After another smoke test it appears I have found the leak still giving me lean codes on my 2006 XK8. Smoke is coming out of the bottom of the throttle actuator control motor; I had to record a video of it to be sure it wasn't the pipe below it

Has anyone ever had this before? You can see in this pic where I stopped the video the smoke is coming out the two channels in the casting. I assume there is a gasket or O-ring between it and the aluminum housing? Or do these somehow fail and cause this condition?

And what are these crazy screws holding it on? They are not Torx like most of the others. They sort of look like them but have 5 points instead of 6. Nor are they Allen. I have a set of what I thought was every bit made and none fit.

Thanks!

 

I sure hope there is an easy fix for this since I see the throttle air actuator motor is not considered replaceable, have to replace entire throttle body at >$600.

 

The shape of that channel his is leaking from makes me wonder if it is something simple like the throttle body gasket?

 

Your crazy fasteners are called Klutch drive.Typically used for tamper resistance. Fun, another set of tools to buy.

 

5-point torx:

 

Thank you. I guess the question is do I bother since the motor is not separately available, have to buy entire throttle body (guessing for reasons of calibration).

Makes me wonder if it's as simple as the throttle body gasket. I'll pull the throttle body off next and see if that is it or perhaps it's something that can be addressed with a sealant.

 

I pulled the throttle body off and confirmed this has nothing to do with the base gasket. As you can see in this pic of the underside, there is plenty of material between where the gasket seats and my leak.

So what is the purpose of these two channels in the throttle body where this plastic throttle position sensor mounts? This is where the smoke comes from when I test it and it would appear they are intentionally there as perhaps some sort of drain? If so, probably a bad idea to try to block it off with epoxy or something. Or was there perhaps some sort of plastic part blocking them and it fell out?

I don't want to try to remove this since per the previous posts it's not separately available and is on with anti-tamper 5 point Torx screws. I see from other posts it's a common failure item and not separately available, though mine is working fine (runs good, no limp mode or P2135 code).

Appreciate any insight from this good forum.

 

I wish I could rename this thread. The leak is actually at the bottom of the smaller throttle position sensor on the driver's side, not the much larger actuator on the passenger side.

 

I'm with you, that is strange.

 

If you cover the point of the leak with something temporary (i'm thinking just tape to test), does your lean code go away? If it does, I would look at some sort of gasket material to fill the holes. I don't really recognize the part from the picture with that perspective, but if I understand the location I can't imagine it's a drain that is supposed to be open, but causing a leak. The sensor attached looks brand new? Did the old one have a different shape that blocked those ports?

 

I have nothing to offer by way of help, just moral support as I too am chasing leaks and sealing them when I find them... been at it for 8 days now. I haven't found your one but that doesn't mean it isn't there..... good luck and keep plugging!

 

Your leak is probably from throttle shaft or bore wear. The TPS sensor mounts directly on the shaft. I like Rover Joe's idea of temporary taping over the holes to see if your lean code goes away. If it the code resets your are chasing the wrong leak.

 

I assume so also. We don't drive this car a lot so it only has 76,000 miles on it and all that looks really good. But still could be throttle shaft wear.

 

I have 97k on mine and no such problem. I suspect that it is a dtill undetected leak elsewhere. What youe seeing at the TPS may be near normal.

 

I don't think it's normal since didn't show up on previous smoke test. Literally no smoke coming from anywhere else (though guess there are some components tucked away not in the engine bay). Also makes sense would be in throttle body area since am getting lean DTCs for both banks. I suspect it's worn throttle bushing despite the low miles. I've sealed it off with some RTV and will drive this weekend and check fuel trims.

 

Done.

Cheers,

Don