New to me ML320

Joined
Oct 4, 2024
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38
The good: 1999 ML320. 140k miles. 2 previous owners. 2nd owner since 2004. Carfax showed ~4k miles since 2020. Very clean inside and out. Very nice price.

The bad: Virtually no Carfax history from 2nd owner. Arabic last name -- I don't think this dude was turning wrenches in his driveway. It was donated to a charity and then re-sold. Didn't speak to and don't know the actual previous owner.

The ugly: Oil fill-cap was very tight and hard to remove. Looked pretty coked up inside. Signs of oil leaking from valve covers that had gone ignored. Well, 2-owners and only 90k from 2nd owners. Passed emissions check too. How bad can it be, I thought.

I bought it back in late Feb and had driven it about 2500 miles since then. It ran well and most importantly didn't seem to be burning or leaking oil. Though the engine was covered in dried-up oil leak residue it was mostly all dry and hadn't gotten any worse since I'd started driving it. It had a Jiffy Lube oil change right before I bought it (paperwork was included). The oil level hadn't come off the full line on the dipstick at all. So, time to pop the valve covers off and replace the gaskets and reseal the PCV chambers.

This was what I was met with. My almost immediate thought was "Oh Sweet Baby Jesus, what have I done?"

I should have taken more pictures, but honestly I was too shook.

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I had a 2004 ML350 for several years and it was fairly bulletproof except I had to replace the radiator which develped a pinhole leak. Other than that it was a very solid vehicle and the '99 ML320 is built on the same chassis, I believe. I ran Mobil 1 0w40 exclusively in mine. Best wishes to you in your new adventure!
 
Here's the after. They cleaned-up ok. Those scary PCV chambers actually seem genius now. I think they capture the worst of the worst like little refractory towers. While they are a 12 out of 10 for disgusting, the underside of the valve covers are only an 8/10, I think.

I also replaced the PCV breather hoses and spark plugs and wires. The plugs were not OE, I don't think, but they were heavily worn, so maybe they were. IIRC, the gap was 1.45mm vs. 0.8 or 0.9 I think on the new ones. (Sorry, forgot pictures.)

Jiffy Lube did an engine flush and refilled with Red Line HP 0W30. I changed the oil yesterday at 3000 miles even and the oil filter was loaded. In hindsight I should have checked the filter and probably replaced it 1500 miles ago and left the Red Line in. The PAO was definitely doing it's thing. I refilled with Valvoline R&P 5W30.

Filter is wrapped in paper towels and drying out now. I'll post photos of it tomorrow.

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The tight oil cap is very common on many Mercedes. I changed my Mercedes V8 engine oil every 2500 miles, I almost always needed a tool to remove the oil fill cap.

There are numerous knowledgeable on MB members of BITOG. Post up your issues/ questions/ concerns, I am sure you will receive back helpful tips, techniques, and procedures.
 
How much did you pay for this fine automobile?
$3000 for vehicle, which included a new $200 battery and the aforementioned oil flush and change.
$550 for a set of new-used Goodyear Workhorse Wrangler AT's... a guy on FB marketplace works at Ford dealership and sells the take-offs when guys upgrade the OE tires on their new trucks ($400 for the tires, $150 for the mounting and disposal).
$700 for PCV & valve cover gaskets, plugs & wires, and all the other vital fluids -- transfer case, diffs, brakes, and coolant. Also planning to do power steering fluid. Have tank and fluid, not installed yet.

Biggest known issue: torque-convertor does not lock-up in 5th gear. Guessing bad solenoid on the trans valve body. Will have to take that in to a trans shop. Maybe another $500-700 for that.
 
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Before you pay a tranny shop, try changing the fluid and filter yourself. Not sure if that model also allows for you to drain the torque converter. If you can tackle the PCV project, the transmission service will be a walk in the park. This may clear up your perceived valve body issues. Four Rhino Ramps or equivalent is all you need to keep it level during the service.
 
NIce work. If you can do your own diagnosis and labor, a car like this can save you a LOT of money. The depreciation alone on a new vehicle in the first year of ownership is approaching 5 figure money on typical models.
 
The M112 makes sludge like crazy compared to the inline engines of the era. I recently pulled one apart, 390k km. First owner probably didn't maintain it very well and second and last owner from around 90k km until now did oil changes every 8-10k km and it stayed sludged like yours. Oil consumption was about a quart every 2000 km. Valve steam were hard and brittle and cylinder glazing was evident.
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