This Porsche Cayman 987 came to us with coolant in its gearbox. Another workshop had already replaced the transmission cooler and flushed the gearbox oil three times, but coolant was still inside. Here is what we found and what we did.
Job completed: August 2026
| Car | Porsche Cayman 987, Tiptronic automatic gearbox |
|---|---|
| Symptom | Coolant in the gearbox oil that three flushes at another workshop did not clear |
| Fault found | Coolant still inside the gearbox when our team opened it |
| Repair done | Full gearbox overhaul |
| Parts | Quality overhaul parts and fresh transmission fluid |
| Time taken | Timeline confirmed after strip-down |
| Cost | Quote shown in the cost section; final bill not published |
| Warranty | 2 years or 40,000km on the gearbox overhaul, whichever comes first |
Coolant had got into the gearbox oil on this Porsche Cayman 987. Another workshop had replaced the transmission cooler and other cooling parts, and flushed the gearbox oil three times. After the third flush, the owner was told there was still coolant inside. He came to us having already spent money on a fix that had not worked.
This Cayman 987 has a Tiptronic automatic gearbox, a hydraulic unit that depends on clean gearbox oil. Its gearbox oil runs through a transmission cooler that also carries engine coolant. If that cooler leaks inside, coolant can get into the gearbox oil.
Coolant in a transmission is serious because water strips the lubrication properties from transmission fluid and causes rapid wear of internal seals and clutch pack materials. The longer it runs contaminated, the more damage builds up inside the unit.
Before the car came to us, the transmission cooler had already been replaced at another workshop, and the gearbox oil had been flushed three times. Coolant was still inside after the third flush.
When our team opened the gearbox, there was still coolant inside, with milky residue in the casing. A flush changes the oil. It does not repair seals or clutch materials that coolant has already reached.
On this gearbox, the oil runs through a transmission cooler that also carries engine coolant. If that cooler leaks inside, coolant gets into the gearbox oil.
Once coolant is in, changing the oil does not repair the seals and clutch materials it has already reached. The job record does not show how the coolant first got into this gearbox, so we will not guess.
We stripped the gearbox down and overhauled it with quality overhaul parts and fresh transmission fluid. The torque converter was quoted as a separate item.
When the work was done, our team told the owner the car was good and ready for collection.
Our quote for this Cayman put the gearbox overhaul at $4,800 and the torque converter at $1,800, both including GST, before a discount. That is the quote, not the final bill.
What another car costs depends on the condition of the internals and whether the torque converter also needs attention. We quote before any work begins. The overhaul comes with 2 years or 40,000km warranty, whichever comes first.
Check your transmission fluid colour if you ever notice a sweet smell from the engine bay, unusual shifting behaviour, or overheating. Milky or discoloured fluid is a warning sign that coolant has entered the gearbox.
Do not keep flushing if the fluid keeps coming back contaminated. That can mean the leak is still there, or that coolant is still inside the gearbox. Acting early before the clutch pack absorbs too much coolant keeps the repair cost significantly lower than a full overhaul.
This Porsche Cayman 987 (Gearbox overhaul) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. For Porsche, we use dealer-level PIWIS diagnostics. The work is backed by our 2-year, 40,000km warranty. We hold a 4.9★ rating from 1,836+ Google reviews.
WhatsApp us your car model, mileage and the symptoms. We diagnose the root cause first, then quote before any work begins. Gearbox overhaul comes with 2 years or 40,000km warranty.
We quoted this Cayman's gearbox overhaul at $4,800 and the torque converter at $1,800, both including GST, before a discount. The figure for another car depends on what is found inside the gearbox. We quote before work begins and the overhaul comes with 2 years or 40,000km warranty.
Not always. Flushing changes the oil, but it does not fix a leaking cooler, and it does not repair seals or clutch materials that coolant has already damaged. On this Cayman, coolant was still inside after a cooler replacement and three flushes at another workshop, so we overhauled the gearbox.
On this gearbox the oil runs through a transmission cooler that also carries engine coolant, so a leak inside that cooler lets coolant into the gearbox oil. On this Cayman the cooler had already been replaced at another workshop, and coolant was still inside the gearbox when our team opened it.
It depends on parts availability and on what we find when the gearbox is opened. We confirm the timeline once we have assessed the condition inside, and keep the owner updated throughout.
Yes. We use PIWIS, Porsche's own dealer-level diagnostic system, to read gearbox fault codes, run adaptation routines and verify correct operation after the overhaul. This is the same tooling used by Porsche authorised service centres.
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