Help - Anyone done a Gearbox oil change on a 380/410/430?

[Paul_D]

I'm attempting to change the gearbox oil on my 410, and I've got a bit stuck.

On cars with an oil cooler, the procedure is a bit different to the non cooled cars. You need to remove the oil return pipe and plug from the top of the gearbox.

The Lotus Service Notes state to remove the M6 securing screw (which I've done) and then "With the return hose still connected carefully withdraw the return plug from the casing"

Never mind carefully, I can't withdraw the bloody thing pulling on it fairly hard. I can rotate it slightly left to right, so it IS free to move. But when I try and pull it out it doesn't move at all. I've put a fair amount of effort in, but maybe not 100%.

Has anyone else done this? Was yours just the same? Do I just need to be stronger?

Any help appreciated.

Thanks.

[Seriouslylotus]

Paul

Is it the hose rotating on the plug or the plug rotating in the box? The plug has an O ring which can 'stick' or the plug can get stuck (seized into the gearbox). We carry the plugs in stock for workshop use for this very issue as they are easy to break if not careful. If the plug is rotating it will be the o ring stopping it coming out....!! 

[Paul_D]

@Seriouslylotus Thanks for the quick response mate.

The plug is rotating in the box. Well I assume so, as I could see the retaining piece that the fixing bolt goes through rotating. I guess that part is fixed to the plug?

So in theory it should just pull out with enough force? It doesn’t help that it’s not exactly easy to get to is it! 

To be honest, if that piece is easy to break I might just put it all back together for now. I’ve got a track day next week, so don’t want to risk making the car undriveable. 

 

[Seriouslylotus]

If the plug rotates it should come out, Its the plugs that are seized that stand a chance of breaking (In my experience)

[Paul_D]

@Seriouslylotus Ok, cheers. 
I’ll give it another go tomorrow then with a bit more effort. 🙂 
 

Out of curiosity, when it does happen, in what way does the plug break? Are you left with part of it in the gearbox? And if so how the the hell do you get it out without taking the box off?

[rmaurer]

I had all sorts of issues removing that plug on my car (2014 V6 S) when I fitted the KomoTec gearbox cooler. Here is the plug when out (tapped and threaded for the KomoTec temp sensor):

I snapped the original using a spanner to try and rotate it to free it off:

In the end I bought a socket off ebay that fits any shape and used that in an impact gun to break the seal free and remove the plug:

Edited June 16, 2022 by rmaurer

[Paul_D]

@rmaurer Thanks mate, that's useful information. 

[Paul_D]

Thanks for the help everyone. Got home tonight, sprayed a tiny bit of penetrating oil around the area (to try and lubricate the o-ring), gave it a little twist, and then it pulled out with virtually no effort. 🙂

[cuprapw]

Super helpful information @Paul_D. I have to do the same next month

BTW what did you use to check the level when refilling. Did you build a handcrafted dipstick as per the service notes ?

[Paul_D]

@cuprapw

I did indeed make a handcrafted dipstick, but really just as a sanity check. The problem being that in the service notes you manually run the oil pump for a while, then let it settle for 5 minutes before taking the reading. This means some oil will definitely be in the cooler loop before you take the measurement. Obviously I don't have the ability to do that.

What I did was measure out the amount of oil I'd drained out, and then replace the exact same amount back in. (This was exactly 3 litres)

The 'dipstick check' showed a level that was maybe a few millimetres higher than the services notes suggested, which would make sense if I didn't have as much oil in the cooler loop. The service notes say level should be 60 - 45mm below the casing, and I think mine was 40mm. 

[cuprapw]

Good point about manually run the oil pump, I can't do that either as I don't have the bloody lotus tech center. I will do the same you did.

Thank you for the tips:)

[Bravo73]

3 hours ago, cuprapw said:

Good point about manually run the oil pump, I can't do that either as I don't have the bloody lotus tech center.

Couldn’t you disconnect the plugs and turn the engine over with the starter motor? Would that achieve the same effect?

[Paul_D]

@Bravo73 The gearbox oil pump is electric and is only turned on when the car sees an oil temperature above 100°C and the speed is above 25mph. 

[Bravo73]

Ah, of course. I was thinking about engine oil pump. ☺️

[Toqcars]

I am pretty sure the best way is to change the oil in cooler as well. What if we just change the oil in the gearbox (without the oil cooler) once or twice per year. Wouldn't that keep the whole oil and gearbox quite healthy? Am I missing something important?

[Paul_D]

Yep, the gold standard for the job would be to drain the oil cooler at the same time, and also replace the oil filter.

In reality, changing 90% of the oil for fresh oil should give you most of the benefit. If you then change it again once it's been mixed up for a couple of months you'll then more or less have 99% fresh oil anyway.  That should be more than enough to keep the gearbox nice and healthy.

[cuprapw]

I did it 2 weeks ago, in my case 2.9 liters came out in mine. I also ended up with the level around 40 mm below the casing.

I'm checking now if there's a way to read the oil temp from the sensor, as It would be nice info to have