I'm finally getting around to cleaning the throttle body on my 1991 240 B230F LH3.1. I am a total novice.

I have decided not to remove the TB switch assembly- just to avoid _any_ question of it needing readjustment.

I am using the CRC throttle body cleaner. I am avoiding getting any of it on the switch.

My question is this- should I remove the brass vacuum fittings and spray throttle body cleaner down in those vacuum holes?

Any other suggestions?

Thanks,
Keith Ostertag

Looking at you PIC. Yes take the brass fittings off. The whole in the Brass nipple does not directly line up with the hole in the throttle body. So take the nipple off, clean it out and then clean the hole in the TB.


There are two very small holes close to the butterfly, look for and clear those as well.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/

Thank you Tony for the clarification. I really appreciate it!

Keith

Sure.

welcome to the BB



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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/

Thanks!

Here's another related question- when replacing the brass fittings should I (after cleaning them) apply any kind of lubricant to the threads?

The reason I ask is that I have always tried to put some kind of lubricant on threads so the next time they aren't so difficult to remove. My grandfather always used plain soap on bolt threads. I guess just grease is OK. But since these are vacuum fittings I'm not sure that any kind of lubricant used on the threads would have a chance at getting sucked in and possibly fouling things...

Thanks,
Keith

Best is to use teflon pipe thread tape, but use very little and only the upper threaded part of the nipple so none gets into the orifice.

In my 500k miles and three 89-92 245's I've never removed those brass nipples, just use the TB spray directly into the orifice and nipples, both directions, blow out with compressed air, do it twice.

Use a toothbrush on the TB throat around where the throttle plate contacts the TB where the two aforementiioned small orifices are. This area of the TB is the most important part to get squeaky clean. Prop open the throttle plate so you get into the corners. This effects idle control immensely!

Judging by the look of your TB, the crankcase breather has been busy, and I would look at the flame trap and all the hoses and nipples especialy the one from the top of the flame trap housing to the intke manifold. Those two small nipples I would take out and clean. You may find the hose and nipples completely clogged shut with a TB like yours.

While your at it, remove the IAC valve and clean it also. I use 50/50 mix of carb cleaner and WD-40 and a Q-Tip.

FYI the LH 3.1 throttle sensor doesn't need adjustment like the LH 2.X switch, but I leave it on when cleaning the TB, too.

I think there were incorrect responses to your original question. You should spray cleaner down the vacuum orifices with threaded fittings, but I don't think you need to unscrew them. Make sure that you blow through them and that they are clean and clear. Those are my thoughts - but if you did unscrew, I don't think that you need to do anything special with brass fittings for sealing, just tighten well and don't strip the threads.

I put a dab of anti sieze compound on the threads.

I like having it easy to disassemble next time too.
Don't slop it all over the place and you wont have any Vacuum issues.

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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/