GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Oil leak, what am I looking at?

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Old May 25, 2020 | 12:53 AM
  #1  
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09 GL450
Oil leak, what am I looking at?

Hi

I discovered a small oil leak today. It's in the front of the engine, driver side, right under the plastic cover, behind the power steering reservoir (picture attached). First, I thought it was power steering fluid leaking. However, I do not think that's the case now since the fluid would have to travel up the engine block. Plus, the color and smell are similar to the engine oil and not power steering fluid.

Where is it coming from then? I suspect it's leaking from under sensors 1, 2, and/or 3. Sensors 1 and 2 are attached by 1 bolt only, sensor 3 is attached by 3 bolts. Can you tell me what these sensors are and whether there are O-rings inside that I can replace? I suspect it's actually sensors 1 and 2 that are leaking, since I see puddles and gunk bellow each one of them.

Thanks


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Old May 25, 2020 | 04:31 AM
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Sensors 1 and 2 are the Camshaft Position Sensors; 3 is a Crankshaft Position Magnet (there is another located to the right of Sensor #2, behind the power steering reservoir); they all have serviceable o-rings.

It's rather tricky getting those Magnets off on the driver side without removing the power steering reservoir, but it IS possible by loosening the reservoir without completely removing it and using a 1/4 wrench to remove the bolts (be VERY careful not to strip the bolts; the passenger side is much easier.). Search the forum for a DIY.

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Old May 25, 2020 | 02:26 PM
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Before you replace anything, get a couple cans of non-chlorinated brakleen and clean everything really well. Then, monitor closely to see exactly where the leak is eminating from.
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Old May 25, 2020 | 10:16 PM
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Thanks, I looked at the other bank and I see a bit of gunk there as well. I'll clean first and try to figure out where it's coming from.

BTW, are these sensors and magnets maintenance items? Once I remove them, shall I just replace the o-rings, or sensors and magnets as well? My truck as 11 year old now with 85K miles.
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Old May 26, 2020 | 01:29 AM
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Also, do you have by any chance a link for the driver side sensor replacement? The one describing what to do with PS reservoir? I did a search and found several mentions of that but no concrete instructions.
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Old May 26, 2020 | 03:33 AM
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Originally Posted by GLguy
Also, do you have by any chance a link for the driver side sensor replacement? The one describing what to do with PS reservoir? I did a search and found several mentions of that but no concrete instructions.
PS reservoir is tricky - it sits with three or four torx screws in the cylinder head; as well as one c-clip on the pump inlet pipe. You’ll need a 2” long torx bit collection to get access. The c-clip pulls off easy but is impossible to get back on unless you tighten the torx screws first. While you’re in there replace that o-ring as well - it will eventually harden and create a horrendous leak; one often misdiagnosed as an engine oil leak. That being said you are likely right about your leak being engine oil.

tl;dr ps procedure is:
Suck fluid out of ps reservoir
remove c-clip
undo torx bolts
remove reservoir
remove and replace o ring
seat reservoir
carefully tighten torx bolts
install c-clip
refill ps fluid

Last edited by Max Blast; May 26, 2020 at 03:38 AM.
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Old May 26, 2020 | 01:14 PM
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Thanks, I see you removed PS reservoir completely. I'll try first just to get a loose to see if I can remove bolts with the right tools.

BTW, the PS o-ring you mention, is it on the reservoir side, pump side, both?
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Old May 26, 2020 | 07:49 PM
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Sits in a groove on the pump inlet pipe.
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Old May 26, 2020 | 09:37 PM
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A very common leak in this area is the gasket between the oil cooler and the oil filter housing. This has the potential to mix motor oil and coolant.
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Old May 26, 2020 | 10:29 PM
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Yep, I saw that. Once you remove PS reservoir, it's an easy job to remove the cooler. BTW, do I need to drain a coolant a bit if I plan to replace oil cooler gaskets?
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Old May 26, 2020 | 10:34 PM
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BTW, are position sensors and magnetic sensors worth replacing as maintenance items? I'll be removing them anyway to replace the o-rings. Debating whether I should just replaces the ones that are difficult to reach. Are all positions sensors identical? All magnetic sensors identical? I assume so but would like to double check.
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Old May 27, 2020 | 04:59 PM
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Originally Posted by GLguy
Yep, I saw that. Once you remove PS reservoir, it's an easy job to remove the cooler. BTW, do I need to drain a coolant a bit if I plan to replace oil cooler gaskets?
yes

https://blog.fcpeuro.com/how-to-repl...e350-c300-m272

https://blog.fcpeuro.com/the-definit...d-m273-engines

Last edited by lkchris; May 27, 2020 at 05:06 PM.
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Old May 27, 2020 | 09:25 PM
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Awesome links! Thank you
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