Allpar Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
169 Posts
Discussion Starter · #1 ·
Have a recently acquired 2001 Dodge Ram B1500 van with standard 3.9L V-6. So far it's been a good runner but recently noticed a bad leak of antifreeze from what looks like bottom of the water pump. While trying to narrow this down further, I discovered that it leaks only when the engine is shut off! When I start up the van, it quickly stops leaking; when I shut it down again, it looks like it's taking a whizz. Had started to tear it down, but it occurred to me that I should, um, research this on Allpar before jumping to conclusions. :rolleyes: So after reading another thread I put it back together so I could pressure-test, etc., but didn't get that far before discovering the above peculiarity.

It doesn't run hot until it loses enough coolant to have an adverse effect. I actually can drive it on errands and, upon parking, stick a drain pan under the spot before turning off the engine to avoid getting the toxic stuff all over the ground.
 

·
Registered
Joined
·
5,423 Posts
When you shut down a warm motor, the water pump stops circulating coolant and there is still residual heat in the block, the temp can actually go up after shutting down the motor within seconds to minutes, and that means the pressure will go up as well. That might explain a squirt out of a bad seal just after shutdown.

So, is it leaking from the water pump? Although your leak sounds a bit unusual, it doesn't change the fact its a leak and what ever is leaking needs to be replaced. If its leaking from the water pump, replace the water pump.
 

·
Super Moderator
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
Joined
·
22,020 Posts
I have seen intermittent water pump seal leaks. If there is any evidence of wetness or coolant stain at the seal weep hole, replace the pump.

Edit: If the leak is at the suction side of the pump (the lower radiator and heater return hoses) and the engine is running, it may not leak. This may be what is happening here.
Engine temperature does soar after the vehicle is shut off and coolant circulation stops. It is known as 'heat soak'.
 
  • Like
Reactions: Rick Anderson

·
Registered
Joined
·
4,922 Posts
There are several places on the water pump that can leak. As mentioned the shaft seals can leak. Other sources of leaks in and around the water pump: lower radiator hose at the pump, heater return pipe at its mating at the pump housing (angles into pump on driver side), bypass hose on the top of the pump, bypass hose into horizontal connection above the pump and at the intake manifold, thermostat housing at intake manifold, heater hose nipple / hose connection at the manifold on passenger side. There are two mounting areas with 2 bolts each that mate the pump to each end of the engine block that also can leak.

Follow this link to a video on replacing a water pump 2002 3.9 V6 or 5.2 V8 engine. Forward to the 11:00 time interval and you will see the components I described.


You have to remove the A/C compressor, alternator and the mounting bracket to get access to the water pump and bypass hose and other items. Do this and then secure a radiator pressure tester. Apply about 15 psi to the system when cold and the leak(s) should be easily identifiable.
 

·
Super Moderator
Joined
·
38,296 Posts
I had one that only leaked at the water pump when it cooled down on a 5.9 Dakota. Found out the lower radiator hose where it went on the water pump was weak. Sucked air in while it ran, spit coolant out as it cooled.
 

·
Got parts?
Joined
·
2,610 Posts
This has happened to me before on Mopars, and every time, it was the water pump. As Valiant said, it may be the lower hose; if you can see from the bottom, you might be able to determine whether it is. If you, or the previous owner, haven't replaced all of the hoses recently, now may be a good time to do so. Also, check the thermostat housing; that needed to be replaced on my Dakota V6 shortly after I bought it. Can you see exactly where it's leaking? If not, the pressure test should help you.
 

·
Registered
Joined
·
5,423 Posts
Well, you seem to be saying its from the water pump, that is why we are all saying replace the water pump. But if you're saying its from the area of the water pump, like anything, do a visual inspection. A broken clamp or loose clamp can do the same thing you describe as well. I had a loose clamp on a lower water pump hose that did the exact same thing, squirt out a lot of fluid just after shutdown and leak while off, but didn't leak while running. I guess the suction from the water pump caused it to seal, like IC was saying.
 

·
Registered
Joined
·
169 Posts
Discussion Starter · #8 ·
Thanx for the feedback, folks! Since I have competing projects and snippets of time, the mention of the lower hose/suction side of the water pump may help me zero in on the location.

ImperialCrown, the "heat soak" phenomenon may be why I'm not seeing leakage before the engine warms up.

AllanC, your video is very useful. Anyone move an A/C compressor on a B-van (to get it out of the way of something else)? Haven't looked closely yet, but the confined space may be a PITA.
 
1 - 8 of 8 Posts
Top