Mr. Wonderful

I discovered my 69 small block was running w/o thermostat, so I installed an AC Delco 180 deg. stat, hoping to solve two problems... anti freeze overflowing from my expansion tank when I shut off car, and to cool the running temp. Engine is a 350 built with solid lifters and rollers, with about 375 hp. and a 4.11 rear. No A/C. This is how I bought the car, and don't know much else about it. With new stat, I'm still running same temp as without it. Car has a 6 blade fan on it. Water pump seems fine. Any suggestions as to how I can bring down temp, as it's only 80 degrees here now, and summer is around the corner, with 90s every day. I'm afraid I won't be able to drive it in the summer unless I figure out how to cool it off. Would a high flow water pump do the trick ? Any other suggestions ? Thanks

Captain Morgan

It's quite possible that your radiator is clogged. If the anti-freeze was not changed very often or the radiator was not flushed on a regular basis, then sludge could have built up inside the radiator causing less than full cooling capacity and decreased flow. This could also cause problems because some of the sludge could break loose and then block the water passages in the engine. You may have to pull the radiator and take it in to be rodded. First suggestion would be to look inside the radiator and see what the small holes look like. If they look blocked or corroded, then you quite possibly have a problem. You can attempt to flush the radiator, but if it's clogged as bad as mine was, you won't have any success. If it was running without a thermostat when you bought it, then chances are it has a clogged radiator and the previous owner didn't know what to do or didn't want to hassle with pulling the rad. It's not a fun job but I have a feeling it's needed for your vette.

JSB69

Before you rip into things, you ought to determine the actual temp that the motor is running, either by putting a thermometer in the overflow tank or having a radiator shop hit it with their laser thermometer. Also, determine if ALL of the radiator seals and air dams are as they should be. They are very important in keeping a 'vette cooling properly. Remember, the T-stat only determines the minimum operating temp. It has nothing to do with max, unless it fails in the closed position. If none of the above works, I'd try a couple of flushes before pulling the rad. Also, don't be suprised if you need to buy a new rad suppoprt when you get a good look at the one you have.

Mr. Wonderful

Thanks sharklover..... I looked inside radiator when coolant level was low, and it looked to be clean and in good condition. I guess it would be a good idea to flush it anyway. How would I be able to tell if I had a high flow water pump already on my car ?

GWHITE75

You will probably get others with similar advice: What condition is your radiator in? Clutch fan? Flex fan? Radiator cap? Rubber/foam seals around the radiator installed (including the seal between the hood and radiator support)? Shroud installed and sealed? Air dam underneath installed and in good shape? Motor timing set for your combination? Vacuum advance working properly and set?

Someone probably removed the T-stat, because it was not cooling adequately to begin with and they thought removing it would help, but in most cases, it won't. Will it idle w/o overheating? Does the temperature come down while driving the vehicle at medium speeds? With 4:11, you're going to tach higher with less air passing in front of/through your vehicle. How fast does it get to 210 degrees? Before the oil temperature rises? You did not mention what transmission or cam you have and these can help the problem, if they are not working properly or you have a high stall converter, if you're running an automatic.

73-454

Flushing a rad is always a good idea. Also make sure you are using an after market temp gauge to check your temp I would not trust the vette temp gauge. Always make sure you rad cap is working properly. Good luck

jerryp58

A thermostat will not make your car run cooler. If it's designed well, it won't make your car run hot either. All a thermostat does is cut off water flow until the coolant reaches operating temperature (180 degrees in this case). If you go on a short trip and somehow it's so cold outside that you never reach 180 degrees (I've seen this on mine when the weather is in the 20s and I'm out on the highway for only 15 minutes or so), then the thermostat will be closed the whole time trying to get the engine temp up (which is exactly what it should do). If, on the other hand, the coolant temp reaches 180 degrees, the thermostat will open and allow flow through the radiator. The outside temp will just make the 180 degree make slower or quicker to reach. At this point the thermostat's job is done. It's now up to the cooling system to keep your car from overheating. Just because your car is at 210 now doesn't mean that it'll get hotter as the temp increases. My temp runs at 195 to 200 when it's anywhere from 35 to 95 degrees outside.

There are several things you can do to cool things off:

1. Get a free flowing thermostat (one that doesn't disrupt flow too much once it opens up). I don't think this is a problem in your case since you're runing 210 with or without the thermostat (sounds like the thermostat is working fine).

2. Make sure you have the plastic lower front spoiler (necessary for highway cooling).

3. Make sure that your fan clutch is functioning properly.

4. Make sure you have the proper coolant/water mix.

5. Make sure that the hoses are in good condition.

If you're still not satisfied that your system is doing what it should, you could:

1. Flush & refill the system (I'd change hoses too unless you know they're fairly new.

2. Use an additive like "Water Wetter". I've not used it, but some have said it's very effective.

3. Get a larger radiator (although it seems I've read that you don't get much improvement from a thicker radiator, just one with more frontal area).

4. Get an aluminum radiator (expensive, but effective).

5. Some here have also been happy with electric fans (if you're not a stickler for originality).

Well, I've babbled on too long (and I'm sure I've left a bunch of stuff out), but hopefully, some of this will be helpful.

Good Luck.

Mr. Wonderful

GWHITE75 wrote: "Rubber/foam seals around the radiator installed (including the seal between the hood and radiator support)? Shroud installed and sealed? Air dam underneath installed and in good shape? " The only foam seal I found is located between the top of the fan shroud and the radiator. I see no foam between hood and radiator support. What is meant by shroud installed and sealed ? Is there a website that shows the seals/weatherstripping needed for my application ? I have a Mid America catolog, and it doesn't show any radiator foam etc. Do these seals effect cooliing? My front chin spoiler is in good shape. Thank you all very much.


[Modified by FathomGreen69, 12:48 PM 1/21/2002]

shoptek

FathomGreen69,
I'm SO GLAD to see another South Florida C-3 here!!! :cheers:

All the above advice is right on the money. I would first make sure your gauge reading of 210 degrees is actual. 33 year old gauges and sending units can be off. As mentioned above, the laser method is fine, or the good old fashioned themometer.

As far as diagrams for seals, air dam, Etc., check the Dr. Rebuild catalog. It has great pictures, and is worth the $4.00 catalog charge.

Shoot me off an e-mail if you need help neighbor (shoptek@aol.com) I'd be glad to meet you and try to help.

bence13_33

All a thermostat does is ensure that your engine gets up to temperature before coolant from the radiator is passed through the engine. The engine is still going to get up to temperature. I would check your guage to make sure it is accurate. I'm glad to hear that you installed a thermostat, running without one can result in pre-mature engine wear.

GWHITE75

Sounds like shoptek can assist you with this problem, but the fan shroud bolts to the radiator support. There are two long 3/4"x3/4" hard foam rubber seals or gaskets between the shroud and radiator running vertically. It seals the shroud and prevents the shroud from contacting the radiator. Yours are probably installed. On my 75, which is what I was thinking when I wrote you, I have a rubber seal, attached to the top of the radiator support, running horizontally that seals to the hood when closed, preventing air from bypassing the radiator. Some people modify or replace their hoods and create an air gap there. You have the stock hood, and I think your year model had a seal running horizontally on top of the support. I could be wrong. Also, there should be a horizontal rubber seal between the fan shroud and radiator at the bottom. If it's missing, air can go between the radiator and support down there as well.

Smokehouse69

According to the 69 owners manual 210 degrees is normal operating temperature on all engine configurations.
GWHITE is right the 69 models had several different designs of rubber seals that went across the radiator support. Another hint is to run 30% coolant and 70% distilled water (throw in a couple of bottle of Redline Water Wetter, for good measure.) Water cools much better than anti-freeze, and in South Florida you shouldn't have any freeze up problems.
You could probably go with 20% coolant 80% water with no worries.
Also have you checked your mixture? If you are running lean it can raise your temps.

GTR1999

I had the same problems last summer. I went throught the whole cooling system:
New Mr Gasket 180 Tstat
Distilled water 60% - 40% antifreeze
Flow Kooler waterpump impeller- increases flow by 30%
checked gauge- dead on the mark!
replaced hoses, flushed radiator, replaced seals
Checked fan clutch- ok
Checked timing- ok
used water wetter- waste of money in my opinion, I didn't see any change!
The car still hit 210* I finally had the carb off so I shipped it to Lars and he found it jetted way too lean, I installed it afterwards and it seems ok now- It stays on 180* all the time. I 'll see how it acts under high temps of summer, but judging from the 90* days it was in the problem was the carb.
Gary

Carl in LA

I think what your seeing here is the temperature that a car operates at is dependent on so many engine variables... timing and carb mixture being harder to relate to the equation... I throw in a few more... pluged EGR valve passage, piston blow-by - of course these are more inclined with an old engine. My car was in your heat category before the rebuild... Even worse... could not go more than 15 miles without full on overheating! I went all out and got the aluminum radiator as well as several of the other items mentioned above... results??? So far so good... around town 180 - 190, highway 180. I am so against heat in my car that I will gladly install tranny and oil coolers next to beat the heat.

yogi78

Also check your lower radiator hose, if it is one of those cheap ones without the spring, get one with the spring inside. It will keep your water pump from sucking the hose closed on itself. If you are able try looking into your radiator to see the amount of flow through it at an idle, the water should be pouring through the tubes and it you rev it just a little the level should drop and the amount increase through the tubes, but be careful because they have a tendency to overflow when returned back to idle. I've seen lower hoses that look good collapse at higher rpm's and choke off the flow. Hope this helps. :chevy


[Modified by yogi78, 8:21 PM 1/21/2002]

mrvette

When I moved here to Jax Fl. from the NE, I had that silly front license plate thing in place...remove it...dropped MY highway temps by about 20f...
allmost 30% airflow increase...
I run a gutted thermostat, restrictor plate, slower warmup for sure, but I have had lotsa thermostate stick closed over the years...just not worth much for those things....
I never had much luck with fan clutches, even new ones...I most allways did a 7 blade aluminum fan conversion from junkyard -- check diameter,....
another better solution for fighting traffic type driving is a flex fan..7 blades or so...but need check them for metal fatigue on blades...cracking....
I have never seen personally a failed water pump cause overheating for lack of circulation, except when they leak, then it's obviously over....
lower hose is a good suggestion, especially at highway speeds....
after all that, and doing the radiator rubber replacement, checkout as required....and it's still overheating, a new radiator can be had for less than 200 bucks from Delco indepandant dealer....look for one from a late 80's camaro V8.....core size is same....adapt hoses as necessary...works fine....

GENE

jerryp58

Gene, one of the TNN shows a couple/few weeks ago had a thermostat that would fail to the open position. Just an FYI.

Jerry

Mr. Wonderful

Thanks yogi78 and mrvette... My lower rad hose has the spring inside so that's okay. And I removed the front license plate holder.... great idea !
Next week I plan to flush and refill and also add some Water Wetter. All great ideas from fellow members. I really appreciate the input, and will let you know how things work out. Thanks also to Steve (Smokehouse69) for his generous suggestions. :D

JD/76-ZZ4

A couple of of other things I have done besides the other ones mentioned:
1) I run 2 tranny coolers in series instead of running the tranny oil through the radiator cooler
2) Use a flexalite fan NOT the flex...
3) straight distilled water with a couple of cans of water pump lube/rust inhibitor
4) 160 deg thermostat

My temp gage hovers at about 180F even in the summer time in stop and go traffic....

soundguy

My 75 ran @ 170 on the gauge. Put on new aluminum heads, still read 170. Put in a new "correct according to the parts catalog' sending unit just for the hell of it. Has read 210 ever since. :)

This topic comes up 2 or 3 times a month, so obviously, there's a whole mess of 'wrong' senders out there, maybe you have one too. Use a meat thermometer in the filler neck to find the actual temp. (btw, mine is exactly 180 when I check the temp in the driveway)