And possibly have a good snicker at my expense...

Yesterday, after completing the somewhat disagreeable task of changing the gasket on the upper timing cover of my '92 300SE (M104 motor), I decided to change the oil. Changing the gasket was particularly disagreeable because of the carelessness of the previous owner/mechanic that did the head gasket job on the car before I bought it.

I have one of those vacuum-extraction devices for changing the oil through the dipstick. I've modified mine by machining a plug which fits the top of the dipstick tube, sealing with an o-ring. This gives me a larger diameter orifice to pull the oil through. The extractor came with a small hdpe (high-density polyethylene) tube that fit down the dipstick - but that took forever to pull the oil.

I'd already started the motor and determined everything to be in working order, both lubrication and coolant-wise.

The extractor works good, but it doesn't like changing hot or even warm oil. The heat causes the plastic tank to soften to the point where the vacuum pulls the sides of the tank in towards the end of the extraction process. That causes the scale on the side of the tank to improperly indicate the true extracted volume.

I further modified the tank to allow me to use air-pressure to reverse the extraction process and use the hose to transfer the oil back to the now-empty bottles used to provide the new oil.

When the extractor was sucking nothing but air, I - and I still don't know why - decided to use air pressure to re-shape the tank back to the right dimensions so I could read the volume of oil extracted. Nevermind that when I return the oil to the bottles, I'll know how much was extracted....

I turn the pressure down on the compressor - way, way down. So low that I can hold my finger over the end of the air gun and stop the flow. I have one of those great (but not OSHA-spec) air guns with no bypass holes on the tip.

So, I press the tip of the air gun to the hole in the fitting on the end of the tube and apply some air pressure. I hold it for like maybe 5 seconds and I start to hear gurgling from the tank.

And then it happens... oil starts coming out of the tank around the shaft of the handle. I release the air gun, but it's too late. There's sufficient air space in the tank to the point where it takes too long for the pressure to drop via the air escaping through the now open hose. The stupid tank (sitting the floor next to the even dumber idiot with the air gun in his hand) has turned in to an oil geyser!!!

The extractor is nothing more than a large-capacity, heavy-duty hand-pump garden sprayers you see at your local home center. It says it will handle about 8 quarts of oil. The pump mechanism is modified by capping the end with a pvc fitting, to which is attached a hose and a one-way valve. This valve is located high up in the tank, secured to the pump mechanism via a zip-tie. Apparently, the tank had collapsed to the point where the oil had covered this valve (a bad thing). I'm guessing the valve failed, allowing the oil back into the tube, and out through the pump.

It belched about a quart of oil out the top - splashing onto me, the car (with the hood up means also all over the external fans and fan grille) and the floor of my once-clean garage.

Fortunately, the tank was sitting partially on some cardboard I had on the floor to catch the drips from the previously mentioned leaky gasket. I quickly grabbed the tank and moved it to the center of the cardboard to reduce the mess.

How an otherwise intelligent individual can be so completely STUPID is beyond me. At least the car's not a diesel... I'd never get the ink-black stain out otherwise.

I've now got to make sure that I got all of the oil off the car - especially around the fan resistors.

.........That's what I was thinking as I read the post.

.........BTW, the factory does provide an oil drain plug at the bottom of the crankcase..........might be useful for you.

lmao..oops

Sorry to read about the oil shower!

Here's a suggestion for the clean-up around the electrical connections...use distilled water in the process...it's electrically inert and will, hopefully, get any "engine carbon" off the resistors in order to prevent "carbon tracking" and related problems...rinse everything off the best you can, then "final rinse" (twice or more) with the distilled water, then use a hair dryer to help remove any additional moisture from any of the electrical parts/connections...

Good luck with the clean-up...

__________________

M. G. Burg
'10 - Dakota SXT - Daily Ride / ≈ 172.5K
.'76 - 450SLC - 107.024.12 / < .89.20 K
..'77 - 280E - 123.033.12 / > 128.20 K
...'67 - El Camino - 283ci / > 207.00 K
....'75 - Yamaha - 650XS / < 21.00 K
.....'87 - G20 Sportvan / > 206.00 K
......'85 - 4WINNS 160 I.O. / 140hp
.......'74 - Honda CT70 / Real 125
.
“I didn’t really say everything I said.”
. . . . . . . . . . . . . . . . . . ~ Yogi Berra ~

Appreciate the remarks and suggestions.

As I typed the original note, I couldn't for the life of me figure out why the stupid extractor continued to gush oil after I released the air pressure.

Later it dawned on me - the inlet for the hose is attached to a tube on the inside of the container that goes all the way to the bottom of the canister. The air I was injecting was going in under the oil - bubbling up to the top and then pressing down on the oil. No way for it to escape back up the hose...

My modification to allow me to use air to force the oil out of the canister involves a male quick-connect fitting on the top of the canister where I can connect the air hose. I cap the fitting with a rubber plug for extracting oil. If I'd have simply put my finger over the end of the hose and connected the air at the added insertion point, all of this mess would have been avoided.

Haste makes waste...

In hind-sight, I guess I shouldn't have changed the oil hot. The canister doesn't deform when the oil isn't hot. The "max fill" line is at about 8+ quarts, and I extracted a maximum of 7 quarts, since that's my normal refill amount.

However, extracting 20W50 oil cold is a lot more time-consuming than 20W50 hot. Plus I hear that Larry Bible "change it often, change it hot" quote in my head.

Oh well - live and learn.

Here's a new quote for you:

Change it at 5K (syn).........cold.........and let it sit overnight.

you have my permission to go inside and smoke a beer.

__________________
"It's normal for these things to empty your wallet and break your heart in the process."
2012 SLK 350
1987 420 SEL

I've had one of those pneumatic mityvac fluid extractor for a few years now. I'm on my 4th one after snap on said they wouldn't replace any more of them, so I no longer use it to change hot oil. The first 3 I had sucked shut on themselves after a little bit of use and then once it had been pinched shut would do it everytime I used it afterward, hence the replacements. The 2nd one actually imploded on itself- loud as hell and made a huge mess since it already had about 5 quarts sucked into it. Since keeping oil out of it, the 4th one has lasted the last 3 years without sucking shut, but I guess that kinda defeats the purpose of it.

__________________


1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350