Exige leak on top of Transmission - LotusTalk - The Lotus Cars Community
 
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post #1 of 20 (permalink) Old 05-29-2019, 06:48 AM Thread Starter
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Exige leak on top of Transmission

After my last track weekend there was a fair amount of fluid on the undertray, maybe a few ounces. The transmission case seems to drip at the lowest point under the flywheel but the flywheel itself is dry. When looking from the top I can see fluid on top of the transmission, near the sensor and a few other plugs. When I remove the transmission fill plug the fluid level is even with the bottom of that hole, maybe a few drops come out but there does seem to be air pressure released when I remove that plug. The fluid in the transmission is 4 or more likely 5 years old. I also have the BOE oil catch can but when I drained that very little oil came out and the parts of the engine around that do not seem to have an oil mist on them. Do the plugs on top have a seal to them, would they develop a leak? Could the sensor be leaking? Should pressure build in the case or is there some type of vent that might be clogged? Any other thoughts on this or a fix? Trying to avoid pulling the transmission if I don't have to. I can try to get some better pictures but these should show the area I see the fluid.
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post #2 of 20 (permalink) Old 05-29-2019, 09:40 AM
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The vent is circled in this picture:

Name:  vent port.JPG
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I would think there is a chance of fluid being pushed out in case that vent is plugged, but I don't know for sure.
My amateur assumption is that the axle seals would be the first to leak in case there is pressure building up.

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post #3 of 20 (permalink) Old 05-29-2019, 09:54 AM Thread Starter
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Originally Posted by Mr.C View Post
The vent is circled in this picture:


I would think there is a chance of fluid being pushed out in case that vent is plugged, but I don't know for sure.
My amateur assumption is that the axle seals would be the first to leak in case there is pressure building up.
Thanks for pointing out the vent. Any way to test that? I would have though the axle seals would leak as well but I cannot see how a leak at the axle would end up on top of the transmission where I have it.
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post #4 of 20 (permalink) Old 05-29-2019, 10:27 AM
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Can you verify that the fluid you see is indeed transmission oil?
That stuff has a very distinct smell and should be easily identifiable.

The leak might be at any of the plugs or seals.
You should try to clean the transmission as good as possible (liberally spray it down with brake cleaner) and see if you can identify the source.

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post #5 of 20 (permalink) Old 05-29-2019, 10:43 AM Thread Starter
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I'm fairly sure it is transmission oil. It does not have as strong of a smell as the fluid in the transmission but it smells more like that then the oil in the oil pan. I can clean it up and try to see if I can find where it is leaking from, the issue might be running it at a high enough speed to leak and shutting it down before it spreads. I'll try that this weekend.
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post #6 of 20 (permalink) Old 05-29-2019, 11:28 AM
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The transmission doesn't really care much about speed but more so about RPM.
You should be able to do that at normal speeds in a lower gear.
Try to see if you can narrow the source down to a certain area.
After that, you can get some oil leak developer spray to identify the exact source.
I would also check and make sure all the plugs etc. are snug.

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post #7 of 20 (permalink) Old 05-29-2019, 12:13 PM
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How hard do you push on the track and how long are your sessions?

The trans oil can get VERY hot if you do not have a cooler. If your oil was a bit too full, it might have leaked from the relief valve (a bit too full makes it even hotter). You think you saw 60ml? Like 1/4 cup? That's quite a lot. My car has always leaked a bit of something after a track day, but not quite that much. I'd clean it up and see what happens for the next few track days. If you track more than once every few years, I'd change that oil now. I do not find MT90 works well (unlike others). I use Motul 75W90 or 75W140.

It is normal for the trans case to be under vacuum after cooling down from a heavy session.

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post #8 of 20 (permalink) Old 05-29-2019, 12:56 PM Thread Starter
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How hard do you push on the track and how long are your sessions?

The trans oil can get VERY hot if you do not have a cooler. If your oil was a bit too full, it might have leaked from the relief valve (a bit too full makes it even hotter). You think you saw 60ml? Like 1/4 cup? That's quite a lot. My car has always leaked a bit of something after a track day, but not quite that much. I'd clean it up and see what happens for the next few track days. If you track more than once every few years, I'd change that oil now. I do not find MT90 works well (unlike others). I use Motul 75W90 or 75W140.

It is normal for the trans case to be under vacuum after cooling down from a heavy session.
I took it easy this list time out but usually 20 minute sessions and I'd say the car is working a good amount. 1/4 cup might be on the high side, but in that range after 3 days on track where I cut several sessions short as I was watching the leak, maybe 60 minutes combined of hot laps.

I do not have a cooler as I have not read about many Eliges running one, I'll dig a bit more on that though. I do plan to change the oil before my next track day but would like to address the leak instead of just watching it the next time out. It might also be possible my garage is slopped enough for the oil level to be above the fill point enough to be causing an issue at high temps (especially if it is still at that level and I've lost some fluid).

Pic of undertray, some fluid still on the engine and some found its way onto the diffuser and ground, that's where my estimate on volume is coming from.
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post #9 of 20 (permalink) Old 05-29-2019, 01:26 PM
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Check you axle boots?
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post #10 of 20 (permalink) Old 05-29-2019, 01:32 PM
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Hmmm. I'd also question whether that is for sure trans oil (I don't mean to be rude, sorry). There is enough there to smell that sulphur stench. It is not that bad a leak though. I'd put it in a "normal amount" category.

I wonder if it is not coming from the dipstick block-entry-point and blowing round the corner. Is the side of the oil pan clean? I'd also check the oil cooler lines like a hawk.

You can always drain the trans oil, collect it and refill with it if you hate wasting trans oil (it is unfiltered and there is a nice magnet in there to pick up ferrous filings). The car should be roughly level when you fill it. Send a sample to Blackstone and they'll be able to see if something really nasty is going on in the box.

What model car are we looking at?

2007 Exige S
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post #11 of 20 (permalink) Old 05-29-2019, 01:32 PM Thread Starter
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Originally Posted by SS Lotus Elise View Post
Check you axle boots?
I have but will look again, no sign or wear on them over the winter. Just seems odd that much fluid is on top of the transmission. I'll get it cleaned well and see if it appears up top again or if somehow it is being slung up there (I don't think I spilled anything up there...).
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post #12 of 20 (permalink) Old 05-29-2019, 01:40 PM
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The CV joint grease is like sticky black tar and will not run. It will be spun everywhere. If the joint is going, the grease will boil and the boot will blow up like a puffer fish, then it will shrink back like someone sucked the life out of it.

If the oil is on top of the tranny, I bet it is coming out of that pressure relief valve.

Here is another obnoxious set of questions: is your BOE catch can tap shut? could it be leaking? do you clean that filter at the top of the catch can like EVERY track day?

2007 Exige S
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post #13 of 20 (permalink) Old 05-29-2019, 01:44 PM
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Check the bulkhead going into the catch can.
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post #14 of 20 (permalink) Old 05-29-2019, 01:46 PM Thread Starter
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Hmmm. I'd also question whether that is for sure trans oil (I don't mean to be rude, sorry). There is enough there to smell that sulphur stench. It is not that bad a leak though. I'd put it in a "normal amount" category.

I wonder if it is not coming from the dipstick block-entry-point and blowing round the corner. Is the side of the oil pan clean? I'd also check the oil cooler lines like a hawk.

You can always drain the trans oil, collect it and refill with it if you hate wasting trans oil (it is unfiltered and there is a nice magnet in there to pick up ferrous filings). The car should be roughly level when you fill it. Send a sample to Blackstone and they'll be able to see if something really nasty is going on in the box.

What model car are we looking at?
I'm not 100% certain it is trans oil but seems likely. I can do the dye stuff in one or the other to make sure, I'll try to clean and use some of that spray suggested earlier. The triangle shape ledge of the transmission in this pic is now fairly covered in the fluid, maybe it sprays around a lot but seems an odd place for oil to end up. I'll check the catch can fittings and hose again, maybe there is a small hole in that?

This is an '07 Exige.
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post #15 of 20 (permalink) Old 05-29-2019, 01:48 PM Thread Starter
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Check the bulkhead going into the catch can.
I'll check that, not much fluid in the catch can but could be a leak in that fitting and it is in the area.
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post #16 of 20 (permalink) Old 05-29-2019, 02:35 PM
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Maybe the fluid is not in the can because it is on top of the tranny . (sorry for the low blow)

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2007 Exige S
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post #17 of 20 (permalink) Old 05-29-2019, 02:55 PM Thread Starter
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Here is another obnoxious set of questions: is your BOE catch can tap shut? could it be leaking? do you clean that filter at the top of the catch can like EVERY track day?
The BOE catch can tap is shut, the drain hose was bone dry inside until I opened it, and fluid flowed for one maybe two seconds. Filter was cleaned over the winter and this was my second outing, so not cleaned Every track day but no oil comes out when I drain it so didn't worry about cleaning the filter. I'll inspect it tonight.
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post #18 of 20 (permalink) Old 05-29-2019, 06:21 PM Thread Starter
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It does not appear to be the catch can. I did find this hole while looking some more before cleaning, not sure what on the other side of this would leak though.
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post #19 of 20 (permalink) Old 05-29-2019, 06:28 PM Thread Starter
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Another pic of hole.
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post #20 of 20 (permalink) Old 05-29-2019, 07:04 PM
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There are all sorts of threaded holes on top of these transmissions to accommodate various applications. I'll attach a couple of photos. One is a photo of the top of an MR2 tranny I bought from MWR (the various c6x's look different, so don't focus too closely); it has a defunct speed-sensor (wires ground off) and a filler plug that I put in the reverse-switch location to keep the dust out. Another is a photo of the top of my tranny in situ; you can see the blue transmission oil leaking from the reverse-switch (blue wire is apropos) (I'll be tightening that or adding teflon tape).

As background, I had this tranny out over the winter for a rebuild (thanks Jon Vo at Trackspec). We put the SSC longer 3rd and 4th and a longer 4.3 final (now I don't need 5th at Sonoma and Laguna Seca but I do find 2nd to 3rd a bit far apart). We also found an oil control tube broken off in there getting chewed up and slowly spat out into my transmission oil cooler (those suckers are held in place with one bolt and one spot weld, the spot weld failed).
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2007 Exige S
Stripped down and turned into a track animal

Last edited by thebuzzard; 05-30-2019 at 09:28 AM. Reason: Typo
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