slbcar

My daughters 95 Chevy Lumina, 3.1L V6, has an "over heating" problem. Really it is getting air into the coolant system and losing prime on the pump. The air/steam builds up in the engine sending the temp gauge soaring. The heater starts blowing cold air while the coolant sits in the radiator. If I bleed the air out at the water pump I can drive about 5 - 10 miles before it builds up. I replaced the intake manifold gaskets (Felpro) and thermostat. I have also become quite good at bleeding this thing. No ping or scratching from the engine... yet. Oil looks OK (still translucent, not milky) and the car passed a hydrocarbon test. Could I still have a head gasket or cracked head issue???

cardoc

Hi.
Might be worth pulling the water pump to look at the impeller.It may be damaged.This is easy compared to the intake.
Good luck,Cardoc

slbcar

So far... new thermostat, intake manifold gaskets (Felpro upper and lower w/pushrod guides), Inspected water pump (no sign of leakage or excessive play, no sign of wear on impeller, spins much easier than new pump). Radiator flush (twice). Problems with bleeding system out every time. Changed radiator cap and drove for almost 3 hours. problem reoccured next day. Re-bleed system and drove 1 hour - OK. Today, over heat again and over flow was full. Coolant warm but not hot. Open bleeders and full of steam.
Next?

wrench97

Sounds like it could be a Head Gasket to me.
You could try removing the spark plugs and pressurizing the cooling system overnight then checking for coolant in the cylinders the next morning.
Or
There are adapters that screw into the spark plug hole and allow you to hook an air compressor up to them if you remove the thermostat and pull the top hose off the radiator side and refill the coolant then hook up each cylinder one at a time and look for bubbles if you see any you found the problem.

cardoc

Sounds like a head problem but you said it was tested for HC's in the coolant.That would usually confirm it.You could also find someone with a block tester kit (inexpensive). This uses a HC sensituve fluid that changes from blue to yellow if it picks in up.You suck some fumes(only) from the open radiator cap thruough yhe devise and watch for the change if any.I've found it to very accurate.
Also did you actually look at the water pump impeller with the pump out.Outwardly the pump can look fine but have a broken/loose/damaged impeller.In my shop we see about 4 of these a year on differant cars, some after another shop spends a lot of someone's money.Most recently on a Lexus from another shop.It may pay to pull the pump.
Cardoc

slbcar

Sounds like this car is going to be my hobby for a while. The HC test was done with a sniffer (25ppm) and then re-done with the chemical (Blue liquid - no change).
I pulled the water pump out and it looked great/new.
I'm afraid I'm down to the heads. I have also been told it sounds like a cracked head more so than a gasket. Only one way to find out and my work doesnt change. Pressure test or tear down?
Bummer... Is there really no "Miracle -in-a-Can"???
Merry Christmas to me.
Thanks for the help. If you have any more suggestions I'd be happy to hear them (buy new, used, reworked, Murrays, Auto-One, Junkyard...??).

bruiser

You could get a leak detector kit. Comes with dye and a UV light. Pour the dye in the coolant and let circulate for a few minutes. Then use the UV light to see where the leak is.

SABL

There is no miracle in a can.... I have seen sodium silicate used with some degree of success but I wouldn't use it.

Right now I would keep it simple and merely confirm the thermostat is installed with the "pellet" on the engine side within the Tstat housing. Another quickie is to remove the thermostat and see if the issue remains.

2strokedetroit

head gaskets are common in these carssss not sayen its the problem as i didnt even read everyone elses roply do a cylinder leak down test or pressurize your system and see if its a head gasket and look for other leaks when the system is pressureized may require flash light to

tallguy1979

You were saying the coolant was warm..not hot..is the t stat installed backwards? Also some cheap stats wont open all the way. Feel the lower hose also..if its cold or warm..replace that stat.

slbcar

I pulled the intake manifold and found that I had crushed the gasket... DON'T OVER TORQUE BOLTS. No coolant in the oil but it looked very suspicious. So I'm opting for the $50 rebuild (another intake manifold gasket) and test again with a new heater pipe conector also, before diving into the heads. I replaced the T-stat twice and also replaced the cap. I'll update tomorrow on status.

slbcar

I had to take a break from my Lumina in order to replace rotors and 1 caliper on my F150. Fun week.

mack1

Hi slbcar,

I have a couple of ideas that hasn't been mentioned yet. Have you flushed the radiator yet? Water will flow through the heater even if the radiator is stopped up, so don't be mislead by that.

Also, check the bottom hose and make sure the coiled spring inside it is still in tact. Just grip the hose and make sure you can't squeeze it together. Suction from the pump can collapse it if there is any restrictions in the radiator.

Don't wait for the car to overheat, stop every once in a while and check for leaks on the ground. From the HC tests, it sounds like it is simply comming out of the vehicle somewhere while the engine is hot.

Best of luck,
Mack1

autoken

Being a 3.1L, the intake is the most likely suspect. When you say it has gotten hot are we talking above red line? This would push the head gasket to the front of the pack. Dye would be a excellent choice for pinpointing the leak point. And even though intake was done, I've seen many jobs that had to be done again. Was this work done at a shop? By all means, best of luck!

slbcar

Wow... Thanks for all the feedback first of all. I definetly appreciate it. Here's my update...
I'm doing the work myself. Am I qualified? Maybe not but I am willing to learn and not willing to give up. Besides I just got a 20% pay cut so I can't afford the Garage.
I just completed the 3rd Intake Manifold Gasket job and I was extremely careful. Although the car has ran for 3 days, I still believe there is an issue. I burped it two or three times and finally let it go. Tonight the gauge was almost up to the RED zone but it droped to Normal once I reved the engine and began driving (holding at 1500 - 2000 RPM). The "Low Coolant" light came on after about 10 min. and once I got home (20 min) I checked the overflow bottle. I noticed that the coolant was about 1 inch above the HOT line and there was a constant stream of bubbles in the over flow tank (from radiator). I think I have to pull the heads.
By the way, no sign of a colapsed hose or any leakage. Could it be burning off small amounts of coolant in the cylinder without me seeing it?
FYI - When this started it deffinetly reached the RED zone. Although I told my daughter to shut it off, I don't know how long it was like that.

mack1

Hi slbcar,

You didn't say if you had flushed out the radiator or not. Also, not sure the fan is working. Does it have electric fans?

On a tight budget, you could at least flush the radiator with a garden hose. Pull both hoses loose, wrap a rag around the hose such that it will fit well against the radiator inlet. Run the water in both dirrections through the radiator and see how much gunk you can get out. If you have a short piece of small hose, 3/8 or 1/2 inch, tape it to the garden hose and push the small diameter hose down toward the bottom of the radiator. Turn on the water and stirr up the crud at the bottom on each side of the radiator.

I don't know about the 95 lumina, but a 98 malibu has aluminum heads and steel block. The co-efficiency of expansion with heat for aluminum is much greater than that of steel. Also, there are 8 head bolts per head. Lots of distance between bolts. When a Malibu engine overheats, then cools, the torque on the head bolts will be much less than they were before the overheat occured. The head will no longer be flat. It will be dimpled downward at each bolt location. It is common knowledge amongst mechanics that you have to have the heads trued up when replacing the leaky head gaskets. Someone had their heads up their rearends when they designed that engine. Someone has designed special head gaskets for the engine to help this problem, but I don't recall who makes them. I've told you all of this so you will know what to look for if the Lumina has aluminum heads and steel block.

Good luck with the car,
Mack1

tinner105

How about the radiator cap.... if its bad it wont let the system build pressure, and it will overheat.
here's a post to explain better

http://books.google.com/books?id=Yn9...um=2&ct=result


a Stant cap and pressure tester is waht you need, dont know if you can rent them from a AutoZone, or Pepboys.
but i would check out your cap and radiator to see if they hold pressure before i did anything else.
tony

i sent u a pm as well.

slbcar

More details:
I used Prestone Radiator flush twice, simply draining afterwards. Then I later installed a flush kit and flushed the radiator with a hose (about 2-weeks ago). I replaced with new fluid each time. It was green when I bought the car so I'm sticking with the green coolant.

The electric fan (primary) kicks on when the temp gauge is just a bit past MID. I have observed this several times this past week and the gauge droped below mid each time... when the system wasn't full of air.

I has aluminum head and steel block. Per Chilton, I need to replace the head bolts when I replace the head gasket. I guess I also need to send the heads out to test for cracks/warpage.

I replaced the cap around Christmas... to address the pressure concern. I have not done a radiator pressure test.
I'm going to try the cylinder compression test and pressure test with a compressor today (looking for bubbles in the coolant).

slbcar

I gave up on the pressure test/bubble test and went for the cylinder head. I finally got the exhaust disconnected and removed the back (1-3-5) cylinder head. Next to #1 I found a spilt in the metal ring of the gasket and a huge blow out in one of the water ports on the gasket, next to the split. I'm still working on removing the front head. It's probably OK, but I'm done taking chances. I'm stuck on removing the engine brace/air conditioning compressor bracket. I can't get it over the stud, so I need to buy a huge torx bit (T160 - T200??).

mack1

Hi slbcar,

Thanks for keeping us updated.
Don't forget to get the heads trued before putting them back on. Since the heads are aluminum, play close attention to torque settings.

Wishing you lots of luck,
Mack1