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Discussion Starter · #1 ·
My 91 Previa is leaking a bit of oil just under the sliding door. I am pretty sure the distributor cap and shaft O rings are the culprits. Has anyone here worked on them? how hard was the job and any special tools required?

Another issue is the engine light comes on and off, I was told the O2 sensors are "flashing" and I only need to replace the front one, what's the part number for that? Thanks...
 

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Has anyone here worked on them? how hard was the job and any special tools required?
I did the job with relatively little knowledge. I recommend buying a Previa repair manual. sense its under the car you have to do the hole job on your back. I recommend using some eye protection. As for tools I dont remember exactly but a basic tool kit will get the job done.
 

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Discussion Starter · #4 ·
It could also be the valve covers leaking-have you eliminated that possibility? That is a pretty straighforward job.
The leak is right beside the exhaust pipe/cat, so I am thinking its the distributor seals. Its a slow leak but because its drips onto the exhaust pipe, I smell smoke and afraid the van might catch fire unless I power wash it once awhile.
 

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97 Previa DX AWD; 97 4Runner 5 spd
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The leak is right beside the exhaust pipe/cat, so I am thinking its the distributor seals. Its a slow leak but because its drips onto the exhaust pipe, I smell smoke and afraid the van might catch fire unless I power wash it once awhile.

The valve covers leak internally, then it pools up until it spills out, runs to the right rear of the engine and drips onto the exhaust very near the distributor. You should be able to tell if this is where its coming from if you look carefully from underneath, Or to be certain pull the access panel to the valve covers and you'll see oil in there if they're leaking. I find working on the distributor much more awkward than getting to the valve cover area.
 

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Discussion Starter · #6 · (Edited)
Van was leaking a bit of oil, gasket between flanges in exhaust pipes were leaking, van was very sluggish going uphill, idle rough sometimes and stalled a few time during idle, engine light on and very poor gas milage when I bought it a year ago.

Update of what I have done since, welded the flanges together to sealed the leak, changed all fluids and filters, disconnected the oil reservoir pump because of faulty oil float, added a litre of Lucas oil treatment. Drove 6000km and van burnt 1/2 litre of oil and ran prefect! Its still a bit wet where it was leaking but parked van for 2 weeks and happy to report NO oil on ground. Engine light on because 1 of 2 bolts holding down the O2 sensor was so rusted it broke off, its currently held down by a clamp.

Had a Toyota mechanic who owns a Previa himself look over the van while I was in Florida. He told me I need new plugs, wires, distributor rotor and change the valve covers while I am at it. "DO NOT remove distributor or timing will be f***ed". The exhaust system is so rusted that it can't be taken apart and put back together, "so new pipes or weld a new O2 sensor to the pipe".

PS. I think it was the Lucas oil treament that slowed the leaks and improved engine performance. I will do a regular oil change and see if van struggles like it did.
 

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If it's leaking out the exhaust then your valve stem seals are ruined. Let me tell you from experience that that job is better off done out of the van. So you have the 2TZ-FE or the 2TZ-FZE?
 

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97 Previa DX AWD; 97 4Runner 5 spd
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Interested to hear how it went with the oil leaks. I use Lucas Tranny fix in my tranny and love it. I've never used the oil treatment but even after changing my valve cover gaskets I have a couple small leaks that I'd like to be even smaller


Van was leaking a bit of oil, gasket between flanges in exhaust pipes were leaking, van was very sluggish going uphill, idle rough sometimes and stalled a few time during idle, engine light on and very poor gas milage when I bought it a year ago.

Update of what I have done since, welded the flanges together to sealed the leak, changed all fluids and filters, disconnected the oil reservoir pump because of faulty oil float, added a litre of Lucas oil treatment. Drove 6000km and van burnt 1/2 litre of oil and ran prefect! Its still a bit wet where it was leaking but parked van for 2 weeks and happy to report NO oil on ground. Engine light on because 1 of 2 bolts holding down the O2 sensor was so rusted it broke off, its currently held down by a clamp.

Had a Toyota mechanic who owns a Previa himself look over the van while I was in Florida. He told me I need new plugs, wires, distributor rotor and change the valve covers while I am at it. "DO NOT remove distributor or timing will be f***ed". The exhaust system is so rusted that it can't be taken apart and put back together, "so new pipes or weld a new O2 sensor to the pipe".

PS. I think it was the Lucas oil treament that slowed the leaks and improved engine performance. I will do a regular oil change and see if van struggles like it did.
 

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Discussion Starter · #10 · (Edited)
I changed the distributor rotor, cap wires and plug, there was no oil leaking from there. I opened the valve cover and the leak was definitely the valve cover gasket(Previologist got it right). I bought the gasket but one of the bolt was stuck, so I just tighten the other bolts. Happy to report the oil leak has stopped.

PS:cleaning the MAS has improved the engine idle, gas milage and performance. Lucas oil treatment might helped, if did not hurt. I now use heavier oil(10w40 in summer and 15w50 for winter).
 
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