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  #1  
Old 10-05-2004, 08:56 AM
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Location: York, PA
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W201 190E HVAC Vacuum Issues

Well, I replaced the heater core over the weekend and also double checked all vacuum connections while the dash was out. I noticed today that when I have the floor vents/partial defrost selection that I noticed at certain points while accelerating that I could hear more air flow from the defrost vents once in a while. More air blowing out of them than before I accelerated. Does not happen all the time just kind of random. Now I know that my vacuum resevoir is fine and all vacuum connections are fine as well. So I am asking if this is normal in certain circumstances due to the intake vacuum pressure dropping and just not holding the vent flap for the defroster half way open as it should be and just letting it open the rest of the way? Or is it a bad vacuum module for the vent flap? Of course I hope it is normal since I would have to remove the dash to get to that vacuum module again!

Also I have a slight noise in my Auto Tranny Shifter Selector! Sounds like pennies vibrating in an ash tray at high RPM's just before a shift! Really strange as it just started to happen and I also noticed that I get some sloppy clunking noises when I move the shifter. I can hear the workings more now than before. Is there some sort of bushing in there that may be bad and cause the shift level to vibrate or the linkages to vibrate on an Auto Tranny?

Thanks,
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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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  #2  
Old 10-05-2004, 04:18 PM
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Bump please!
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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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  #3  
Old 10-05-2004, 07:35 PM
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Location: Evansville, Indiana
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Jaimie:

Make sure the check valve on the vacuum supply line is working. If not, you will lose vac on acceleration and the defrost flaps close.

Otherwise, you have leaking rubber connectors on the switchover valve -- all of the right angle ones on the TE were bad when I replaced the evaporator. I would also check the actuators, likely some of them leak as well.

You will need to purchase a MitiVac hand pump for diagnosis.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #4  
Old 10-06-2004, 08:51 AM
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Thanks. I think it is the check valve. My flaps open when I accelerate, which I think is the default when there is no vacuum as I recall from when I had it apart. All my right angle connectors are good on my switct over now. I replaced the bad ones. So I guess the next thing will be the check valve! Can you just get them at the local parts store or are they special to MB?
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~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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  #5  
Old 10-06-2004, 08:06 PM
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Location: Evansville, Indiana
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Any check valve at the auto parts store that fits will work (some blue ones for Fords fit nicely), but the MB ones will probably last considerably longer. The 32 year old ones on my 72 are fine, but the vac lock one on my brother's 75 failed.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #6  
Old 10-06-2004, 08:37 PM
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Join Date: Sep 2004
Posts: 162
Quote:
Originally Posted by psfred
Any check valve at the auto parts store that fits will work (some blue ones for Fords fit nicely), but the MB ones will probably last considerably longer. The 32 year old ones on my 72 are fine, but the vac lock one on my brother's 75 failed.

Peter
What is the cost a check valve? And what should I ask for at the parts department when I go get one? Finally, how difficult is it to replace one of these things? Thanks
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  #7  
Old 10-06-2004, 09:34 PM
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I ordered one today from *********************** and it was less than 7 bucks for it. 10 with shipping.
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~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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  #8  
Old 10-06-2004, 09:40 PM
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Location: Evansville, Indiana
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They install by plugging into a rubber hose connector, just pull out and push in.

Make sure when you put it in that it holds vac on the passenger compartment side! Otherwise the AC system won't work at all.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #9  
Old 10-06-2004, 10:08 PM
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Join Date: Sep 2004
Posts: 162
Quote:
Originally Posted by psfred
They install by plugging into a rubber hose connector, just pull out and push in.

Make sure when you put it in that it holds vac on the passenger compartment side! Otherwise the AC system won't work at all.

Peter
I have a 98 clk 320. Can you give me a part number for this? Or even tell me where it is on my car so I can look at it and find it that way. Thanks for your patience. -John


P.S. Are these things actually called "Check Valves" because I couldn't find anything of the sort on the parts site. Thanks again
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  #10  
Old 10-07-2004, 08:33 AM
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Quote:
Originally Posted by CLK320MIA
I have a 98 clk 320. Can you give me a part number for this? Or even tell me where it is on my car so I can look at it and find it that way. Thanks for your patience. -John


P.S. Are these things actually called "Check Valves" because I couldn't find anything of the sort on the parts site. Thanks again

Does the 98 use vacuum to control the HVAC system? I would think it would be electronically controller by then!
__________________
~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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  #11  
Old 10-12-2004, 02:31 PM
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Got new check valve and the same issue is there. Still not closing the heat valve either when I select off or coldest settings like it should either. Check all vacuum lines when I had the dash apart for heater core and no leaks anywhere. Also checked resevoir and heater valve operation if I actually suck on the lines and no leaks there either. I am getting very frustrated with this damn car. It still has an idle that I can feel and no matter what I do it still has it. Funny it runs smoother when the engine is cold than it does when hot and idling. I have replaced everything but the fuel injectors. Regulator, filter, sparks plugs, wires, cap, rotor, temp sensors, cleaned injectors by soaking in carb cleaner, replaced all rubber hoses on the intake from the IACV, I have done it all..... Any ideas???
__________________
~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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  #12  
Old 10-12-2004, 11:43 PM
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Join Date: Aug 2001
Location: Evansville, Indiana
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Bad injectors will certainly cause a rough idle, BTDT long ago on my Audi Fox. One that dribbles at idle will make it shake something terrible, and ajdusting the idle mix won't help.

However, if it runs smoothly cold, you probably have an overly lean mixture warm if the injectors are good, this will cause rough running.

You should get a Mitivac hand pump to check the vac system, it has a guage so you can test for integrity. Sucking a vac by mouth will only detect major leaks in my experience, and you really don't want all the residual stuff in there in your mouth anyway! There are several restrictors in the system, so you will have dampers closing with only a minor drop if vac. Worst part I found on the TE after replacing all the servos and getting exactly what you have was leaking right angle fittings on the switchover valve. Minor leaks here allowed the dampers to partially close while accelerating.

You should have a reservior in the system to "float" it over the low vac caused by acceleration. However, if the mxture is off, you will be low on vac anyway, and will no have enough.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #13  
Old 10-13-2004, 08:44 AM
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Join Date: Jul 2004
Location: York, PA
Posts: 621
Quote:
Originally Posted by psfred
Bad injectors will certainly cause a rough idle, BTDT long ago on my Audi Fox. One that dribbles at idle will make it shake something terrible, and ajdusting the idle mix won't help.

However, if it runs smoothly cold, you probably have an overly lean mixture warm if the injectors are good, this will cause rough running.

You should get a Mitivac hand pump to check the vac system, it has a guage so you can test for integrity. Sucking a vac by mouth will only detect major leaks in my experience, and you really don't want all the residual stuff in there in your mouth anyway! There are several restrictors in the system, so you will have dampers closing with only a minor drop if vac. Worst part I found on the TE after replacing all the servos and getting exactly what you have was leaking right angle fittings on the switchover valve. Minor leaks here allowed the dampers to partially close while accelerating.

You should have a reservior in the system to "float" it over the low vac caused by acceleration. However, if the mxture is off, you will be low on vac anyway, and will no have enough.

Peter
Thanks. I am more mistaken about that cold idle being good. That only happens once in a while. I actually noticed that it is still the same this morning. Also notice it is a hair smoother when I get a full tank of gas. But not much. I am thinking I have a leaking or few leaking injectors. This car was poorly maintaned before I got it. Also notice on the highway at 75-80 under load, going up slight hill, that she seems to just not want to move to much. Even at 70 it needs to downshift to 3rd to accelerate. On flats she is fine and peppy. So I am thinking that it is starving for fuel due to bad injectors. **** they are only $100 for all four, I guess I will just break down and get them. The loss of vacuum problem does not happen all the time and is sometimes hard to reproduce. All vacuum elbows were checked and the few that were bad were replaced. I am thinking though that my vacuum change-over for the HVAC system is going bad as it no longer sends vacuum to the heater valve to close it when it should. Maybe that is the issue. There is another damn $100.... Oh well, that does not need to be fixed til next year when it is warm again I guess. Thanks for the help and if you have any more ideas based on what I said please let me know.
__________________
~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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  #14  
Old 10-13-2004, 07:04 PM
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Replace the fuel filter and check the fuel pump relay -- if it's hot after running a bit, replace it, this may cure the rough idle, lack of power, and occasional stalls while running.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #15  
Old 10-14-2004, 08:48 AM
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Join Date: Jul 2004
Location: York, PA
Posts: 621
Quote:
Originally Posted by psfred
Replace the fuel filter and check the fuel pump relay -- if it's hot after running a bit, replace it, this may cure the rough idle, lack of power, and occasional stalls while running.

Peter

Brand new filter and the relay does not get hot as far as I remember, but I will check it at lunch after I have ran it. Thanks again, and I am leaning toward injectors since I have replaced everything but the fuel pump and AFM.
__________________
~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....
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