Tiffany's GL450

Didn't know there was a separate water pump on the car behind the driver's side headlight. It looks like it is leaking, how do I get it out?
1) Do I have to remove the bumper?
1a) Do I have to remove the tires to get the bumper off?
2) Do I have to remove the headlight assy?
3) Do I have to do all the above?
Or is there another way to get to it without tearing the front of the car apart?

Chad

Tiffany's GL450

What is the purpose of this Auxiliary Water Pump? Does it go to the Turbo's or the engine or the radiator or to the seat warmers?

Chad

rapidoxidation

Do you have a REST button on your climate control? The electric auxiliary water pump is used to circulate hot coolant through the heater core when the car is turned off. That plus low speed fan will keep the cabin warm for as long as the engine is warm (or until the car says the battery can't keep up).
It's a super handy feature in wintry climes, and one that I dearly miss. The '05 E320 CDI had it.

Tiffany's GL450

Wow, the things I learn about the car on this Forum is amazing, never knew that feature was on the car, how cool is that!
Sadly, I think I have an *** load of work to do to change it unless somebody knows where there is a Zipper where I can un-zip it and get access to it and then zip it up! Ya know I would sacrifice some of the WOW factors that came on the car for some Quality Attributes instead.
Like coolant parts!!

Chad

arsupisemnet

Fender liner and wheel.

Tiffany's GL450

So I might be incorrect in my initial assessment of the water/coolant leak that I had ASSummed it was coming from the Auxiliary Water Pump. Yesterday I hosed the engine bay down to remove any residual coolant so I wasn't chasing coolant coming from every nook and cranny. This morning I crawled under the car and removed the splash covers in hopes of getting a good view of the leak, seen/saw nothing so I started the motor and let it idle for about 20 minutes, still nothing. Noticed the Coolant reservoir was low so I filled it up with distilled water.
Started the car again and watched coolant/water rise up and out of the coolant reservoir so I put the cap back on and let the system pressurize to operating temperature.
Drove it around for a while and checked for leaks but seen nothing. Removed the radiator cap and it bubbled out fluid (as I would expect) and ended up coming our from underneath the car in the exact same place as the location from yesterday.
Could the radiator cap be weak and allowing pressurized coolant to seep out?

Chad

arsupisemnet

If your radiator cap weak you would be boiling engine all the time (usually looks like busted gasket). I would do exhaust gas coolant test as precaution.

rapidoxidation

This.
With the engine cold, there should be zero residual pressure in the cooling system (squeeze the upper radiator hose to get a feel for it). If you open the expansion tank cap on a cold engine and there's pressure coming out, there's a problem.

Tiffany's GL450

Ok, car was cold and I took the cap off, nothing came out.
But when I squeeze the hose (the upper radiator hose) I can get fluid in the tank to go up and down, that should be right, right? I mean if you squeeze a hose (any hose) fluid is going somewhere right? I mean, what happens when you squeeze your hose?
This post could get out of control at any minute!!

Chad

arsupisemnet

Both caps for turbo intercooler and main cooling are the same. Just take middle cover off and swap caps. If something changes buy new cap

Tiffany's GL450

Well I was able to get limited access to the drivers side AUX pump and sure enough, that is where the leak is. Also, it is attached by a rubber grommet that came off pretty easy so if I can get the clamps off it should pull right off and I can change it out pretty easy. I was watching a video of this Shop pulling the motor out of a GL450 and could see the pump that is leaking on my car, its the short pump. As the guy was explaining his removal he showed the AUX Pump that goes on the Passenger side, the long one, and he called it an Aux pump as well.
My concern now is getting the correct part for my problem, hopefully the pump I pull out today will have a part number on it and I can order that one.

Man, these cars are a pain! They are gorgeous, comfortable, roomy, fast, quite and luxurious but son of a *****, you pay for those things either at the Dealer or in your driveway!!

Chad

Tiffany's GL450

Thanks for the help man, the best thing about these Forums is guys like you who help out readers like me!
Hats off to ya my brother!

Chad

Tiffany's GL450

Bosch PA66-GF30

That is the P/N on the pump and from what I have found, it crosses over to P/N 0392023004. Can anyone verify that? I would like to get that ordered and installed ASAP.
Thanks

Chad

chassis

PA66-GF30 is nylon pump housing material with 30% glass reinforcement. It is not the pump assembly part number.

You need an MB part number that starts with “A” then a platform number like 164, 166, 222 or similar. Look it up on mbparts.mbusa.com

arsupisemnet

That is not the pump you need. The one you looking is the one with whole plastic housing suspended on rubber hanger. That one is indirect magnetic drive type. Unless i mistake something.

arsupisemnet

Something like that https://www.partsgeek.com/gbproducts/WC/29099-01206638.html

Tiffany's GL450

Found it!
Ordered it!
Thankful for this Forum!

Chad

EddieEdd

Hello Chad,
Did replacing the pump fixed the issue. I have a similar issue with my GL 450 were it leaks from the hose that goes from the pump to the passenger side. The weird part is that it leaks only when the car is off after driving. Thanks...

Ed,

Tiffany's GL450

Hey Ed, yes replacing the pump solved the problem. When I ordered the pump I had to order the two hoses as well. I just cut the old hoses and got them out of the way. The pump is not bolted in, it is held in place by a rubber Bushing/Grommet/Hanger thingy that reminds me of an exhaust hangar. I didn't have to take anything out or loosen anything else to get the pump out. Once I cut the old hoses off I was able to finagle the pump & grommet off of this Bushing/Grommet/Hanger holder thing/bracket. I installed that grommet onto the new pump along with both hoses and put it back onto that hangar and then secured the hoses to their existing locations.
I got the New OEM Bosch Pump off of eBay for $64.98 and the hoses from O'Reilly Auto Parts. It took a few hours to get the pump off and on just cuz there is absolutely NO room to work with.
"CAUTION"
If you haven't already replaced many of the brittle hoses that are in this area or next to it, then be prepared to replace more than just the hose you are going after. The plastic crap Mercedes uses for coolant lines is absolute Dog **** and will break if you touch them!! You can read the horror stories thru this forum about wanting to replace a $45 hose in 30 minutes turning into replacing 6 hoses for $600 taking 2 days! So disappointing Mercedes chose the route of cheap over quality on this engine set up.
But if you have the patience, some wrench turning ability and will read thru these forums about the same issues that guys like me and many others have already experienced you can fix these nuisance problems and enjoy the car for many years and many miles!

Good luck to ya sir!
Chad

EddieEdd

Hello again Chad,
Thanks for the reply. I already dealt with the turbo coolant lines. Hopefully this one is not as crazy. Were you getting any codes with this pump? I'm getting random misfires on cylinders #5 and #8. intermittently. I read about the issues with this engines after 100k miles, so hopefully that's not my issue. The car would run fine for a while and check engine light goes away. Also, did you performed a coolant flush before/after the pump replacement? Thanks...

Tiffany's GL450

No I wasn't getting any codes, just a constant slow drip. What started this off was I had a local Garage drain & fill the AC with fresh Freon. When he went to disconnect his equipment from the car he touched the rubber hose going from the pump to the reservoir (the small one) and it snapped and blew coolant EVERYWHERE!!
So I replaced that line first, it took a month or so before I started seeing coolant in the driveway and traced it down back to the AUX pump. I thought I might not have gotten the new hose on tight but as the motor was running I took an inspection mirror and looked behind the pump and could see it weeping out. It was a S.O.B. to get out just because there is no room. But like I said, be patient, cut the hoses off first so you have room and you can finagle the pump & grommet off of the bracket it slides onto and get it out.
Attach new hoses to the pump and THEN slide it back into place, you can tighten all the clamps once the pump/grommet is back on the bracket.
I replaced the coolant about two (2) years ago at 78K miles. Then about 4 moths later I replaced all of the coolant hoses from the Turbos and water pump and all of the small lines (except for the AUX pump lines, didn't know they existed) and replaced the coolant again. I replaced the AUX pump and lines and dumped about a gallon of coolant and had to replace that. Since we've had the car I have put 5 gallons of coolant in it, we bought it in April 2021 with 72K.

Chad