Page 6 of 6

Re: 2017 GLS550 Coolant Leak

Posted: Tue Dec 23, 2025 6:08 pm
by rpaoness
These guys, with shipping, were about the same as ECS and had the one idler pulley I missed in my first order (RockAuto didn't list it).

https://www.autohausaz.com/

Re: 2017 GLS550 Coolant Leak

Posted: Wed Dec 24, 2025 6:03 am
by kevm14
I've heard of them.

Re: 2017 GLS550 Coolant Leak

Posted: Sun Jan 04, 2026 12:46 pm
by rpaoness
Went to install the stock style hoses and fittings for the one I broke and to swap out my plumbing tee. Also installed the last two idlers I now had.

Everything went OK until I broke this part off in the block:

0099972972
https://www.autohausaz.com/pn/MB-009997 ... 9lEALw_wcB

Wish I knew I should order it when I bought the other hose. Certainly cheap enough. Garbage plastic - came out in almost microscopic pieces. I had to flush the hole out by pressurizing the cooling system to keep them from falling into the housing.

Re: 2017 GLS550 Coolant Leak

Posted: Sun Jan 04, 2026 12:47 pm
by rpaoness
Hopefully New London has one in stock. Very frustrating that they don't subscribe to the standard MB parts website stuff.

Re: 2017 GLS550 Coolant Leak

Posted: Mon Jan 05, 2026 7:44 am
by rpaoness
Warwick has it for $3 and change. List is $5 something. New London wants $7.

Re: 2017 GLS550 Coolant Leak

Posted: Mon Jan 05, 2026 8:06 am
by kevm14
Fortunately, it is a single digit price. But those are wild percentage swings.

Re: 2017 GLS550 Coolant Leak

Posted: Mon Jan 05, 2026 1:17 pm
by rpaoness
Yeah, not the actual $'s, but that's a big % different. Picked up and installed this morning and let it sit at 12 psi for 90 minutes to verify no leaks. Buttoned up, reinstalled the undershield (I dropped a socket and had to pull it to retrieve it). Back to all stock hose routing/connections/locations. Based on casting numbers I think the Dorman turbo line tee fitting was the same as MB OEM. Hopefully no more coolant leaks for at least a couple weeks. Kinda interesting that the turbo underboost code has not returned recently at least.