Still chasing cooling issues (1 Viewer)

Joined
Jan 11, 2009
Messages
887
Location
Oakland CA
Drove the 60 this weekend for the first time in a few weeks. Started to run warm on me... AGAIN! Didn’t over heat but the needle ran past the half way point. I am now on my 3rd CSF 2708 Radiator. First one leaked. 2nd one leaked. This one does not appear to be leaking at all but all of a sudden she’s running warm.

Yesterday wasn’t that hot outside, in the low 80’s. I was running down the freeway at 65 mph with the AC on when the needle started to creep past half way and then a bit further to say 3/4. I turned the front and rear heater on full blast and it dropped the temp to the 1/4 mark right away.

The new clutch fan seams to be working fine. The water pump and all hoses are brand new.

Maybe I need to just move on to an expensive 4core aluminum rad??? Maybe I’m being paranoid...

What am I missing here? Clog? It’s been flushed about 10 times in the last year. Bad new water pump. When I put the thesis-cope to the water pump I can hear it spinning. The burped the system multiple times. It’s full for certain. I’m not currently leaking coolant as far as I can tell. The overflow reads at full level.

Any ideas?


DC7C14AD-7911-467E-A479-5D647030CB61.jpeg
 
Joined
Feb 15, 2017
Messages
844
Location
Kentucky
When cruising on the interstate (summer temps) mine will creep up to where yours is in the photo (or just past) and fluctuate back and forth between the middle (normal) and there as the thermostat opens and closes.

I'd say it gets as high as 3 needle widths from the end of the white line. If that makes sense.
 
Joined
May 5, 2017
Messages
282
Location
98110
Ah shoot...is your temp sender on the head new? I remember reading somewhere debate between using teflon tape on the threads vs. no tape and it skewing the readings. Keep an infrared thermometer in the truck to measure temps when it's getting hot? Time to install a mechanical gauge? Replace your OEM gauge?
 

HemiAlex

TLCA #24987
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Joined
Sep 28, 2015
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2,755
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Houston
Get an external temp gauge. The factory gauge is not linear and 1/4 past your normal resting area of the needle may not be as much as you think.

I tuned mine with an inline resistor and it reads much more normally.

I still use a little motorcycle temp gauge and it works flawlessly.

8B724813-2A19-49F3-BF0E-EF7EA7208EF5.jpeg


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Joined
Apr 29, 2015
Messages
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Coeur d' Alene, ID
I could be wrong, but I through I read in your "Elma the Red" thread that you had an external temp gauge at one point. Do you still have one?
 
Joined
Jan 4, 2011
Messages
4,252
Location
Vermont
Unless coolant is boiling out your radiator cap it’s not running warm. The stock gage is notoriously bad and just gives a general area. The common problem with these trucks is air stuck in the system. If your pump is circulating fluid and you have no leaks or coolant mixing with oil or leaking from head etc then you are probably fine.
 
Joined
Oct 30, 2007
Messages
9,747
Location
Plano texas
Hi, How good of a flush have you done on the engine? I worked on mine for a solid week to get all the crud out. I also did the 10,000 fan clutch mod. Radiators fail when new if the engine is running too hot. How’s the smog equipment,it’s all probably shot. Mike
 
Joined
Jan 4, 2011
Messages
4,252
Location
Vermont
Basics.

all air must be out of the system otherwise pockets and bubbles will cause all sorts of confusion and headaches.

make sure your radiator cap is sealing properly and holding pressure. A system pressure test would be a good thing to do. 15psi is the number to hold iirc. If your system is t holding pressure it will Boil faster and cause issues.

cooling fan clutch. Your fan clutch should really roar for the first 20 seconds or so when you start driving and then gradually quiet down.

Thermostat. Make sure it’s cycling open and closed. One trick is to warm the truck up, open the hood, wear some safety glasses, stand at the drivers side fender so you can feel the air coming off the fan. If the t Stat is working properly you should be able to feel a noticeable blast of hot air then cooler air and then hot as the thermostat cycles open and close. Wear the safety glasses do a bit of sand kicked up by the fan doesn’t go in your eye.

coolant. Make sure it’s a nice clean 50/50 mix
 
Joined
Nov 16, 2004
Messages
1,120
Location
Simpsonville,SC
Sitting in the driveway, A/C full blast for 30 minutes, with CSF radiator doing a test of sorts. Message of the pic is- get a mechanical gauge, it will alleviate so much worry & questions.

20201008_145723.jpg
 
Joined
May 29, 2007
Messages
3,408
Location
no.california S.F.O BAY AREA (EAST BAY)
Just would like to add to what @Seth S posted, the thermostat can be installed upside down i found this out when i notice that my gauge always stay on the bottom just above the C after replacing it and bleeding it properly it reads just pass half the gauge or a bit higher on warmer days.

@ff347 Could you post a pic where you installed the sensing bulb for your mechanical gauge?
 

MTB Land Cruise

SILVER Star
Joined
Jun 18, 2020
Messages
132
Location
Los Angeles
Drove the 60 this weekend for the first time in a few weeks. Started to run warm on me... AGAIN! Didn’t over heat but the needle ran past the half way point. I am now on my 3rd CSF 2708 Radiator. First one leaked. 2nd one leaked. This one does not appear to be leaking at all but all of a sudden she’s running warm.

Yesterday wasn’t that hot outside, in the low 80’s. I was running down the freeway at 65 mph with the AC on when the needle started to creep past half way and then a bit further to say 3/4. I turned the front and rear heater on full blast and it dropped the temp to the 1/4 mark right away.

The new clutch fan seams to be working fine. The water pump and all hoses are brand new.

Maybe I need to just move on to an expensive 4core aluminum rad??? Maybe I’m being paranoid...

What am I missing here? Clog? It’s been flushed about 10 times in the last year. Bad new water pump. When I put the thesis-cope to the water pump I can hear it spinning. The burped the system multiple times. It’s full for certain. I’m not currently leaking coolant as far as I can tell. The overflow reads at full level.

Any ideas?


View attachment 2463265
Just fyi……My 89-FJ62 had similar symptoms last August, temp needle moving to hot (3/4 mark or more) during street driving/idling. Needle drops with vehicle moving. In Freeway driving, gauge needle would drop, but would spike again if slowed for traffic. Tested with AC Off and then ON. (It also had these symptoms twice before but that’s how I found the radiators were leaking and I replaced them).

Did basic inspection, No Leaks anywhere, checked water pump, thermostat, hoses, Radiator and Cap, etc. radiator coolant good, reservoir level normal, Fan Clutch OK. I’ve had my 89 since new, and run all OEM parts except for the Radiator (CSF 2708). Temp gauge is stock and has always registered just above the ¼ mark. So, when the needle jumps up and down, something is amidst.

Decided to do less costly approach first; Flush the entire system (last flush was 3 years ago when the Radiator was installed) and add New Coolant “Green” ( I know; others have different views on type/color coolant they prefer), but the Green has worked for me.
I had my local mechanic perform the service (I didn’t have time and needed my LC asap for a trip) Had the Flush/pressure test service done; for 50 bucks including the Coolant.

Test drove after Flush and New coolant. Gauge Needle returned to my “Normal” just above ¼ mark, during street driving/idling and on freeway. Tested both with AC on and Off.

I see you have flushed/burped your system several times so, maybe its not a Flush problem, but something else as others have suggested. All ideas are good. I would start with the basics and least expensive, then move up with the bigger items. good luck.
 

Gretsch

SILVER Star
Joined
Apr 3, 2017
Messages
1,512
Location
Plano Texas
Joe, mine does the same as yours with a new CSF radiator. Checked for leaks and found a few which were handled, but still does it. Around here it seems like when the temps get cooler like 75-80 outside, the air is still warm enough to warm up the engine more than usual, but not warm enough to cause the fan clutch to engage to keep the temps down to normal. Seems like its just in that middle zone where it gets warmer than normal but not warm enough to engage the fan clutch to keep it cool if that makes sense. When its in the 100's around here the fan comes on as needed and keeps things in the right area on the factory gauge. Mine only creeps up when driving Hwy speeds. Idling its fine so seems its related to higher pressures.

I am sure you have done pressure tests on the system for leaks, but if not prolly a good thing to do as others have mentioned. I thought I had all leaks figures out, did another test, and found more. Silly stuff but easy. I am not saying anything new, but just wanted to add someone else sees the same thing you do. HTH.
 
Joined
May 14, 2018
Messages
123
Location
San Francisco Bay Area
mine runs towards the 3/4 to almost to the end of the white on the gauge. i replaced my water pump, tstat, hoses, and fan clutch and it still runs around there. the fan roars on/off when i'm on the freeway. i haven't installed an inline electric gauge like @HemiAlex but it's on the list. IR temp readings are around 195F right after I park.
 

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