2005 Toyota Sienna radiator drain plug problem

I went to loosen the drain plug on my 2005 Sienna and it would not budge. Long short, finally got it out and was going to replace it, but the new one doesn’t fit. The new one is the Dorman 61112 that all the websites say should fit, but it only gets a turn in and then gets stuck. It looks like the old one was the same kind, but they put some plumbers tape on it and just crammed it in there.

Any idea what’s going on here and/or what the correct plug/petcock should be?

It sounds like you might have an aftermarket radiator, and the drain plug is slightly different. I never use the drain plug anyways, because it is cheaper and easier to remove the lower radiator hose when it’s time to change the coolant, and the hose can easily be replaced if necessary. Drain plugs can leak once disturbed, and a replacement O-ring may be difficult to find.


Thanks for the input bcohen. Radiator was replaced by the previous owner at the shop where he did everything, so I assume they also put in the wrong plug, which is weird.

I would buy a new radiator, and get a good brand, such as Denso First Time Fit. It is well worth the additional cost versus a cheapo brand. If in doubt, replace the hoses too.

Just take the old one down to Napa or some place and let them match it. You could have just put a new o ring on the old one if it wasn’t destroyed. Use some faucet lube on the o ring, or maybe the new one is the right one after all. Maybe you can get a picture of it on rockauto. I’m no help laying on your back trying to reach the dang thing. I suppose mechanics have got a tool or something like a split socket.

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I would be looking for the missing O-ring that is missing and probably stuck in the hole, looks like rubber at the end of the hole in your picture, but then again I can’t see it very well either…
Or it could just need replacing as a whole… You might get the previous owner to call and see if there is any warranty on the rad, a lot of rads have a limited lifetime warranty, may not be transferable, but who is to say you aren’t bringing it in for the previous owner… paying labor is cheaper then paying parts and labor… The labor pays 2.3 hours, I think you have to remove the bumper…

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That’s the wrong part number. According to rockauto it should be 49036 for 04-07. For 03 it lists the Dorman part 61136 which looks a little closer to what you have. You can try plugging in the number you have to see what it is supposed to fit, but generally rockauto is pretty accurate if you read the fine print and exceptions.

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Those are two different plugs

If you look at the old one, there’s a 45 degree taper below the o-ring.

The new one doesn’t have that feature.


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You are absolutely correct, good catch, I thought something looked different, but I am running on low sleep also… lol

You as well Bing, I didn’t look up the part numbers…

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Yeah something wrong I think. Dorman says it fit 04,05;06 07 and 08. This does not jive with rock auto that says 490236 and a different one for 08. Back to the store but look at the pic at rock.

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Little confusing trying to follow everyone’s thoughts. Rockauto lists my part# as an alternate part number for the one Bing mentioned.

Good point that they are not exactly the same. The one I took out was really jammed in there. Had to heat up a flathead and jam it in to get enough grip to turn it out.

Agree that it looks like there’s still some o-ring back there to clean out.

I think one way or another the threads are a little goofed up. I’m thinking about trying an M14 1.25 tap or bolt to get them sorted out enough to accept the new Dorman 61112.


Unknown radiator and unknown proper pet cock? Maybe try and get your finger in there to see if it has a taper or not. If the old one fit though I’d try to match it. Use faucet grease on both the o ring and threads though and it’ll come out again easier.

After cleaning, examining, and hemming and hawing, I decided the plug was probably correct and gently ran a M14 1.25 tap. The tap met some gentle resistance but followed the threads. Afterwards the plug fit perfectly. Thanks all for the help!

Did you find the old o-ring?

Obtaining the correct part for the application of course is the best start. I’ve had pretty good luck cleaning up marginal threads for something like that by purchasing the same part in metal, brass, copper, galvanized steel, then cutting a slot at 90 degrees to the threads using a dremmel tool. Creates sharp edge at each thread crossing. Then threading it in and out of the problematic hole helps return the hole’s threads back to usable condition. Easy to do, & worked like a charm for a leaking water heater drain valve.

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Interesting to have the correct tap on hand. I’ve got the single use $20 set. Use it once and throw the tap away. I should maybe upgrade to more metric.

Lol no. I went out last night to find either a tap or a matching bolt and found the tap on only my fourth stop.

I did not find an o-ring inside. After cleaning with a straw brush (thanks kids!) and vacuuming it out and taking more pictures I decided the oring wasn’t in there (if it ever had been).

I suspect the previous plug was not the right thread and somebody did something special to it to make it work, which made it extremely difficult to remove and gummed up the threads. But I’m pretty confident I got everything out and have a working system now. The engine is up and running and the plug works as it should.

The best news is that the engine does not appear to be leaking oil any more, so replacing the seals seems have done the trick.

Thank you for the update…