NorCal124

It's usually when a motor is completely disassembled and the internals are rebuilt. It's often done on fleet vehicles, semi trucks, and even big time drag cars (it's crazy how they can tare down and rebuild a motor within hours). When my buddies were doing their overhaul they were taking apart a 305 that was going into a Monte Carlo SS. The second engine I saw was a 4G63 Turbo going into a Mitsubishi Mirage hatchback drag car converted to all wheel drive w/ a GSX drive train. The owners of both cars stood faithful to their usage of Pennzoil (I was there when they were being bought) and at both instances my buddies knew that if they bought the car an overhaul was in order.

jrmd01

Whew...finally finish changing my MAS potentiometer. Since that was my first time, it took me 5hrs. Next time I can probably do it in 1hr. Calibrating that is a beeeeoooottttch. I hope it's all set. I tried using a multimeter, but it freaking broke. The good thing is my surging idle is cured (...hopefully). If not, then it looks like I'll be changing the O2 sensor.

AMG_Eric

Thanks for your input, now I'm more at ease trying the lower octane gas.

BTW nice paint job. I lived in San Diego for 9yrs. I never needed to get my car painted but if I had to, I would also take it to TJ. I don't know how you found your shop, but as a warning to others who want to go south of the border...as with anything do your research and ask questions to make sure the place is "legit" before leaving your car. It's better to take it to a shop where others have had their car done. Oh and another thing....make sure you have full coverage insurance in case someone decides to do some "midnight 5 finger discount shopping" on your car. (Translation: In the dark, steal anything on your car that they can get their hands on)

NorCal124

Thanks for the heads up on the Pennzoil. I've never bought that brand since it was never on sale, but now I'll avoid it even if they're giving it away.

Wadster

What is octane?

I'll paraphrase my notes...

Octane are hydrocarbons used as a fuel. Octane rating is a measure of how resistant petrol is to premature detonation (knocking). Hence the higher the octane, the more efficient your engine will be. Using a fuel with a higher octane allows an engine to be run at a higher compression ratio without having problems with knock. Compression is directly related to power, so engines that require higher octane usually deliver more power.

What are the circumstances when an engine might need it?

KEY here is that your engine has to be a "high-performance engine" which are designed to operate with a compression ratio associated with high octane numbers, and thus demand high-octane petrol. Most "daily driver cars" are NOT high performance engines. So regular 87 octane gas should be fine...as long as it doesn't cause your car to "knock". Personally I used to use 89 octane in my Mercedes for daily driving and 93 octane for long distance driving. Now that the truth behind the myth has been revealed the other night on the investigative show 20/20, I'm going to switch to 87 octane. (If my car begins to knock, I'll switch back to 89 octane).

ChrisDPham

In a nut shell, an overhaul is where they take your engine apart and replace all rings and gaskets (and springs in some cases). They also re-seat the valves, resurface the head, and clean up all the sludge build up. Most elect to get some additional work done (ie. port and polish) when the engine is apart since it won't cost much more. If done right, the engine will be as good as buying a new car.

CDP

How much do these Overhaul go for? and...how long would one take? lol

NorCal124

You don't want to know. Unless you're upgrading certain parts for performance gain, using it for racing purposes, or have the tools/know-how to do an overhaul, you're better off buying a new or rebuilt engine. In both overhauls I witnesses there were many minute internal engine adjustments for the sole purpose of gaining as much power as possible. Import motors and Chevy small blocks have a wide range of performance options to choose from when rebuilding a motor unlike most MBs. In other words they're costly and unless you have a large business utilizing vehicles, a racing program w/ deep pockets, or just want to build a motor that can launch you to the moon then you might consider overhauling your motor an option.

CDP

haha...then I guess I'll just stick with my plan and just do a rebuilt.

NorCal124

when u say rebuild what are you planning to do? if you're going to remove the motor and strip it down all the way to the block to put new internal parts then that's an overhaul. to have someone break down and put back a motor is very expensive. you can purchase a rebuilt or new motor for the same or slightly lesser amount. the plus side to buying a complete motor is that you at least have a warranty if anything goes wrong as opposed to having a mechanic do the work w/ no or a limited warranty. and if you provide the parts for him to use you yourself have to deal with the warranties individually from each manufacturer or from where ever you got them from if anything were to happen.

Wadster

That's all true except this information is a bit outdated. You're not going to hear engine knock because for more than a decade, cars have been equipped with anti-knock sensors. The ECU will retard timing to account for lower octane. And keep in mind that from the early 90's on, Mercedes normally aspirated engines have a compression ratio of 10:1. So the few cents you're saving at the pump is probably lost as engine inefficiency.

P.S. Your '86 with its 9.2:1 compression is probably fine with no more than 89 octane.

jeffreyli86

i get about 26mpg... mixed driving conditions...
note that's with A/C on nearly all the time...
at best, i've had about 30mpg...

however, mine is a 93/94 E220 M111 engine

jrmd01

Sorry for bringing up an old thread, but I wanted to update what I posted on this thread about the O2 sensor.

I just changed mine yesterday with the Ford Bosch sensor. Someone was asking about the wires (2 white and 1 black). The black is self explanator, the white takes a little common sense...This is what I did to keep the wires accounted for: Since the black wire is in the center, I marked the RIGHT white wire with a RED marker and left the Left white wire alone. (Red=Right). I also cut all 3 wires at different length so that I could easily which wire belongs where. It took me 15minutes total to fix the O2 sensor. The car runs good.

Now if I can only figure out how to increase the idle a little...(maybe another 100-200rpm)

CDP

By the way...

I changed my old stock OEM filter to a K&N and Ive noticed that I've been getting better gas mileage. I guess I've been making my car suffocating. lol

jrmd01

Hey Chris...

I don't know what forum I read this off of, but somewhere someone said that the K&N were not good for our cars. I don't remember the exact reason, but it had something to do with the MAS, O2, and all those good little stuff. I think I'll change mine too, but I'm leaning towards OEM.

Can someone with expert knowledge on this please advise?

neanderthal

K&N isnt too big a deal on the 103 engined cars as they have the manual fuel injection. the 104 cars have HFM or something (hot film or hot wire) and the oil used in the filter can end up on the sensor, messing up its readings.

I wouldnt use one if it meant the oil was slowly being sucked into my engine., and it does.

Dav_Daddy

My mom drove her 76 Datsun F10 over 500,000 she used Pennzoil religiously. For years we used to see it around town the old couple she sold to still using it to pick up and haul around gardening supplies and whatnot.

Her last car a 94 Geo Prizm went to 415,000 although we ran many brands of oil it over the years. Motor was still strong when she went to the scrap yard. She'd still be driving it if it hadn't gone through 2 transmissions in 3 months.

I live in Phoenix, AZ with the average temperature here the manual for her 300E calls for straight 40 weight due to the heat. (Actually the summer temp here is so high it goes right off the chart.) Last oil change I used 30. Before that it'd need a quart every 4-6 weeks. Been over 2 months now and last I checked it was over half full. (Doesn't smoke the valve cover gasket needs replaced.)

I changed the O2 sensor with the Mustang one no problem. (Thank you SO much for the tip!) I didn't think to take pics, what I did was before cutting one of the two white wires I wiped some red paint on one, then also on the corresponding wire on new plug making them, black, white, and white/red.