Hey guys, I'm really puzzled with my rebuilt 350 I put in my vette. I know some are going to say I screwed up doing it this way, but....
My 82 crossfire vette, I basically went old school on it, engine was wore out, crossfire was giving me too many headaches so I pretty much just went old school on it, carb, I bought a rebuilt 350 off a local guy (mistake, idk) it's bored 40 over, flat top pistols, comp cam with a 520 lift which I hate, heres my issue, its not staying cool like it should, I have a champion 3 core aluminum radiator, 170 thermostat in it, I don't drive it more than a couple miles at a time cause the temp just keeps rising, just today it got to 200 degrees & kept rising slowly so I shut it down, I'm tired of throwing parts at it with no resolve, its got a stock water pump & non electric fan on it, the guy said the motor has 10.2/1 compression, so any ideas what I'm doing wrong, why it won't stay at 190 degrees or lower at least, is it going to do any good to go with a high volumn water pump, I'm just puzzled

 

Does it get hot just idling? or is it only at hiway speeds?..

 

Couple questions.... what thermostat is in it, 180? 195? Next... when the radiator was replaced, were all the seals still there to ensure ALL the air goes through the radiator?

 

200-220 is the range of normal operating temperature. You say your car will sometimes rise above 200. How far above 200 does it rise?

 

I'm not seeing a problem with 200. Yes, ideally you would want it to run under 200, but mine runs about 220 or so on the highway and I've been driving it like that for the 10 years I've owned it. I would let it run longer to see if it levels off, rather than shutting it down at 200.

 

I replaced the radiator right after I replaced the motor, thermostat is a 170 & I'm not sure which seal you mean, but as far as for there maybe be an air pocket which I think that's what you may be leading to, I would doubt it, I've ran it with straight water & also just replaced the water with antifreeze & some royal purple stuff that claims to make it run cooler

 

Both

 

I don't know, with the larger aluminum radiator& 170 thermostat, I would think it wouldn't get that high in temp

 

What is the timing set to?

 

My '82 runs at about 205. I have a 195 T-Stat and the system is totally stock--- it is 100 degrees in Texas right now.

Have you ever let it it "run up" a bit to see where it goes? Does it top out or are you "pulling the plug" as soon at it hits 200ish?

 

Ok, I'll keep it running to see how hi the temp gets before boiling over, here's the part that I get confused with, I've done engines before & never had one get this warm with the aluminum rad & 170 thermostat, this is a 82 vette but because of everything I have changed/removed from it, crossfire gone so no computer or anything related to it, its basically it's a 350 with a carb, best way to describe it is "old school", so for it to get this warm, idk, but anyway, I'll screw with it some more today & post the results, I do appreciate everyones posts on this matter

 

12btdc

 

I shut it down when it gets just over 200, I've only seen them get about 5 degrees about what thermostat is in it then go down to it, as in go to 175, then level off at 170, never had a 170 thermostat run up to 200+

 

Do you have the fan shroud installed and are the seals around the radiator installed. If not, that could be contributing to your problem. The seals are needed to help keep the air going through the radiator not around it. My stock 77 L48 runs around 210 even yesterday when it was 114 here in Arizona. Check around on the Internet for a diagram of the radiator seals for your year vehicle and you'll see what's needed.

 

Oh ok, I gotcha, I do have gaps, open spaces if that makes sense, I'd have to fab my own which I don't think would be that big of a deal, I'll try that, thanks

 

Are you running a clutch fan?

 

Running a 170 T-stat on an engine that normally runs @ 195-200 for example is not going to "let/make" the engine run at 170/175 degrees - ever. That's not they way they work. A SBC's temp will "soar" right over 170 once it's warmed up (in most cases -even in cold weather).

Normally your T-stat will remain closed until (about) 170 degrees. When the temp reaches 170 the wax inside melts, the T-stat opens (and in your case, that's where it's going to stay "forever" especially in this weather until the car is shut off and it cools down). In colder weather etc, if the water temp drops below the 170 range, then it will close until temp again gets past the 170 degree mark when it will open - but normally the T-stat allows the engine to warm up quickly to operating temp (to reduce emissions etc) then it opens. On a high perf engine that runs over that, once it's open, it's open.

The T-stat is not going to open/close and reduce temp in an engine that normally runs above the T-stat's rating. When it's open, you are seeing your operating temp which will normally be below 210 (for the sake the argument).

It's different if you throw a 195 degree T-stat in a car that normally runs at 180 degrees. In that case, it will remain closed until temp rises to 195 then open. As is remains open, and the operating temp drops to it's "normal operating range", it will close again. This "cycle" can keep a cooler operating engine "warmer", but it doesn't really work the other way around. Your 170 T-stat isn't going to keep your engine at 170 (Unless of course, it normally runs at 160 degrees - which it doesn't.

If temp is continuing to rise you have an issue obviously.

Are you are getting the temp reading from the temp gauge in the dash, is it original? or are you using an aftermarket gauge or and I.R. Temp Gauge?

Whenever I think I have an issue like that, the first thing I want to do is verify that my temp gauge is reading accurate.

What you may want to do is this:

Remove the T-stat altogether so you can verify you don't have a T-stat that is sticking. Although many fail "open", not all of them do. It could be stuck closed.

You may want to remove it and then check Temp and see where it falls. Even with no T-stat, the "average" SBC may hover around a normal operating range of 175-185-190 AFTER it's fully warm (depending on outside temp - which in this weather should not be pose a problem). A performance engine / large cam etc, may hover a bit higher, but usually not over 205-210 or so.

You can also leave the radiator cap initially OFF when you start the car after the T-stat is removed and make sure you are getting flow. You should be. Don't run it too long that way -you will see the water level in the radiator eventually begin to rise so you don't want it to begin spraying out etc.

Also, are you getting any "overheating symptoms" like pinging when you are driving or water pushing out into the overflow tank??

It may be something as simple as a bad gauge / incorrect gauge or quite possibly, you may be running at 205 degrees and you are just shutting down (getting nervous) before it levels off.

I agree that "around 200" depending on weather should be in the ballpark. The 383 I have now runs around 190-195 at it was 97 degrees yesterday - just to give you an idea. I run a 185 T-Stat in it.

 

The T-Stadt will keep the engine at a minimum operating temperature, it really won't have much of an influence on the overall temp. The "High end" temp will be dependent on the overall condition of the your system, driving conditions, outside heat/humidity, air flow/speed...etc.

If memory serves, on the '82 the auxiliary fan was designed to come on at 238 degrees so that tells me that some GM Engineer thought that 237 is just fine.

BTW, my auxiliary fan will come on occasionally and when I check the heat with my Thermo gun, the water pump and top hose both say 205. Weird.

 

These are the ones I was talking about.... they seal those gaps around the radiator support to force air through, not around... as sullyman said. Especially the top one, that seals between the hood and radiator support.

 

76C3FORME is correct about how the T-stat works and if it were me, I'd remove the 170* stat and put the 195* back in it which is correct for an 82 350 motor. You have issues if the system can not keep it at around 195-200* especially if it is happening while driving and idling. I never understood why GM thought almost 240* was an ok temp. My aux electric fan goes ON at 200* and OFF at 190*. I don't like seeing my temps ever go over 205* and I also live in Arizona.

1st. You MUST install the radiator dam pieces that go around the radiator and the hood for the cooling system to work properly, it funnels the air through the radiator, not letting it go around it.

2nd. Are you sure that is the correct stock water pump? If the pump shaft is the long shaft it will push the fan too far into the shroud and NOT cool properly, it will cavitate the air vs. pulling the air through the radiator. The proper length of the shaft is evidenced by the fan blades being about half way into the edge of the shroud. The closer to the edge, the better.

3rd. Do you have the correct radiator cap rating? 15lbs is correct. and lastly, you may also have an issue with the clutch fan if you are still using one.

Hope this helps some for you. Good luck.