Overheating with cold radiator

Mfee2079 · 02-13-2022, 03:32 PM

Trying to help a friend with his 2002 LW 300
I just did his timing belt and water pump but he now has an overheating issue
Thermostat is opening, fans are kicking on, upper and lower hoses are hot but radiator is cold as is the air being blown out from the fans
I'm leaning towards a clog in the radiator but anything I might be missing in this assessment pointed out to me would be helpful.
(3.0 V6)

fdryer · 02-13-2022, 05:56 PM

Are you sure the cooling system was refilled, engine started, allowed to idle as air remaining in the cooling system self purged with or without the coolant container cap on? On level ground, the cooling system will self purge any air in the system into the coolant container. A brief drive around the block will do the same. Then top off. Saturns do not have heater core shut off valves. Coolant always flows for immediate heating as the engine warms up, regardless of t-stat operation. Approximately 7 qts needed.

Mfee2079 · 02-13-2022, 06:16 PM

Yes. Put in almost 2 gallons. Even if it was a little low the radiator should still get at least warm to the touch.

fdryer · 02-13-2022, 08:12 PM

How do you know the t-stat is opening? Temperature gauge needle moving from cold to ...? Can you connect a reader/scantool to monitor coolant temperatures from startup to overheating? It's rare for t-stats to stick closed when most open sooner, resulting in cooler running. Sometimes an error code points to the engine temperature being lower. L300s should be running 195F.

Mfee2079 · 02-14-2022, 10:04 AM

Don't have a scanner with that capability. Needle goes from cold to over 3/4 mark with fans kicking on just below 1/2 way point.
Radiator fill bottle fills up completely when t-stat opens so I know that is working which happens when about time fans kick on.

lrbraner · 02-14-2022, 10:27 AM

Possibly an issue with the water pump, or the installation

02-13-2022, 03:32 PM	#1
Mfee2079 New Member Join Date: Feb 2022 Posts: 3	Overheating with cold radiator Trying to help a friend with his 2002 LW 300 I just did his timing belt and water pump but he now has an overheating issue Thermostat is opening, fans are kicking on, upper and lower hoses are hot but radiator is cold as is the air being blown out from the fans I'm leaning towards a clog in the radiator but anything I might be missing in this assessment pointed out to me would be helpful. (3.0 V6)

02-13-2022, 05:56 PM	#2
fdryer Super Member Join Date: Jan 2006 Location: NYC Posts: 45,658 fdryer's Photos 2003 L-Series 3.0L Sedan	Re: Overheating with cold radiator Are you sure the cooling system was refilled, engine started, allowed to idle as air remaining in the cooling system self purged with or without the coolant container cap on? On level ground, the cooling system will self purge any air in the system into the coolant container. A brief drive around the block will do the same. Then top off. Saturns do not have heater core shut off valves. Coolant always flows for immediate heating as the engine warms up, regardless of t-stat operation. Approximately 7 qts needed. Last edited by fdryer; 02-13-2022 at 06:04 PM.

02-13-2022, 06:16 PM	#3
Mfee2079 New Member Join Date: Feb 2022 Posts: 3	Re: Overheating with cold radiator Yes. Put in almost 2 gallons. Even if it was a little low the radiator should still get at least warm to the touch.

02-13-2022, 08:12 PM	#4
fdryer Super Member Join Date: Jan 2006 Location: NYC Posts: 45,658 fdryer's Photos 2003 L-Series 3.0L Sedan	Re: Overheating with cold radiator How do you know the t-stat is opening? Temperature gauge needle moving from cold to ...? Can you connect a reader/scantool to monitor coolant temperatures from startup to overheating? It's rare for t-stats to stick closed when most open sooner, resulting in cooler running. Sometimes an error code points to the engine temperature being lower. L300s should be running 195F.

02-14-2022, 10:04 AM	#5
Mfee2079 New Member Join Date: Feb 2022 Posts: 3	Re: Overheating with cold radiator Don't have a scanner with that capability. Needle goes from cold to over 3/4 mark with fans kicking on just below 1/2 way point. Radiator fill bottle fills up completely when t-stat opens so I know that is working which happens when about time fans kick on.

02-14-2022, 10:27 AM	#6
lrbraner Member Join Date: Jan 2018 Location: Ft. Wayne, IN Posts: 402 2002 L-Series 3.0L Sedan 2003 L-Series 3.0L Wagon	Re: Overheating with cold radiator Possibly an issue with the water pump, or the installation ... 2002 L300 Sedan 2003 LW300 Wagon 2005 L300 Sedan

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