Pelican Technical Article: Coolant Tank Replacement Wayne R. Dempsey
Time: 4 hrs
Tab: $350
Talent:
Tools:
-
Applicable Models:
986 Boxster (1997-04) 987 Boxster (2005-08)
Parts Required:
Coolant tank, level sensor, coolant tank cap
Hot Tip:
Replace the tank when you have the transmission out
Performance Gain:
No more coolant in the trunk
Complementary Modification:
Replace coolant level sensor, clutch replacement
This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Check out some other sample projects from the book:
The replacement of the Boxster coolant tank is probably one of the top ten jobs that typically need to be done on an older Boxster. The coolant tank is one of the worst designs I have seen ever come out of an automotive company. Six separate coolant hoses feed into the tank, with three of them internal to the tank mechanism itself. The hoses from the tank feed into an integrated manifold on the engine bulkhead that is manufactured out of plastic and is prone to breaking. In addition, the plastic tank itself often cracks with age and leaks coolant in the trunk compartment. Porsche had redesigned this part several times over the past decade, and to this day, there are still problems with the tanks.
When should you replace your tank? If your tank is looking old or yellow, or if you are finding a pool of coolant in your trunk area, then it's probably time to replace your tank. Lift up the carpet in the rear of your trunk to check. I also recommend replacing the coolant tank when it's really old, particularly if you have your transmission out for a clutch job. The hoses inside the engine compartment can be difficult to reach, and having the transmission out of the car makes a very difficult job a lot easier.
If you are losing coolant from your engine, and you're not sure where it's going, then you can perform a few relatively simple tests to check. First, get an air pressure adapter that will allow you to hook up a shop compressor to your coolant tank cap. Then, pressurize the system to about 13-15 psi. Let it sit and see if you can hear or see any coolant escaping. If the coolant is getting past the head gasket into the crankcase, it will mix with the oil, and you will be able to see that easily when you empty the oil (Figure 1). If the head gasket is leaking coolant into the cylinders, then they will begin to fill up with coolant, and you can see this when you remove the spark plugs.
The first step in replacing the tank is to drain the coolant. I recommend replacing all of the coolant if you are swapping out the tank: refer to Project 29 for complete instructions on how to empty the coolant from the car.
The most difficult part of this project is the disconnection of the existing hoses from the back of the radiator tank manifold. With the car completely assembled, it can be very difficult to reach these hoses. It is possible to reach them from inside the engine compartment, but you may not be able to get tools onto the clamps that hold the hoses. It's also possible to reach them from below, but you need to remove the lower suspension support bars and the transmission cover plate (see Pelican Technical Article: Changing Automatic Transmission Fluid). Photo 2 shows the hoses that you need to disconnect from the engine compartment side of the radiator tank.
Once the hoses are disconnected, move to the rear trunk, pull back the carpet and flooring that surrounds the coolant reservoir. Remove the electrical sender plug in the bottom of the tank, and gently pull out the dipstick tube from the top of the coolant tank. Four screws hold the tank to the chassis: remove them as shown in Figure 4. Remove the oil cap and coolant tank caps. You should be able to remove the tank at this point from the car.
With the tank out of the car, transfer the coolant level sender, the large top tank seal, the bulkhead manifold / oil filler, and the three right-angle hoses to the new tank (or install new ones if you wish to replace everything with new parts). Don't reuse the spring-type clamps: use new ones or clamp-style hose clamps instead. Installation is pretty much the opposite of removal. With everything back in place, refill and bleed your cooling system as per the instructions in Pelican Technical Article: Coolant Tank Replacement.
Figure 1
Shown here is the lower engine sump plate removed from an engine where coolant and oil mixed heavily. The oil will turn a light brownish color with streaks of light brown running through it. If you see this or anything similar to this when you empty your oil, then you most likely have a head gasket leak that needs to be addressed right away. When coolant mixes with engine oil in this fashion, the oil looses its ability to function as a lubricant for the engine bearings, and you can damage the crankshaft and rods.
Here's the best photo I could take of the hoses in the engine compartment. They are so difficult to reach that it's even very difficult to get a good accurate photo of them. This photo was taken with the transmission out of the car, which is indeed the best time to replace the coolant tank. The arrows point to the hoses that need to be disconnected: Oil filler hose (orange), Oil cooler hose (green), Radiator vent hose (blue), Coolant filler hose (yellow), Coolant overflow hose (shown removed, mates to the nipple shown by the red arrow). The lower left inset photo shows the coolant level sensor unplugged. The lower right inset photo shows the top of the tank.
If you're having difficulty reaching some of the hoses from underneath, you may be able to gain some additional access by pulling out the tank and loosening the hose clamps through the rear trunk compartment. For this photo, I was able to first disconnect the filler hose, and then I had enough room to pull the tank out to reach some of the other hoses. You can also push the DME wire harness grommet into the engine compartment and gain some additional access that way (see Photo 5 of Pelican Technical Article: Engine Drop / Removal).
Shown here are the screws that attach the coolant tank to the chassis. The blue arrows point to the nuts that hold the plastic manifold to the chassis. The yellow arrow points to the coolant sensor. The green arrow shows another mounting point for the bottom of the tank. In the inset photo, the red arrow points to a bolt that holds the top of the tank to the chassis, and the purple arrow shows the oil dipstick tube pulled away from the top of the tank housing.
The oil filler tube / bulkhead manifold is one of the goofiest designs I've seen in a long time. On our project car, just as we started up the 3.4 engine transplant, coolant started spilling all over the place from a broken plastic nipple on this manifold. After staring at the puddle on the ground for several minutes I “fixed” the design of the manifold and simply cut a hole in the manifold and ran a hose directly from the engine compartment to the bottom of the tank. This was designed to be a temporary fix until I was able to replace the entire piece, but frankly, it's worked flawlessly and is still installed in this configuration today.
Comments: Ted, can you provide any additional information or steps on how you used the plastic Welder to repair your leaking coolant tank? Where was your crack located? How bad was your leak? Did you completely drain the entire coolant tank? Did you apply the plastic welder on the inside or outside of the tank? Also, how long have you been driving the car with this welder to test it's integrity?
Thanks for the suggestion. I would much rather spend $7.00 than $300, but I'm not sure how long this fix will last.
~Seppe
March 14, 2012
Ted
Comments: Here is a ghetto fix - try this before removing coolant tank
I tried J-B Weld $6.75 Home Depot takes 15 hours to cure sucks to work with handles temp range did not work then I tried the J-B Weld Putty $6.50 Home Depot - cures in 1 hour - did not work period.
Then I did some research and found VersaChem Plastic Welder Part No. 47809, cream color $7.00 O'Reilly's Auto Parts - this product handles temps up to 300 degree and 3500 PSI - easy to work with after a 2 minute wait time, cures in 15 minutes, hardens fully in 24 hour, WORKS great saved $295 on new coolant tank. You would need to unscrew all 4 bolts on the tank to get it to move around so you can get your fingers into the leaking spot used paper napkin to trace leak and empty coolant out of tank. Hope this helps someone...
Regards
Ted
February 13, 2012
bobatious
Comments: artandscience's comments reflect a broken link at bottom of article.
Rather than the "recursive link" should be a link to flushing the coolant system project, which is
Comments: How do I remove the trunk liner so I can check for coolant tank leaks under the liner. I have a 2006 Boxster
December 27, 2011
Followup from the Pelican Staff: The trunk liner is held on simply with a set of plastic screws & snaps. Take my word for it - you will break a bunch removing the liner, so just order some new ones (from Pelican) to have as spares. - Wayne at Pelican Parts
artandscience
Comments: What am I missing? This article appears to be Coolant Tank Replacement but I cannot find any instructions to refilling and bleeding the cooling system. Instead, just a reference at the bottom of this article to "itself" for details.
Am I missing something? Love your articles and on the recommendation of a local shop who knows I do a lot of my own work bought your book on the Boxster.
Looks like a first-rate piece of technical writing! Thanks for the great contribution to keeping our cars alive.
