BOOST & A Bunch of Bad ALDAs (& "disabled EGR melted that SD's engine") - Page 2 - PeachParts Mercedes-Benz Forum

veg_burner · #16 04-17-2005, 01:17 AM

so maybe i should take the time & adjust the wastegate instead of just pinching it off (i think i read to do that in an old thread).
twitch, good idea...

my123ca · #17 04-17-2005, 09:56 AM

Quote:

Originally Posted by SD Blue

I would bet all of those "bad" ALDA's could be repaired by a simple resealing.

Do you know where to I can get those seals, especially the smaller one? I suspect mine is leaking more than it should. Couldnt test it though, my vacuum pump only does vacuum(unlike mityvac?).

veg_burner · #18 04-17-2005, 07:00 PM

Quote:

Originally Posted by boneheaddoctor

I seconf that....I had a boost controller on my W116 and I thought I had it cranked down enough but it still went up to 20 psi in the time it took me to pull my foot off the go pedal.....that was in about 50 feet.....so yes it happens REAL fast.

Quote:

Originally Posted by Brian Carlton

Be careful when you drive it with a pinched wastegate hose. Watch the boost carefully. It will climb pretty quick if things are working properly.

isn't the overboost sensor switch supposed to open and dump the boost if the boost climbs above 1.1 bar in the event of a stuck wastegate?

boneheaddoctor · #19 04-17-2005, 07:33 PM

Quote:

Originally Posted by veg_burner

isn't the overboost sensor switch supposed to open and dump the boost if the boost climbs above 1.1 bar in the event of a stuck wastegate?

Mine was bypassed when I bought the car as it was stuck in a purge boost mode.............never replaced it yet. Had it been hooked up and functioning I would have experience a boost dump and loss of power.

Brian Carlton · #20 04-17-2005, 07:47 PM

Quote:

Originally Posted by veg_burner

isn't the overboost sensor switch supposed to open and dump the boost if the boost climbs above 1.1 bar in the event of a stuck wastegate?

It is supposed to work that way. But, it depends on a working sensor on the manifold and a working overboost protection valve. You want to take the risk of these 20 year old parts working as designed????

veg_burner · #21 04-17-2005, 09:02 PM

well i decided to live on the wild side so i pinched off my wastegate hose (with a pressure gauge teed into the line to monitor)(for the record, last time i went to the wrecking yard i grabbed a bunch of rubber vacuum tees, couplers and line for this purpose. teed in off the overboost sensor.) here's what i found:
i was able to get the boost pressure up over 11 lbs but it wasn't happening fast - only up into the higher RPM range. also, i was able to control the boost very easily as it got up there by letting up on the pedal. i didn't notice the operation of the overboost sensor, nor did i really want to test it...
what kind of pressures should i be getting through the RPM range? IIRC i was only getting 5-6 lbs @ 2000 rpms.
so i guess what i'm getting at finally here is the turbo seems slow to spool up. i seem to recall in my reading through old posts that the wastegate gasket sealing surface can get rough over time and you can lose a bit of boost pressure before it builds up enough to seal it. would this make sense?

Brian Carlton · #22 04-17-2005, 10:30 PM

The turbo doesn't even begin to do anything until 2200 rpm or so. In fact, I'm quite surprised that you can get 6 psi at 2000 rpm.

Run it up to 3000 rpm and see what the gauge reads. Without this level of airflow, the turbo can't reach full boost.

It sounds like the turbo is functioning normally. However, if you test it with the wastegate functional and the boost is less than 11 psi, then the wastegate spring needs adjustment.

veg_burner · #23 04-18-2005, 12:03 AM

with the wastegate functional i was getting ~9.5 lbs
definitely plan on adjusting the wastegate. from what i've read it's not so easy to get in there. how much time should i allow?

Brian Carlton · #24 04-18-2005, 12:11 AM

Quote:

Originally Posted by veg_burner

with the wastegate functional i was getting ~9.5 lbs
definitely plan on adjusting the wastegate. from what i've read it's not so easy to get in there. how much time should i allow?

My SD has about the same amount of boost. Let me know how long it takes you.

Johnhef · #25 04-18-2005, 12:16 AM

I've been wanting to do it as well. I gave up when I couldnt easily get the wastegate cover's rusted nuts off and bought a manual boost controller. never did put it in though. oil seeping from the rear of the headgasket and my turbo needs an overhaul- way too much play in the shaft apparently. Car still has about 9.5 lbs of boost, this seems okay for the time being, but I'd still like it to be better. Since I noticed the blades nicking the housing, it seems to be not as quick as it once was, but maybe I'm just imagining that since the boost value hasn't changed.

is 2-3 lbs more that much noticible? I was going to aim for 12-13 eventually.

Brian Carlton · #26 04-18-2005, 12:20 AM

Quote:

Originally Posted by Johnhef

is 2-3 lbs more that much noticible? I was going to aim for 12-13 eventually.

Well, "noticeable" is a relative thing. If you have any visions of getting down to 10 seconds (0-60), you can just put that to rest right now.

You might shave one second off the time, if I had to guess.

Johnhef · #27 04-18-2005, 12:22 AM

Well now that I think about it, I adjusted the trans cable around that time, much better and smoother shifts but I think I may have lost a little in the off the line department.

veg_burner · #28 04-18-2005, 12:23 AM

i'm going to get into it this week -- i'll keep you posted.
thanks for the help!

autozen · #29 04-18-2005, 12:52 PM

After reading this whole thread I'm inclined to think you have a vacuum problem. The proper vacuum signal to that trans is key. Also Johnheff is correct about cable adjustment. Proper adjustment of vacuum with the proper orrifice installed in the line and the adjustment on the side of the vacuum valve, can turn that car from a sled into a rocket. As soon as the throttle is touched that vacuum valve should start dumping vacuum and go quickly to zero.

Peter

boneheaddoctor · #30 04-18-2005, 01:01 PM

Quote:

Originally Posted by Johnhef

I've been wanting to do it as well. I gave up when I couldnt easily get the wastegate cover's rusted nuts off and bought a manual boost controller. never did put it in though. oil seeping from the rear of the headgasket and my turbo needs an overhaul- way too much play in the shaft apparently. Car still has about 9.5 lbs of boost, this seems okay for the time being, but I'd still like it to be better. Since I noticed the blades nicking the housing, it seems to be not as quick as it once was, but maybe I'm just imagining that since the boost value hasn't changed.

is 2-3 lbs more that much noticible? I was going to aim for 12-13 eventually.

If you have the T-3 turbo I understood the adjustment took place inside the canister not the wastegate housing...................there is a circular clip that holds the shell on....or did I misunderstand what you meant.