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1994 s600 coupe
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684 Posts
Discussion Starter #1
finished up the EGR blocking job.
there was a hidden problem uncovered-
driver's side left EGR valve, had a small hole in the intake manifold side pipe,
right at the accordioned flex section of pipe, it was leaking vacuum there all the time.
checked in a pot of water, blew air into the pipe, the hole was visibly bubbling like checking a leaky tire.
so...I PERMANENTLY blocked them this time,
but they can be unblocked if need be.
after the EGR's were removed, tapped both exhaust side tubes of the EGR's
with 1/8" tapered pipe tap, then screwed in 2 pipe plugs (49 cents each at hardware store)
on the intake manifold side, I cut 2 "H" shaped gasket blocking plates,
to block the port in the intake manifold under the throttle bodies.
this can be undone by just removing the H plates, and pipe plugs.
bolted it all back together, the car idles much better- rock solid.
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1994 s600 coupe
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684 Posts
Discussion Starter #3 (Edited)
a couple tips on this job-

#1 remove the squeeze clamps completely, from the crankcase vent hoses, that attach to the throttle bodies.
when reinstalling, do NOT reinstall the clamps. the rubber pipe will press on/off the throttle bodies and stay put,
without the clamps. and it makes it a LOT easier to remove them again later, if you want to.

#2 the driver's side crank vent tube, is precisely and strategically located between the engine block, and the throttle linkage mounting plate. if it is situated outboard of the linkage mounting plate, you CANNOT get it back in place, without once again removing the throttle body and linkage.

#3 you saw how oily and filthy the inside of the throttles were in previous thread. here they are again. in my case, I also
BLOCKED the crank vent tubes on underside of the throttles, because I don't want oil mist going back into the engine. I'm letting it vent to atmosphere just like the 1950's ???. I also disabled the crank vent vacuum fittings at front right valve cover, but upon doing so, both crank vents that used to be attached to the throttle bodies, exhibited oil mist at idle. so I'm keeping the vacuum feeds at front right valve cover connected- for now.
basically it's a 1960's vintage PCV system, vacuum feed, but also vented on the draw side. to be true 1950's vintage it would have no vacuum feeds at all, just vents, period. but then I'd have to fashion a true road draft tube, to vent the oil mist downward under the car. I may do that next

#4 there definitely ARE long vacuum tubes in each intake manifold, from the front and back, that extend to just behind the throttle plates inside the intake. I could see them with a light protruding there, but didn't take a picture. that is to direct oil mist to the rear of the throttles so it's distributed equally to all cylinders, not just the nearest cylinder by the fitting the vacuum hose is connected to.

#5 I obtained 2 used rubber intake tubes for the throttle bodies on Ebay, for less than new MB or reproduction parts. they had no cracks and were easy to install, by using lubriplate grease on the part that slides over the throttle bodies. they did not rip. I also obtained 2 reproduction intake tubes, and was going to cut one to use on the opposite side, if I wanted/needed new ones. as it turned out, I may just return the repops cuz they were $180 and I don't need them.

#6 I was able to repair the original intake tubes using E6000 pliable clear epoxy glue sealer, this stuff is amazing, I glued a propeller on a boat trolling motor and it's still holding. now that's saying something. I glued both intake tubes and tried them as well, they went on/off and would work just fine. see pics below of the repaired originals

#7 the difference between the left and right intake tubes, is the left side is slightly longer. the problem with repop tubes, is only the left side is available new. they are $90 each. new ones are $127 each from MB. you can buy 2 left side tubes, and hand trim one to the length of the right side, and use it in a pinch. just move the clamp back. I was contemplating doing that.

#8 the used intake tubes were $50-$60 each on Ebay

#9 throttle bodies and throttle plates cleaned up like new using Brakleen from Walmart. very important to do, as the throttles were not closing all the way, they were a tiny bit held open more than should be, due to carbon buildup.

#10 for now, I'm not re-installing the side heat shields on the inner fenders. IMHO they are like teets on a bull, useless. but I will save them just in case. likewise with the cat converter heat shield under car, the cats are gone, and it was hanging down onto the exhaust, rusted through at bolt holes, so I removed it.

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1994 s600 coupe
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684 Posts
Discussion Starter #4 (Edited)
here are the repaired intake tubes using pliable E6000 epoxy adhesive sealer
they would now work just fine, in fact I tried them already.
going with the used originals from Ebay for now...
all options were investigated, new repop, used original, repairing original.
except for buying new from MB, $260 for those hoses is just insane
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1994 s600 coupe
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684 Posts
Discussion Starter #5
E6000- this stuff will glue soles back on shoes and they WON'T peel back off, extremely pliable, one part, just put it on, let it sit overnight

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The late 70s fuel injected VW bus had a similar style S-ahaped intake boot that would harden and crack with age, also unavailable with few alternatives. Soaking it in kerosene will restore its pliability
 
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