Anyone ever had an issue with their engine running too cool??

I have a fresh 383 in a 72 wagon.

Alumitech radiator
new water pump
Stock GM fan clutch
Replacement 7 blade fan
Stock fan shroud

While driving a speeds of 55 mph or greater I cannot get the engine up to the t-stat temp. I've tried a new Napa 180 stat....temps only get to 150 going down the road. I then tried a new Mr. Gasket hi-flow 180 and experienced the same thing. I just now finished installing a Napa 195 stat and the temp got to 165 going down the road. I have verified the temp with a good mechanical gauge, a new auto-meter electric gauge and my DVOM.

Even sitting at idle I cannot get the temp to come up to operating. The last thing I can think to check is to make sure I am completely full of coolant. Maybe I have some air bubbles trapped.

Any ideas???

Wonder if the sending unit is accurate? Would be easy to test or just replace.

I would have to say the sending unit is accurate. I have a mechanical gauge installed AND an electric autometer gauge and they are both reading the same as my DVOM when I had it installed......but I have been wrong before............Many times if you ask my wife. lol

I forgot to mention the 383 has vortec heads. Are they harder to burp air out of then old style heads?

if you had an air bubble, it would run hotter, not colder.
since you have excess cooling capacity, start experimenting with blocking off the grille to limit airflow thru the core. in my Monte during the hot summer, i can totally block off the grille and the temp never gets over about 210 degrees- which is just below the point where my electric fans turn on. the major benefit, tho, is that it gets better mileage and handles noticeably better at highway speeds without all that excess air trapped under the hood lifting the front end up..
i just made some simple aluminum block off plates that bolt to the back of the grille, so the airflow is cut off at highway speeds, but the core is still totally open so it keeps cool at low speeds. it's a "bottom breather" now, like most every late model car.

I figured as much with the air bubble but I'm out of guesses. I'd like to think I'm a fairly good trouble shooter and examine these things before asking questions but I'm stumped.

I can't look at the car again until Tuesday. Even sitting still there's absolutely no reason why the system shouldn't hit operating temperature. The radiator cap is only 6 months old but I will pick up a new one tomorrow and try that.

Otherwise, the system is working good. I did forget to mention that the napa 180 stat and the mr. gasket hi flow 180 stat I removed this weekend both were closed when I removed them and both were stamped with the correct temps. I will try to find a temp gun to borrow and check temps.

Wait a minute guys. If the temp is so low that the Tstat is never opening, then there is no capacity and no coolant flow. It seems impossible that the engine never gets warm with no coolant flow. Something has got to be inaccurate. This is strange. I would bring it up to temp with the cap off and look for coolant flow. If it is cool with no flow find out why and we will go into business togther selling it. LOL

chuck

Wait a minute guys. If the temp is so low that the Tstat is never opening, then there is no capacity and no coolant flow. It seems impossible that the engine never gets warm with no coolant flow. Something has got to be inaccurate. This is strange. I would bring it up to temp with the cap off and look for coolant flow. If it is cool with no flow find out why and we will go into business togther selling it. LOL

chuck

Well you might have a very good cooling system ....but to me it sounds like a few things to check ...i/r gun will give you true readings shot at the t/stat housing .. I never trust gages alone ..another simple test .. while cold at start up is there coolant flowing .. this would show t/stat not fully closed ...there should be no flow till stat opens then the upper hose gets hard .
air in the system would cause hot conditions along with not enough fluid in the system .

Most guys would kill to have your problem ... I have told people to pull the t/stat to see what the capacity of the cooling system will do ...when they see 210 thats the best the rad can do with no t/stat or valve ...means a poor cooling system or rad , in your case its just the other way around ....I have seen several bad t/stats right out of the box .. boil it to see what happends

Don

I am wondering if it has anything to do with the Vortec heads and how he has his bypass setup. I am not sure...but it seems it could be the culprit. To you have an early block with the internal bypass (third hole above the waterpump passage on the front of the block...I think on the driver's side)? Do you have an external bypass setup on the waterpump? Original Vortec blocks do not have the internal bypass and instead have an external hose that goes from the waterpump to the intake manifold. If you have a late block and vortec heads you need to have this external bypass. If you have an early block and vortec heads you do not need this external bypass. I am guessing, but if you had an early block with internal bypass, vortec heads with external bypass hooked-up...perhaps you have to much capacity in your bypass???

My '85 GMC Pick-up did the same thing. The t-stat was not closing all the way. I opened the rad cap with the engine cold and fired her up and the water started circulating right away. New T-stat solved it, but, since you have replaced several t-stats...that is probbly not your problem.

On another note, how do you like your 383 with the Vortecs?

That is the same engine I'm putting in my wifes wagon. What is the rest of the combo like? cam, carb etc?

I am wondering if it has anything to do with the Vortec heads and how he has his bypass setup. I am not sure...but it seems it could be the culprit. To you have an early block with the internal bypass (third hole above the waterpump passage on the front of the block...I think on the driver's side)? Do you have an external bypass setup on the waterpump? Original Vortec blocks do not have the internal bypass and instead have an external hose that goes from the waterpump to the intake manifold. If you have a late block and vortec heads you need to have this external bypass. If you have an early block and vortec heads you do not need this external bypass. I am guessing, but if you had an early block with internal bypass, vortec heads with external bypass hooked-up...perhaps you have to much capacity in your bypass???
vortec heads are no different than any other small block heads.
and even if he has a late model vortec block without the bypass, if the heater hoses are hooked up, that is the bypass.
but that would have nothing to do with the engine not heating up.
i think the engine is just too efficient- there isn't much heat getting into the cooling system, so it never gets up to temp. if you have an external oil cooler, that will take quite a bit of the load off the cooling system. an external trans cooler keeps a good chunk of heat energy out of the coolant, as well. put some synthetic oil in it, and keep most of the combustion heat inside the chamber (which the vortecs are good at), and you could get by with a radiator out of a Honda Civic.

I think Don's advise it right on the mark, as usual. The thermostat is really there to allow the engine to heat up until it requires the flow of coolant. If the tstat never shuts off, the engine never warms up. Try to think of it this way, the tstat is as much responsible for making sure your engine gets up to temp as it is to allow the coolant to cool the engine. I'd follow Don's advise and check to be sure the tstat is fully closed (no flow) when the motor is cold and running.

Good luck. This is strange.
Chuck

Related problem ..With alum heads and a good cooling system, my motor reacts the same . Can running to cool cause damage ? On the road I rarely run above 150 deg and at the track waiting in the stage lane it will reach 210.

Hey guys. To answer a few questions.

I have an early 010 350 block with the vortec heads and NO bypass hoses hooked. I want to agree with Don and everyone that suggested the t-stat is the issue. Unfortunately my wife's 25 page paper is due this Saturday for her Master's class which means I get to put my skirt on and start doing laundry, dishes, helping grade her regular class papers (she's a teacher)......Sooo, it will be Sunday before I get back out to see the car. :-(

To answer another question about the engine, I LOVE IT!! I only have about 12 miles on it but I installed a 3.42 posi, a built th350 with a 2200 stall and the 383 consists of the eagle stroker assy (9.6:1 compression when figuring in my piston depth, gasket, etc..) The vortec heads are a stock style that I had ported. Stock rockers and a 224/234 @ 050, .465/.488 lift cam. I could have easily added a larger cam but am glad I didn't. The engine idles nearly like the stock engine did and runs awesome! I've yet to really put a good tune on it so it should only get better. I will probably add 1.6:1 rockers on the intake in the future but for now even the wife is happy with the way it drives and THAT is worth going with the smaller cam.

I will keep you all posted on my cooling issues after this weekend.

Thanks for you help!!

Do not use a stant super stat, use the cheap stant std stat. Ounce we had a super stat that we heated with a mini torch and it wouldnt open until 250*. I have seen super stats open and not close. Buy a std stat from stant

I had the same problem with my 350 in my truck and found out it was the new chrome o-ringed water neck ! The water neck didn't properly hold the high flow thermostat in place inside the groove on my performer intake and it would let the T-Stat just barely leak past the outside flange. I could look in the radiator and it didn't have much movement, but it was just enough that on these cold days my engine took forever to even warm up. I got a regular gasket and put it in place instead of the o-ring and it fixed the problem ! Now my truck is getting better mileage due to being in the proper temp. range. :hurray:

Rick

Here is a good GM part number for a water neck that faces towards the driver side. It is aluminum and is not the cheesy chrome one. It cost 4 bucks at Scoggin Dickey if your not wanting to get into a bidding war for an original. Slightly different as it takes 2 short bolts and no spring tab but other than that should be fine. GM part # 10108470

I wish my 383 had this prob.

Okay, I got to spend some time on the car tonight. I drove it for about 7 miles and let it idle in the shop for about 15 minutes. Using an IR gun the temp at the water neck never got over 155 and that's with a new 195 stat. It then occurred to me to close the manual inline valve going to the heater core. This was on the car when I bought it and I don't know if it's factory for the '72 year or not.

After I closed the manual valve, thereby shutting off all flow to the heater core the temp at the water neck immediately climbed to 182 degreees but would not go above this.

Is this temp good enough for a 195 stat? I don't think so and it should climb to operating temp even with the manual valve open. Afterall, I do need a heater in 27 degree temps here in Kansas this time of year.

Any other suggestions? I suppose I could try another 195 stat. I have the heater hoses set up like the factory 350. Hose from the pump to the core (this has the shutoff valve inline) and the hose from the core to the top of the intake (next to the water neck).

Also, I am using the factory water neck and have been the entire time.

Thanks.

Okay, I got to spend some time on the car tonight. I drove it for about 7 miles and let it idle in the shop for about 15 minutes. Using an IR gun the temp at the water neck never got over 155 and that's with a new 195 stat. It then occurred to me to close the manual inline valve going to the heater core. This was on the car when I bought it and I don't know if it's factory for the '72 year or not.

After I closed the manual valve, thereby shutting off all flow to the heater core the temp at the water neck immediately climbed to 182 degreees but would not go above this.

Is this temp good enough for a 195 stat? I don't think so and it should climb to operating temp even with the manual valve open. Afterall, I do need a heater in 27 degree temps here in Kansas this time of year.

Any other suggestions? I suppose I could try another 195 stat. I have the heater hoses set up like the factory 350. Hose from the pump to the core (this has the shutoff valve inline) and the hose from the core to the top of the intake (next to the water neck).

Also, I am using the factory water neck and have been the entire time.

Thanks.

Like I had mentioned before ...the t/stat should fully close to keep the temp at setting ...after reading some of the other t/stat problems here i wonder if your getting some fluid bypass from the stat .
lesson one ...clearing the myth about the job of the t/stat ...in simple terms ...if the cooling system is not effective enough to modulate the t/stat (it only controls opening temp ) and remains open till the is parked for a while mean while watching the temp gage clime to 220 degrees ...putting in a 160 stat will do nothing to bring down temps if the cooling system is crap ....in a efficient cooling system the t/stat will do its job to modulate the temp ..opening and closing to keep the car at temp not letting it drop to 140 or what ever the cooling system is capable of dropping to . ... I have had guys drop our rad in with 700 h/p and a 160 t/stat ..then call me saying my car wont heat up ...hello .. whats this tell you about your cooling system now ... the t/stat id fighting to keep the car at 160 ..time to put in a higher t/stat .
I still think your getting by pass fluid ... did you start the car cold and chect to see if there was fluid move ment in the rad ?????
Don

Hey Don,

I agree 100% with you about the function of a stat. I just can't figure out why she's running cool and that's why I'm asking the pros. I appreciate your help.

No, I didn't check for flow when she was cold. It slipped my mind at 8 p.m. last night while walking out to the shop fighting a wind chill of 20 degrees. haha

I will definetly get back out there tonight, pull the cap, fire up the car and check for flow. I am also buying another stat this weekend from a different parts store (different brand) to see if that has any effect.

If I see no flow in the radiator when cold, then what? (I do agree there must be a bypass somewhere but there's nothing left other than the stat right?)

Why don't you make sure the stat opens and closes at the right temp by removing it from the car? Place it in a pot of clean water and turn on the heat. (My wife loves when I use her pots for this kind of stuff) Then put a meat thermometer in the water and watch the stat open and close. -- Do not touch the pot with the thermometer as this will screw up your reading. I had your problem with my 69 Camaro 350 and that was the culprit.

Why don't you make sure the stat opens and closes at the right temp by removing it from the car? Place it in a pot of clean water and turn on the heat. (My wife loves when I use her pots for this kind of stuff) Then put a meat thermometer in the water and watch the stat open and close. -- Do not touch the pot with the thermometer as this will screw up your reading. I had your problem with my 69 Camaro 350 and that was the culprit.

Yup ...ya know when it was built on a monday with the guy on the line with a hang over cause it was stamped 195 ... but there were 160 stats ... could be the culprit.

I will find out tonight what the stat opens at but first things first.

I came home tonight and fired the engine up cold. While someone started it for me, I looked into the radiator and as soon as it started approx 4-6 inches of the coolant sucked down and each time you rev'd the engine you could watch the coolant get sucked down.

I figure there was air in the system then??? There is NO coolant in the oil, the heater core shutoff valve has been manually closed and I'm losing Zero coolant.

I then pulled the stat. The radiator had finished draining but as soon as I removed the water neck and popped the stat from the intake I heard a sucking of air and the coolant started draining out of the radiator again. This makes me believe I had air trapped in the engine??

By the way, the stat was closed. I will get back to you later tonight to let you know what I find out with the test on the stat. When I put the stat back in I will definetly fill the engine through the stat opening first and then top off through the radiator.

Keep the suggestions coming.

Tested the 195 stat.....it works perfectly.

I even tested the Murray plain jane 180 I had replaced earlier and it tested perfectly.

Any idea where I go from here??

I'll be putting it all back together tonight or this weekend.

not knowing what area you live in and temps right now in your state ....you may have to try a higher rated t/stat like a late model car maybe a 205 ... even though the 195 should close to keep the block at 195 ..the rad is so efficient that it may be cooling things down very quickly .
I dont know alot about the vortech head system ... you may want to post something in performance to get some feed back there ...I have had guys ask for a additional 3/4 inch outlet for a return line to the rad for engine head set ups .. where there running newer style motors .. its sometimes called a steam line .

going down the road your getting alot of good flow and alot of CFM going threw the rad ... a simple test would be block off part of the rad with some cardboard to see how this effects cooling .. i know its a bit cooler out this time of year ... i had a truck i had to do this with .. even with a 195 stat .. in winter never got good heat .

not knowing what area you live in and temps right now in your state ....you may have to try a higher rated t/stat like a late model car maybe a 205 ... even though the 195 should close to keep the block at 195 ..the rad is so efficient that it may be cooling things down very quickly .
I dont know alot about the vortech head system ... you may want to post something in performance to get some feed back there ...I have had guys ask for a additional 3/4 inch outlet for a return line to the rad for engine head set ups .. where there running newer style motors .. its sometimes called a steam line .

going down the road your getting alot of good flow and alot of CFM going threw the rad ... a simple test would be block off part of the rad with some cardboard to see how this effects cooling .. i know its a bit cooler out this time of year ... i had a truck i had to do this with .. even with a 195 stat .. in winter never got good heat .
there is nothing special about the vortec cooling passages. altho, my Nova had vortec heads and a crappy old long water pump on the 10:1 HOT cammed 355, and with a tiny little crusty 2 core radiator, it never got over 200 degrees on the 195 stat i was running- even when it was over 100 degrees out and i was flogging it in a not-so-very-nice fashion.
so maybe they do keep more of the heat in the chamber where it belongs.
and now that you also recommended what i did (blocking off airflow to see what happens), maybe he'll try that..

Okay, I found a solution. I had no quarrels with blocking off the radiator but I've never had to do this with the many small blocks I've owned over the years here in Kansas.

I filled the system with coolant making sure there were no air bubbles. Temps only got to 180 with a 195 stat and the heater core blocked off. That's not quite warm enough when it's 20-30 degrees out since when I turned on the heater the engine temps dropped to 160.

Soo, I blocked off 1/3 of the radiator and got the temp up to 192 degrees, as shown by the IR gun and as verified by my now fixed temp gauge.

Thanks to everyone for your help. I appreciate it. It's kinda nice knowing I have a cooling system that is almost too efficient. haha

Jason