Relay getting too hot!

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Baker7888

G-Body Guru
Dec 3, 2021
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Maine
I have an electric water pump on my lt1 wired to a 40a relay. I have a small white label “WP” on the relay and noticed its turning black. It is hotter to the touch than the others. Upon closer inspection the plug is beginning to distort, specifically the power wire that goes to the pump from the relay. I am getting power to the relay from the battery with a 20a fuse in the middle. And the trigger wire goes to the fuse block (fused as well - i want to say this one is only 5a) and comes on with the key. I do not believe my wires to be undersized. Does this indicate a bad relay?
 
How big are the wires?
Not 100% sure but the relay is mounted near the battery. The power wire from battery to relay is about 12 gauge.

The wire going to the WP is a little smaller than that but matches the wire coming out of the WP. This is the wire on the relay plug that appears to be getting hot.
 
With a volt meter see what the voltage in from the battery is versus the voltage coming out of the relay and going to the water pump. If they are not the same the contacts in the relay are getting burned and have a resistance which will cause a loss in voltage which will increase the current drawn.

Or use an ohm meter across the terminals of the relay, should be zero ohms anything higher shows the contacts are getting burned.

Is this a true bosch relay or some amazon/fleabay knockoff?
 
With a volt meter see what the voltage in from the battery is versus the voltage coming out of the relay and going to the water pump. If they are not the same the contacts in the relay are getting burned and have a resistance which will cause a loss in voltage which will increase the current drawn.

Or use an ohm meter across the terminals of the relay, should be zero ohms anything higher shows the contacts are getting burned.

Is this a true bosch relay or some amazon/fleabay knockoff?
Thanks.
13.90 in , 14.12 out
Showing between 108 and 120 ohms on the 200 ohm range.
Yes its a knockoff.
Replace with bosch? The others seem fine
 
Seems pretty light. Start up current may be higher and Actual is what you need to know.

You could measure under 10 amps with most multi meters.
Thanks for the reply. Using a 40 amp relay,
I should be covered, no?
 
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