Oil Pooling in Intake Manifold

That video, and a whole wack more, are by member @NutzAboutBolts , have been linked in a thread pinned at the top of the 3rd gen maintenance forum:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Yeah, it's a common third gen "issue", not just the Plug-In, which is essentially a third gen for the most part.(note you've posted in 4th gen Prime forum), and cleaning is something you can fairly easily do yourself.

The apparent culprits are likely oil/gas/water being introduced by the PCV valve, for the most part, and to a lesser degree a bit of "spit up" coming the from the intake ports, maybe just the nature of Atkinson Cycle engines? I'm out of my depth what an AC engine is, but I have seen an oil trickle from each intake port, when I had ours off.

I would suggest:

1. Clean the intake manifold.
2. Install an Oil Catch Can, in series, along the hose between PCV valve and intake manifold.
3. Clean the EGR circuit, stem to stern.

For item 3, again, there's a video on that subject, in the above link.

 

The dealer tried the same thing with me and my My Gen 3 Prius (2010). I was at about 150,000 miles. Everything was running fine, so I didn't get it done.

 

welcome!
63,000 sounds very early. i have 55k, but do not know how to check it.
i always syphon out the extra oil after an oil change. again, not sure if that is part of the problem.
how would the dealer go about looking for oil pooling during a fuse replacement? i have not read about any plug ins having the issue, but do agree that after 100k, it might be possible.

 

Watch @NutzAboutBolts video (maintenance sub-forum) on throttle body cleaning, it shows the steps to get to the throttle body. Just pushing open the throttle blade and looking through, you can get a fair view. Removing two bolts and two nuts, you can lift the throttle body right off (leave coolant hoses attached, they have enough play), and get a much better view. Torque for both the nuts and bolts is 7 ft/lb.

Only thing, it hardly needs checking: it's pretty much for certain there will be a swimming pool there, depending on the time of year either mostly oil, or a mix of oil/gas/water.

There's the MAP sensor just to the right of thottle body while your're there, you can disconnect unbolt and remove. It'll likely be oil drenched. MAF sensor cleaner should be safe for it. It seems pretty sturdy, but do go easy on it: it sells for somewhere around $200 IIRC.

You could swab it out, but without a Oil Catch Can on the PCV circuit it'll back as it was soon enough. Perphaps even with OCC: I'll take a look at ours come spring to check. There is a bit of oil spit back from the intake ports, that the OCC doesn't deal with. I think not as much though. I hope.

 

do you think some dealers are now savvy enough to check all gen 3's when they come in? new profit center, i suppose.

 

They probably do it for all vehicles.

I once owned a car with throttle-body fuel injection, and the gunk in the intake manifold really did make a big difference, so I suppose it's not out of the realm of possibility for some cars to be more sensitive to it than others.

 

The EGR passages within the intake manifold are prone to gunking up too.

 

what happens if you don't clean it until you have symptoms?

 

There's nothing conclusive, but I've heard a properly functioning EGR is helping to keep the engine cooler. And if the engine's running hotter, there more chance of head gasket failure??

Again speculation, but maybe what the PCV valve is dumping into the intake manifold, is getting sucked into the combustion chamber, and then back into the EGR, accelerating it's clogging???

 

You get engine knock from oil/water/fuel sucking into the combustion chamber. We had that happen @72k on our 2010. Intake manifold cleaning with a blue shop rag and oil catch can fixed the problem. I just pulled the intake tube off and opened the throttle body, pushed the rag in past the throttle plate and swabbed it to soak up the standing oil. I did not remove the intake manifold at all. Our 2010 has 122k, our 2011 has 312k with no knock and no oil burn, both cars run great. My 2011 has more interior noise due to miles. Thats really my only complaint.

 

I would unbolt and pull off the throttle body for that operation. It's not hard, and you just need to disconnect one electrical connector. You can leave the coolant hoses attached, and just lift it up and out of the way. The throttle body bolts/nuts torque is 7 foot pounds (84 inch pounds).

 

also, how many of your 63k are hv miles?

 

I had a 2005 prius. The dealer cleaned the throttle body. A couple of thousand miles later, it would not start. It was towed to the dealer. They replaced the throttle body for $1200 plus. Now I have a 2013 Prius V with 60K. Now they tell me the PVC is sticking and the intake and the MAF sensor needs cleaning. I'm afraid to have them touch it.

 

Just out of curiousity I looked up the price of the throttle body: $385.54 (US), through McGeorge Toyota:

2001-2009 Toyota Prius Throttle Body 22030-21020 | McGeorge Toyota Parts

Unless it's completely different than 3rd gen, replacement is a simple job, one hour at most. Where there other things done. If that was it, it's a rip.

 

Plenty of used throttle bodies as well.

Posted via the PriusChat mobile app.

 

The PCV valve is around $10 to replace. It's easier to do if the intake manifold is pulled off, but you can it from below, just taking off the engine underpanel. The MAF sensor is very easy to clean yourself: get a can of CRC MAF sensor cleaner, and watch their video.

It's very likely both those items are ok though, sounds like your dealership might just be trying to drum up business.

 

The PCV valve replacement (from below) is @NutzAboutBolts video #15 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

 

I've been chasing this problem on my 2014 PIP for a while now, after discovering the large puddle of oil in the bottom of the intake manifold at around 150k miles. I replaced the PCV and added an oil catch can. There seemed to be no oil in the OCC at the first 5k miles oil change (I had to have a shop do it due to being on the road). At the second 5k oil change after adding the OCC, the can was 3/4 full and again I had a puddle in the the IM. It seems to me that the PCV is a simple check valve that should allow gas (pressure) to pass, but not fluid. I'm currently hypothesizing that the check valve works based on gravity and needs to be installed in the vertical position to work properly. Could it be a design flaw on Toyota's part to install a check valve in the horizontal position? I know it's far-fetched but I'm struggling to understand how a large quantity of oil is passing through a fairly new check valve (if indeed, that is where the oil is coming from).

As an experiment, I have replaced the PCV in the block with a 5/8" hose barb fitting (16.5x1.5mmx5/8" barb approx) and put the PCV at the opposite end of a 12" length of 5/8' hose after it turns vertical (the PCV is in the vertical position). Then 3/8" hose from the PCV into the OCC, then 18" of 5/8" hose back down to the intake manifold from the OUT port of the OCC. I'm anxious to see if this will help cut down on the oil that gets passed into the IM.