LT1DG

Hello everyone hope all is well and family's are safe at a time like this.

So I wanted to discuss some information base on the title above.

​​​​​​I've came across some threads talking about how some people have had bad experience with 160 stats, including myself.

Overheating~ ​slow rise as you cruise.
I was having this issue for a while, after my cam install that is...

After the cam install I was having some odd overheating.. A lot of confusion was going through my head knowing I just replaced waterpump, rebuild heads, new resorvoir and hoses all at the same time. Not to mention tune.

Got the coolant system bleed 3 times then flush by some professional who knows the reverse coolant system quite well. But I still was having the same result after all that

I was pretty clueless at this moment cause I could not figure out why I was having these "slow spikes" I guess you can called them.

A month ago I decided to switch back to a 180 stat. Cause I couldn't help but think about those threads I read.

​​​​​I purchased stant superstat off of rockauto cause I seen some good feedback.

Once received I tested it in a pot of boiling water and checked out good.

​​I had to send out my pcm to my tuner solomon to reflash it cause I made a mistake while using the hypertech to just change my fans and ended up overwriting solomon tune.

Week later when I got my computer back I installed it, let it warmed up and took it for a drive. I was pretty damn surprise that with the 180 stat the slow rise symptom went away and stayed at a steady range 205 to 214. Literally a night and day difference.

Couple of days ago I replaced my radiator and now it stays real cool and run very efficiently.

My question is why was I having issues like that with the 160 stat with all the appropriate requirements? There others that run it with no problem.

But yet I was having issues with a pretty healthy coolant system.

I heard Theorys that 160 stats form bubbles because it opens up too early causing the coolant to heat up, and not stabilize.

What you guys think? Im really curious of why some have issues and some don't.

Pls somebody elaborate.

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Germansheperd

I cant give you the science but my car with a properly flushed system, properly bled, new water pump, 50/50 antifreeze and distilled water, and new AC Delco 131100 Thermostat (OE 180) runs incredibly well. Operating temp is generally just over the first bar on the gauge. I for the life of me don’t see these cooling/overheating LT1 issues or horror stories.

Chimera96

OP

FWIW I have used a 160 Tstat for 20+ years because of the tune and never experienced this "creep/spike" in engine temps

You noted you "over wrote" a Solomon tune with a Hypercrap...that may have been your issue or you had some air in the cooling system that was not all bleed previously. This assumes your radiator was in fact good during your 160 stat usage

The only negative, if at all, on a 160 stat is in cold climate areas the heater is not as hot as desired because of the lower operating temp of the motor with a 160 stat

shoebox

You probably just had a bad thermostat. Never had a problem in the 19 years I ran one. Warm up time should be the same until it reaches operating temp.

Injuneer

100% agree. Like Rob, the Hypertech 160°F was one of the first mods I made to my 94 Formula, more than 22 years ago. Same t'stat has been in the car since then, and never had a problem with overheating or “slow spikes”. At first I used the Hypertech programmer to change the fan temps. Still using my factory PCM with those settings for fan control (although most other engine management runs on a piggy-backed aftermarket ECU). Even spraying a 300-shot of nitrous on the stroker there's never been a problem (although I do have an aftermarket Griffin aluminum radiator).

Over the 21 years I've been helping people on this site and others like it, never noticed any significant number of problems when the correct LT1-specific Hypertech was installed. Most t'stat problems arise when an incorrect Gen 1 SBC t'stat is installed.

LT1DG

Right now it's running really Good since I switched back to 180, plus tune. I got a fairly healthy coolant system and with a 160 it runs hot.

That's odd. I got my system bleed/flush a couple of times and still same result. Unless I had a little bit of air swimming around, I can't think of anything else that would cause that weird symptom.

The heater always blew nice and warm at operating temp.
Probably, but I think that radiator was on its last leg

See and that's what I was thinking.. I brought three different 160 thermostat and still the same result. I dismiss that theory long time ago



Hmm it's weird but that's what I was experiencing... Don't know why but it's fixed now since I'm running a 180.

It could be that my old radiator was shot.
I've read on threads ppl replacing there old radiator and have good results after

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RUDEDOG

I've had no problems with the 160 stat since I installed it 15 years ago ECT stays at 185*

LT1DG

I think my radiator was shot..
Maybe if I would of replaced it sooner things with the 160 stat might of been different.

I Might switch back later on this year if that's the case.


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ACE1252

Definitely something out of the ordinary going on. The 160 stat was one of the best things I've done to my car....wished I had done it sooner. My CC503 install bumped my cruise temps in 6th gear up around 20 degrees. Was 190, went to 210.....the cam is running leaner than stock when cruising. The 160 stat pulled them down to 180-185.

LT1DG

That's is really interesting.. Cause my issue started after my cam (cc502) installed. I didn't realize cams can bump up Temps..

You think that was my issue? Plus a bad radiator.

DrewHMS97SS

More power means more heat. Maybe the combination of those two boiled over.

Injuneer

Incorrect indexing of the cam can throw ignition timing off. Maybe the tune - ignition timing in particular - was off, particularly after you compromised the tune by over writing it with the Hypertech. Nothing builds heat like too much timing advance. One problem with the Opti cam position sensor is that if the cam isn’t indexed correctly, the PCM Incorrectly computes the crank position.

ACE1252

If you had it going over 220 I don't think the cam was causing it. I'd pin that on cooling system issues or maybe even block/head/head gasket problems. I overheated my LT1 when the cooling fan fuse blew and it ended up warping my heads around 0.003". That caused the coolant to start leaking between coolant passages. When the heads were pulled, you could see on the head gasket where the coolant was leaking between passages. The symptom showing up was that at steady state cruise(65mph), the temp gauge was moving around alot.....would go 190, 200, 210, back to 190....constantly moving. Before the overheat....it was rock solid at 190 during a 65mph steady cruise....so I knew something was hurt after the overheat.

I've never had my car on a dyno to dial in anything....so I know the timing is not quite right.....as for that matter the MAF and VE tables as well. I've just got a mail order tune that I tweaked.

After the cam change, I had temps creep up, but only in 6th gear. I would watch it go from 200 to 220(at it's worst...averaged around 210) during very light throttle on I40, in 6th@70mph. I would drop it to 5th and watch the temps fall back to 200...I could also put the accelerator to the floor in 6th and the temps would drop. Very slow accel in 6th, but that told me it was a lean issue. For my case, I don't think it was a cooling problem, I think it's a fueling/timing issue....but only at lean cruise. The 160 stat provided more cooling flow to compensate. Have not had any more creep.....but I still need to get this thing on a dyno and work the tune over. I've got all the tools I need to do it....but I'm waiting on a good set of heads before I commit to the tuning work. I've also got an oil leak I need to nail down before I pull the engine for the head work....going to also fix the oil leak.

raroz28

I have a mishimoto thermostat and it stays dead set at all times. Haven't had any creep whatsoever.

LT1DG

​​​​​​That's a good theory. It's which reminds back then when I had my 01 3.8 firebird , which I modified to the extreme.. It had a stage 2 cam and I noticed that temps rose 5* degrees more then before.

But isn't that why we have to tune the pcm to compansate, not only for the cam changes but to slow down engine speed which produce more heat??? Depending on cam

I didn't realize to much timing can make engine temp rise.. Is there way to tune a engine to run cooler??
If​​​ I'm not mistaken (correct me if I'm wrong Fred) but doesn't the pcm automatically bump up timing while using the 160 stat or is the when the engine gets too hot.





It's crazy that you mentioned timing of being the cause... I agree.
My coolant system is fairly healthy and I couldn't figure out why my temp would creep up slowly as cruising.
I'm up here running a 160 stat with rebuild heads, new waterpump, new hoses and tune for fans to come on early and Temps was still in the 220s

While others are in the 180-190 depending on their coolant system set up.


But like I stated above, my radiator was probably shot, Cause since replacement my temp doesn't even go over 209 with a 180 stat

Same here, there's oil leaking out the crank position sensor that I don't even use.



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I got that thermostat, I switched it out when going back to 180. Good quality.