JeffC1500TBI

ok.. it got about 20 degrees warmer here last week-end.. and my damn engine was still only running at a max of 130degrees.. I have a stewart stage 1 pump with a robertshaw 180 that is drilled by stewart.. do you guys think I should just buy a gm 180 stat and put that instead of drilled one??? some guy told me if it runs too cold It could caused damage to the pistons or something? anyhow if this is what I should do .. how hard would it be to change it without have antifreeze all over my new engine?? do I just have to drain below the upper rad hose??

thanks guys.. also I was told that by the engine not running hot enough the ecm will not operate at optimal.. the other thing is I have to advance my base timing to 8 degrees pretty soon as my breakin period is done.. would this make it run a little hoter?

dimented24x7

iTrader: (2)

If your engine doesnt run hot enough, ypou will never enter closed loop mode and your engine will run inneficently. Replacing it woudlnt be a bad idea. Too much coolant is probably getting through

Its pretty easy to change, just open the drain valve on the bottom of your radiator to drain it down a bit and take off the upper hose fitting on the intake. You will find the thermistat below it. Just clean the gasket surfaces, put your thermistat in, replace the gasket with a new one after applying some rtv, refill the sytem, and viola! your done.

zippy

the robertshaw is great, but doesn't need to be drilled. pick up a robertshaw that isn't drilled.

Mark A Shields

130*???, are you sure your temp gauge is properly working.

Vader

Jeff,

It is very unlikely that you will get piston damage from running too cold. It is possible that if the engine was assembled with forged pistons that were cam ground, and were fit loose to allow for higher RPM operation, running cold may cause sealing problems and could theoretically burn the side/skirt of a piston. Still, that would be a long-shot, like a slapper from the opposite blue line.

However, running a lower temperature will prevent the ECM from reaching optimal control unless you have altered the PROM temperature points. The key temperatures with MOST stock PROMs are 50° for TCC lockup (122°F), 56° for EGR enable (133°F), 67° for detonation control (153°F), 70° for EVAP purge, diagnostic communication, and hot closed-loop mode timer (158°F), and 80° (176°F) for final target idle, full EGR duty cycle, and final fuel trim tables. Because of these factors, I always suggest a 180°F stat as a "safe" number to satisfy the basic needs of a stock ECM.

And I'm grinning as I write this, but the Robershaw thermostat is just fine. (I'm grinning because I know that Robershaw is the O.E.M. supplier to GM for thermostats, and a whole lot more.) Just because the thermostat that came out has "AC/Delco" stamped in it doesn't mean that they had anything to do with its manufacture. The oil filters you see at K-Mart really aren't made by suburban slave-labor kids at K-Mart's headquarters in Troy, Michigan. Just because it says something on the labelling - well, you get the picture. Anyway, the Robershaw should be just fine, and holes aren't really necessary. You can drill a small weep hole in the perimeter if you wish, but use something like a #60 (1.0mm/0.040") drill to limit the flow to a minimum.

And don't forget to apply a little anti-seize compound to the steel bolts that you thread back intot he aluminum intake. You'll thank me later.

Danno

Sorry to break the news, but Stant is the primary supplier to GM for stats. I have bought many stats. over the years and if you look on the bottom brass piece it is stamped STC,(temp stamped next). I had occasion to talk to Stant about a month ago and currently they are almost the SOLE supplier to GM. Don't get mad at me O great one but I have a whole box of old parts in the garage among them probably 15-20 old stats. EVERY one is stamped by Stant. Hey, it's Sat. night, gotta start a little trouble. Danno, 89 IROC, 5.7, Stant therm.(180), no holes.

zippy

i couldn't say this for 100% sure, but i do believe stant is the gm supplier. like i said, not positive but i do believe he's right. the robertshaw is considerably different from the stock gm besides that.

Vader

Danno/Zippy,

Thanks for the info. I used to work for a place that supplied Robertshaw with some component parts (for various items), and I know that they made at least SOME of the 'stats for GM. Maybe that's why the Stant people said they are ALMOST the sole supplier. The double-tier 'stat that came out of my LT1 was a Robertshaw. I've got all three in my spare parts "collection", and you're right about the temperature capsule being different on the Stant units. Maybe when they dumped the reverse-flow systems they resupplied. IIRC, the radiator and fuel caps are almost exclusively Stant as well.

Speaking of spare parts, I sometimes wonder why I save all this crap. Like I'm ever going to reuse an old thermostat if I change one. For less than ten bucks for a new one, I'll probably never mess with the old "spares". I guess I need to clean out a little more before I have to move it all. At least I don't save old spark plugs (any more).


Danno,

I hope you didn't get into TOO much trouble, just enough. Eating up too much rice can give you an upset stomach....