Cannot source a gearbox leak

[AJRFulton]

C64

Extreme near side of the car, it is covering the edge of my diffuser and spraying the camber arms and exhaust with gearbox oil. The oil on the diffuser top is at the extreme near side of the gearbox, suggesting it is coming from there (circled rough area in attached)

Drive shaft seals are dry, no sign of any leaking (and the oil on the diffuser is a fair bit away from them - under them is dry). Nothing coming out the breather either.

I cannot see any oil actually on the gearbox, and I've had it on the ramp. The gearbox seems dry - nothing at all obvious where its coming from, no residues even - it really is dry - there isn't really any part, seal or connection in the general area of where the oil is being found that I'd expect to potentially leak, which is really confusing me. The gearbox has just been reconned, so it's still fresh paint coating and 'should' easy to spot any leakages on it.

However it was leaking oil and giving a lovely plume of smoke as it hit the exhaust - but only occasionally, it was puffs rather than constant, and only when up at track temperature.

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[AJRFulton]

Perhaps a better illustration. Oil is being found on diffuser and body components in this area

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[Dev]

I would rule out the CV joint boot. If there is a little pinhole it can fling liquified grease mixed with contaminated water in the area of the control arms unless you are absolutely sure that it's transmission fluid. Generally the boot will remain somewhat clean until you find the hole which eventually gets worse. The area you point to is directly in the path of the inner boot.

[Call the midlife!]

Is the redundant speedo cable cap seated fully and screwed down? It's a bit of a long shot but might be venting when you're up to temp and driving it hard.

[AJRFulton]

I would rule out the CV joint boot. If there is a little pinhole it can fling liquified grease mixed with contaminated water in the area of the control arms unless you are absolutely sure that it's transmission fluid. Generally the boot will remain somewhat clean until you find the hole which eventually gets worse. The area you point to is directly in the path of the inner boot.

Definitely gearbox oil. 100%.

I'm going to have a have look again this afternoon, put the inspection camera on for a proper look.

I just cannot see how it is possible the gearbox case is completely clean of oil, but so much has leaked.

Only logical conclusion.... it's coming out at pressure. If it was weeping as opposed to spraying, it would surely leave a sign.

[Joesson]

I would rule out the CV joint boot. If there is a little pinhole it can fling liquified grease mixed with contaminated water in the area of the control arms unless you are absolutely sure that it's transmission fluid. Generally the boot will remain somewhat clean until you find the hole which eventually gets worse. The area you point to is directly in the path of the inner boot.

Definitely gearbox oil.

Something fishy!

[Dev]

I would rule out the CV joint boot. If there is a little pinhole it can fling liquified grease mixed with contaminated water in the area of the control arms unless you are absolutely sure that it's transmission fluid. Generally the boot will remain somewhat clean until you find the hole which eventually gets worse. The area you point to is directly in the path of the inner boot.

Definitely gearbox oil. 100%.

I'm going to have a have look again this afternoon, put the inspection camera on for a proper look.

I just cannot see how it is possible the gearbox case is completely clean of oil, but so much has leaked.

Only logical conclusion.... it's coming out at pressure. If it was weeping as opposed to spraying, it would surely leave a sign.

 What I do in a situation like this is use some paper towels and rub the areas on the transmission where you can get potential leaks to see if you can get the slightest wicking transfer of oil from where it escaped. I have found hard to find leaks this way.
 Another alternative of last resort is to try a UV dye kit which will certainly find it. Good luck.

[AJRFulton]

Taking the rear wing off gave me better access to get in and properly look. The pipe I thought was the gearbox breather from below was..... just a 12" bit of silicone hose that must have got tangled or dropped in during installation... funnily enough it's the same pipe the new gearbox breather was made from.

The gearbox breather, which I eventually found tucked behind a bit of the wheel arch guard..... has oil dripping from it.

Which now asks the question, the gearbox was empty and was filled with 2.2L of 75-90 Millers NT+, which is the spec sheet amount. It was definitely empty, bar some assembly lube on the internals - unless the gearbox fairies came in and filled it when it was out the car.

So why would my breather have spat out (an estimated) 250-500ml of oil, but only when at track temperatures.

[1979scotte]

Taking the rear wing off gave me better access to get in and properly look. The pipe I thought was the gearbox breather from below was..... just a 12" bit of silicone hose that must have got tangled or dropped in during installation... funnily enough it's the same pipe the new gearbox breather was made from.

The gearbox breather, which I eventually found tucked behind a bit of the wheel arch guard..... has oil dripping from it.

Which now asks the question, the gearbox was empty and was filled with 2.2L of 75-90 Millers NT+, which is the spec sheet amount. It was definitely empty, bar some assembly lube on the internals - unless the gearbox fairies came in and filled it when it was out the car.

So why would my breather have spat out (an estimated) 250-500ml of oil, but only when at track temperatures.

Is 2.2L correct?
I've never filled one up that was brand new or rebuilt but doesn't it usually take less than 2 bottles of MT90 which are just under 1L each.

[AJRFulton]

Taking the rear wing off gave me better access to get in and properly look. The pipe I thought was the gearbox breather from below was..... just a 12" bit of silicone hose that must have got tangled or dropped in during installation... funnily enough it's the same pipe the new gearbox breather was made from.

The gearbox breather, which I eventually found tucked behind a bit of the wheel arch guard..... has oil dripping from it.

Which now asks the question, the gearbox was empty and was filled with 2.2L of 75-90 Millers NT+, which is the spec sheet amount. It was definitely empty, bar some assembly lube on the internals - unless the gearbox fairies came in and filled it when it was out the car.

So why would my breather have spat out (an estimated) 250-500ml of oil, but only when at track temperatures.

Is 2.2L correct?
I've never filled one up that was brand new or rebuilt but doesn't it usually take less than 2 bottles of MT90 which are just under 1L each.

Service manual says 2.3L Dry, 2.1L Wet. I put 2.2L accounting for assembly lube and oil can squirts.

[1979scotte]

Taking the rear wing off gave me better access to get in and properly look. The pipe I thought was the gearbox breather from below was..... just a 12" bit of silicone hose that must have got tangled or dropped in during installation... funnily enough it's the same pipe the new gearbox breather was made from.

The gearbox breather, which I eventually found tucked behind a bit of the wheel arch guard..... has oil dripping from it.

Which now asks the question, the gearbox was empty and was filled with 2.2L of 75-90 Millers NT+, which is the spec sheet amount. It was definitely empty, bar some assembly lube on the internals - unless the gearbox fairies came in and filled it when it was out the car.

So why would my breather have spat out (an estimated) 250-500ml of oil, but only when at track temperatures.

Is 2.2L correct?
I've never filled one up that was brand new or rebuilt but doesn't it usually take less than 2 bottles of MT90 which are just under 1L each.

Service manual says 2.3L Dry, 2.1L Wet. I put 2.2L accounting for assembly lube and oil and residue.

No clue then.

Perhaps drain it and see how much you've lost.

The car drove well I assume?

[AJRFulton]

Few teething issues - I lost lift - but 95% it is a broken or dodgy wire as it has been a recurring issue on the car and well.... this is the 3rd engine it has happened on - there are no actual engine components affecting lift on this engine that have been reused from previous ones, so really a broken wire is the only thing it can be now.


Also started to develop a bit of hesitation at the top of the rev range as the session went on - again I reckon this is a loose wire - cam sensor being a likely culprit.

Issue with the loom is it is X amount of years old, and the car has had the engine out 9 times in my ownership, and god knows how many times it's been unclipped before I acquired it. Clips are starting to break often, and wires get snagged/squashed every time you move the engine in and out.

However that is it run in on the dyno, and did 30 odd track laps. Did a leak down test on the engine and it's giving excellent numbers and all within 1% - so fundamentally the engine is good.

I did want to do a compression test kit but I broke mine

[Dev]

Are you adding the amount based on the book value or are you adding it to where it is full and leaking out the filler hole to let you know it is full. There are some that use the speedo hole to fill the amount blindly  or they cram in the amount by pumping it in quickly into the fill hole and then quickly closing it off  without having it level off by having the excess drip out of the fill hole. If the transmission fluid is overfilled it will come out of the breather.

[AJRFulton]

Are you adding the amount based on the book value or are you adding it to where it is full and leaking out the filler hole to let you know it is full. There are some that use the speedo hole to fill the amount blindly  or they cram in the amount by pumping it in quickly into the fill hole and then quickly closing it off  without having it level off by having the excess drip out of the fill hole. If the transmission fluid is overfilled it will come out of the breather.

I have a 1L measuring jug I use for oil.

[Call the midlife!]

If it's a "standard" box it's around 1.9ltrs from empty so chances are it's been overfilled.

[Dev]

Are you adding the amount based on the book value or are you adding it to where it is full and leaking out the filler hole to let you know it is full. There are some that use the speedo hole to fill the amount blindly  or they cram in the amount by pumping it in quickly into the fill hole and then quickly closing it off  without having it level off by having the excess drip out of the fill hole. If the transmission fluid is overfilled it will come out of the breather.

I have a 1L measuring jug I use for oil.

Did you let the oil dribble out of the fill hole once it was filled up. 
That is the only way to know that its at the proper level.
 
The best way to know if you are losing fluid is to open up the fill hole and add fluid until it runs out. That will be the amount you lost. However if you open the fill hole and fluid comes out of it then it is for sure overfilled.  Let it drain from the fill hole until it stops and then cap it off.

[J88TEO]

"Is 2.2L correct?
I've never filled one up that was brand new or rebuilt but doesn't it usually take less than 2 bottles of MT90 which are just under 1L each"

That's how much I filled mine when I last changed the oil...lest than 2 bottles of MT90. I bought 3 thinking I needed 2.2L!

[AJRFulton]

Are you adding the amount based on the book value or are you adding it to where it is full and leaking out the filler hole to let you know it is full. There are some that use the speedo hole to fill the amount blindly  or they cram in the amount by pumping it in quickly into the fill hole and then quickly closing it off  without having it level off by having the excess drip out of the fill hole. If the transmission fluid is overfilled it will come out of the breather.

I have a 1L measuring jug I use for oil.

Did you let the oil dribble out of the fill hole once it was filled up. 
That is the only way to know that its at the proper level.
 
The best way to know if you are losing fluid is to open up the fill hole and add fluid until it runs out. That will be the amount you lost. However if you open the fill hole and fluid comes out of it then it is for sure overfilled.  Let it drain from the fill hole until it stops and then cap it off.

With 2.2L it looked full but not to the point of overflowing. I've always filled my gearbox with this guidance and it hasn't came out the breather - although this is the first time I've filled with >2.1L of oil as it is the first time I've filled the box 'dry'. However I've changed the oil in the box about 10 times (or rather... I usually strain the oil and reused it during an engine drop - at £60 a pop for oil that has done very few miles, I'm not in the habit of replacing it)

The service book I am using is American to be fair and states 2.4 Quarts of oil (2.3L) for a dry gearbox, and 2.25 quarts (2.1L) for a wet gearbox (I put 2.2L in the box) - However it is for the same gearbox number. Unless the European C64 had a different oil capacity? but then I have been putting 2.1L into a wet gearbox with no issues - seems reasonable to assume that there is 150-200ml of residual oil in a wet box after draining.

[jonbill]

do the US cars have an LSD? does yours? LSDs take up considerably more volume than open diffs.

[JB21]

2.2L is overfilled from my experiences with the C6* w/diff.

I done exactly like you with 2.2L and once hot I was struggling to engage gears, I'm presuming once hot the oil expanded further leaving no space in the box, causing the issue. Not sure if the C series boxes are under pressure, but that's what it felt like.

Once I opened the side fill hole and let it drain until it was level with the top of the hole, no more gear issues.

Recently done another service with 2 x 946ml bottles of MT90 and even then gear oil was pouring out of the side fill hole, I'd say 100ml or so lost. So with that i gathered the correct amount was 1800ml.

[J88TEO]

Recently done another service with 2 x 946ml bottles of MT90 and even then gear oil was pouring out of the side fill hole, I'd say 100ml or so lost. So with that i gathered the correct amount was 1800ml.

That's what happened to me...wasted quite a bit...

[Dev]

do the US cars have an LSD? does yours? LSDs take up considerably more volume than open diffs.

Most all US transmissions have open diffs. LSD was an option in 2004-2005 on very few cars and it was even more rare on manual transmission. It was observed by those that had LSD or had an LSD fitted that it does take a little less fluid than the open diff.

Edit: It appears that for the C56 transmission is 2.2 quarts and with LSD its 2 quarts.  The LSD does in fact take up more space. 
 

[Dev]

Are you adding the amount based on the book value or are you adding it to where it is full and leaking out the filler hole to let you know it is full. There are some that use the speedo hole to fill the amount blindly  or they cram in the amount by pumping it in quickly into the fill hole and then quickly closing it off  without having it level off by having the excess drip out of the fill hole. If the transmission fluid is overfilled it will come out of the breather.

I have a 1L measuring jug I use for oil.

Did you let the oil dribble out of the fill hole once it was filled up. 
That is the only way to know that its at the proper level.
 
The best way to know if you are losing fluid is to open up the fill hole and add fluid until it runs out. That will be the amount you lost. However if you open the fill hole and fluid comes out of it then it is for sure overfilled.  Let it drain from the fill hole until it stops and then cap it off.

With 2.2L it looked full but not to the point of overflowing. I've always filled my gearbox with this guidance and it hasn't came out the breather - although this is the first time I've filled with >2.1L of oil as it is the first time I've filled the box 'dry'. However I've changed the oil in the box about 10 times (or rather... I usually strain the oil and reused it during an engine drop - at £60 a pop for oil that has done very few miles, I'm not in the habit of replacing it)

The service book I am using is American to be fair and states 2.4 Quarts of oil (2.3L) for a dry gearbox, and 2.25 quarts (2.1L) for a wet gearbox (I put 2.2L in the box) - However it is for the same gearbox number. Unless the European C64 had a different oil capacity? but then I have been putting 2.1L into a wet gearbox with no issues - seems reasonable to assume that there is 150-200ml of residual oil in a wet box after draining.

  On my previous C56 gearbox which is a 5 speed that has an open diff I remember having to buy three quarts. It would take the full two quarts and once I got to the third and started pumping in very little it would run out. It felt like I was slightly less than 2.25 and much closer to two.

 On My C60 gearbox which is a short ratio 6 speed box for the 2ZZ with open diff it only takes exactly 2 quarts and then it dribbles out. I don't know why since its the same bell housing but its probably the additional gear that displaces the fluid is my best guess.

 The bottom line is the level is the level as indicated by the BGB procedure not the quantity that is listed.

[AJRFulton]

I do have a Quaife LSD in there, but I'm not getting any spillage on filling. As said, the oil level looks full but not overflowing.

I've always put 2.1L of oil in the gearbox and not had this issue until the rebuilt - which then had 2.2L of oil and giving the issue.

How do you know what gearbox you have? Mine is stamped C60 but........ I was told that it was a C64 based on the synchros as the rebuild ordered C60 synchros and they were different. The C64 ones matched and that is what is fitted.

But on various groups there is a bit of confusion with C6X boxes as what the box is stamped doesn't mean that is what is inside. Obviously I don't have the VIN of the original donor car.

I don't particularly like the gearbox I have for track use - it ends up in the range between gears a lot, but then it probably has about 40-50mph worth of gearing at the top end I don't need - it is the one part of the car that doesn't have a track focus - but it starts getting big money to track focus the box.

[Dev]

I do have a Quaife LSD in there, but I'm not getting any spillage on filling. As said, the oil level looks full but not overflowing.

I've always put 2.1L of oil in the gearbox and not had this issue until the rebuilt - which then had 2.2L of oil and giving the issue.

How do you know what gearbox you have? Mine is stamped C60 but........ I was told that it was a C64 based on the synchros as the rebuild ordered C60 synchros and they were different. The C64 ones matched and that is what is fitted.

But on various groups there is a bit of confusion with C6X boxes as what the box is stamped doesn't mean that is what is inside. Obviously I don't have the VIN of the original donor car.

I don't particularly like the gearbox I have for track use - it ends up in the range between gears a lot, but then it probably has about 40-50mph worth of gearing at the top end I don't need - it is the one part of the car that doesn't have a track focus - but it starts getting big money to track focus the box.

 The way Toyota lists gearboxes can be confusing.  There are two families of gear box housings as an example there is the C50 and the other C60 and it is what will be stamped on bell housing which is not the actual gear box designation. However for whatever reason Toyota will call their first gearbox in the family the same as bell housing designation. To add to the confusion some C5X boxes will have a C60 bell housing. 

 The C64 gear box has the same gear ratios as my C60 gear box but the only difference is the 6th gear is shorter on the C64 which is probably better geared for track as that is what I read. 

 I also felt that the C60 short gear ratios was in-between gears but over time I adjusted to it for street use by having the motor rev higher when performance driving than how I would drive 1ZZ where I am keeping the revs lower.

  What I would do in the present is lift the car evenly and open the fill hole. If fluid comes out then it was overfilled. If not add fluid until it does to have the proper amount.  If it continues to spray fluid then its some other issue with the gearbox that needs to be investigated.