1xsculler

2007 GL450 117k using 1 qt every 1000mi. Sure that the engine was failing and very close to trading it in, even though I loved the vehicle, I decided to check the plugs and compression. None of the plugs had any oil on them and they were all burning a nice shade of light brown. The compression is very even at about 115-120 psi in all cylinders. I found no oil in the area of the cam housing plugs and I never get any oil drips on my garage floor.

So, it's very unlikely my engine is failing and the oil consumption is not due to burning.

Where to look next as I obviously have a leak somewhere. A MB dealer service guy suggested that the oil cooler may be leaking and the oil gets into the bell housing and only leaks while driving but not while standing still?????

BlownV8

Try the cam plugs.

1xsculler

Like I said, I found no oil around the cam housing plugs and I checked them several times while I had the large plastic intake filter housing off. If it was the cam housing plugs I believe I would find some oil drips on my garage floor based on what I have learned from this forum.

Any other ideas? Am I checking the cam housing plugs correctly? There is zero oil on the engine at the backs of the heads and cam housings.

alx

when you come to a stop sniff between the hood and the windshield wipers. do you smell burnt oil? especially if you stopped on an incline?

1xsculler

I'll check that. What would it mean if I smell burnt oil?

alx

it would mean you have a leak that dumps oil on occasion (depending on how the vehicle is tilted) on the exhaust so there is no oil on the ground.

a liter per 1000 miles is a lot. if you are leaking it and burning it there should be a strong smell under the hood occasionally,

1xsculler

I'm going to try some leak detector dye, talk with, and show my spark plugs to, my mechanic and get to the bottom of this oil loss. If the engine is burning it, or it's not an expensive or easy DIY leak fix, the GL is going to be traded in where it will be auctioned off as I will NOT put a new engine in it. The previous owner paid MB $8000 to install a new tranny at 100k and I am not playing that game even as much as I like this car and it fits my needs perfectly.

ItalianJoe1

115-120psi sounds low. The engine could very well be worn out and consuming oil if there are no leaks and it's still using a quart/1000 miles.
If there's oil leaking, you will see it under the truck. Look at the underpanels, are they wet? If so, remove them and see where it's wet. Guessing at it doesn't help much.

1xsculler

That is, of course, my fear and what would cause me to trade it in but, worn out at 117k?

ItalianJoe1

Something as stupid as a failed air filter allowing excess dust/sand in could easily wear an engine out in a couple thousand miles. Have you owned it since new? Maybe it was subject to high stresses (towing, extended idling, extreme temperatures) or greatly extended maintenance intervals, or maybe poor quality oils/filters were used resulting in premature wear. 117K is plenty of time to wear out an engine.