coolant leak

45

Asked by Sep 14, 2016 at 06:47 PM about the 2003 Pontiac Grand Prix GT

Question type: Maintenance & Repair

I have a small amount of coolant on the ground between the back of the engine and the firewall.  Pressure tested, no loss of pressure with the tester on all day.  Not intake manifold, just replaced the gaskets.  Not the elbows.  Not a freeze plug.  It leaks when the car is cold.  If it is warm or running, it doesn't leak.  The drip is coming between the oil pan and the transmission fluid pan.  I've checked hoses.  Car does not over heat, just noticed small amount on drive.  Maybe a few tablespoons.  

9 Answers

45

Sorry, forgot to provide info. 2003 Pontiac grand prix, 3.8L, not super charged

1 people found this helpful.
35,255

I would isolate the heater core and test that individually. See if the puddle is near the drain tube from the heater core box. You may have a tiny leak in the heater core that is dripping out the drain tube to the ground. When the engine is running and everything heats up the leak seals.

2 people found this helpful.
78,015

Check your belt tensioner. There's two plastic elbows that carry coolant from the engine, through the tensioner, to the heater core. They can be sneaky leakers. If that is the problem replace them with the better metal elbows. The two heater hose connectors on the belt tensioner are also suspect. Check them as well. HTH. -Jim

78,015

The knock sensors screw directly into the cooling system. Check them. HTH. -Jim

78,015

Did you do the lower intake? Or just the upper? Did you replace the plastic upper intake and not reuse the original one? They crack. HTH. - Jim

45

It's not the elbows, replace intake upper and lower gaskets. Gaskets are metal. Coolant collects on a bolt between the tranny and oil pan. Where are knock sensors located?

2 people found this helpful.
78,015

Knock sensors screw into the bottom of each head. One per head. You'll have to jack up the front of the car to see them from underneath. HTH. -Jim

45

Seems like the only way to see the leak is to drop the tranny. What are options? Freeze plug? Rear seal? Anything else?

1 people found this helpful.
78,015

There is a dye you can add to the coolant to trace leaks using an ultraviolet light. Freeze plug is a good suspect. These engines rarely, if ever, have head gasket issues. So I'd rule that out unless there's definite evidence of it. The block and heads are cast iron like in the old days so that's a big plus! The intake gaskets fail because you have plastic, aluminum, and cast iron all bolted together. Each has a different expansion and contraction rate when heated then cooled. Personally I wouldn't drop the transmission unless it's absolutely necessary to get to the freeze plugs. I've never replaced the freeze plugs so I really don't know (yet) what's involved there. Try the dye and see what you can find out from that. HTH. -Jim

Your Answer

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 1,805 nationwide Grand Prix listings starting at $2,008.

ZIP:

Pontiac Grand Prix Experts

  • #1
    Js08016
    Reputation
    4,650
  • #2
    Tom Demyan
    Reputation
    3,220
  • #3
    munron
    Reputation
    2,690
View All

Related Models For Sale

Used Chevrolet Impala
397 Great Deals out of 25,595 listings starting at $799
Used Chevrolet Monte Carlo
3 Great Deals out of 937 listings starting at $3,900
Used Pontiac Bonneville
316 listings starting at $3,395
Used Chevrolet Camaro
224 Great Deals out of 28,922 listings starting at $3,900
Used Pontiac GTO
358 listings starting at $2,950
Used Ford Mustang
270 Great Deals out of 37,082 listings starting at $2,150
Used Pontiac Grand Am
723 listings starting at $1,700
Used Chevrolet Malibu
480 Great Deals out of 49,315 listings starting at $2,000
Used Pontiac Firebird
7 Great Deals out of 674 listings starting at $3,695
Used Nissan Maxima
200 Great Deals out of 17,499 listings starting at $1,900

Used Cars For Sale

2007 Pontiac Grand Prix GT For Sale
42 listings starting at $2,725

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.