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Pelican Technical Article:

Heater Valve Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$100 to $150

Talent:

***

Tools:

T30 Torx, flathead screwdriver

Applicable Models:

Mercedes-Benz C350 (2008-14)
Mercedes-Benz GLK350 (2010-14)

Parts Required:

Heater valve

Hot Tip:

Replace the pump with the engine cold

Performance Gain:

Working heat

Complementary Modification:

Flush cooling system

The heater valve shuts off the flow of coolant to the heater core to allow the engine to come up to temperature quicker on cold starts. If your heater valve has stopped working you can replace it without a lot of trouble but be prepared to work in a crowded area and do some things by feel. I have removed the intake manifold to get pictures of what you are going to be doing. You do not need to remove the manifold to replace the valve. It makes it easier but adds about 4 hours of work plus the cost of intake gaskets.

If you are going to be replacing the valve you might as well replace the coolant as well. If it is an emergency and you need to get the car right back on the road it is possible to remove the valve without draining the radiator. But you will loose all the fluid until the level gets even with the valve. I recommend doing it right and draining the coolant. Even with the coolant drained, you should expect a little spillage when removing the hoses, so be prepared for it.

You will need to remove the engine covers (red and yellow arrows) and air intake ducts (green arrows) to perform this work.
Figure 1

You will need to remove the engine covers (red and yellow arrows) and air intake ducts (green arrows) to perform this work. Please see our article on engine cover removal for additional assistance.

If you are draining the coolant you will need to remove the under body trays to access the radiator drain plug (red arrow).
Figure 2

If you are draining the coolant you will need to remove the under body trays to access the radiator drain plug (red arrow). Please see our article on coolant drain and flush for additional information.

The heater valve is located between the MAF and the left cylinder head below the main wiring harness (red arrow, not visible).
Figure 3

The heater valve is located between the MAF and the left cylinder head below the main wiring harness (red arrow, not visible).

You next need to remove the MAF (red arrow) and vacuum line (yellow arrow).
Figure 4

You next need to remove the MAF (red arrow) and vacuum line (yellow arrow). Please see our article on MAF sensor replacement for additional information.

Disconnect the breather hose from the rear of the right cylinder head (red arrow).
Figure 5

Disconnect the breather hose from the rear of the right cylinder head (red arrow).

Unclip the two plastic clips on the elbow piece between the MAF and throttle body (red arrow) and remove the elbow and attached hose.
Figure 6

Unclip the two plastic clips on the elbow piece between the MAF and throttle body (red arrow) and remove the elbow and attached hose.

Disconnect the electrical connection by lifting up the gray tab with a small flathead screwdriver and then squeezing the tab back and pulling the electrical connection straight up and off (red arrow).
Figure 7

Disconnect the electrical connection by lifting up the gray tab with a small flathead screwdriver and then squeezing the tab back and pulling the electrical connection straight up and off (red arrow).

Next use a flathead screwdriver and pry up the quick release clip on the heater hose (red arrow).
Figure 8

Next use a flathead screwdriver and pry up the quick release clip on the heater hose (red arrow).

Use care when separating the hose from the valve (red arrow).
Figure 9

Use care when separating the hose from the valve (red arrow). The hose end is plastic, and you do not want to damage it or you will end up replacing the hose as well. Whether you have drained the coolant or not expect some coolant to come out and be prepared to catch it and dispose of it in accordance with the regulations in your area.

There are two T30 bolts that you need to remove (red arrows).
Figure 10

There are two T30 bolts that you need to remove (red arrows).

The lower bolt on the pump can be a pain to get a T30.
Figure 11

The lower bolt on the pump can be a pain to get a T30. Make sure you do not drop it when removing (red arrow).

Wiggle and pull the valve from the opening in the head (red arrow).
Figure 12

Wiggle and pull the valve from the opening in the head (red arrow). Installation is the reverse of removal. Do not forget to replace or top up the coolant.


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Page last updated: Fri 12/9/2016 02:55:36 AM