How to tell intercooler pump is working?
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
How to tell intercooler pump is working?
Question as stated.
I don't have a reason to believe mine is NOT working, but I want to make sure, as the circuit is shared with the alternator.
I don't have a reason to believe mine is NOT working, but I want to make sure, as the circuit is shared with the alternator.
Junior Member
Joined: Aug 2014
Posts: 50
Likes: 7
From: Seattle, Washington
2006 S65 AMG, 2001 S600, 1995 RX7, 1994 840Ci, 1975 XJ6-C, 1971 Celica Coupe
check your heat exchanger with a laser thermometer & see if it’s getting hot coolant circulated. If it’s working you should see a pretty big variable on the two different sides of the heat exchanger
Newbie
Joined: Apr 2021
Posts: 9
Likes: 0
W215
Easier ways just look up “ jump relay intercooler pump” here. You’ll be able to tell if it’s running with the car off. Mine was shot they are usually junk. Only other ways to have a scanner and watch the values. If they don’t drop while you’re on the throttle, it’s not working
Member
Joined: May 2020
Posts: 247
Likes: 57
From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
Touch the intercooler pipes coming out of the top-mounted heat exchangers. if you don't burn your fingers, it's working. I'm also able to see coolant moving from my fill cap once the car has warmed up.
Super Member
Joined: Sep 2021
Posts: 537
Likes: 115
From: Ann Arbor, MI
2004 SL600
Has anyone documented typical IAT (Intake Air Temperatures) when just driving at e.g. 70 mph on a 70F day?
Just guessing, I would expect 90F if everything is working and maybe 140F if the pump and/or system are not working.
Just guessing, I would expect 90F if everything is working and maybe 140F if the pump and/or system are not working.
Member
Joined: May 2020
Posts: 247
Likes: 57
From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
Took pics recently, my CL65 was steady at 55C (131F) in about 95F weather cruising at 75MPH, AC on. My pump is upgraded so that may not track with a standard bosch unit.
I think the common expectation is 40-50f over ambient. With my pump dead, the IAT was 95C+, with a huge loss in power.
I think the common expectation is 40-50f over ambient. With my pump dead, the IAT was 95C+, with a huge loss in power.
Last edited by JustTXn; Jun 18, 2025 at 03:35 PM.
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Super Member
Joined: Sep 2021
Posts: 537
Likes: 115
From: Ann Arbor, MI
2004 SL600
Took pics recently, my CL65 was steady at 55C (131F) in about 95F weather cruising at 75MPH, AC on. My pump is upgraded so that may not track with a standard bosch unit.
I think the common expectation is 40-50f over ambient. With my pump dead, the IAT was 95C+, with a huge loss in power.
I think the common expectation is 40-50f over ambient. With my pump dead, the IAT was 95C+, with a huge loss in power.
I am considering adding an "Interchiller" which cools the water using the A/C system, often bringing the IAT below ambient temperature.
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