Need Help w/ Overheating Issue
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Joined: May 2008
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From: Los Angeles
Need Help w/ Overheating Issue
Hey guys, I need some help with overheating issues. I've searched through all the posts regarding overheating, but I haven't found an answer to my issue. Here is what the car has right now for cooling system (2004 350Z w/ 41,000 miles):
1) OEM fan shroud/fans
2) Koyo performance radiator and cap
3) Nismo T-stat
Issues: overheating, fans seem to operate during active test, but not fully operational during driving.
When I turn on the car, let it idle and warm it up, once it hits 212 degrees, the fans turn on then bring it down to about 194-195 degrees then turn off. But when it goes back up to 212+ degrees for the 2nd time, then fans don't turn on, and temp will keep climbing; not working consistently.
I've checked the 3 fan relays, all 3 had resistance when checked (80 give or take ohms).
During the IPDM active test, this is the how the fans work during the test:
1st sequence when the fans turn on - driver side turns on first, then pass side turns on, then both turn off together
2nd - same as first set
3rd - both turned on and turned off at the same time
Is this the normal fan operation during the entire active test?
Does anyone know what else I can check?
Is it a bad fan?
Is it a bad relay?
Is it normal for the fans turn on at around 212 degrees? Then off around 195 degrees?
Why doesnt my fans turn on again after the 2nd time coolant temp creeps up and past 212 degrees?
Thanks in advance!
1) OEM fan shroud/fans
2) Koyo performance radiator and cap
3) Nismo T-stat
Issues: overheating, fans seem to operate during active test, but not fully operational during driving.
When I turn on the car, let it idle and warm it up, once it hits 212 degrees, the fans turn on then bring it down to about 194-195 degrees then turn off. But when it goes back up to 212+ degrees for the 2nd time, then fans don't turn on, and temp will keep climbing; not working consistently.
I've checked the 3 fan relays, all 3 had resistance when checked (80 give or take ohms).
During the IPDM active test, this is the how the fans work during the test:
1st sequence when the fans turn on - driver side turns on first, then pass side turns on, then both turn off together
2nd - same as first set
3rd - both turned on and turned off at the same time
Is this the normal fan operation during the entire active test?
Does anyone know what else I can check?
Is it a bad fan?
Is it a bad relay?
Is it normal for the fans turn on at around 212 degrees? Then off around 195 degrees?
Why doesnt my fans turn on again after the 2nd time coolant temp creeps up and past 212 degrees?
Thanks in advance!
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Joined: Dec 2023
Posts: 1
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From: Preston
Hey guys, I need some help with overheating issues. I've searched through all the posts regarding overheating, but I haven't found an answer to my issue. Here is what the car has right now for cooling system (2004 350Z w/ 41,000 miles):
1) OEM fan shroud/fans
2) Koyo performance radiator and cap
3) Nismo T-stat
Issues: overheating, fans seem to operate during active test, but not fully operational during driving.
When I turn on the car, let it idle and warm it up, once it hits 212 degrees, the fans turn on then bring it down to about 194-195 degrees then turn off. But when it goes back up to 212+ degrees for the 2nd time, then fans don't turn on, and temp will keep climbing; not working consistently.
I've checked the 3 fan relays, all 3 had resistance when checked (80 give or take ohms).
During the IPDM active test, this is the how the fans work during the test:
1st sequence when the fans turn on - driver side turns on first, then pass side turns on, then both turn off together
2nd - same as first set
3rd - both turned on and turned off at the same time
Is this the normal fan operation during the entire active test?
Does anyone know what else I can check?
Is it a bad fan?
Is it a bad relay?
Is it normal for the fans turn on at around 212 degrees? Then off around 195 degrees?
Why doesnt my fans turn on again after the 2nd time coolant temp creeps up and past 212 degrees?
Thanks in advance!
1) OEM fan shroud/fans
2) Koyo performance radiator and cap
3) Nismo T-stat
Issues: overheating, fans seem to operate during active test, but not fully operational during driving.
When I turn on the car, let it idle and warm it up, once it hits 212 degrees, the fans turn on then bring it down to about 194-195 degrees then turn off. But when it goes back up to 212+ degrees for the 2nd time, then fans don't turn on, and temp will keep climbing; not working consistently.
I've checked the 3 fan relays, all 3 had resistance when checked (80 give or take ohms).
During the IPDM active test, this is the how the fans work during the test:
1st sequence when the fans turn on - driver side turns on first, then pass side turns on, then both turn off together
2nd - same as first set
3rd - both turned on and turned off at the same time
Is this the normal fan operation during the entire active test?
Does anyone know what else I can check?
Is it a bad fan?
Is it a bad relay?
Is it normal for the fans turn on at around 212 degrees? Then off around 195 degrees?
Why doesnt my fans turn on again after the 2nd time coolant temp creeps up and past 212 degrees?
Thanks in advance!
A friend at the garage Identified my fans not kicking in as a relay.
hope you get sorted!
Jack
Last edited by Clev; Dec 30, 2023 at 05:20 PM.
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Joined: May 2008
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From: Los Angeles
I'm not 100% sure however I think a relay maybe the issue there, logically if the fans are operational (even if momentarily) it would make sense that the problem lies beforehand... The relays decide whether to pass or stop the electricity, I'm no expert and still learning, but regardless of If I'm right or not replacing the relays and seeing if that fixes the problem will come at fraction of the cost compared to the other way round so if you find no other solution that should be your first port of call, also check both fuses in the fuse block, failing that a fan motor might not be working properly
A friend at the garage Identified my fans not kicking in as a relay.
hope you get sorted!
Jack
A friend at the garage Identified my fans not kicking in as a relay.
hope you get sorted!
Jack
Anyone know if thats how the active test is supposed to run?
I would start looking at the coolant system -
Are your coolant hoses both hot when the engine overheats?
is your heat blowing hot air when the car overheats?
How long has the car had the upgraded thermostat and radiators?
Fans only cool the radiator/coolant when the car is stationary and/or driving very slow … if you are driving above 15mph to 20mph than passive airflow does far more cooling than the fans.
Your next big step would be a compression test and leak-down test to ensure your heads are sealing
I supect you have air bubbles in the system (from when these upgraded cooling items were installed) …
Are your coolant hoses both hot when the engine overheats?
is your heat blowing hot air when the car overheats?
How long has the car had the upgraded thermostat and radiators?
Fans only cool the radiator/coolant when the car is stationary and/or driving very slow … if you are driving above 15mph to 20mph than passive airflow does far more cooling than the fans.
Your next big step would be a compression test and leak-down test to ensure your heads are sealing
I supect you have air bubbles in the system (from when these upgraded cooling items were installed) …
Thread Starter
New Member
Joined: May 2008
Posts: 12
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From: Los Angeles
Thanks!
I would start looking at the coolant system -
Are your coolant hoses both hot when the engine overheats? Yes
is your heat blowing hot air when the car overheats? Mostly yes. There was only 1 time recently when the air was luke warm when it was on max heat.
How long has the car had the upgraded thermostat and radiators? 3-4 months
Fans only cool the radiator/coolant when the car is stationary and/or driving very slow … if you are driving above 15mph to 20mph than passive airflow does far more cooling than the fans.
Your next big step would be a compression test and leak-down test to ensure your heads are sealing
I supect you have air bubbles in the system (from when these upgraded cooling items were installed) … I thought so too, I bled it 3x. I believe most of the air is out. I'll defintely try once more, but I'll start by getting 3 new relays first.
I'm not sure if my fans are working properly. When they turn from low to high, is it one fan on, then second turns on? Or is it both fans on low, then both on high?
Are your coolant hoses both hot when the engine overheats? Yes
is your heat blowing hot air when the car overheats? Mostly yes. There was only 1 time recently when the air was luke warm when it was on max heat.
How long has the car had the upgraded thermostat and radiators? 3-4 months
Fans only cool the radiator/coolant when the car is stationary and/or driving very slow … if you are driving above 15mph to 20mph than passive airflow does far more cooling than the fans.
Your next big step would be a compression test and leak-down test to ensure your heads are sealing
I supect you have air bubbles in the system (from when these upgraded cooling items were installed) … I thought so too, I bled it 3x. I believe most of the air is out. I'll defintely try once more, but I'll start by getting 3 new relays first.
I'm not sure if my fans are working properly. When they turn from low to high, is it one fan on, then second turns on? Or is it both fans on low, then both on high?
Thread Starter
New Member
Joined: May 2008
Posts: 12
Likes: 0
From: Los Angeles
Problem solved! I just bought 3 replacement fan relays from Amazon, and now my fans turn on when they are supposed to. They turn on about 212/213 degrees, then turn off around 193/194 degrees. Thanks!
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