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Running "hot" at idle

CLSegraves

NAXJA Forum User
Location
Phoenix, Arizona
01 XJ

I just replaced my factory water pump (and t-stat neck) with a Wesco high flow pump (and neck). Prior to the water pump swap, idle temp was around 180-185. Now it's idling at around 200. If I idle up to 2500 RPM, the coolant temp comes down to 185.

The cooling setup consists of:
- 3 core aluminum radiator
- Volvo 16" 2 speed fan
- 180 degree T-stat
- expansion tank mounted on firewall (self purging system)

I'm measuring a 60 degree temp drop across the radiator (hot tank at 195/cold tank at 135) using an inferred temp gun (painted tanks black to get reliable reading with temp gun). I seem to remember reading somewhere that high temp drop across the radiator means insufficient water flow (water's moving too slow) but would expect the new Wesco pump to be moving more water than my old 150K mile factory pump.

Ideas? I called Wesco but they wanted to blame the issue on the 180 t-stat and fans, even though those were there beforehand. :rolleyes:
 
Did you by chance mean Hesco?
 
About 195° is the normal operating temp. IMO higher idle temps are a lack of air flow. What CFM's airflow do the fans provide ?
 
Note: All of this is sitting still in the garage with the electric fans providing airflow... no vehicle speed involved so radiator airflow is a constant.

You only speak of one fan in your op, do you have more than 1? Typically electric fans don't pull enough air when sitting still. The proper t-stat would be a 195*.
 
You only speak of one fan in your op, do you have more than 1? Typically electric fans don't pull enough air when sitting still. The proper t-stat would be a 195*.

I have a 16" volvo 2-speed fan and a 10" spal fan. I've never been able to find an actual rated CFM for the Volvo fan, but the general consensus is 3400-3600 cfm on high (it pulls 27 amps on high) and lots of guys used them to cool BBCs in hot rods. The spal fan seems to be rated at ~750 cfm. Both fans are mounted on a shroud.

I like the 180 because it reaches full open around 195, which seems to help out here in the summer (if anything it makes me feel better to not see the needle at 210).
 
I went home at lunch, drained and flushed the system (water in the block was nasty rust colored), and then ran it up to temperature.

Starting to look like either my t-stat is stuck closed or my radiator is plugged up. The*hot side tank got to*208, cold side was 100 and the "hot" of the radiator stopped about 3" from the hot tank. Perhaps the new pump dislodged scale/rust in the block which plugged up the radiator?
 
All I can say is that tomorrow will be my 57th yr in Phx, I wheel when it's 122* with the A/C on and let it idle for hours. I've always owned a Jeep and can't even count on my hands/fingers which one I'm on now. If your system ain't cuttin-it, somethings wrong!
 
All I can say is that tomorrow will be my 57th yr in Phx, I wheel when it's 122* with the A/C on and let it idle for hours. I've always owned a Jeep and can't even count on my hands/fingers which one I'm on now. If your system ain't cuttin-it, somethings wrong!

Agreed, that' why I knew something had to be wrong. My XJ never runs hot, even with the AC on in the summer so what it was doing told me something wasn't right. The pump was just preventative maintenance.
 
Are you going on the 21st annual CK run next weekend?
 
Nice that you got it resolved. When was the last time you drained/flushed prior to the incident? Just curious as to how long it took to cause the radiator to plug. I flush my yearly and each time it looks new when draining.
 
Nice that you got it resolved. When was the last time you drained/flushed prior to the incident? Just curious as to how long it took to cause the radiator to plug. I flush my yearly and each time it looks new when draining.

Probably 6 months ago and it came out clean at that time.

As I said, I think the new pump (which is supposed to flow 20% more) likely caused scale and "junk" to come lose in the block and it got swept into the radiator. Fortunately it wasn't "sludge", just particles because the radiator shop was able to back wash the radiator and thereby clean out the tubes.
 
Probably 6 months ago and it came out clean at that time.

As I said, I think the new pump (which is supposed to flow 20% more) likely caused scale and "junk" to come lose in the block and it got swept into the radiator. Fortunately it wasn't "sludge", just particles because the radiator shop was able to back wash the radiator and thereby clean out the tubes.

Good to know...thx.
 
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