blue one. Orange ones are lim coolant ports.

[TonyO]

wow seems like a lot of work.

[The Guz]

The little blue seal is for the MAP sensor.