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Running Hot on Freeway

M

moustacio

New member
Joined
Mar 10, 2012
Location
Colorado
Hey everyone,

I thought I would ask for opinions on why my car runs warm on freeway trips. I installed a coolant temperature sensor in the block of my b230ft where the drain Petcock is last year. My commute at the time was ~40 miles climbing ~1000' and doing around 75mph at 3,200rpm during the hottest part of the day. Had a mechanical fan at the time and have since went to an electric puller fan, this made no difference in highway engine temp though. Newer radiator, 82*C/180*F thermostat, and fresh 50/50 type C coolant. Also, I used the prestone clean and flush stuff before installing the new cooling system components. Heater works fine and I believe the system to be properly bled.

My concern is when it was 90*F and above outside the block temperature gauge would stay around 200*F and not come back down until exiting the highway. Sometimes it would climb to 210+ and rarely 190 and below, agian during highway trips. Around town the e-fan does a great job, kicking in around 190*F.

The car seems to keep a good temperature during all other seasons. I'm now driving 2,000' uphill in the morning but it's cold But with warmer weather coming up I thought I would ask y'all.

Cylinder #3 reads 30 psi less compression than the others which seems to be being lost past its piston rings. I also have no cat and newer cat back exhaust. I haven't tested coolant for exhaust gas, is this recommended? Any other ideas as to what's going on?

Thanks for any help
 
Sure the coolant overflow tank has water in it cold?

Belt on waterpump tight?

You mention a 'newer radiator' but look at the radiator temperature high, middle and low with an IR thermometer. Less than $10 on ebay. My right tank was clogged up to the point that water was only flowing across the top third of the cores.
 
Hi testpoint and thank you for your response.

That sounds like an excellent idea, I will have to look around and order one.

I guess I forgot a few thing in my already long post. By newer I meant I replaced these last year when I noticed the higher temperatures, sorry for that. Yes, overflow is within the correct range cold and hot. Also have newer 75kpa coolant overflow cap and Hepu water pump (less than 5K miles on each), continental belts (around 10K miles). The belt for the water pump is tight.

I will get an IR thermometer and post back with what I come up with.

Thanks again

*Edit: I should maybe also mention that around town, when the e-fan kicks on the temperature drops quickly. Maybe 10*F in 30 seconds or so. Going to order the IR after work.
 
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Bad point for temp sensor.
You have a glowing turbo and a very very hot downpipe nearby.
What do you expect? ???

A cooled point of the engine??


Shaking head Kay
 
mocambique-amazone said:
Bad point for temp sensor.
You have a glowing turbo and a very very hot downpipe nearby.
What do you expect? ???

A cooled point of the engine??


Shaking head Kay
Click to expand...

This is a good point, but doesn't really explain why you have high readings on the freeway and not at slower speeds.

What puller fan did you install? Is there a shroud? how is it controlled?
 
Hi and thank you for your responses.

I was under the assumption that the reading from the block drain location would be lower than if I were able to get a reading from the head. I'll take a look at how I have it routed though, it is a mechanical gauge so you have a point I had not considered. I could maybe put in a light in the dash to indicate whether the e-fan is running or not. That may help in determining if the block temperature is actually reading higher due to the exhaust?

I am using a 2 speed fan and relay from a 940. I mounted the e-fan in the original 740 shroud, using your page as a reference actually. (Thank you by the way, some great info there). I have yet to fill in the gaps with some weatherstripping or the like though. Low speed is being triggered with the radiator sensor, on at 92*C and off at 87*C.

Thank you
 
Do you use synthetic oil or dino? Make sure the grid on the oil cooler for both the trans and the engine oil are clean? No trans cooler if it's a manual but you have one if automatic.
 
moustacio said:
I am using a 2 speed fan and relay from a 940. I mounted the e-fan in the original 740 shroud, using your page as a reference actually. (Thank you by the way, some great info there). I have yet to fill in the gaps with some weatherstripping or the like though. Low speed is being triggered with the radiator sensor, on at 92*C and off at 87*C.
Thank you
Click to expand...

It's my opinion that the 940 fan has serious limits. It's designed for a larger radiator and a shroud with rubber vents for better flow at highway speed, but in the configuration you have it, I think it becomes a bottleneck. But first do some IR temp measurements to see what your temps are before making changes.

When I used a 940 fan like that years ago in my 245 I found it performed worse than my stock belt driven fan on the highway in warm or hot climate.
Dave
 
dbarton said:
It's my opinion that the 940 fan has serious limits.
Click to expand...

I used the 940 fan and 940 shroud trimmed down to fit a Nissens 3 row radiator (in my 245) for five or so years with absolutely no problem.

I did not, however, try to "trigger" it. Mine was on with key and had a switch on dash for cold weather operations.

Therefore, I say that the problem is not necessarily with the 940 fan but the problem lies in the way you have re-purposed it.
 
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moustacio said:
I am using a 2 speed fan and relay from a 940. I mounted the e-fan in the original 740 shroud, using your page as a reference actually. (Thank you by the way, some great info there). I have yet to fill in the gaps with some weatherstripping or the like though. Low speed is being triggered with the radiator sensor, on at 92*C and off at 87*C.

Thank you
Click to expand...

The OE Engineers chose to take temp data from the head ports for good reasons.... aluminum head on iron block; higher temps leading to detonation, not to mention a warped head and failed HG. You should have a tapped port right under the #4 intake runner, which I would suggest to relocate your gauge sender to.

Also, if you are triggering the fan on at 92*C, that is a bit high for my taste. I believe you can easily find an 88*C on and around 83*C off switch. This is the unit I run on my DD:

https://www.ebay.com/itm/Wahler-823...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Did you confirm that your wiring to your 9 series relay is bringing on the fan HIGH speed (same as when AC runs) or the low speed?

Lastly, previous comment about radiator function; you should be seeing ~ 20*F / 10*C drop in temp as coolant flows across your radiator. A plugged up radiator cannot remove this energy and you will see "temp creep" as you have described.

Keep us posted of your findings.
 
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swedefiend said:
I used the 940 fan and 940 shroud trimmed down to fit a Nissens 3 row radiator (in my 245) for five or so years with absolutely no problem.
Click to expand...

Well I should also add that I find lots of exceptions. Some cars work this way. Some don't. I think that 16 inch fan is borderline with a smaller than intended radiator and a shroud without vents. It worked for me until it got over 90 degrees and I needed to drive up any sort of grade. My stock belt fan (with tropical clutch) was able to handle the heat.

Also, since the OP has a 740T, it has an IC and probably an AC condenser slowing airflow. Did your 245 have both of those? If not, then I'll say that's probably why you had no problems.

I haven't run a belt fan in my (current) 242 for a long time, but I've considered going back to one to see how it would do. The only thing stopping me from trying that now is that I would need to construct a fully custom shroud to work on my big Griffin radiator. Not impossible, but I would want it to look nice and I think my sheet metal skills (and tools) might not be up for it. Until then I have other projects keeping me busy.
Dave
 
dbarton said:
Did your 245 have both of those? If not, then I'll say that's probably why you had no problems.
Click to expand...

Yes and yes (NPR tho).

edit:// probably only four years. When I converted to a 2.3, I deleted the a/c and power steering. I also had a manual transmission, so no trans cooler.
 
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Hey thank you everyone for the responses and discussion.

Just to mention this again: I first noticed the high temperature with the belt driven mechanical fan installed and there was no change in highway temperature after installing the e-fan.

But yes I will definitely post back when my IR thermometer arrives. And I will also take everyone's suggestions and let y'all know what is going on.

I am using rotella T6 synthetic 5w40 currently and I use M1 10w40 or 15w40 semisynthetic or some mix of the three in the summer months. Synthetic redline racing ATF in the m46 and SAE 80w90 in the axle. And I'm currently only using low speed on the e-fan but have a switch in the dash for both high and low if needed. I may wire high speed to come on with the a/c though.

Thanks again for the help everyone, I appreciate it much
 
swedefiend said:
I used the 940 fan and 940 shroud trimmed down to fit a Nissens 3 row radiator (in my 245) for five or so years with absolutely no problem.

I did not, however, try to "trigger" it. Mine was on with key and had a switch on dash for cold weather operations.

Therefore, I say that the problem is not necessarily with the 940 fan but the problem lies in the way you have re-purposed it.
Click to expand...

Just because you half assed your install doesn't mean everyone else did.
 
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