2 questions: Cold air from ctr vents/Pegged out oil pressure guage - PeachParts Mercedes-Benz Forum

Avatar45 · #1 10-09-2007, 04:10 PM

1991 190E

He all! First I'd like to thank everyone for their help on removing the ignition assembly! What a pain but thanks to all of your help it was completed with no left over parts!! But now I have two more problems that I would like to put before you:

1) When the heat is on all of the vents blow warm aur with the exception of the center console vents. Does not matter what setting the heater is on only cold air blows through there. Any comments?

2) The oil pressure guage is pegged out at the top. It goes back to zero when the car is switched off so I know it at least moves! I checked all of the engine fluids and all are good. Car runs fine, temp. is good but would like to know if there is something I need to check out.

Thanks for the help in advance and look forward to hearing from you!!

brewtoo · #2 10-09-2007, 04:48 PM

When you have the heat on, no air at all should exit the center vents.

It is normal for the oil pressure to peg at the top while driving. The gauge only reads to 45 PSI.

vegadonovan · #3 10-09-2007, 09:50 PM

Hi,

From what I have gathered, the center vent does not blow heated air. If you look at the manual, it says center vent will blow fresh/cold air. So it should be normal and well within specs. Make sure the fresh air flap is closed in cold weather or you will freeze.

Thanks and hope it helps.

crhenkel · #4 10-10-2007, 01:51 AM

In time the contacts on the motor pod that drives the gauge needles can build up oxidation and start to make poor contact. A bad ground or a poor contact can peg a gauge. Usually it is the temp gauge though. Your oil pressure gauge should read high. SHould read atleast at the 3 bar mark when you are driving. Typically no less than 2 bar when idling is ok. Oil pressure pegged is typically not bad.

Avatar45 · #5 10-10-2007, 11:15 AM

You guys ROCK!! Thanks for all the info! I've been looking for an owners manual and found they sell for about $60.00, OUCH!! But thanks again and I'm sure I'll be talking with you all again!

mctwin2kman · #6 10-10-2007, 12:07 PM

Just to add to this. Is is perfectly normal for the oil gauge to be pegged. That is a good thing. You may find that on hot days when the engine is run well and all heated up that you may get it to drop a hair at idle. Spec calls for anything over 2000RPM to peg that gauge.

As for the center vents. Well they are designed to only allow fresh air and AC air, no heat what so ever.

G-Benz · #7 10-10-2007, 02:38 PM

I guess I would define "peg"...

...if the needle "pegs" when the ignition is switched on the accessory mode but the engine has'nt been started, then you need a new oil pressure sender...about $60-70 and a 15-minute under-the-car job with a short crescent wrench.

brewtoo · #8 10-10-2007, 04:36 PM

Quote:

Originally Posted by G-Benz

I guess I would define "peg"...

...if the needle "pegs" when the ignition is switched on the accessory mode but the engine has'nt been started, then you need a new oil pressure sender...about $60-70 and a 15-minute under-the-car job with a short crescent wrench.

That is a good point.

Avatar45 · #9 10-11-2007, 08:29 PM

Glad for the last response! I went out and turned the key without starting it and the needle went to the top! So it would seem that I would need that oil sender unit. Any websites that tell how to do it?

G-Benz · #10 10-12-2007, 05:37 AM

Quote:

Originally Posted by Avatar45

Glad for the last response! I went out and turned the key without starting it and the needle went to the top! So it would seem that I would need that oil sender unit. Any websites that tell how to do it?

I've done the procedure once (and after a top-end-rebuild, discovered that I need to replace it again).

I don't know about the 190E, but this is the procedure for the M104 motor on the 300E:

The sender is accessed under the vehicle on the driver's side near the starter. A wiring connection is attached. Don't need to disconnect battery or drain oil for this procedure. I believe it requires an 11mm crescent wrench to remove, but I don't remember. Because of the tight confines, a short wrench is best, so there is enough room to turn the wrench to loosen/tighten.

Once you remove the plastic panel beneath the engine, the replacement procedure takes about 15 minutes.