Help determining coolant leak
 

Currently experiencing a coolant leak issue but finding it very difficult to determine what was the cause, hoping I can get some advice from some knowledgeable other owners here.

90,000mi
Boxster (non S)

3 Weeks ago the water pump went out, replaced it myself, carefully bled the system, heat cranked, filled to proper levels, and checked it continuously the following days, bleeding any remaining air and re-filling very small amounts to proper levels when engine was to temp.
Have put probably 350mi maybe 400mi in since the pump replacement.

Last night drove around for roughly 3hrs straight, temps fine, everything totally normal.
Cruising down the highway 70mph, not driving hard just cruising in 5th, when suddenly in my rear view mirror, big cloud of white smoke.

Coolant light comes on, I roll down the window (still driving) and I can clearly smell coolant.

I monitor the temp which starts to gradually increase but never exceeded serious levels, and I continued to drive 3-4min to my garage.

Finally turn the car off and start taking a look,
- Coolant vapor all over the rear bumper.
- Coolant actively leaking near passenger rear tire.
- Some but very little coolant seen IN the trunk.
- Coolant on a good portion of the passenger rear internal engine bay

My first thought, naturally, was that the pump had gone out again and during the original repair I did something incorrect.

Further investigation shows no coolant coming anywhere from the belt side of the engine or from the coolant pump.

It appears like a large leak is coming from where the Oil > Air separator is located.

Though it does not appear that any hoses have burst or that the expansion/fill tank has broken.


Ideas?

I'm in the process of taking the fill tank out to check for cracks / leaks, but the fact that very little coolant was inside the trunk area makes me think it is not that.
Also having a LOT of difficulty getting to the hose claps on the engine bay side of where the coolant tank connects to.

I'm also a little confused as to why this issue happened when it did while just cruising, when I was driving around much harder with it in the days before, after the pump was fixed.

My ideas are...
- That a hose is damaged or ripped and I am just not seeing it from the angle I am trying to look from.
- That additional pressure from somewhere else caused the coolant tank to nearly completely purge itself.

I think the worst case scenario from what I'm reading about elsewhere, is that I may have a head gasket leak or now a blown head gasket, and I think that's a possibility because when I was re-filling the tank after the pump replacement, the fill tank was experiencing pressure before the engine was warm, which I thought was odd, maybe not a symptom though.
The fluid would creep up, I capped it so as to not cause a spill into the trunk, and once the engine started to warm, the coolant lowered and I was able to fill more to meet the appropriate levels.

If the head gasket had blown, would I have been able to keep driving it after?
I have not yet dumped the oil to check for coolant.
Have yet to smell or see any oil through this whole event.

Please and thank you.

Reads like coolant tank. The tank can develop a split along the mold seam at the tank bottom. This split may only open up when the engine gets good and hot and thus pressure inside the tank is greatest. A good sign the tank is leaking is coolant leaking around the passenger side rear tire.

When my Boxster's coolant tank let go it gushed and the tank was in short order nearly empty. After letting the car sit overnight took almost a gallon (maybe more than a gallon) of distilled water to bring the level up.

There was no coolant in the rear trunk.

BTW, if you replaced the water pump you should have replaced the T-Stat too.

Great info, the tank was basically empty by the time I did get home and pop the trunk, so I believe that was at least the main source for where coolant came from.
Also good to know there wasn't any in your trunk, I'll suspect that is the problem then and look for replacements.

Any tips for removing the hoses inside the engine bay attached to that transfer part between the engine and the trunk?
I'll look up some more videos on that process.

I did purchase a thermostat, though on the day of install for the water pump I realized it didn't come with a gasket, so I ended up not replacing it as I was on a weather permitting install window.
.... and I really really wanted to drive it again haha

Had the coolant tank replaced at a dealer. The tech said the hoses at the tank were particularly a pain. I recall offering to let him cut the hoses and then install new hoses, even replace all the hoses in the car, but he said "no". He went on to say the hoses are long lived and no need to go to the considerable expense of replacing all of them. He managed to get the tank changed -- he had done this job a number of times -- and the car was back on the road in just a day or two.

You really should replace the T-stat. The problem is the SOP is to replace the T-stat when the water pump needs replacing. The water pump almost always fails first so all we know is the factory T-stat at least has a life than is longer than the water pump's life. But if you try to stretch the service life of the T-stat it might fail and with a failed T-stat you don't get the warning sign of a noisy water pump or like with my Turbo on a hot day the odor of anti-freeze which I knew is a sign of a leak so I dashed right over to the dealer -- just a few blocks away -- and the tech got the car on the lift and confirmed the water pump was bad, it was leaking and had signs of having been leaking a while.

I don't have it handy, but I have a pic of a Boxster and the coolant tank and the hoses. I can post it early in the AM. You might find the picture of some value.

Here is the pic I mentioned....

https://cimg1.ibsrv.net/gimg/rennlis...b198b45fa0.jpg

Really appreciate the input Macster, since half the coolant is gone anyways, might as well go ahead and buy the gasket for the thermo and do that too while replacing the fill tank.
Mine does look very similar to the photo you uploaded except the large hole to the left of the hose adapter has a whole bunch of wires feeing to a computer, so I cannot really remove those easily to clear way to remove the other side of the hoses.
I've ordered a special tool to help remove the hose claps though and then I'll replace them with new screwdriver based clamps.

Those hose clamps on the inside of the bulkhead are always pointing the wrong direction to get a hose clamp compressor on. Harbor Freight sells a set of hose clamp pliers are okay. You'll also need something like this: https://www.ebay.com/itm/Flexible-Ho...-/131748090561

The thing with worm gear hose clamps is that they are just as difficult to get a tool onto. If you were close, I could help you, it's a learning process. Some say that the aftermarket (cheaper) tanks are no good. I got mine for about $60 and it's worked out well so far. I ended up cutting hoses, too, the replacements are standard sizes, and straight hose. They need to be pretty close on length, otherwise you'll never get them to connect. Expect the oil filler pipe to fall apart, they get brittle with age.

Be sure to replace the radiator cap with the most recent version. It does make a difference.

I took more time to get a closer look today and I do see that the hoses in the engine bay are only about 6" long except maybe the oil fill hose and the overflow hose. So cutting the hoses may be my preferred choice here, I understand why I get so much resistance by pulling on that bulkhead adapter now too.

Thinking about removing the adapter from the equation entirely and with a new tank just running straight hoses all the way to the the engine bay.
Zip-tie into a trio through the hole and call it good.

I agree coolant tank. typically these go when the water pump does

I am curious though as to how the majority of coolant does not end up in the trunk when the expansion tank cracks or fails.
Which my only guess is that the crack (looking around online, often happens on the bottom of the tank) must be a split between the main supply cavity and the overflow route.

I will be dissecting my soon to be removed tank for further analysis.

I've ordered OEM replacements and tubing for the whole system that runs from the trunk to the engine bay.
Tank, tubs, caps, gaskets, clamps, it's all getting tossed and replaced, don't want to do this again in the next 5-10yrs.

Tempted to replace the entire oil to air system as well, but I've decided to hold off on that as those don't seem to fail all too often, or not nearly as much.

I also picked up a gasket for the thermostat, so I'll pull that and replace the thermo, essentially doing a 2nd full coolant flush within 30 days, after this should be running great again!

Doing an oil change as well just for good measure.

Finally got all the parts and had time to work on it.
Replaced the expansion tank, the coolant and oil cap, the whole kit of hoses, the flange for all the tubes.
Also replaced the thermostat.

Filled it back up with coolant, let it fill and bleed out air. Spent about 15min doing this while the car was warming up. No leaks.

Took it out for a drive around the block and I'm losing coolant on the opposite side of the engine bay now. In front of the driver rear tire.

When throttle is given it seems to spray somewhere onto the exhaust and also up towards the top of the engine bay, as I have coolant dripping off the engine cover, onto the intake tube.

Can you have someone rev the engine while you're looking for the leak? There is a crossover hose from the area of the reservoir (and oil tube, and dipstick tube) that goes to the engine cooler. That hose has a plastic quick connect in the middle of it, which gets brittle with age. To my best recollection, that's the only coolant handling component on the driver's side. Also keep a close eye on your coolant and oil--you really don't want intermix.

Sorry for your ongoing troubles. It all can be handled, but it takes some investigation. Happy Sunday.

Before I turn it back on, I'm continuing to poke around for more symptoms.

I have after market exhaust with two outlets unlike the stock system where it melds into one gas while still in the muffler, I remember noticing steam coming out from the left side and not the right when I first turned it on yesterday, it wasn't thick white smoke, but it was noticeably white and dissipating fast once out of the rear, possibly steam?
Eventually that went on to disappear before I went out for a test drive and I assumed that was just residual coolant now burning off of the exhaust pipes below.

I took at look at the tube you're referring to as I worked with it a few times while troubleshooting this issue originally when determining if I should replace the expansion tank. That tube appears fine and no liquid is anywhere near the expansion tank and its connections this time.

When I jack it up and have a closer look on the driver side, it still isn't obvious as to where the coolant may be coming from, however there is clearly still fluid that has yet to dry overnight, all around and in the tight places of the exhaust manifold where it mounts to the engine.

It's hard to determine where on the top side of the engine any coolant may have been coming from, I'm suspecting the few areas that have a drop or two on the driver top side of the engine are areas where vaporized coolant condensed and began to run while I was doing the test drive.


I have yet to do an oil change during this project, though I have continued to check the dip stick multiple times during this adventure and every time there is no evidence of any coolant being mixed with oil.
The coolant in the reservoir is also still the color of new coolant.

The fact that I had steam coming out of only the left side exhaust worries me greatly.

More thoughts? Thanks for replies!

I had over my mechanic buddy and we took a look underneath the vehicle after I had turned it on, to us it appears like a blown head gasket on the driver side.

My theory currently is that originally the head gasket blowing caused unwanted additional pressure to the coolant system, thus forcing all the coolant in the reservoir out through the over-flow valve.
Making it appear is if the reservoir had failed.

Is it possible the Heat Exchanger is the culprit now leaking coolant?

Is it possible for a failing heat exchanger to cause the rest of the coolant system to purge through the overflow in the expansion tank upon failure?

The leak when viewed from under the car, appears to be coming from directly below the heat exchanger, to the unexperienced eye, it looks like it may be coming from the head gasket.
As I read more and more the experience of others, slowly I am more and more convinced it cannot be the head gasket and it is either simply a leak coming from another component in the same area, which narrows it down to the heat exchanger, or something much worse like a cracked head or cracked cylinder sleeve.

Because I don't have coolant / oil intermix, I am starting to think it's not a cracked head, and because the engine still sounds like normal when it's turned on, and the fact that it still turns over at all at this point, suggests to me that it's not a broken cylinder sleeve.

:confused: