warped intake on '73 M110?

[Larry Delor]

Hello folks!

While putting on the carb, and tightening the bolts, I noticed that the throttle linkages were sticking. Loosening the bolts helped, but then of course I have the proverbial evil vacuum leak. So, either my carb is warped, or the intake is. (or both are) Question is, which one is more likely to be in need of a straightening out? Somehow I have a feeling they both are...thing is, is everything moved freely before I took it apart, although upon removal I did clean up a bunch of blue silicone, that I am guessing was used to...plug a leak. Should I try to make a gasket with soft gasket material (cork maybe?) or would I be wasting time?

Thanks for your help...I am itching to take it for a spin and dust it off.
-Larry

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03/83 300D 184k
07/73 280 160k

Larry, I am not familiar with that particular installation, but I hope the description I provide can be adapted to fit your specific configuration.

I assume the carb has a flat surface that fits over studs on the intake. Bring the carb to your local machine shop or tech center and set it on a surface plate. This is a precision ground chunk of granite that is extremely flat. Slip a feeler gage between the carb and the surface palte to see if it is flat. If not, spray some WD-40 on the surface palte and lay a sheet of fine "emery cloth", cloth side down, abrasive side up, and then "lap the carb's mating surface by moving it in a figure 8 motion. This is so simple and quick that youshould be able to do this by bringing in a six pack or a dozen doughnuts for the host. They will proabably get nervous about the abrasive around the surface plate , especially if they don't know you.

For the intake, there are precision straight edges (probably harder for you to obtain) that can be used the same way to measure with the intake still installed. If studs need t be removed, install two nuts on the stud and using two wrneches, tighten the nuts against each other, very tight. Then put a wrnech on the nut closet to the insttake and turn to loosen. If both nuts slip, tighten them a little more and try again. This will let youget the studs out without damaging the studs or buying special tools. And now for the saftey pitch, think about what your knuckles will impact if the wrench slips! Be smart, be careful!

If the intake is not flat, using a new fine cut flat bastard (file that is) you can probably resurface it in place if you take your time!

If you really want to get fancy, youcould use transfer blue to check the fit, but this is overkill in my opinion.

Sorry if this is too verbous, but I would rather provide too much detail so all readers can get maximum knowledge or stimulate other ideas.

Good luck and let us know how it turns out!

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Deezel
87 300TDT
150,000 miles

[jeffsr]

Check your linkage. It sounds like something got bent. If it worked before you took it apart, then it's highly unlikely either the carb base plate or manifold got warped. You didn't say where the blue rtv came from. Also, why did you take it apart in the first place?? What was the problem??
At any rate, what you describe would have to entail some major distortion of either component (not likely), unless you did something nasty when you reassembled it.

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[Larry Delor]

Thanks Deezel for your tips!

Jeff, bent linkages is what I thought at first too, but after I lubed the hell out of every moving part, I decided that (duh) maybe I should disconnect the linkage closest to the carb to see where its sticking. This lead to the ultimate conclusion that the linkage was sticking within the carb..well actually the throttle plates didnt want to move freely. I thought in horror for a moment that maybe I did screw something up in re-assembly, but once lifted off the intake, everything was normal. I am starting to lean in the direction that the intake is warped, since the carb does not slip on over the studs and pretty much fall into place...I have to push it down to make contact with the intake. I am wondering if intake warpage is a common thing, an isolated incident, or a telltale sign of trauma in the past.

thanks for your replies!
-Larry (slightly warped)

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03/83 300D 184k
07/73 280 160k

[jeffsr]

What kind of shape is the top of the intake? Did you use a new gasket between the throttle plate and the manifold? If the throttle plate binds after you sock it down, then something is distorting that part. Make sure there are no pieces of trash between the carb base and the manifold. You still didn't say where the blue RTV came from. That could be a give away as to where your problem might be. Also, if the engine has done any backfiring, the throttle shaft might be slightly bent.

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[Larry Delor]

Jeff,
the top of the manifold looks fine. The blue silicone sealant was found on the two out of the three layers of the carb. I imagine that the previous owner may have had either a. a vacuum leak or b. something warped. If there was a vacuum leak, then it could have backfired due to the lean condition. the kit that I used to refresh the carb, did not come with the lower gasket, just the two that go between the layers. Thats why I was thinking of maybe making my own...the old one is in good shape as far as using it for a template goes. (I was thinking of just adding the homemade gasket on top [or below] the old one)
whaddaya think?
-Larry (like a walrus, hoping for a tight seal)

[This message has been edited by Larry Delor (edited 04-13-2000).]

[jeffsr]

Larry, is the old gasket a metallic fiber one or is it composition? In my experience, that gasket does not come with a carb rebuild kit b/c it's not part of the carb itself. I would go with a factory replacement for that fella. Also, I wonder why you found so much RTV inside of the carb. They are usually investment cast items and don't warp, but they can be distorted if assembled with excessive torque. If the RTV was between the air horn and the carb body, probably had a fuel leak, if between the carb body and throttle plate, probably a vacuum leak. If you want to avoid future problems, I'd replace the carb.

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[Larry Delor]

Jeff,
The old gasket appears to be of a fibrous nature, kinda like particle board, but smaller and denser, and very dark in color. The blue silicone may have been used for a vacuum leak and fuel leak...fuel leak for sure...as I saw it pool on the bottom of the intake and leak out the side by the accelerator pump. (it is tight now, as far as fuel leaks go) If partsshop carried this gasket, it would be great, as my hours and the dealer hours do not match at all...unless parts is open on saturdays, which I highly doubt.
I would like to avoid getting a new carb, besides I don't think they make these anymore, and a Weber carb would cost me more than I paid for the car.

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03/83 300D 184k
07/73 280 160k

[jeffsr]

Larry, Try Atlanta-Stuttgart Autoparts. They have tons of old MBZ parts etc. The number is 1-800-635-1445. Punch in 1110 for extension and you'll get Dave. Either speak to him or leave voice mail. He's real good about calling back. You may get lucky. That "gasket" sounds more like a spacer which in some applications was used to insulate the carb body from manifold heat. That item could be your problem. Give it a try...

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 04-14-2000).]