coolant leak

35

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

35

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

1 out of 1 people think this is helpful.
23,845

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 out of 2 people think this is helpful.
64,975

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

64,975

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

64,975

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

35

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?

1 out of 1 people think this is helpful.
64,975

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

35

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

1 out of 1 people think this is helpful.
64,975

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

Add photo

Related Questions

  • Leaking coolant 2 answers

    Leaking coolant while car is not running replaced water pump and thermostat what next

    2008 Pontiac Grand Prix Base

    -

    Maintenance & Repair

  • coolant leak 2 answers

    Drove 15 miles to work when I parked most of the coolant was on the ground and my car overheated. The coolant was under the lower radiator hose. Now looking for the leak the car retains fluid and keep...

    2005 Pontiac Grand Prix

    -

    Maintenance & Repair

  • Coolant leak 4 answers

    I have a coolant leak that I can't find the where abouts, I've replaced the elbows, and reservoir/reservoir line.

    2001 Pontiac Grand Prix GTP

    -

    Maintenance & Repair

  • Leak 2 answers

    I replaced lower hose today. Car seemed fine. Drove it around buy on way home started over heating. I checked hose and could hear a whistle like sound coming from around that hose area. With glove...

    2006 Pontiac Grand Prix Base

    -

    Maintenance & Repair

  • coolant leak? 2 answers

    I have recently replaced the water pump, thermostat, resovoir bottle and coolant on my 99 grand am. My problem is that im getting the heat on and off and losing coolant. Today i noticed coolant sp...

    1999 Pontiac Grand Am 4 Dr SE Sedan

    -

    Maintenance & Repair

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 2,846 nationwide Grand Prix listings starting at $1,995.

ZIP:

Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Js08016
Reputation 4,120
#2 Tom Demyan
Tom Demyan
Reputation 2,760
#3 munron
munron
Reputation 2,150
View All

Related Models For Sale

Used Chevrolet Impala
513 Great Deals out of 28,995 listings starting at $1,100
Used Pontiac Bonneville
540 listings starting at $3,699
Used Chevrolet Monte Carlo
13 Great Deals out of 1,390 listings starting at $1,995
Used Pontiac Grand Am
1,218 listings starting at $950
Used Pontiac GTO
5 Great Deals out of 432 listings starting at $5,995
Used Ford Mustang
361 Great Deals out of 46,750 listings starting at $1,500
Used Chevrolet Camaro
157 Great Deals out of 32,775 listings starting at $1,995
Used Chevrolet Malibu
810 Great Deals out of 81,104 listings starting at $995
Used Honda Accord
711 Great Deals out of 86,747 listings starting at $1,250
Used Pontiac Firebird
8 Great Deals out of 729 listings starting at $1,800
Used Nissan Maxima
279 Great Deals out of 26,273 listings starting at $1,990

Used Cars For Sale

2007 Pontiac Grand Prix GT For Sale
79 listings starting at $2,999
2006 Pontiac Grand Prix GT For Sale
83 listings starting at $1,999