1997 3100 Overheating with A/C on - among other things

[Freeloader]

Ok, so this has been an ongoing problem with summertime and my GA.

First post in a long time, by the way. Woo hoo!

Anyway - I'm driving uphill for a short while with the A/C on max, but the temp gauge isn't all the way down. I get to the top of this hill, and the temperature readout is telling me that I'm out of the "operating temperature" box and closing fast on the red zone.

'97 GA owners can sympathize when I say that they could have done much better with instrumentation markings on this car, but regardless, what can I do to fix this? Just cool it with the A/C?

I just had a flush and fill and a new water pump installed in the past 6 months, and I had a small leak (or I'm somehow consuming coolant) so I used the stop-a-leak additive, but I still periodically have to add some coolant. Could the additive be gumming something up?

I had some sort of grey gooish stuff in the spillover reservoir when I added coolant the last time, I don't know what that was all about. Any answers would be great, other than "go see a mechanic", which I intend to do, barring some simple fix.
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While I'm at it, there's a couple of other things. The more unsettling problem is a clacking, or a "knocking" (I hate to say that word) that sounds like it could be a valve. I'm due for an oil change, so should I use one of those special additives to try to remedy this? How should I add it, like it was part of the oil volume I put in? What about moving up from 87 octane to 89?
* * * * *

Lastly, this is easy. My driver's rear door window doesn't seal right. I know it's most likely because it doesn't go up all the way. I can't quite get the door apart (I found the tutorial, but if you could link it here that would be great) but when I do, how do I get the window back on track, or whatever?

[Big Dawg 23]

I here your pain. First is never use stop leak. That only masks a small problem to a bigger problem. If you ever use stop leak do in the cars final days before death to get you by. Did you find any Antifreeze in the oil? If you are loosing it definitely is going some where. At this point you may now have a plug somewhere near the heater core. My '97 3100 did this two years ago after a flush and fill then a radiator replace. Have you taken a hose to the condenser in front of the radiator? That was my issue. I went from running warm even in the winter to back to normal.
You should never have issue with the A/C running in high heat. Just this week I sat in traffic with upper 90's and high humidity and my temp gauge barely moved up. Since you were moving and temp does not go down check the condenser and radiator for a lot of bugs.
Does your fan kick on? When it is warm let the car idle the drive way w/ AC to make sure it does. Possible the sensor went out. WHat is your Antifreeze mixture? Are you using the 50/50 to add it the missing fluid? Too much straight antifreeze is hard to cool back down.
There should be no need to go to 89 octane. Once in awhile it can be just bad gas or as I mentioned earlier small amount of antifreeze in the oil. Dont panic and jump to the conclusion it is the head gasket. If you have never done your Lower Intake Manifold gasket, that is where the leak maybe. Trust me I speak from exprience.
Lastly, how is the thermostat? Is it opening? Hope this helps.

[Agquadon]

well i have had the same problem with my car as well and like Big D said never use stop leak unless you really really have to because it really just hides a much much bigger problem. The person who owned my car put a bunch of stop leak in and it hid a little problem i didnt know about. it could be possible that your heater core is going out and you not know about it i didnt know mine was going out until the under side of it broke loose and went everywhere. There is an overflow pan underneath the heater core so you might want to take you car on a long drive some day then stop shut it off and then look underneath your car for a minute because that could be why your needing to add coolant and trust me putting in a new heater core is not easy but it will save you about 300 bucks if you do it yourself. Also you said there was a funny grey gooish stuff when you opened the resovior last well i dont think it would be oil because oil keeps itself separate from other liquids so it would be very noticeable as oil in your resovior but if a little bit has leaked in your engine from the head gasket you might want to check you oil for lots of little bubbles and a sort of dark milky color. also take a look at your cooling hoses and make sure they are normal size because i found out my cooling issue was coming from a massive air lock in my top radiator hose and it expanded 3 times its normal size and it ended up massively overheating my car.

[Freeloader]

I'm due for an oil change, but I haven't done it yet. Once I do, I'll let you know about milky-ness. I'm really, really hoping it's not a gasket.
I'll be trying to clean the condenser out today or tomorrow, along with the oil change, and let you know.

I know the fan kicks on, that's not a problem. My mix ratio is around 50/50, I bought unmixed DexCool, and I've been putting it in with about the same amount of water each time. This last round, though, I put straight water for the same reason you mentioned: straight coolant is hard to cool down.

I suppose I'll have to replace that LIM gasket if I find coolant in the oil, although I have to drive to Tennessee soon and I don't want the car all sorts of ripped apart and break something major...

If I have the car all ripped apart, I suppose I could fix any kind of sticky valve. How could I tell if that's what it is, and how much would a new part be? Also, there is a walkthrough to taking this engine apart to do the LIM gasket here, I hope.

[Freeloader]

I just looked under the hood.

It's the LIM gasket. Crap.

Now, how should I go about this, or should I have my repair shop do it? What's the difference in cost, roughly, or how long would it take?

[mikem220153]

1. Disconnect the Battery and relieve the system fuel pressure
2. Drain the cooling system
3. Drain the oil
4. Mark and disconnect the plug wires from the spark plugs
5. Remove the coil packs and ICM with plug wires attached as one unit.
6. Disconnect throttle and cruise control cables and remove bracket from top of upper intake manifold (UIM)
7. Disconnect electrical connectors on the following:
Fuel Injection harness where it connects to the main engine harness at the Alternator.
Variable Assist Steering connnector at power steering pump(if the car is equipped with variable steering.
Temperature sending unit connector in LIM
EGR valve electrical connector
TPS electrical connector
IAC electrical connector
MAF electrical connector
IAT electrical connector
MAP electrical connector
8. Disconnet the vent line in the rear valve cover and where it connects in the rubber air inlet duct.
9. Remove the top half of air filter housing and loosen the clamp holding the rubber air inltet duct to the throttle body and remove the air filter upper cover, MAF sensor, and rubber air inlet duct as 1 piece.
10. Disconnect the vacume line from the PCV valve and the Port in the UIM. (the port is just behind the throttle body)
11. Disconnect the vacume line on the MAP sensor
12. Disconnect the vacume line to the power brake booster at the UIM.
13. Disconnect the bypass hoses at the top of the coolant tank to the metal lines.
14. Disconnect the rubber hose from the coolant line that runs underneath the UIM.
15. Disconnect the retainers holding the metal coolant lines to the front valve cover
16. Remove the 2 nuts on the throttle body studs that hold the metal coolant line.
17. Follow the metal coolant line from the throttle body, and you will find another nut holding the line the engine block. Remove this nut.
18. Remove the screw in the coolant bleed pipe where it attaches above the water pump and pull the pipe up.
19. Disconnect the 2 small rubber hoses from the bottom of the throttle body.
20. Remove the serpentine belt
21. Remove the alterntor
22. Remove the 2 studs and 10 bolts holding the UIM to the LIM and remove the UIM from the engine.
23. Disconnect the radiator hose from the thermostat housing on the drivers side of the engine.
24. Disconnect the heater bypass pipe from the LIM where it connects to the LIM by the thermostat. This is quick disconnect type of connection. You should be able to squeeze the plastic ears together and using a twisting and pulling motion, pull it from the fitting,
25. Disconnect the fuel supply line at the fuel rail and the fuel return line at the fuel pressure regulator. (put a cloth under the fuel supply line to catch any fuel remaining in the rail)
26. Place a jack under the engines oil pan and place a block of wood between the jack ram and the oil pan. Jack the engine to take pressure off of the engine mount.
27. Remove the upper engine mount.
28. Remove the power steering pump mount bolts and pull the pump up and move it out of the way. There is no need to disconnect the power steering lines.
29. Remove the front and rear valve covers
30. Loosen the valve rockers and rotate them out of the way.
31. Remove the pushrods Keeping them in the exact order they came out. EACH PUSH ROD MUST GO BACK INTO ITS ORIGINAL LOCATION WHEN THE ENGINE IS REASSEMBLED.
32. Remove the 2 bolts holding the fuel rail and fuel injectors in place. Rock the fuel rail back and forth until the injectors come loose of their bores in the LIM.
33. Remove the 8 mounting bolts holding the LIM in the engine.

Reassembly is pretty much just the reverse.

Some suggetions while you do the job.
If you have the time, take the UIM and LIM to a shop and have them professionally cleaned.
Remove the throttle body and give it a thorough cleaning, paying particular attention to the IAC passage.
Clean the EGR passage in the UIM.
Clean all gasket mating surfaces thoroughly with a BRASS (Not Steel) brush and brass scraper. Also a Scotchbrite scouring pad works well.
Get a good bead of RTV sealant on the front and rear engine decks (actually Left and right engine decks for a transverse mounted motor)
Place a small amount of RTV sealant on the area where the valve cover, head, and LIM meet.
Repalce the seals on the fuel injector tips
Replace the seal on the fuel supply line where it attaches to the fuel rail

As you can see this is not the most enjoyable job. But, with patience and attention to detail, it should go smoothly.

[Freeloader]

Ok Mike, some newbie questions here.

1) How do I relieve the fuel system's pressure?

2) What the hell is #8 even talking about? If that's the cockpit vents you mean... then can I get to the vent filter too while I'm under the hood?

3) Shouldn't I have to pressure test the coolant system? How in the hell am I supposed to do that without a compressor or the first clue on how to do it? Should I get a flush, considering I used the forbidden stopleak?

4) Since I'm at the valves, how would I diagnose a "sticky" valve, and can I replace one, or should I replace all of them? Would it be worth it to replace all of them? How about the pushrods?

5) Excuse the ignorance, but where are the block decks? Is that a flat section of the block that touches the LIM? Is it in the GM shop manuals (which I happen to have :P ) ?

Could somebody please link that other thread about this... where somebody replaced the LIM gasket (red GA?) and took pictures?

I think I'll take some pictures in the morning and have you guys take a look for me. I can't find any puddles or anything, and if I did, I couldn't be sure if it was my car or not. My neighbors drive a bunch of junkers that are always leaking fluids. After looking at 99grandamse's (Kelly?) pictures, I think it might not be the LIM gasket, although now that I think about it, his is a 3.4 and mine is a 3.1. Regardless, I'll get pictures for you in the morning.

[Freeloader]

Here's the pictures. I'm more certain every time I look that it's a LIM leak.

If this is the engine...
http://img104.imageshack.us/img104/7452/limleak00114wq.jpg

Then here's a look at where the LIM meets the block...
http://img104.imageshack.us/img104/8342/limleak00310cv.jpg

And a close up.
http://img63.imageshack.us/img63/7465/limleak00212ip.jpg

Take a look at the coolant sitting on my block.
http://img63.imageshack.us/img63/8816/limleak00510mx.jpg

[Freeloader]

Could somebody please come and take a look at these pictures, and let me know what they think? I don't want to bump my post, but I'm really indecisive about tearing my engine apart for nothing.