Normal coolant temp versus guage reading/position?

[E9Wayne]

Hey all, I picked up my E9 this morning after the new radiator install and thanks to SFdon for getting me the right replacement. It took a few more weeks as the local repair shop unfortunately damaged the lower passenger side rear quarter panel and part of the door when they drove it out of the garage into the lot to take in some new cars (Covid parts logistics has screwed up their repair times and lot car placement) while my repair was paused awaiting the radiator. The scratch was huge and when the photo was sent to me, I was horrified. But what can we do? After seeing the repair today, it looks really good, especially the paint match, but some visible orange peel so that needs to be wet sanded out, I think, versus the super smooth Coupe King paintjob I had done in 2011.

Anyway, so Don's aluminum radiator is now installed, along with new upper and lower hoses, a temp sending unit and 80 degree centigrade thermostat. My car, before all of this, always seemed to run cool - the coolant temp needle was typically in the 4 to 4:30 pm range even on the hottest days, worst case 3:30 or even 3 pm. But on my drive home today, I noticed the needle was more in the 2:30 to 2:45 pm range (see photo) -- above the halfway point on the guage and, uncomfortably for me, closing in on the red zone. So I got home and hooked up my Megasquirt computer to see what temps I was getting and they are here after a few hours of cooling down:

4 pm position - 170 degrees
3:30 - 182
3:00 - 190
2:45 - 194
2:30 - 197

The needle does not seem to point above 2:30 (at least on the cool 42 degree F day we are having here in Virginia today) and stayed around 197 degrees, more or less. Sadly, I never documented my engine temp relative to the temp guage before today to compare those actual temps with what I've grown used to seeing on the dail since 2007, which all seemed normal or maybe even better than normal...

Other notes: fan is operational. Coolant was flushed, too, in the repair.

I thought our cars ran about 180 degrees overall, but now I'm curious if I simply need to get use to the new gauge baseline reading, or if this new radiator runs hotter, or if the new temp sending unit or thermostat are to blame?

Thanks for any feedback, especially from Don Lawrence.

Wayne

 

[sfdon]

Did they install a new thermostat?

Hood open, you by windshield- do you feel warm air being blown at you?

 

[Ohmess]

I see why you are concerned Wayne. I would not think that to be normal operating range. The only time I see my gauge looking like that is on a hot day, a/c running, sitting at a long stop light after driving a bit. And my car will drop right back down below 3 oclock once I start moving.

 

[E9Wayne]

Did they install a new thermostat?

Hood open, you by windshield- do you feel warm air being blown at you?

Hi Don, yes they did. Ireland originally sent me a 71 degree thermo and repair shop recommended 80 degree variant. I don't feel warm air being blown at me and car is running great otherwise...

 

[sfdon]

call me

 

[jefflit]

I'm sure Don will get you sorted out but I'm constantly amazed at how many people think aluminum radiators are "better" than the old copper core radiators with brass tanks. Aluminum is used on new cars because it is lighter and new computer controlled, fuel injected engines are more thermally efficient but copper is much more efficient at transferring heat. Of course, you probably just have the wrong thermostat and your new aluminum radiator will be fine.

Also, see this post for gauge calibration. https://e9coupe.com/forum/threads/temp-gauge-translation-tip.39411/ Depending on the particular gauge, 3:00 is about 85-90 C.

Rank	Metal	Thermal Conductivity [BTU/(hr·ft⋅°F)]
1	Copper	223
2	Aluminum	118
3	Brass	64

 

[ChrisWrench]

it sounds like there is air in the system. Open the bleed screw located on the thermostat housing when the car is cool. (you may need a pick to push down in the thread hole if nothing comes out). let the coolant run out until there is no bubbles and is a solid stream. At the shop we put a small 1/8 th in hole in the thermostat located at the 12 position to allow for air to rise to the surface.

 

[E9Wayne]

Thanks, all, for this feedback and I'll try you today/tomorrow, Don!

 

[E9Wayne]

Well folks, the saga continues. After talking with Don I checked several things - no air in system in the usual places, thermo has the hole drilled in it already, fan operational, etc. I took the car back to my service shop this morning and they used an infrared temp gauge and found my temp to be normal - in other words about 180 degrees and the temp gauge was at around 2:45 pm on the dial. They think the temp sending unit is not working right and sending incorrect output to the gauge and I guess my Megsquirt computer too. So I will swap the temp sending unit next. I bought this and the thermostat from Ireland and I need to send both back, the latter because they sent a 71 degree centigrade unit. Is swapping this unit easy to do? Do I need to bleed the system again afterwards? Also, Pelican, Autohaus and ECS have the temp sending unit all around $35 to $40 bucks - any recommendations on the best one? Thanks all

 

[sfdon]

Wait a minute there Mr. Coupe

two different senders
one direct to gauge
one direct to computer

trust the one on your computer screen

what does it say?

 

[E9Wayne]

Sorry Professor Lawrence to miss you call. I'm on solid business calls today. And thanks for reminding me there are two temp sending units - duh! There are the Megasquirt readouts I got the other day and it was 42 degrees F outside:
4 pm position - 170 degrees
3:30 - 182
3:00 - 190
2:45 - 194
2:30 - 197
I don't have comparable readings for before the radiator swap as I never felt the need to find out what my actual coolant temp was since the guage was always normal...

Sound like I need to send two things back to Ireland for a refund - thermo was wrong one and this sending unit may not be working correctly!

 

[sfdon]

Let’s talk this weekend

 

[sfdon]

All better hopefully for my friend Wayne-



It’s time for the annual Engine parts are not the same as Car parts chat.

thermostats, oil filters, spark plugs, plug wires, distributor caps, rotors, coolant hoses and so much more are specific to the engine NOT the car.

If your mechanic expects to install any 1973 engine parts in your car with a 1987 engine it is going to be a long, long day.

Don’t go there. Write a note and put it in your glovebox.

”Note to Self- my 1972 coupe has a 1985 engine”

putting a early thermostat in a late thermostat housing can be fatal to your engine.

 

[Ohmess]

Its funny you say this. I'm in the process of redoing my cooling system hoses - with a shut off valve to change coolant routing in the summer and a Korman tstat housing to accommodate the triple webers, which also changes the hoses. And I have a slightly shorter air conditioning belt because with the stock belt I was unable to adequately tighten the stock belt with the Sanden compressor, and I am now relocating my power steering pump to run off the crank instead of the water pump so it too will have a belt that is not stock.

I'm making a list of part numbers for all this stuff.

 

[E9Wayne]

Yey, Doctor Lawrence saved my ass again. I've ordered the updated thermostat to swap in for the E9 thermostat I have there now which my local mechanic ordered not knowing I have the later style thermostat housing with the "A" letter on it - this was in response to Ireland sending my a 71 degree centigrade thermostat. So while my car is running warmer than it should, I'm lucky it's not running hotter with this incorrect thermostat. I sent Don a few photos of my engine compartment while we were talking and he remarked about the position of my coil output wire to the distributor which is too close to the radiator upper brace and he also remarked that I'm running a 12 year old distributor cap and rotor. So need to reposition my coil wire to the distributor and order some new parts ordered today and I'll have the local repair shop install and hopefully return my engine temp to normal once again! It is simply amazing what Don can pick up from a few photos...

It was almost a tragic ending today too as I washed my car after Don made a few well deserved comments about my engine compartment not being the cleanest. So after doing the outside, I did some strategic gentle spray hosing under the hood around the inner fenders and -- of course -- created a short somewhere in a wire or two resulting in turning over but no start. A few hours later, she started. Whew! Another note to self -- never ever wash under the hood with a hose again!

 

[E9Wayne]

Hey Don and ChrisWrentch, I'm going back to my local shop tomorrow morning with the correct thermostat, new distributor cap and rotor. A key question: I assume, even with the correct thermostat, you still recommend the 1/8 inch whole in the thermostat? Thanks much! I'm hoping this will finally get my car back to the temp range I've seen since 2007!

 

[sfdon]

Remember to clock the tstat and to drill it.
if you need a picture let me know. Many thermostats have arrows stamped in them so you know which way is up. If yours doesn’t - think about the flow of water and how it best goes through the tstat. Or call me. Coming back from airport at 6:30 this morning.

 

[E9Wayne]

thanks, Don, should be good - my thermo has an arrow at the up position!

 

[sfdon]

Yay! Drill the hole next to arrow.

 

[Ohmess]

I don't bleed my car with the bleed screw (and hence have not drilled a hole in my tstat).

Instead, I remove the expansion tank side connection of the small hose that runs from the top of the expansion tank to the radiator and attach a shorter piece of the same size hose in its place. I then place a small rag around the top of the hose still attached to the radiator, hold it up above the expansion tank and blow gently into the shorter hose until I get coolant coming out of the other hose. I find I can consistently get my system bled the first time using this technique.