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Discussion Starter #1
Hi Guys,
Just bought a Prius MK1 (NHW10) which was a Jap import in New Zealand in August 2003. Before I bought the car I knew that it has got a transmission oil leak. We have inspected it a bit more in detail. There is
drain/vent hole on the bottom of the motor housing which is used for draining out any leak. The transmission oil is leaking through this hole. I have now kept the car in my garage and put a paper underneath. Will inspect this evening to see if there is any spillage. I will suspect that there might not be any spillage at all. I would think it would only happen when the car is moving and the transmission oil is churning.

In order to inspect this leakage, the engine needs to be taken out. Understand that that there is a master switch on the back of the car attached to the main battery. Is it safe to turn the main battery off with the help of this switch and then work on the engine? Will that reset the Navigational system? What implication the main battery will have if it is turned off.

See the problem here in New Zealand is Toyota does not want to know that MK1 owner exists in this country and other mechanics do not have much expertise to handle this car. Hence we owners have to be quite
knowledgeable in order to service this car.

If some one can share a service manual for MK1 or MK2 (NHW10 or NHW11), that would be the best. I would not think that there is a lot of change in MK1 or MK2. Understand that in US, people should be having MK2 service manual in English.

Going back to my earlier query, I need to have this Transmission oil leaking problem sorted. Appreciate all kinds of help. Please let me know your thoughts.

Kind regards
 

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Hi hannah,
Sounds like you've taken on quite a project. You definitely want to disconnect the hybrid battery before working on the motors. In the NHW11 model, this involves pulling a connector from the middle of the battery pack while wearing electrician's gloves. I don't know about the NHW10, but it does have a significantly different battery pack. So it doesn't sound like NHW11 information will help you with that.

Disconnecting the hybrid battery will not affect the Navigation system. That's powered solely from the 12 Volt supply. But the Toyota manuals usually suggest disconnecting the 12 Volt supply also when working on major engine/transmission components. That probably will erase Nav info, but I'm not sure (my 2001 didn't have that option available).

The oil leak may also be troublesome due to model differences. For the NHW11, Toyota changed the way the oil seals worked and the position of the oil pump.

Anyway, the NHW11 repair manual suggests 4 possible causes for transmission oil leakage:
- Oil level too high
- Gasket on the drain plug damaged
- Differential oil seal or input shaft oil seal worn or damaged
- O-Ring between oil pump and transmission worn or damaged

The first two aren't too hard to deal with. The third requires removing engine/transmission, then separating them. For the NHW11, the fourth can be done "on vehicle" by removing the oil pump and replacing the O-Ring. But I recall that the NHW10 has the oil pump on the engine side, so it may be harder to access.

There's are special Toyota tools called an SST for removing and replacing the oil seals (part. no. 09308-00010 for removing, 09350-32014 for replacing). They also list parts 09351-32130 and 09351-32150, perhaps as substitutes, I don't completely understand the nomenclature. I can't find part numbers for the actual seals, so maybe they're part of a kit?

Well, good luck, but if it's more that the first two, you probably need to track down the NHW10 repair manuals.
 

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Quick follow up. The parts listed above were for the differential oil seal. For the input shaft oil seal, the replacement tool is part 09388-40010. There is no removal tool, a hammer and flat-head screwdriver will do it, but they warn you to be very careful not to damage the input shaft and transaxel housing.

Oh yeah, the repair manual uses the term transaxel, not transmission.
 

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Discussion Starter #4
Guys,
Just thought that I will give you a quick update on my Transmission oil leakage problem. First we drained all the transmission oil and then refilled it. Then cleaned the affected area and drove the car for couple of days. What we are trying to do here is to identify where the leak is coming from. We found the bolt circled is where the leakage was happening (this is around the transmission oil tank). Took the bolt out, cleaned it and then put silicon on it and then put it back. There is no leakage problem now. It cost me NZ$50 to do the whole job.

cheers
 
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