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Discussion Starter #1
I know this gets asked all the time, but there is so much conflicting information out there. I flushed the tranny over the weekend, replace the plug, gasket and filter and since then the levels have been all over the place. I have the special dipstick which has hot (80deg C) and cold (25deg C) readings. From a video I was watching, the car sitting cold should read between the two bars for the 25deg C mark, however the proper way to check the level is with the engine running. As soon as the engine is started, the fluid starts heating up. Not to mention that after the first level reading, there is residual fluid in the tube that will accumulate on the dip stick and throw off your reading. I have also read that you ONLY check the temp when hot. That would mean aligning the level between the two marks for 80degC. Another conflict - someone on mbworld contested that you must check the level in gear and not in park... what? I am really nervous about checking the 722.6 level when hot as that means go drive the car hard for 20mins and then check the levels - what if you overfill, underfill before you take that drive and also... wouldn't that put your oil temps over the 80deg C temp? Hopefully the tranny is more resilient than what my gut is telling me and I won't do much harm until I get the level where it should be. However, can you please advise the CORRECT way (hot or cold, engine running and how long) to check the tranny fluid? Do I need to check the fluid temp on the dipstick with an IR thermometer? It can't really be that hard to figure out, what am I missing?

 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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If it's underfilled one symptom is the transmission will disengage sporadically. And yes, the fluid participates in cooling the transmission so the wrong amount of fluid can bias the temp (in theory at least). Safest would be to measure the temperature before measuring the fluid level.

I thought the fluid should always be checked with the engine running.
 

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Discussion Starter #3
Found another article from Pelican that is more suitable for my car...

Pelican Technical Article: Mercedes Benz - Automatic Transmission Fluid Change

This part here...

Here's where the procedure gets a little tricky. You'll need to monitor the temperature of the fluid as the car warms up. For this task, an infrared pyrometer is an invaluable tool. This tool allows you to point a laser beam at any given object and see the temperature in both Fahrenheit and Celsius scales. In this case, you would want to set the tool to Celsius and point it at the transmission pan until it reads roughly 80 degrees C (this will take a while). At this point, pull the dipstick out and read the level. If the level is correct, it will read between the lines for the 80 degree gradient on the dipstick. If it does not register, add more fluid until it does. You'll need to have the engine running and the transmission in park as you do this. Keep in mind that you will need to circulate the fluid between each time you fill by running the transmission through the gears. Once done, put the car back in park and re-check the level. It's a time consuming process, and you want to make sure that you get it just right. The fluid level MUST be correct or you could cause damage to the transmission.
 

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I agree with jpowelso that it would be great to have a definitive explanation of this. It seems bonkers, you wouldn't think it would be so hard!

My experience recently of this was that taking the level when cold is maybe a waste of time, I was advised the reading didn't mean much.

When warm, but how warm?, I'm getting a level half way along the plastic part of the stick, exactly in the middle of hot and cold, which therefore might mean I'm a little low. But then the box is working perfectly, so I don't want to add and overfill.

But maybe 5 miles ain't enough to warm it, maybe I should have been in gear not park (really!?)

Anybody know how a dealer would do it?
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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Buy a cheap laser thermometer and measure the temperature at the transmission pan?

Just because the car is moving and the transmission is shifting as you expect doesn't mean the level is correct!

I have a small 5' tube; I push one end down the pipe until it reaches the pan; put my finger over the other end; pull the tube out, and measure the depth. I'd buy the tool if I wasn't so cheap :)

If you use a tube like this, you'll find there are two bends in the pipe to push through before you actually reach the pan.
 

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Discussion Starter #6
Takes a bit of patience, but I in the end I got it just right. Right now I have the levels sitting right between the two lines for 85degC. Checking the level when cold, did me no good (car running). I was mostly concerned about causing damage by being overfilled/underfilled, however I was slightly underfilled at first and took her on a good 25+ minute drive and drove pretty hard. When I brought it back in the garage I was right at the bottom line of the 85degC marks. I added 2-3 ounces, and drove around another 10-15 minutes. That's all it took. When I came back my levels were perfectly centered between the marks. Be very careful when adding fluid --- when getting close, it's literally just a few ounces off, give or take. I had already read this in another post, so knew going in and only added fluid in small increments. BTW I used all Mercedes parts (gasket, plug, and filter), however I filled with Valvoline Max Life ATF (red bottle) which is rated for the 236.10 (772.6) tranny.

*edit* temping the oil pan, my temp gun never read 80degC as was suggested in that Pelican article. Only way was to go out for a drive. Have fun!
 

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Discussion Starter #7
I'm having a little bit of an issue. It's been almost a week since I changed the tranny fluid, been driving every day. Came out this morning and there is a puddle of fluid under the car. I had replaced the plug and gasket. Looks like fluid coming from the pan. I think I tightened the 6 bolts while the tranny was raised with my jack. Could I have a bad gasket? Bolts were pretty darn tight.
 

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I'm having a little bit of an issue. It's been almost a week since I changed the tranny fluid, been driving every day. Came out this morning and there is a puddle of fluid under the car. I had replaced the plug and gasket. Looks like fluid coming from the pan. I think I tightened the 6 bolts while the tranny was raised with my jack. Could I have a bad gasket? Bolts were pretty darn tight.
I certainly am no authority when it comes Mercedes transmissions but I have had some experience with autos built by domestic manufactures. Both with older classics and modern rides. Drag strips in particular are very picky about oil leaks of any kind on their tarmac. My experience has been the bolts can easily be over tightened, thereby causing the pan to be just the least bit malformed. Transmission fluid has a way of escaping. Sometimes it seems to have the ability to seep through a glass Ball Mason jar. Did you check the torque chart? most domestic vehicles are in inch pounds. Mercedes probably use a different system.
 

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Discussion Starter #9
I certainly am no authority when it comes Mercedes transmissions but I have had some experience with autos built by domestic manufactures. Both with older classics and modern rides. Drag strips in particular are very picky about oil leaks of any kind on their tarmac. My experience has been the bolts can easily be over tightened, thereby causing the pan to be just the least bit malformed. Transmission fluid has a way of escaping. Sometimes it seems to have the ability to seep through a glass Ball Mason jar. Did you check the torque chart? most domestic vehicles are in inch pounds. Mercedes probably use a different system.
That is probably what I did then. This is my first completely DIY car and I tend to make a few mistakes. Would it be recommended to drain and pull the pan off and clean the gasket, or just set bolts to correct torque? I was out of town this weekend, so I am just now addressing the issue.
 

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Discussion Starter #11
Well this just got interesting. Oil is dripping from 3 of the 6 bolts. Two of them I apparently stripped. I was definitely over-tight, but now in a predicament. Oil is dripping at a pretty good rate since Thursday evening.

1) I need to figure out if I stripped just the pan bolts or if I need to go helicoil (which material fails first pan bolt or tranny side?)

2) Should I be considering warped pan or damaged gasket like I originally thought? I live in a rural area so I must order my parts which creates more downtime.

One thing is obvious, I have to drain all of my new fluid and pull the pan. Any more thoughts or suggestions on this one?
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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Reuse the fluid!

If my middle name isn't "heli-coil" it's "JB Weld".

MB recommends replacing the pan bolts every time, which tells me they're sacrificial. Did you reuse yours?
 

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People just drain the transmission fluid without thinking to measure the drain. If you add back what you have drained out, you'll have no worry about the level being too high or too low. Then correcting the level after service is no more than a minor adjustment.

This one will really upset you. Some shops and DIYer never bother with the finer points of this service. They just add back what was drained out plus a smidgen more to make up for any difference and button it up.

The pan bolts are very fragile and need to be replaced at every service which will likely be once! As for reading the temperature, forget it. When the car is thoroughly warmed up, it'll be at the right temperature or close to it. And suppose it isn't? What are you gonna do about it?>:D

BTW, the reason to thoroughly warm the car up is to have the ATF completely circulated in the system. It is only then you can check its level.:nerd:
 

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Discussion Starter #16
Wow... just wow. I don't know how I managed to do this, but pulled the pan today and there is a tear in my new gasket. I also found threads from the transmission housing on the two pan bolts. The pan bolts appear to be fine. In an attempt to inspect the pan for warping I laid it upside on the flat surface in my garage and if it is malformed, it is off maybe 1/8 inch. Not sure if the pan is the problem with the leaking. Tear... definately.

I have attached a pic of the gasket tear. I think the gasket was NOT OEM, like the filter and plug in my purchased flush kit.

Now for the helicoil... I believe the pan bolts are M6x1.00x30mm, so what size coil do I need?

Crossing my fingers that the stripped thread holes can all be drilled a little for the helicoil (through holes).
 

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Have you tried running a tap in the holes? If you were able to get the bolts out, then you should be able to do this to clean out the threads.

Also there isn't that much wall material to put in a helicoil. You might be able to drill and tap out to the next bolt size - maybe?
 

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Discussion Starter #18 (Edited)
I don't have a tap set, so I have not tried this. Pretty sure I would not be able to clean the holes since thread was lost. Bigger size, sounds better, but I would also have to drill our the spacer that clamps down on the the pan.

Should I be worried about my pan, since the gasket was torn? Don't know how that happened by over-tightening. Cheap gasket?
 

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If your pan isn't flat on the flange I'd get another.

The heli-coil kit ( tap and insert ) should be labeled with the bolt size you're putting into the repaired hole.
 

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I don't have a tap set, so I have not tried this. Pretty sure I would not be able to clean the holes since thread was lost. Bigger size, sounds better, but I would also have to drill our the spacer that clamps down on the the pan.

Should I be worried about my pan, since the gasket was torn? Don't know how that happened by over-tightening. Cheap gasket?
I don't know what you mean by the thread was lost. Exactly how did you remove the broken bolt? There are likely some vestiges of threads left in the hole.

I would buy a tap and try it before you go any further.
 
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