I'm cool, do you think I'm cool? I think I'm cool. (question on being cool)

[WarWagon]

IR gun is a good idea. Where would be the best place to lay the IR point? Top of the radiator? Bottom? Heads?
I

Point it at the sender for the gauge to verify the gauge is reading in the ballpark. IR changes with the color of the item pointed at so it's a ballpark device. Also the t stat housing keeping in mind the temp on the outlet will be colder if the T stat is closed.

Lincoln is like a lock washer GMC difference over a Chevy. Kinda hard to see that lock washer in 1 picture.

 

[Hink]

Welp, I only had about 15 minutes today so I didn't get any pics but I did get the 195* thermostat in.
It did make a difference. Running at a steady 70mph, it ran at ~165*. So a solid 30 degrees warmer and in a good range, I think. I'll leave it in for the next time I tow something and if it keeps things cool enough, I'll leave it.

While we're all here and on the subject, can somebody correct me if I'm wrong on the dynamics of the cooling system?
The way I understand it is that all thermostats start the day closed. In my case my 180* thermostat starts out closed just like the 195* that I just put in.
When the engine warms up to 165*, that thermostat should still be closed. When I hit about 180* or so, it should start to open (or just then be fully open?) and begin the cooling cycle.
The 180* thermostat starts the cooling cycle a full 15* sooner than the 195* and thus helping rid the engine of heat sooner, keeping it from getting in an overheating cycle that can't be overcome, especially while towing. (I have simplified things here because I believe that most but not all have a gradual opening/closing action that allows more or less coolant into the radiator to keep it in a good temperature range.)

So, if all that is true, then putting a 180* thermostat in should not, by itself, cause the engine to run cooler during normal driving because the engine hasn't even reached the activation point of the thermostat to being with.

Am I on track here?

 

[GM Guy]

If it was not for an IR gun, I would have stroked out by now from stress on my new 95.

Everything reads 165 even though the guage sits at 210. I just changed sending units, so we will see what the new one reads.

The IR gun is a Harbor freight unit, but took a neck artery reading and it reads 95 degrees, so its gotta be close!

Back on the t-stat, it seems 6.5Ls are picky, on single t-stat units I buy mine from Leroy diesel.com, he gets some special specification AC Delco that is made in germany, and has a really deep bypass blockoff plate.

On the duals, I get the same PN the dealer sells. Note I only do that on the duals, I would not buy t-stat for the single from the dealer, it does not seem right.

All of mine will run 195 under load, and for the most part get great mpg, so I am happy. also great when you are idling for warmth in Wyoming.

 

[Hink]

If it was not for an IR gun, I would have stroked out by now from stress on my new 95.

Everything reads 165 even though the guage sits at 210. I just changed sending units, so we will see what the new one reads.

The IR gun is a Harbor freight unit, but took a neck artery reading and it reads 95 degrees, so its gotta be close!

Oh wow, yeah that blows.
And yeah, let us know what happens there, I'm curious to see how all this works out.
I'll try to look in to an it gun tomorrow.

 

[Will L.]

Hink, please take pictures of the thermostat you took out and of you thermostat housing. Also spin your fanclutch by hand to ensure it is not stuck engauged.

Want to sell me the old tsat for $20? I really want to test with it. I've chased that scenario for a long time and never duplicated it.

You are on track with cooling system understanding. In theory the engine should run at its balanced temperature regardless of a lower opening tstat. So yes, running a 180 vs 195 should allow the engine to get to the same temperature but take a little longer to do so.

If your radiator can disperse way more btu than the engine produces, then a lower tstat will cause lower constant ect. This is really rare and shouldn't happen with your truck by the signature line.

 

[Hink]

Hink, please take pictures of the thermostat you took out and of you thermostat housing. Also spin your fanclutch by hand to ensure it is not stuck engauged.

Want to sell me the old tsat for $20? I really want to test with it. I've chased that scenario for a long time and never duplicated it.

You are on track with cooling system understanding. In theory the engine should run at its balanced temperature regardless of a lower opening tstat. So yes, running a 180 vs 195 should allow the engine to get to the same temperature but take a little longer to do so.

If your radiator can disperse way more btu than the engine produces, then a lower tstat will cause lower constant ect. This is really rare and shouldn't happen with your truck by the signature line.

Will, I'll get some pictures. The fan clutch is not engaged. I'll spin it again tomorrow to double check.
And I'll PM you two things... A link to the radiator that I installed with the new motor. The only Brass tank/copper core radiator that I've seen, although I'm pretty sure that it won't fit a hummer? And a link to where you can get the 180* t-stat for $10. No way I'd take your $20 for a $10 Stat.

But I'll still have the one that caused all the confusion in case it's a rare bird and we want to experiment. If the 195* stat doesn't keep my rig cool while towing, I want to be able to put it back in.

 

[Will L.]

For the other readers, I saw and responded to Hink's pm before this thread. -just wanting testing on the tstat for abnormalities. I can't run the block off tsat in my crossover. The 180 AC Delco tstat is a normal block off one.

And no the pickup radiator doesn't work in Hummers. But Hink's is a nice one.

The 195 stat bringing the temp up to 165 I think tells us his radiator is dropping btu faster than his engine is producing it. Quality of radiator making the difference?

 

[THEFERMANATOR]

The temp on a t-stat is the temp where it should begin to open. A 190(factory stat is 190 or 192, not 195) should be full open under use around 210 or so. I personnally see no problems running 210-215 so long as everything is working properly. For contrast, the DURAMAX uses 2 stats, a 180 with no blocker, and a 185 with a blocker to stop the 3/8 orificed bypass. The blocker isn't closed until 212, and the actual stats aren't full y closed until 230 according to the service manual specs.

 

[Twisted Steel Performance]

PM me a link for the radiator , I'd like to have a look.

If I wasn't confident in the gauge I'd get a manual gauge & sender and see what it shows..

I have a 180* single stat in mine and my dash does show 180* didn't fluctuate during winter at all.. I am going to go back to 190* soon..

 

[JayTheCPA]

. . . spin your fanclutch by hand to ensure it is not stuck engauged.

The fan clutch is not engaged. I'll spin it again tomorrow to double check.

At firtst I thought about a partial locked engagement, except the part about towing temps never went over 210. Were the fan partially 'locked', I'd expect temps while towing to want to go over 210 and struggle to keep them under 220 on mild extended grades (1% - 2%). When empty I struggled to get to 160 - 170 with the 195 T-stats. (Temperature measurements were per the ECM at the thermostat housing.) At least that was how mine acted when I finally realized the new clutch was partially locked. Also, suspect that I also had a stuck T-stat as part of the mix too. A new clutch, new set of T-stats, installation of a bypass restriction, and things were much better.


For Moby, am still leaning toward a dorked ECT sending unit as part of the mix.

 

[Hink]

One thing that Will reminded me of that I didn't mention because in and of itself, wouldn't cause such a dramatic drop in temp...I do use Redline water wetter and did see a drop of about 20* when I first started using it.

Here's the whole system that I listed for Will:

-The spectra radiator was actually just put in this Jan.
-The water pump is older, I installed that on the old engine some time ago from SS Diesel. It was advertised as his 130 GPH unit.
-Fan clutch is Kennedy 180* engage temp.
-The thermostat is the 180* unit from the link I sent.
-The Cap, Standard NAPA.
-NAPA antifreeze with Redline water wetter.
-I run the '93 single t-stat housing and only just removed the crappy heater line connector and plumbed in a piece of hose so no restrictor to a stock heater core.

Also spin your fanclutch by hand to ensure it is not stuck engauged

I just spun it and it spins fine.

except the part about towing temps never went over 210

I did get temps over 210 once. My little RV is supposed to be 4500lbs so a total of about 12,500lbs with the hammer down trying to maintain 65 mph (and succeeding) up a long grade (Not sure the % but It's going West on interstate 84 through Hood River Oregon if anybody knows the area) in a pretty good head wind.
Temps got up over 210 and I got pretty worried when they didn't seem to want to drop as fast as I wanted them to. But they did come back down fine when I reached the top and descended.

For Moby, am still leaning toward a dorked ECT sending unit as part of the mix.

I have an unused temp gauge in my A pillar that I originally installed for fuel temp (for my WVO) that I could set up for this and completely bypass the whole factory BS. Where would a good place be to drill and tap for sender? T-stat housing?

 

[JayTheCPA]

I did get temps over 210 once. My little RV is supposed to be 4500lbs so a total of about 12,500lbs with the hammer down trying to maintain 65 mph (and succeeding) up a long grade. . . . in a pretty good head wind. Temps got up over 210 and I got pretty worried when they didn't seem to want to drop as fast as I wanted them to. But they did come back down fine when I reached the top and descended.

Were the fan partially locked, you would have struggled to keep it under 220

I have an unused temp gauge in my A pillar that I originally installed for fuel temp (for my WVO) that I could set up for this and completely bypass the whole factory BS. Where would a good place be to drill and tap for sender?

Should not need to tap a new hole as the head should have a port. Presuming the 93's work the same way as the OBD-II trucks, the dash gauge's feed is on the front end of the driver's head. Can just un-plug the wire and plug-in your aux gauge. If your sending unit is not working properly, at least the aux gauge will act just as wonky and verify that the dash gauge is good.

And there is an un-used port on the rear side of passenger side head. The passenger's port is a bit of a PITA to install a sending unit given its close location to the downpipe (I paid my favorite shop to install a sending unit here).

Naturally, if this is not the same on your truck as mine, apologies in advance.

 

[Hink]

Were the fan partially locked, you would have struggled to keep it under 220



Should not need to tap a new hole as the head should have a port. Presuming the 93's work the same way as the OBD-II trucks, the dash gauge's feed is on the front end of the driver's head. Can just un-plug the wire and plug-in your aux gauge. If your sending unit is not working properly, at least the aux gauge will act just as wonky and verify that the dash gauge is good.

And there is an un-used port on the rear side of passenger side head. The passenger's port is a bit of a PITA to install a sending unit given its close location to the downpipe (I paid my favorite shop to install a sending unit here).

Naturally, if this is not the same on your truck as mine, apologies in advance.

Yup, it's in the same place. I just figured it'd be worth bypassing everything but you're right, it would be easier to just swap to the new gauge and see first.
I won't be able to do anything soon, but I'll try to get to it as soon as I can and report back here.

 

[Hink]

Ok, just a quick check with ir gun right on the pick up at the head showed 177* when the gauge showed 155, so a total of 22* off.
I'll check it several more times under different conditions to see if its consistent.

 

[Will L.]

The right rear water port location is a great place to add an extra gauge, seeing as how it by #8 cylinder which is where the cylinder usually cracks as well as head...

 

[NVW]

I drilled and tapped the two blocking plates on the back of my heads for future temp gauges.

 

[Hink]

The right rear water port location is a great place to add an extra gauge, seeing as how it by #8 cylinder which is where the cylinder usually cracks as well as head...

Did the optimizer heads have the same issue?
I thought I understood that they improved both the metallurgy and coolant passage design on them.

 

[Will L.]

Yes, they did improve metulurgy, and changed passage a little. Can't remember if they did anything else with the seat area.

I heard some guys on the hummernetwork forum talking about them cracking- but not a single picture. The same guys a good friends with a vendor that sells p400, and they almost chastise people for rebuilding instead of buying a new p400.

I know of one guy that lost his coolant in an optimizer and was about to do a duramax conversion, already had most the parts. He purposely drained his coolant then drove it about an hour before it seized. He tore it down just for fun, cylinders swelled into the rings and twisted rings on 2 pistons. Otherwise everything else looked fine. Fluke?

Any head can crack, and the p400 got more head improvements so why did they bother doing that if optimizers were all perfect.

 

[ak diesel driver]

I thought the heads were the same. Only difference being whether it was turboed or not for the valve seats.

 

[schiker]

Not sure how good IR guns are today but different surfaces will have different emissivity. Not sure I would argue 5-10 degree difference in IR gun readings depending on different surface emissivity. What have ya'll seen?

It is my understanding that thermostats aren't exactly digital but pretty consistent. A 195F stat might open at 194-196? in a switch like fashion to I don't know 80-90% open and this for most part should be considered open and closed. Depending at 10-20 degrees hotter it will open to max. Not sure how much more flow you'll get at the last bit of wax pellet phase change. I don't think its really suppose to be another phase of cooling.

The thermostat is not suppose to influence or control the max temperature at all. The thermostat is suppose to maintain the minimum coolant temperature and it may modulate at first if the radiator is cold. Seems every car I have had truck included acts about the same. Seems my dash gauge reaction time vs stat modulation and considering amount of coolant and my local temps usually above freezing but sometimes in 20'sF . It basically warms up to dang close to 180F (stat temp) and stays there until I add load AC/towing etc and it goes up but doesn't really ever fall below 180F. Except coasting very light throttle down a long decent grade it will get colder especially in cool weather. Level ground normal driving in mild climate it can maintain the minimum temperature no problem even in winter. Its been a long while since I sat and watched it warm up from cold and see if there is an actual opening oscillation when the cold radiator flushes the opening stat but normal driving after 10 minutes its pretty standard - 180F or above.

The correct thermostat should not control or really influence the upper temperature limit. It may slightly increase time involved to climb up to max temp just from the starting 15 degrees cooler if air flow isn't enough but a 180F is not going to solve an overheating problem if a 195F overheats (all else being equal). Except maybe if you were looking at some short rolling hills where the little time difference allowed you to crest a hill and reduce heat load before it got too hot.