Sprung two coolant leaks on a track day!

Hey all, Sprung two leaks at my first track day yesterday one is from the coolant plate on the back right side of the engine. This was leaking a few years ago but stopped so I didnt replace it - should have! The second is from the back left side of the engine, my understanding is that it could be the hoses to the AOS or perhaps the hoses to the coolant tank? Just trying to get some intel before I start the inspection (my car is in its off site garage). Whats the torque on the two bolts that hold the plate in place? Have this pic from Asahi: The second leak seems to be coming from just above the sway bar, any guesses aside from the AOS? Coolant tank was replaced around 3 years ago but maybe the hoses running to it? I also have a Uview 55000 on the way just need to figure out the second leak! Also one other question - if using a vacuum filler/bleeder do any hoses need to be removed to drain off coolant? Or can all the coolant be drained via the mail plug then the vacuum filler/bleeder can remove the rest before refilling? Thanks

Posted this awhile back, can't quite see where the hoses to the AOS run on this one though.

Hey Dan, Sorry, I have no suggestions on the second leak, but can tell you Ahsai's coolant draining procedure is the real deal! Simple and effective coolant drain

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Thanks I had read that before looks like a great procedure - I've got a uview on the way so ill use that to evac the remaining after removing that main hose. Now to find that second leak!

Dan, with Ahsai's method, you don't need the uview to empty the system, only fill it. I'd have a look at your tank and associated fittings. They seem to be notorious for leaks and trouble, particularly on the 996.1s. Admittedly, it's really hard to get a good view up in that area, as it's really tight. Good luck and keep us updated!

Thanks JTT Got the change to get under there today, not great news but not terrible news... Looks like its definitely leaking from that cover but it also looks like there is a leak from above the cover too, highlighted on this image in blue:

That doesn't look like fun to get to. I seem to remember when I had my transmission off, it was accessible.

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Looks like an absolute royal PITA if it's the cooler that's leaking. I know the coolant cover is leaking too so I'll replace that first and then retest. Hoping the coolant sprayed upwards?? I'm just being very very optimistic

Does anyone know if it could just be the rubber O rings that are leaking on the oil cooler possibly? Or at 14+ years old maybe ill just swap the exchanger out with new O rings and save the hassle later on? Seems like a big job

Quick question - didn't want to resurrect that thread! So am I correct that these are the complete drain steps: 1. Remove coolant drain plug 2. Re-insert drain plug 3. Remove big hose to the thermostat 4. Keep big hose disconnected - blow under 10PSI down the coolant reservoir neck 5. Remove drain plug again 6. Remove heater core coolant supply line (keep big hose disconnected) 7. Blow under 10PSI down heater core supply line? 8. Reconnect all lines Any assistance from @Ahsai would be much appreciated! Thanks!

That sounds right Dan, but Ahsai will confirm I'm sure. Its been a couple of years for me and I've only done it the once, but it works incredibly smoothly.

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Thanks, got a bit confused with the instructions will make more sense when I put it in application - at present it's just theory to me!

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Yes, those steps look correct to me as far as I remember. You could just follow my diy write-up.

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Thanks, there were just a few points I wanted to clarify I used your write up as the basis - thanks! Any tourqe specs on that coolant cover/plate? What's it there for?

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7.5ftlb or 90inib and please use only an inlb small torque wrench.

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Thanks Ahsai, I have a 1/4in torque wrench that has inlb - didn't even know that was a thing until I bought it! That in the factory manual thought I sifted through it but couldnt find it

Another question for everyone, can the heat exchanger O rings be changed without removing the unit completely? Not really keen on removing the PS pump or the AC compressor. Was hoping to replace the O rings if need be by undoing the bolts from the top and then replacing the O rings from the back perhaps - or am I being way too optimistic and the PS pump, AC compressor and right side manifold need to come out? Was thinking about removing the airbox, throttle + plenum - then getting in that way undoing the heat exchanger bolts (they are also 7.5ftlb/10Nm to do back up) and replacing the leaking O ring from underneath if I can reach up behind and just slide it out of the way?

I would think you'll need to drop the engine 4"- 6" to give you enough room to work up/back there... It's been 2 years since I had my engine out so it's a bit foggy now, but I know it's an extremely tight spot. Either way (dropping engine or removing PS pump & AC compressor), it's a lot of work to get back there. Take your time and do it right, so you don't have to do it twice!

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Thanks dporto, I got back there (removed airbox, throttle body + plenum) used to doing that now. I've got a good shot at the two left bolts - right bolts look harder but not impossible - will need to work by feel + extensions etc. I'm not keen to remove the P/S pump or the A/C compressor so i'm going to give this a shot by passing the exchanger down the back of the engine and out! Failing that i'll take out the P/S pump + A/C compressor and remove it through the back. Or remove the starter for more room. An update on this though - spent some time diagnosing the leaks - appears the heat exchanger is shot - leaking coolant from the bottom, top and the back of the unit. There is coolant pooled on top of it as well. Initially thought it was a hose but I think its self combusted. One thing I absolutely cannot work out is why there is also coolant below the starter with no trail to the heat exchanger?? Nothing is wet around it/above it - lost on that one. Only thought is it could have spewed out at some bizarre angle and pooled under the starter or there was a trail from the exchanger and it may have dried but has pooled in the engine crevasses - thats the only logical explanation I have. So much for me thinking it was just the coolant plate!

Okay so latest update for anyone following along! Drained the coolant and then got the 4 bolts holding the unit in place out - relatively straight forward with some joins and extensions. Haven't removed the unit as yet but I spoke to a tech friend at an OPC who said I'd only need to remove the renosance tube (2nd intake tube). Any tips on removing that? Assuming it's just loosen the 4 clamps and pull it out from the left? Last time I tried doing that I couldn't get it free and gave up. Does one side of the intake have to be loosened?

Okay! I'll answer my own question here haha. The 2nd intake needs to come out but unlike the front plenum the second needs to be pushed to the front of the car and removed. That was a pain! To get it back in put the left rubber boot on and then secure it down. Put the right on the plenum and put the right side on the intake and pull the left into the rubber. Got the chance to see if it holds vacuum - does! Just have to fill it now

Hey all, Got yet another leak over the weekend - an intermittent one but enough for me to have lost about 2.5L of coolant and get the coolant low warning light. Whilst looking for the leak I checked my new oil cooler looks like its very white all over it like its leaked coolant and its dried? I don't think it should look like this - it was a brand new Behr unit:

Bummer, hopefully it's just the coolant hose. Do you have a borescope?

Thanks Bill, I don't but i'm thinking about getting one. Its a strange leak had it on yesterday and nothing leaked