Doubts about the oil level in the gearbox of a 2004 Mr2 6-speed manual.

[Dev]

I filled my C60 transmission, which has a similar plugs. The one with the hex is wrong and I got the wrong information from members on Spyderchat. What ended up happening is having a strange vibration with my transmission that could be felt through the clutch pedal when shifting gears. The vibration may have been enhanced because I'm using polyurethane mounts. It might not be felt with the rubber mounts, but it could probably destroy the transmission overtime with the wrong quantity of fluid.

 I come to find out that was the wrong plug after looking at the service manual, which I should've done instead of trusting what you read on the Internet. After filling the fluid in the right hole with the right quantity of fluid, the transmission was working great afterwards. It's good to get information on a forum, but it's always better to double check the manual to verify as you have done.

[Carolyn]

So the 'how to' on this site is incorrect?  I which case it needs to be corrected.  I have an MR-S with a five speed box so I'm not up to speed on six speed boxes.

Any assistence with corrected wording (and illustration) would be appreciated,  so that I can make the correction.

[alexcap]

There was some great teamwork here.
It would be great if you could correct shnazzle's guide "Change Gearbox Oil " in "how's to" because there will probably be also someone with a 5-speed gearbox that runs with more oil than necessary.
I'm not the best person to make corrections or write anything because I don't know much English, but if you need any photos, I still have the car up on the jack stands.

[Carolyn]

@alexcap

Photos with clear markings indicating the correct fill plug would be superb.

I don't think there's an issue with five speed boxes as they don't have the hex key plug.

[Dev]

Also a good idea to get a new set of the aluminum crush washers when doing the job. I had an issue where I reused the washers and developed a tiny leak on the drain plug because of my incompetence of over tightening it to the point where I thought I stripped the threads. Thankfully, it was just the washer that was overly crushed and now I use a torque wrench on those bolts.

[Beachbum957]

A picture showing oil fill plug for C60 (biggest picture I could find.


Diagram from Toyota 6 speed SMT shop manual


We have been running 2 MR2 with 6 speeds (one C66, and one C65 converted from SMT).  Both were filled using the same plug as the 5 speed (now identified as the wrong level plug).  One has 20,000 miles on the last fill, and the other has 24,000 miles and neither has any issues.  In fact, the C66 was bought used and had a noisy 3rd gear, which has gotten quieter over time.  

[Joesson]

@alexcap

Photos with clear markings indicating the correct fill plug would be superb.

I don't think there's an issue with five speed boxes as they don't have the hex key plug.

Am I misremembering a hex key plug on my 02 5 speed?
I recall having a " choice" but the correct one did become very apparent, but it was some time ago.

[Carolyn]

Thanks everyone for cooperating on this.

I have modified the 'How To'.

Please have a look and give any changes/input.

https://www.mr2roc.org/index.php?topic=62272.msg725375#msg725375

[Ardent]

@Carolyn

My 2p would be at step 3.
Check the filler can be removed. Before draining.

And for the ocd amongst us, the torque settings.
Filler and drain plugs. 39 nm

[Ardent]

Speedy updates. Well played C.

[Dev]

I have been curious about the hex plug and what is its purpose. I have been told before that it's called a service plug, but for what I don't know and I have always been curious.

I asked ChatGPT and got a very good answer. Having said that I haven't had any issues with the fill plug on a level surface. I did run into issues with filling from the hex plug where it didn't take the right quantity of fluid. I suppose I will doing it like the method below just because I feel it should be done correctly. It makes me think that when you add fluid into the full plug, some of the transmission fluid fills a cavity which overflows to the other side based on the tilt of the transmission. This is why you cannot fill from the hex plug because the transmission fluid will not pool in the right areas and instead drip out the plug early.

One plug is the actual fill port, and the other is a fluid level / inspection plug.

Why Toyota did this

The MR2 Spyder's mid-engine layout means the engine and transaxle sit at an angle, not perfectly level like in many front-engine cars. Because of that:
    •    Filling from a single hole could overfill or underfill the transmission.
    •    Toyota added a level-check plug so the correct fluid height can be verified regardless of the car's orientation.

How it works (manual transmission)
    •    Upper plug → Used to add fluid
    •    Side/lower plug → Used to check correct fluid level
    •    When fluid just begins to drip from this plug, the level is correct[/

[alexcap]

Thanks everyone for cooperating on this.

I have modified the 'How To'.

Please have a look and give any changes/input.

https://www.mr2roc.org/index.php?topic=62272.msg725375#msg725375

Maybe it would be better to remove the last phrase and the last photo currently in the "how to" because the axial inclination has a greater effect on filling a 6-speed gearbox, which has the filler cap moved to the edge of the car, rather than a 5-speed gearbox, which has a more central cap.


I am adding a photo I took of the 6-speed gearbox if it may be useful.

[Carolyn]

Excellent.  You are a real asset to the club.

Changes made.