L03 running cold

Hey guys. I have a 91 with the L03. A while back I had to replace the radiator and got one from a 92 caprice. It was bigger in comparison and ever since the car is running real cool. I rarely break over the 1/4 line unless im pulling a very steep grade. I noticed my mileage going down hill and the car just smelling a bit rich. Is this just too cold to be running this motor? I cant remember what it mostly ran at before the rad replacement. Around town/highway it just never breaks the 1/4 line. I was thinking of putting the recommended 195 T stat in it, (not sure what is in there now) will this improve mileage and all around make it run better?

Yeah, a warmer t-stat will help you out. My car sits at the same level, just at the 1/4 mark and barely crawls above it. I'm also looking into a warmer t-stat. I'd guess your car has a 160 degree stat in it. I don't know if this is true or not, but that might not be hot enough to send the car into closed loop, so it'll definitely affect your mileage.


Welcome to the forums, by the way. Post some pics of your car.

Hey Sting, thanks for the quick reply boss. Glad I found these forums. The wagon section on the Impala forums seem to be lacking. Or if you dont have an LT1 you are screwed hahaha. I will do a formal intro tomorrow when I can get some pics after I paint the pillars. (hopefully). I guess ill go grab the 195 T-stat tomorrow and throw it in. Ill probably panic the first time it goes over the quarter line since im so used to it being there. haha.

Definitely go with a 180 degree minimum and I think a 195 would be even better.Are you running a thermostat at all presently?
Jim

yeah, I am running one. The thing is, it gets HOT here in the summer 90-100 is pretty normal. I'm assuming the 195 will still be fine eh? You guys using any RTV, or throw it on dry. Thanks again fellas.

I used RTV the first time, but the second time when I checked it and just put it back, I put it on dry. Seems just fine...

Just a light coating.Be sure your mating surfaces are clean and flat and torque the nuts evenly.
Jim

LO3s and LO5s require 205 thermostats or else they do not run hot enough. anything less than the 205 and your emissions and fuel economy will be off. forget what your local parts counter guy tells you and go with what the FSM calls for and that's a 205 year round

Are you sure Pat,that sounds kinda high?
Jim

I have never heard, or seen a 205. They had 195's at the zone.

Jim, that' is what the FSM calls for. they will not pass an ontario e test without it, the exhaust gasses have to be hot enough to make the cat hot enough to work right. at 195 the computer thinks the engine is still cold and will let the engine perform and that affects your millage, it will still seem to run fine but it's not.

even with a 205 stat in my LO engines during the heat waves at the wood ward dream cruise they barely run just above the quater mark on the gage

Learn somethin' new everyday.

LO3 and LO5 engines all left the factory with 205's in em, people and part stores all assume that since small block chevy engines use to use 160,185 and 195 stats that those are ok to use in the LO engines as well, that a wrong assumption if you want your LO3 or LO5 to run right put in the 205 stat year round

I took mine out, ran through one tank of gas in no time, and put a 160 in and went right back to 17 mixed, 23.5 hwy MPG...... your mileage may vary. that's in a very tired L03.
I'm still not sure If I'll go back hotter, but might.

DO NOT use RTV it's a pain in the butt to clean off. just use the paper gasket, it scrapes off easy enough and won't leak. If you have rust under there, be careful you don't shear off the bolt into the intake......there is a thread here on that.

Went thru my FSN last nite and couldnt find anything about a 205 thermostat.Pat if you say so,
I am picking one up this afternoon.I put a 180 in and did notice a slight drop in mpg but it was
only like 1 mpg.Good enough for me Pat!
Thanks
Jim

Yeah I also tried to hunt for mention of the 205.

Found the specs in my owners manual and it calls for a 195 degree thermostat.Both my Auto
Zone and Advance said they will have to order a 205 degree thermostat.Considering my
average year round temps I am going to stick with my 180.My temp gauge in the summer
with the AC blowing climbs up pretty fast in slow traffic.
Jim

People just don't get the concept of what a t-stat and a rad do together,.
when the t-stat opens it lets water return to the rad right? well if it opens early and stays open early then the water simply starts circulating too quickly thru the rad and doesn't have enough time to cool,. a t-stat that is working properly with a decent rad, will be cycling open and close constantly,.it,s not an instant opening to wide open either,. and it,s not an instant closing , the stat will sort of float between open and half closed,.
the size of the rad will affect the ability to 'shed' heat,. you could have a 300gal capacity radiator,. but if your t-stat is working properly the engine will come up to operating temperature,.
case in point (1 of many i have helped folks with) i had a 69 camaro with fairly good 427,it would always run hot then overheat in traffic,. i had a 180 statin it,. i was told to put a 195 in it ,. i didn't listen,. i went with a 160,. it overheated earlier,.and would run hot on the highway,. so against my better judgement at the time i put in a 195,. damn carwould idle for at least 15mins before it was too hot,. i was amazed,. but what was happening was the water flow was slowed down by keeping it in the engine longer and also keeping the water in the rad longer which shed the heat that i needed to lose,. this lesson has helped me and many others that listen,.especially my big olds cars,.
remember a t-stat doesn't switch on and off like somehing electrical,. put one in a pan of water with a thermometer and you'll find 2 identical 195 stats will open and close at different rates,.factor in the poor quality control of aftermarket parts these days,(don't pay to much attention to the name on the box as EVERYone outsources these days,.
you also need to factor in engine rpm, water pump flow, rad capacity, fan performance etc,. etc,. it all has to be a good combo, a 160 stat will make the rad hotter and the fan work more eating more gas,..engine compression builds heat, a 12:1 motor needs better cooling than the same engine with 9:1compression
performance stats are good for some mpfi engines but you need the tuning to match,.
an L zero 3 thats running cool needs the hottest themostat it can get in a big heavy wagon where the little motor is working hard.
pat is right, the 305 needs to run around 200-205 deg for best emissions and mileage,
this is accomplished with a 195 stat,. remember the stat doesn't react instantaneously,.
this isn't rocket science,.it,s pretty simple,. but its amazing how many people only understand half of what they need to know, then pass that half on to others,.
long live the internet.

jm2c
Nick
guys that think they know it all,. bother guys like me that DO know it all,.

Well since you put it that way.Going to get one of those 195 degree fancy thermostats.
Never heard it explained that way but it sure makes sense.
Thanks Nick
Jim

Ill go grab that 195. Appreciate the break down phantom. One more question I have though, is there a difference between these off brand t-stats? for example between the 5 dollar and 10 dollar ones, duralast and valucraft.

Porkwagon wrote:

Ill go grab that 195. Appreciate the break down phantom. One more question I have though, is there a difference between these off brand t-stats? for example between the 5 dollar and 10 dollar ones, duralast and valucraft.

No i don't know the difference, i tend to take things out of the package and make my own mind up about things,.
personally i,d cough up the extra money and get a fail safe stat,.a stat that fails open is annoying,. a stat that fails closed can be catastrophic,.the stat that fails open will let you get home,. one that fails closed,. will need some mcgivering at the side of the road,.
case in point,. i had a stat fail closed motor overheated, only thing available to me for support was a tire iron and a large tim hortons cup,. so i undid the clamp with the tire iron, slid the upper hose off which exposed the thermostat,. i then jabbed a hole in it and bent it sidways open somewheat,. put the hose back on, and used the tim hortons cup to get some water from a convenient puddle in the ditch,. made it home and fixed things up,..

Nick

Bet there were some choice words being thrown around under that hood.Brother gave me one of
those Leatherman multi tools and it has come in handy quite a few times.Only one thing you cant
ever do with these tools is loan it out because they disappear instantly.My FailSafe is out in the
car now.
Jim

I know, I know, beating a dead horse, or so it seems.


Okay so, I followed the advice in this thread and bought a 195 degree stat when one of my coolant hoses blew (figured I'd be in there anyway...)

So I just took it for its first drive after replacing the 160 with the 195, and it runs hot. The car seems to DRIVE just fine, but the needle got ALL THE WAY up to the H. I pulled over, popped the hood. The coolant reservoir was up to the full hot line. That means the radiator is full too, no?

So what gives? I was just sitting in the car in my driveway and it was swinging around just idling. It would get up to H, then go down to half, then go back up, etc. etc.

I've already replaced the coolant temp sensor (in the intake). Is there another one or something? What am I doing wrong?

Was the system burped before you buttoned it all back up? I'd like to know the cause of your issue too.

Yes sir. I did burp it. Maybe needs to be done again.

take it out and put it in a pot of water to make sure it's working right. Sounds llike it is not opening ^^^^ I was annoyed cuz I shelled out 2x price for the Delco and it failed in less than 6 months....

the overflow got filled as it turned to steam in the rad and pushed the liquid out. Old skool like my Healey, the overflow is the ground, so no recovery.

Will boil and check it out. Seems like crap that a 48 hour old part would fail, but I suppose anything is possible.

Stingroo wrote:

Will boil and check it out. Seems like crap that a 48 hour old part would fail, but I suppose anything is possible.

WHOAH people just WHOAH,.

it,s not boiling over right? drive it around, see how it is,. stop lookingtoo closely at the gauge,. if it,s swinging around then its working,.keep a couple of gallons of water with you incase i,m totally wrong,.
keep your heater on full heat/defrost, drive with all the windows open if you need to,.

Re-cap what you,ve done to this poor car,.
didn't you do a water pump because it was overheating and you went ahead and put on a different fan because the other one was too loose etc?? and now you,re trying a 195 stat etc?? (but what the hell do i know) assuming of course the fan you put on was for the correct rotation,. i fixed an overheating van for somebody that way, they added a fancy big bladed clutch fan,. but it was pushing air when hot not pulling,. V-belt fans can't be added to serpentine pumps.

JM2C
Nick
trying to remember if mentioned head gasket last time?

Ray would you just slow down and please reread what Nick posted on the previous page.Sounds'
like your cooling system is doing just what its suppose to be doing.
Jim

Just a note here. Pat is (sadly) from Canadia and they use some weird algorithm combining metric, Imperial and celsius systems. That's why he speaks in strange tongues & numbers. IIRC, 205* Canadian = 194.5926535789* here in the States.

EH?

lol Jimbeau.

Yes, nick. The fan is on the correct way...

Stingroo wrote:

.

Yes, nick. The fan is on the correct way...

the fan ON the correct way,. or rotating IN the right direction.?? i,m just wanting to clarify here y'know,.you sure??

18436,..................

ok,.

Both. lol The car ran fine before changing the stat and coolant hose (this being 4 months after water pump), still seems to RUN okay, but the gauge seems inaccurate.

Sorry to necro this thread. I finally got around to doing the thermostat, was so sick of the doodoo gas mileage. Went to autozone and saw the OEM recommendation was a 192 or 195. Got the 195 and threw it in and its working well. Goes up to the line before half, creeps a little over it then returns to below, repeat. So lets see if my mileage increases. I couldn't track down this mysterious 205, unless I ordered one and I really couldn't be bothered. My friends dad was a certified GM mechanic for 20+ years and recommended the 195.

Porkwagon wrote:

Sorry to necro this thread. I finally got around to doing the thermostat, was so sick of the doodoo gas mileage. Went to autozone and saw the OEM recommendation was a 192 or 195. Got the 195 and threw it in and its working well. Goes up to the line before half, creeps a little over it then returns to below, repeat. So lets see if my mileage increases. I couldn't track down this mysterious 205, unless I ordered one and I really couldn't be bothered. My friends dad was a certified GM mechanic for 20+ years and recommended the 195.

you think you were bad, I'll really bring this thread back from the dead.

Searching the forum for stuff and I came across this. Just posting my experiences here to help others.

1991 OCC 305, of course, all stock. When I got it, it would run cool and fine until a longer highway trip. then it would almost get all the way to the Hot side... I found a small pin hole in a lower radiator hose, squeezed it to see if it held pressure and then I had a hose with a bigger hole... about the size of a thumb. Replaced that. Noticed the coolant was gross and brown. Drained what I could and put it back together. Drove it, same thing. Cool , no leaks though, and climbed up. went to my simple mind of my carb days and got a 180 degree T stat. now it idled super cold... barely moved the needle.... till I drove it longer distances. Climbed back up. Went ahead and drained the coolant and looked in the radiator and found what I suspected. Radiator was completely scaled up and just wouldn't dissipate heat . I just basically became heat soaked. So I bought a new radiator (just an EOM style, didnt upgrade to more cores, or anything). Replaced it. replaced the upper hose and gave it a good flushing. Then it would run cool all the time. Super cool. Regardless of how far, the needle barely moved from what I would estimate 170 or so on the gauge. I dont have a cat on mine so its exhaust smells anyway, and I've never paid attention to gas mileage- I dont on any of my cars... I just put gas in when they need it LOL. Makes me much more sane than to worry with MPGs. But I would assume my mileage was worse... I do believe I filled it a little more often than prior times.... I usually don't let the cars get below 1/2 anyway... just one of my things.

BUT what I did notice, especially with the AC on, the idle speed was quite high. I do have a 1991 GM OEM tachometer in the cluster so its way off.... but I knew the idle was higher.. you could feel it when you come to a stop.... it was like you were two footing it with one on the gas.... I got to thinking about what Fred had said in another thread about it not going into closed loop if it never gets up to operating temp.... i believe my car was staying with a high idle as if it was just started and trying to warm up. I did get a service engine soon light one time- and stopped to scan the code at Autozone and of course they didnt have a scanner.. I bought one but the light went off when I started and hasnt come back. I should be unlazy and check the code but I havent even unwrapped the code reader yet. Its in the glove box.

Anyway, the moral of the story, I put back in the 195 t stat it had before and put it all back together. It now runs warmer... .still left of center, and is super steady and never swings back and forth....just consistent. I believe if you are swinging back and forth when the t stat opens and then closes, you have some other issues developing... it should be nice and smooth and undetectable like in a new vehicle that maintains a steady temp. Anyway, it now idles back down once its warm and feels like it has more power (which, with a 305 and a bloated wagon, isn't saying much. I dont see how anyone would ever try to tow something with one of these...lacking power big time with a 305, but cruises fine, which is what its purpose is for me).


long post to say that if you have temps creeping up , regardless of t stat, check the radiator for buildup or scale and dont run too cool of a t stat, use the stock 195 one... it'll be happier.