2004 Sienna Major Oil Leak - Toyota Nation Forum : Toyota Car and Truck Forums

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post #1 of 2 Old 10-23-2011, 06:29 PM Thread Starter
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2004 Sienna Major Oil Leak

Background - a mechanically-challenged co-worked has a 2004 Sienna and she told me her car was stalling a lot at stops and had the check engine light on and she was renting a car. She bought this vehicle with less than 40K miles and now the vehicle has 150K miles. It appears she never did much for maintenance. She took it to two places and they read the codes and they found (I think) two rear cylinder misfires and two sensor errors. She first took it to a freind who told her it needed a tune up but he said he couldn't do it because he didn't have the special tolls needed to get to the back cylinders. She took it to a dealer who told her it would cost $3000 to repair her vehicle.

I talked to her a bit to get some history and found out her van had been running rough for a long time and she was still running her original plugs. I told her she should first change her plugs, and if that didn't fix the problem then replace the bad coils. She didn't have anyone willing to do the work so I told her if she got it to my house I would change the plugs and see if things improved. Yesterday I ended up removing the intake manifold/throttle assembly and it was pretty easy from there. Since she was told it was the back coils that were bad, while I was changing all the plugs I move the back coils to the front so if they needed to be swapped it would be an easy thing.

Started the vehicle and it was still running rough and the check engine light was still on. Drove through our neighborhood and it stalled at the first stop sign. Pulled out of the neighborhood and drove about a seven mile loop. It idled rough at the two traffic lights but it didn't stall there or at any other stop signs.

When I got home I disconnected the battery to reset the codes. Her gas was almost empty so I threw in a bottle of Seafoam. I put the rest of the vehicle back together and headed off to a local Autozone to get the codes read. I pulled out of the neighborhood and as I was driving it seemed like there was a lot of oil smoke behind the van. When I turned at an intersection about a mile away the oil light came on. I immediately pulled into a side street and shut the engine off. I opened the hood and there seemed to be oil everywhere. I looked under the vehicle and it was the same there.

I called my son to come and get me and he said he had found a bolt on our driveway that he said looked like the drain bolt. When he picked me up he said there was a trail of oil in the road about 3/4 of a mile long. I told him I didn't think it was the oil drain bolt because I had forgotten I dropped a bolt from the rear of the engine that was the brace on the back passenger side of the intake manifold. I couldn't see well under the vehicle because of the time of day and with a hot engine with hot oil all over the place I wasn't going to feel around under the van with my hand.

I went back this morning with some oil and some tools. The oil drain plug was in fact where it belonged but the engine was empty of oil. I put oil in and started the engine. The oil light did not go rirght out like it normally would after an oil change and when i took a quick peek under the vehicle it looked like oile was pouring out of where the oil filter should be. I turned the engine off and checked the oil filter which was coated with oil and it was not tight at all. I could easily turn it in either direction by hand. I tightened the oil filter up properly and put some more oil in the vehicle and started it again figuring I had found the culprit. The oil light went out but then I heard a funny noise and looked under the van again. Oil was gushing out of the left (driver's) side of the front of the engine. I turned the engine off again and looked around trying to find a source.

I really couldn't tell where it might be coming from. My son who has some training said the only thing that makes sense for that large of a quantity of oil to be coming out of the engine would be an oil sela and the rear oil seal would be located between the transmission and that end of the engine.

What I am asking here is if there are any other possibilites that you know of. My son also said replacing the rear oil seal would require pulling the transmission and that is certainly outside of the range of work I am willing to attempt. Any thoughts or other steps I could take trying to find the leak? Thanks for any help and suggestions!

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post #2 of 2 Old 10-29-2011, 06:38 PM
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I didn't notice if you mentioned it, but did you change the oil & oil filter?

If so, are you sure that the rubber gasket for the old filter came off with the old filter?

If the old gasket stuck to the engine instead of the filter when you removed it, then you would have a stack of two gaskets instead of one on the new filter and that could leak a lot.

Even worse, if you put in the new filter without any gasket, then it would really gush out there.

I'm not sure if that accounts for all the locations where you mentioned you're seeing oil, so I don't know if that's your problem, but it's an easy one to check.

Last edited by NoHeat; 10-29-2011 at 07:16 PM.
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