Coolant Leak Diagnosis - Not Tank - Help Please

[Charlestonboxster]

1998 2.7 with 95k miles

As I entered my driveway, I noticed steam type smoke coming out of the rear...then the coolant temp light came on, I immediately drove in the garage and stopped the car.

A trail of leaked coolant stretched for about a hundred yards down the street.

Coolant continued to leak I guess as steam type smoke, smelled of steaming coolant, came from below the car on the passenger side mostly, and from the side vent.

I let the car cool down, it continued to steam a bit out of the side vent mostly, for almost a half hour, as the engine cooled down or leak stopped.

I checked the Coolant tank, it's close to empty but still a bit left in the bottom.

Note: I replaced the cracked coolant tank myself a year ago, and the cap at the same time.

I removed the carpet and the coolant tank is fine, as are the hoses on the tank side.

I checked in the engine bay at the rear firewall where the tank comes out, all 3 hoses on that side seem to check ok, and no wetness or leaks there or around those hoses.

The coolant seems to have leaked from somewhere near the bottom of the engine, as it was dripping from the plastic protector panel under the engine when I looked.

I filled the tank back up, and a bit started dripping again at the bottom of the engine area, but only a few drops.

The coolant tank has stayed pretty much full, so I suspect it's the pressure with the engine running that caused leaking wherever the fault is.

I did start the engine for a second and turned it off again, it dripped just a bit more from the same area.

I do not want to start the engine again unless I get an ok from this board that it's safe, to test.

If anyone can help me diagnose the most likely source of leakage, be appreciated.

I read over numerous past threads, even one of my own when I replaced my tank, all seem to address tank, or firewall area hoses or the water pump, but not leakage somewhere else.

Here is a picture of a hose in the area where dripping seems to be occurring, you can see an orange drop under the shield, perhaps it's leaking either from this hose part, or the metal part to the left of this hose, where this hose connects.

On that metal engine part, I did see a few drops on the bottom of that part.

I'm trying to upload a few other pics, but having photobucket/slow internet problems.

Could it be the water pump? I thought this pump was near the firewall, and the leak "seems" to be from the bottom of the engine, right above where the plastic shield is. There are small weep holes in this shield and the coolant gathered up in this shield and dripped from the weep holes.

Lot's of steam came out, so I wonder if it's not more serious then just a hose or the part near the bottom.

Car is presently jacked up by the passenger wheel, coolant tank is full, not leaking at the moment, I'm concerned about starting to engine to test, and also assume I should not start the engine with the car jacked up, due to oil flow.

Any and all help appreciated, to help diagnose what hose or gasket or part may be the cause, thanks!!

Tony

Edited May 3, 2009 by Charlestonboxster

[Charlestonboxster]

Here are a few other photo's where it seems the problem might be.

Edited May 3, 2009 by Charlestonboxster

[PTEC]

Take that rear most under panel off and take a look at the water pump. Its right there. Its a pretty common leak but of course it could also be from any of the coolant hoses in that area too. I would suspect the water pump though.

[por911]

You might remove that tray and check for the crust of dried/ wet coolant coming from the bottom of the pump(see pic). I doubt your t-stat gasket is leaking but anything is possible. You can see from the pics, the pump is relatively simple to access and diagnose from that point. Best of luck with the repair.

Regards

[1schoir]

Tony:

The water pump (as you can see in the photos in the posts above), is located directly overhead and slightly less outboard that the the thermostat housing. It's also overhead of that wet "Y" hose that you show in your photograph.

So, I too vote for the water pump as the most likely culprit, as you have eliminated most of the other common leak points.

I would remove the access panel behind the seats and have a good look with a light shining from underneath the engine.

You can run the engine for short periods of time, just refill any missing coolant with distilled water (as long as you don't have to pour in so much as to dilute the mixture currently in there). Since you recently did the coolant reservoir, you must have a pretty good idea of the mixture presently in there. You can always premix in a separate gallon jug the correct ratio of distilled water and coolant and just top up with that to your heart's content.

Once you have determined that it is the water pump, get a couple of hose shut-off pliers (cheap, plastic affairs available at Sears), to minimize the amount of coolant that you will loose out of the hoses that you disconnect. Here is what they look like:

I bought these at Autozone, but Sears has similar ones with some in bigger sizes which are just right for the job.

Regards, Maurice.

[Charlestonboxster]

Gentleman,

Thank you gratefully for the guidance, I'm off to Autozone for the plier/clamps, and will report back on further diagnosis.

Just a quick question, is it ok to start the engine briefly (to check leakage location) while the right rear wheel is jacked up?

Tks,

Tony

[Charlestonboxster]

Progress report:

Removed access panel, and removed plastic tray after figuring out there was one last middle area bolt...not easy when car is barely jacked a few inches, a few cracked parts, but it will go back on fine.

Yes, the plastic tray had a lot of coolant dripping form it, both wet and perhaps dried.

From below, the entire area on the bottom and surrounding the water pump has what appears to be coolant spray.

The Y hose & screw clamp have drips and remnants of coolant on their underside, but don't seem to be perforated.

From above/interior panel, all seems fine, I can see the serpentine belt needs to be removed to remove the water pump.

I'm now at the stage where I'm wondering if I should:

1- Run the engine a short while and see of coolant is indeed leaking from below the water pump?

or

2- Just remove the water pump and diagnose further.

If 2...how do I tell if the water pump is the cause of leakage? Worn gasket?

Car is jacked up a few inches, right rear tire, with this in mind, is there a danger with oil flow if I run it for 10 seconds?

It appears the water pump can be removed by removing the serpentine belt, and about 5 bolts, asides form making sure I clamp

the one hose leading out of it, are there any other hoses or aspects I should be aware of before trying to remove the water pump?

I see in the middle photo above that a larger hose and clamp, just below/close to the water pump hose/clamp, have been removed, wonder if I should/need to do this too for convenience/access.

Thanks guys,

Tony

[1schoir]

Progress report:

Removed access panel, and removed plastic tray after figuring out there was one last middle area bolt...not easy when car is barely jacked a few inches, a few cracked parts, but it will go back on fine.

Yes, the plastic tray had a lot of coolant dripping form it, both wet and perhaps dried.

From below, the entire area on the bottom and surrounding the water pump has what appears to be coolant spray.

The Y hose & screw clamp have drips and remnants of coolant on their underside, but don't seem to be perforated.

From above/interior panel, all seems fine, I can see the serpentine belt needs to be removed to remove the water pump.

I'm now at the stage where I'm wondering if I should:

1- Run the engine a short while and see of coolant is indeed leaking from below the water pump?

or

2- Just remove the water pump and diagnose further.

If 2...how do I tell if the water pump is the cause of leakage? Worn gasket?

Car is jacked up a few inches, right rear tire, with this in mind, is there a danger with oil flow if I run it for 10 seconds?

It appears the water pump can be removed by removing the serpentine belt, and about 5 bolts, asides form making sure I clamp

the one hose leading out of it, are there any other hoses or aspects I should be aware of before trying to remove the water pump?

I see in the middle photo above that a larger hose and clamp, just below/close to the water pump hose/clamp, have been removed, wonder if I should/need to do this too for convenience/access.

Thanks guys,

Tony

Tony:

No problem whatsoever with running the engine for a few minutes, even with the right rear tire jacked up a few inches. Just think about what happens to the oil in the sump when you take a long right turn at the track!!

When you start the engine with the firewall acccess panel removed be VERY CAREFUL to not get anything caught in the pulleys and serpentine belt, i.e., no loose clothing, etc...

Once you get the serpentine belt off, grab the water pump pulley at 9 o'clock and 3 o'clock and see if the pulley wobbles. The gaskets are not the usual cause of leaks, most of the time it's the bearing and when the bearing goes, coolant drips out of a weep hole which is located at 6 o'clock on the body of the water pump, directly behind the pulley.

From all of the water you describe finding, you should be able to spot the leak pretty easily.

Regards, Maurice.

[Charlestonboxster]

Excellent, thank you Maurice.