Which temperature gauge to trust? Or, how hot is too hot?

[FABombjoy]

That's how hot they all run. Go and fix some real problems

Here's some of my data from 90+ degree days last year:
https://imgur.com/a/soFILjN

[jangell]

Sounds good to me! I have to get better at using those graphing features. I was concerned about getting up to 210, but you were up to 217, so I guess I have nothing to worry about.

I made it from MA to the other side of CT with no problems yesterday. It was in the high 60s when I left in the morning, and ended in the mid 70s when I arrived. The engine temperature started around the 192, and got up to about 198 for most of the drive. It spiked to 202, at one point while going up a steeper hill on the highway, but went back down to 198 soon after. I was running the A/C pretty much the entire time, too. Nothing else on the car went wrong. Now I just need to get home.

The only remaining issue is the the belt squeals when I turn the A/C on. If I click it off and on again it fixes itself. The belt is probably just a little loose. I replaced the belt and one of the adjustment bar bolts (I'd stripped it), which fixed a much louder and more consistent squealing under much less load, but it looks like I need to tighten it up a bit more (maybe it stretched a little?). I have the old belt in the car just in case it breaks on the ay home.

Thanks!

-- Joe

[FABombjoy]

I actually remember that 217 event. Open the graph again and look at the MPH in which 210 degrees was exceeded.

I had set MS to not engage cooling fans above 40MPH which seemed to work well. Then I got stuck behind a semi going just a little over 40. AC on full blast. Temp gauge starts going up up up. Drafting this truck seemed to really cut down on airflow through the radiator.

In short: I disabled speed-based cooling fan cutoff. But going to 217 didn't break anything

[jangell]

I have the high-efficiency cooling fans, so I decided to let my fans run normally all the time. I made it home today with no incidents, even with getting stuck in stop-and-go traffic for a bit (high 70s/low 80s and sunny today). The temp stayed below 209 the entire time. Oddly, it seems to run most hot (save for when stuck in traffic) at 65-80 MPH, getting to around 202. Going faster than that would drop to around 195, and between 30 and 65 would be more likely to run in the 195-200 range. I'll have to load up my log and see what that looks like in graph form.

Now that I'm home I'll be modifying my MegaSquirt II for A/C Idle Up support (J10/J11 to SPR3/SPR4) -- at the moment I have to turn the A/C off in traffic for fear of stalling at the moment, but at least it starts right back up again.

-- Joe

[Josh]

are you using the coolant temp sensor i sent you (for ms)?
It xrefs to a late 90s saturn, but it uses the same data as the generic gm sensor.




In short, trust ms not the dash gauge. It has lied to me many times.

[jangell]

Yup, that's the one I'm using. I was pretty sure it was a GM, but I didn't see anything about it in my notes. Thanks!

-- Joe

[Josh]

Yup, that's the one I'm using. I was pretty sure it was a GM, but I didn't see anything about it in my notes. Thanks!

-- Joe

https://www.rockauto.com/en/moreinfo...LKbA95lA%3D%3D

[JIMJAM]

I live in Columbia SC and unlike those who garage their cars during the winter, I rarely drive during the summer. Once that SS and motor heats up, that 80s a/c will keep you alive but thats about it. As a general rule, if it is above 85-90 and sunny I don't drive it. FYI my temp gauge has ALWAYS read what yours is showing. I would imagine that after 12 years the motor would have melted if that was to hot so like the gas and alt gauge I take them as a grain of salt. This summer has been very brutal with weeks of 100 degrees nonstop. I have a upgraded radiator and 2 bleeds, one at the rad and one at the engine. I have just accepted my D hates the summer and is a fair weather car.

[jangell]

This weekend I drove it about 20 minutes on the highway. It was sunny, humid and in the mid to high 80s. I didn't have my laptop with me, so I had to rely on the stock gauge. It very, very slowly crept up past 220, but not too far past, mostly because I happened to get off the highway at about that time. It came back down after that, again slowly. I'm guessing this have been around 205-210 on the water pump coolant temperature. I'm curious how high it would go before it leveled off, assuming that happens before the engine overheats. If it gets up to 215 (on the water pump sender) and holds there, I guess that's fine... On the drive home it was better, staying a hair under 220 on the stock gauge, but I think that was because it got a bit more overcast. I was running the A/C most of the time as well.

The coolant bottle is still more than half full, so I'm not losing coolant. I didn't think to bleed the radiator again, but really I shouldn't need to at this point. We're having another hot week, but I don't have any highway driving to do, and hopefully the fall will come early and I won't have to worry about the engine temperature as much until next year.

I also had the car stall on me at a light just before it turned green. I wasn't able to get it to stay runnign until I pressed on the gas while starting (at which point the light had just turned red -- the cars behind me loved that). Not sure what was going on there, and of course I don't have any logs from it. I'm going to start another thread about my issues with stalling at idle once I've gathered some logs. I can get it to happen just sitting in my driveway and shifting from R to N to D and back (but not always), so I should be able to get something sooner than later.

-- Joe