Overheating Issue

Yomonai

New member
7
1
3
Buick Ownership
1994 RMS Limited
1994 RMS Limited 5.7L LT1. Narrowed it down to the fans. The fans do not come on when sitting and idling, allowing the temperature to get far too high.

1. Unplugged the pump sensor, both fans function.
2. Replaced the pump sensor, no change.
3. Tested primary relay - functions.
4. Jumped fans from fuse box - both function.
5. Primary fan functions properly under A/C operation.
6. Primary fan cools to under halfway up the dash gauge when on.

What am I left with? ECU? Am I missing a relay somewhere? Anyone got any ideas?
 

HotZ28

Full Member Since 2005
9,485
1,519
113
SE
Buick Ownership
1996 Roadmaster Limited Collectors Edition 58k - 1996 PAU 2019 Regal GS
I see nothing wrong with you have have mentioned so far.
 

ulycyc

Well-known member
541
272
63
Long Island, New York
Buick Ownership
1987 Turbo Buick, 2001 Park Ave Ultra
"temperature to get far too high" is not reading to suggest help. ECM/sensors turn on the fans at a designated temperature. If your idle temp. is below that point and ac is off the fans will stay off. . I think the low fan turns on around 220deg and high fan around 230 but you will have to check that as I dont have a RMS manual
 

Yomonai

New member
7
1
3
Buick Ownership
1994 RMS Limited
I see nothing wrong with you have have mentioned so far.
It's a problem when I turn the a/c off and the engine gets hot.

"temperature to get far too high" is not reading to suggest help. ECM/sensors turn on the fans at a designated temperature. If your idle temp. is below that point and ac is off the fans will stay off. . I think the low fan turns on around 220deg and high fan around 230 but you will have to check that as I dont have a RMS manual
Staying at under-mid temp under a/c operation suggests the dash gauge functions properly. The fact that it goes to red with no fan operation with a/c system off and a hot pump suggests a faulty system. One that I would like to fix, so I don't need to constantly run the a/c.
______________________________
 

Yomonai

New member
7
1
3
Buick Ownership
1994 RMS Limited
I've bought and taken a laser thermometer to the center of the water pump, and it reads 233.6°F before the primary fan clicks on. Last possible second according to surface metal temp makes me uneasy, but it is technically within spec.
 
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