Disappearing coolant leak?

[bcrdukes]

+1 to the water pump. Same thing happened to my BMW.

Replace the water pump, thermostat, and accessory belt (and pulleys if necessary) while the car is in the shop. Good idea to replace the AOS and coolant expansion tank at the same time.

[Rob175]

Well......my guess is the hoses (20 year old hoses). But I'll report back after it goes in tomorrow.

[Rob175]

Well.....for everyone that said it was the water pump that was the cause of the leak YOU WIN! (and I lose). My shop is installing a new water pump, thermostate and belt and I should have it back tomorrow. The cost quoted is $1350 out the door. I'm not sure if that's high, low or average for the Chicago area but it seems OK to me. My 20 year old 98' with 86,000 miles is my "fun summer car" and since it hasn't ever been maintenace "hog" I'll fix her up and drive on........

[blue62]

a water pump kit is around $350.00 I believe it includes a new belt and t-stat.
So your paying around $1000.00 for labor. If your fine with that more power.to you!
But that $1000.00 is why I always do my own work

[Starter986]

3 hour job, tops, for a mechanic who knows what he's doing.

I'm not a mechanic. I replaced my water pump. Once. I could do it again in less than 3 hours.

I'd be finding another mechanic. One who doesn't take advantage of the unsuspecting.

If you were in SoCal I'd do it for you for free.

Best wishes.

[bcrdukes]

If that includes a full flushing of the coolant, that sounds about right. Make sure the shop is using original Porsche or VW/Audi coolant.

[Rob175]

Yes, that also includes a complete flushing of the system and replacement of Porsche OEM coolant. I was told the filling process is very specific and proceedural to get it right. While I'm sure that if one wants to tackle it themselves they'd "save money"...assuming you have the tools, equipment, knowlege and desire.....I don't. I also accept the fact that IF I use a professional shop, they deserve to make a profit.

I save money by doing the things I can do myself, (grass cutting, landscaping, house painting, deck work, etc etc)........so I have the $$$ to pay others to be "grease monkey's"...lol.....but thanks for the feedback.

[blue62]

Hey Rob175,
Nothing wrong with paying someone else to do work you can't or don't want to do.
That's what keeps the economy going. I just like to do car work myself because I can.
The money I save I just gets spent on something else

[Starter986]

Originally Posted by blue62

I just like to do car work myself because I can.
The money I save I just gets spent on something else

Boom! I'm with ya.

Helps that wrenching, for me, is a hobby and stress reliever.

I'll pay the yard guy to cut grass, trim, blow... as I find zero satisfaction is doing that job. Unless absolutely necessary, I'm not paying anyone $100-$150 an hour to work on a 20+ year old car that's worth hardly anything.

$1350 for WP, thermo, and coolant flush? LOL. **************** that.

$15 an hour to schlep around the yard? Yeah, I'll pay that.

[Rob175]

I wish I had the ability, tools and facility to do some DIY work but I just don't.....and I don't have anyone to to ask for help. If you do, you're lucky!

[piper6909]

Originally Posted by Rob175

I wish I had the ability, tools and facility to do some DIY work but I just don't.....and I don't have anyone to to ask for help. If you do, you're lucky!

It's all good. Each of us has different strengths and abilities. I'm sure some of us pay lots of money for something you can easily do. Like Blue62 said, that's what keeps the economy going.

The important thing is that you still enjoy the car, and if it's worth it to you to have someone wrench it, go right ahead. No judgement here!

[Starter986]

Originally Posted by piper6909

It's all good. Each of us has different strengths and abilities. I'm sure some of us pay lots of money for something you can easily do. Like Blue62 said, that's what keeps the economy going.

The important thing is that you still enjoy the car, and if it's worth it to you to have someone wrench it, go right ahead. No judgement here!

Well said, Piper.

+1

[Rob175]

I am a DYI owner on the stuff I can do. I’ve replaced the air filter, cabin filter, oxygen sensor, ignition switch, dash speakers and window switches..... so I DO do some work myself. I have an Indy do my Mobile 1 oil and filter changes ($105)...... I seldom spend more than that each year. (I only out about 4,000 miles a year on the car and never drive it in the winter).

[Rob175]

OK.....water pump has been replaced so the obvious leaks in front of the rear wheel on the passenger side are no longer........BUT......

I now have some very small coolant drops (at engine cool-down) appearing behind the rear passenger wheel with a few drops where the bumper cover screw is located (the one closest to the passenger rear tire). I pulled the truck lining up and the lining along with the truck floor is bone dry BUT THEN I realized that there is what looks like a "black masonite material" that creates a sub-floor which is raised up from the steel body. After removing the section of "sub-flooring closest to the coolant holding tank there is a very small amount of the newest bright yellow coolant that I soaked up with paper towels. I've NEVER had a leak under that portion of the car and there really wasn't very much....AND it was the yellow colored coolant my mechanic used to refill the system after he drained (the old coolant was more greenish)....so I know it's the new stuff used for the new water pump2 weeks ago.

I wiped the tank and the connecting hoses with paper towel and the towel was dry.....only the metal trunk floor had a little bit of coolant, which as I said, I dried up with paper towel.....

So here's my question, since I've never before had any sort of drops coming from the rear bumper cover area and know its the NEW yellow coolant added 2 weeks ago during the water pump install job (complete coolant flush and fill), and all sides of the tank and hoses are dry, could it just be a coincidence or could it somehow be related to the water pump install? (overfill, sloshing around in the tank, etc)......where does the tank overflow to?

Any thoughts?

Obviously, I plan on driving the car in the next day or two and then once again checking for any additional coolant in the trunk again.

[Starter986]

I'm guessing it burped... maybe some air in the system, or too much coolant.

We're you running it hot and hard before you shut it off/down? I believe the recommendation is to, after running the engine hard, is to let it idle for a couple of minutes in the driveway... then shut 'er down.

Wiser minds?

[Rob175]

I suppose....but IF it "burped" or it was overfilled I would assume it would flow out of the overflow tube (IF there is such a tube) and not deposit a little bit in the trunk.
As I wrote it just seems too coincidental to the water pump replacement 10 days earlier.

I guess I'll remove the trunk carpet and sub-floor after I drive it next and inspect it again.

[alynch]

Originally Posted by Rob175

OK.....water pump has been replaced so the obvious leaks in front of the rear wheel on the passenger side are no longer........BUT......

I now have some very small coolant drops (at engine cool-down) appearing behind the rear passenger wheel with a few drops where the bumper cover screw is located (the one closest to the passenger rear tire). I pulled the truck lining up and the lining along with the truck floor is bone dry BUT THEN I realized that there is what looks like a "black masonite material" that creates a sub-floor which is raised up from the steel body. After removing the section of "sub-flooring closest to the coolant holding tank there is a very small amount of the newest bright yellow coolant that I soaked up with paper towels. I've NEVER had a leak under that portion of the car and there really wasn't very much....AND it was the yellow colored coolant my mechanic used to refill the system after he drained (the old coolant was more greenish)....so I know it's the new stuff used for the new water pump2 weeks ago.

I wiped the tank and the connecting hoses with paper towel and the towel was dry.....only the metal trunk floor had a little bit of coolant, which as I said, I dried up with paper towel.....

So here's my question, since I've never before had any sort of drops coming from the rear bumper cover area and know its the NEW yellow coolant added 2 weeks ago during the water pump install job (complete coolant flush and fill), and all sides of the tank and hoses are dry, could it just be a coincidence or could it somehow be related to the water pump install? (overfill, sloshing around in the tank, etc)......where does the tank overflow to?

Any thoughts?

Obviously, I plan on driving the car in the next day or two and then once again checking for any additional coolant in the trunk again.

Check the dimple in the middle of the underside of the coolant tank. That was where mine had a crack and the coolant was seeping out into the trunk. The coolant was then leaking around the rubber plug in the trunk floor eventually ending up in the same location you described above.

[blue62]

Originally Posted by Rob175

I suppose....but IF it "burped" or it was overfilled I would assume it would flow out of the overflow tube (IF there is such a tube) and not deposit a little bit in the trunk.
As I wrote it just seems too coincidental to the water pump replacement 10 days earlier.

I guess I'll remove the trunk carpet and sub-floor after I drive it next and inspect it again.

If it was me I would leave the carpet and sub floor out for a number of drives and check it each time I drove it. Then I would know for sure. Also there is a wire loop on top the coolant tank it is a bleeder valve there is a gasket under it which can go bad and cause some coolant weeping. Or the service tech could have just spilled a little around the top of the tank and it found its way to the ground.

[Rob175]

Thanks for the suggestion.....I removed the carpet, drove it all day, stopping several times to check the trunk. It took about 3 trunk checks before the leak once again showed up. I drove it to my "indy" Porsche guys and sure enough the bottom far corner of the tank (seen with an inspection mirror) has what looks like stress cracks (btw, the plastic tank is very dark brownish/yellow). These cracks appear to be dripping coolant once the coolant gets hot and the system gets pressurized. It holds the coolant for awhile than just "spits" it out all at once, then pressure goes down a bit, the coolant stops leaking from the cracks, until the pressure builds up once again and it "spits" again.....and the process just keeps repeating. That's why it sometimes appears that the leak is gone in between clean-ups.

So.....it goes to the shop tomorrow for a "genuine" Porsche coolant tank replacement. Between the new water pump replacement 2 weeks ago and a coolant tank replacement this week i'm "tapped out". My 1998 Boxster has never cost me as much as it has in the last few weeks. Hopefully it won't need anything else for this driving season. I can't really complain because the car has barely cost me anything over the 15 years that I've owned it, except for the usual maintenance, tires, brakes, oil changes, battery, etc etc.

Before anyone suggests I perform the work myself, don't bother. I have no way to lift the car, nobody to assist and limited space and expertise to attack it so I "pay the piper"....LOL