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Engine temperature

11-22-2003, 07:55 PM
I have a 2003 Malibu with 29,000 miles on it. I notice my temperature gauge reads a bit over the half way mark when driving around town. I don't notice any type of coolant leak. The gauge almost always reads above the half point, but never gets to the point of overheating. Sometimes it comes close to it but never actually overheats. Anyone else experience this problem?

11-26-2003, 09:10 PM
Document ID# 1396678
2003 Chevrolet Malibu


Engine Oil or Coolant Leak (Install New Intake Manifold Gasket) #03-06-01-010B - (10/24/2003)
Engine Oil or Coolant Leak (Install New Intake Manifold Gasket)
2000-2003 Buick Century

2002-2003 Buick Rendezvous

1996 Chevrolet Lumina APV

1997-2003 Chevrolet Venture

1999-2001 Chevrolet Lumina

1999-2003 Chevrolet Malibu, Monte Carlo

2000-2003 Chevrolet Impala

1996-2003 Oldsmobile Silhouette

1999 Oldsmobile Cutlass

1999-2003 Oldsmobile Alero

1996-1999 Pontiac Trans Sport

1999-2003 Pontiac Grand Am, Montana

2000-2003 Pontiac Grand Prix

2001-2003 Pontiac Aztek

with 3.1L or 3.4L V-6 Engine (VINs J, E - RPOs LG8, LA1)

This bulletin is being revised to change the model Information. Please discard Corporate Bulletin Number 03-06-01-010A (Section 06 - Engine).

Some owners may comment on an apparent oil or coolant leak. Additionally, the comments may range from spots on the driveway to having to add fluids.

Intake manifold may be leaking allowing coolant, oil or both to leak from the engine.

Install a new design intake manifold gasket. The material used in the gasket has been changed in order to improve the sealing qualities of the gasket. When replacing the gasket, the intake manifold bolts must also be replaced and torqued to a revised specification. The new bolts will come with a pre-applied threadlocker on them.

An oil leak may result if the vertical bolts are not tightened before the diagonal bolts.

Diagonal bolts may require a crows foot to tighten.

Tighten the vertical lower intake manifold bolts (1) to 7Nm (62 lb in).
Tighten the diagonal lower intake manifold bolts (2) to 7Nm(62 lb in).
Tighten the vertical lower intake manifold bolts (1) to 13Nm(115 lb in).
Tighten the diagonal lower intake manifold bolts (2) to 25Nm(18 lb ft).
Parts Information
Part Number

Intake manifold Gasket

Intake manifold bolt - short

Intake manifold bolt - long

Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Labor Time

Manifold or Gasket, Intake (Upper, Lower) - Replace Gasket Lower
Use Published Labor Time

11-26-2003, 09:12 PM
Cooling Fan Control
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood junction block. The ground path is provided at G103.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.

The PCM commands Low Speed Fans on under the following conditions:

Engine coolant temperature exceeds approximately 106C (223F).
A/C refrigerant pressure exceeds 1310 kPa (190 psi).
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140C (284F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans on under the following conditions:

Engine coolant temperature reaches 110C (230F).
A/C refrigerant pressure exceeds 1655 kPa (240 psi).
When certain DTCs set.
Engine Coolant Indicators
Engine Coolant Temperature
The IPC illuminates the engine coolant temperature indicator when the body control module (BCM) determines that the coolant temperature is greater than 123C (253F). The BCM receives a class 2 message from the PCM indicating the coolant temperature. The BCM sends a message to the IPC via the class 2 requesting illumination.

Low Engine Coolant Level
The IPC illuminates the low engine coolant level indicator when the body control module (BCM) detects a low voltage level on the signal circuit, indicating a low coolant level condition, for greater than 10 seconds and the ignition is ON. The BCM sends a message to the IPC via the class 2 requesting illumination.

06-05-2004, 12:31 AM
my 02 malibu usually runs at around half way mark too

06-05-2004, 01:39 PM
the owners manual on my 02 malibu says it should run right below the halfway mark, I recently drove from L.a to san fran and towards the end of my trip I was in bumper to bumper traffic and it starting running at the 3/4 mark, but it never actually overheated.

06-05-2004, 04:40 PM
That's what you usually see before the intake manifold goes and you experience overheating.

06-05-2004, 05:34 PM
but driving in bumper to bumper traffic with the temp. in the mid 90's after a 7hr drive can cause alot of cars to run hot.been driving it around the city and on freeways on pretty hot days since then and haven't seen the mark rise at all..I'll most likey take advantage of my warranty though and get it replaced just to be safe : )

06-05-2004, 06:25 PM
I am speaking from experience. I performed a valve job the 3rd time my 99 intake manifold failed. The first time, I had the car for about 2 years and I noticed one day the temp guage went up about 3 cl;icks above half. It wasn't a good 2 months before it happened again. Then, during a trip to Memphis (in the summer), I lost coolant. IOn my return home, the overheating got worse, with shaking and clackling of valves. Westside Chevy performed the repairs (Katy Texas). Said it was the intake manifold. Then I needed a valve job. I agree, a little movement may be normal - just be cautious!

06-05-2004, 07:50 PM
Hello all. This is an interesting article. I just (today) picked up a '04 (0 miles) Malibu 4cyl and the temperature gage hovers at mid point +/- 1/8" when in traffic. I am in Boston and the outside temperature today did not even make it to 70 degrees. Makes me think that this is normal assuming you have the same engine.



06-05-2004, 08:16 PM
mine is a v6 with 3,428 miles on it and the coolant level has been staying the same..These engines seem to run hot in the first place (or I maybe I've just been driving the car to hard)..Anyways thanks for the nfo bcopeland, I'm going to get it checked out this week.

06-05-2004, 09:39 PM
It's typical for the any engine to run right around the middle mark +/- a small margin. The gauge range is selected to cover the operating range of the engine with the normal range being in the middle. Anyways, the thermostat for the 3.1 pops at 190 or 195 degrees, so it runs fairly hot.

As for my personal experience, my 03 Malibu runs at just over the half mark almost always. The fans won't come on hard until around the 3/4 mark so its not uncommon for it to get up between 1/2 and 3/4 on a hot day or in heavy traffic. The only cause for warning is if its running excessively hot when you are running at highway speeds in top gear on a sub 95 degree and its still hot or if it gets over the 3/4 mark at any time. If you are in heavy traffic and its 100 degrees or something, and the gauge keeps climbing past 3/4 and won't come down, turn off the AC and turn on the heat and blast it. You'll need to open the windows so you don't bake, but if you point the vents away from you and towards a window with the windows down its not that bad. The gauge will visually start to drop back down towards the 1/2 mark. But again, the only time I've had to do this is on 90+ days sitting in heavy traffic on I-66 and similar conditions.

04-16-2005, 11:32 AM
Hi Everyone. I have a 97 malibu and a guy at work has 00. We both had cooling problems with fans not coming on. Mine is intermittent and seems to be electrical I might just jumper the fans for the summer months. His turned out to be his reservoir cap. The o-ring was rotten and did not allow pressure to build up. I do not know the circuit path to explain why the fans didn't come on but he had serious problems with over heating and coolant coming out all the time and now he doesn't.

04-16-2005, 10:01 PM
I just had the intake gaskets replced on mine yesterday, and since I've picked it up, the guage has been reading about 1-2 clicks hotter than it did before, and sitting in traffic with weather in the mid-70s it tops out at about 3/4. The mechanic suggested getting a coolant power flush, which i will be doing soon (there was oil in the coolant before, due to the gasket, but the bad coolant was replaced).

Is this normal? I'm just worried that something might be wrong with the gasket again

06-15-2011, 07:49 PM
There are many reasons why ur car gets hot. The temp gauge should not go over half way.
The 3.1 and the 3.4 engines temp gauge normally run at the 1/4 mark when everything is working correctly. The opening on the front of the car must b open to let air thru. If u have a spoiler like the gt has it can't be broken off. Seen it. The fans for high can come on at any temp above 165 f. In shop temp 230 or a little more. There is a bleeder valve on the heater hose tube for bleeding air out of the system when coolant is added. Over time dirt and debris collect in the condenser and radiator fins. That also can cause high temp. Depending on what temp the thermostat is. Say a 195. Will open around 210. To let cooler coolant flow thru the engine. Another factor to keep engine cool is to use antifreeze. Plain water will get to hot. Antifreeze not mixed will also cause high temps. Check your cooling fans let it idle see what temp the fans come on both the low speed and high. If temp is getting over half way turn on the a/c and see if your fans come. Fans are needed for the a/c to blow cold air. There are 3 I believe fuse boxs. One under hood or 2 depending on the year. And 1 drivers side dash and 1 pass side dash. I suggest getting a curcit test light to be certain all fuses are good. You can test your cooling fan motors by jumping 1 at a time with wire from the pos and another from the neg terminals on the batt fans should come on. Then there are the relays. In the under hood fuse box. You can remove them and jumper then across with key on to see if they will run. Then there is the coolant temp sensor depending on car and year there might be two of them 1 for the gauge and the other for the radiator cooling fans. My way of testing this sensor is disconnect it when its getting hot and fans should come on. If your running around with a car that's running higher than 1/2 way your just asking for more expense when it comes to fixing it. You may have to have head gaskets replaced. And on top of that then they will have to find the original problem. Nothing or nobody like to work when there hot. Think about it temp is an enemy.

09-27-2011, 07:44 PM
Check the tensioner pulley.Mine ran at the halfway mark from the day we got it.Battery started losing juice,thought alt was going bad.Then,it threw the belt and died when I pulled over.Upon inspection I discovered the tensioner pulley had broken off the bracket. After replacing pulley my alt now charges quite well AND my temp guage dropped to the quarter mark and holds steady. It's on a 2.4L DOC don't know if this might help.

09-27-2011, 08:16 PM
Our '01 runs a little above midway also. In fact, all of the engines in this family run around 190 to 210 degrees, and even warmer under prolonged load in hot weather with the AC running. This has been my experience with a '94 Sunbird (3.1L/5M), '94 Lumina (3.1l/4A), and our '07 Uplander. The only overheating I've experienced is with the Lumina (radiator cleaning) and the Sunbird (towing 3000 lbs).
I replaced the LIM gaskets on our '01 twice - the Fel-Pro "problem-solver set is what fixed it permanently (after the factory replacements failed again). When the gaskets failed, there was no overheating - just a "low coolant" light.

07-22-2013, 11:20 AM
I have a 2005 Monte Carlo ss.. the temperature gauge reads just over the half-way mark most of the time while going slow or stoped at a red light for a short period. Once I take off, it goes back down under the half-way line. I dont have any leaks, and i had the thermostat removed just to see if it was that, but there is no difference right now. It does the same thing with or without the thermostat. Can anyone give me some kind of hope before i go to the shop and they give me a million "what ifs" and charge me way too much money. Its not over heating, no leaks, no smoke, or anything like that. But the gauge just started to do this like in the last month. And im kinda gettin worried it might be something that will cost a lot.. O, ya, i had the water pump replaced 2 weeks ago, just cause that was my first thought besides the thermostat.
Thanks to anyone who can give me an answer.. :confused:

Tech II
07-22-2013, 12:46 PM
Like any engine, it is imperative, if you ever open the cooling system for any reason, that you remove all the air from the system....if you don't, you have air pockets than can cause higher temps or swings....

You didn't give the engine size.....

Also, have you checked for proper cooling fan operation?

Coolant level is ok? Radiator level should only be checked on a cold engine, first thing in the morning......

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