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70SS454
05-09-2012, 05:51 PM
I have not had my 70 chevelle long. This is the first warm weather I have driven it in. Today my 454 really started running hot while sitting at the light. It usually runs around 200-220 degrees. It was headed over 240 on its way up. It's a Texas car now and was in Wyoming most of its life. It dumps the antifreeze overboard when it warms. There is no resivoir on it. Should there be one? Do I need a differrent thermostat? I think it would have given me a temp light if I had to is t much longer.

Ms Grumpy
05-09-2012, 07:17 PM
You said you haven't had it long. Did you change all the fluids ? I know that it can get pretty hot in Texas, a new thermostat would be a cheap way to try to solve the problem, but maybe a new radiator might be in the cards.

BillsCamino
05-09-2012, 08:05 PM
Tell us more...
What does your car have for a fan? Does it have a shroud? What is the initial & total timing set at? How many rows are in the radiator core?

Hank70SS
05-09-2012, 08:27 PM
As Bill said there is a lot at play here, we need to more. Retarded timing will cause it to run hotter. No shroud on the rad will cause it to run hotter. Tell us your setup and maybe we can help.

70SS454
05-11-2012, 07:14 PM
I do have a fan shroud. The car was a Wyoming car it whole life until a few months ago. I have changed fluids but not the cooling fluids. It looks pretty clean and I have added several times because it dumps it over when it warms up. The car is pretty original. It belonged to my father-in-law who liked for things stay stock. I believe the timing is where it should be, not advanced and I think the radiator is fairly stock. The car runs beautifully. I guess I should start with the thermostat. Then move to installing an over flow tank like I did on my old jeep cj7 when I restored it. I really don't know much about this car yet.

Ms Grumpy
05-11-2012, 07:32 PM
Let us know how things work out. Good Luck.

70SS454
05-11-2012, 08:09 PM
Do you guys run a overflow resivoir on your big blocks?

Hank70SS
05-12-2012, 07:44 AM
You don't fill the rad to the top on these cars. About 4" to 5" below the top. You can add an overflow tank but it's not necessary, I don't have one and mine never overflows. If it's the original rad it could be plugged up. Maybe just a flush or maybe it will need a recore.

If your timing is set to stock specs it probably needs to be advanced some. Chevy big blocks love a lot of timing advance. Try setting it to 16* even 18* at idle. Watch for spark knock, it can kill an engine. You may want to start at 14*, if no knock, try 16* then 18*. You'll need a dial back timing light or timing tape around the damper to check total mechanical advance timing. It should be around 35*, 36* and should be all in between 3,000 to 3,500 rpm. Your mechanical advance may not be working well if it's a stock distributor and not been rebuilt in awhile. The above timing checks are done with vacuum advance disconnected and plugged. If you're sitting at stock timing now that 454 will really wake up with more timing advance.

You have a fan shroud, is it a stock clutch fan setup? Fan blades should be about half way into the shroud. Is the clutch good? May be time to replace it.

Check vacuum hoses, make sure they're all good with no cracks. A vacuum leak can cause it to run lean and that will make it run hot.

70SS454
05-12-2012, 10:43 PM
Thanks hank, I'll check that this week and get back to you. I know the distributor has been updated but can't remember to what. I'll check.

shadowgray396
05-13-2012, 08:29 AM
On a non AC car the fan shroud only covers some of the radiator leaving part of the radiator with no air flow. On a friends car we put a AC fan shroud on it so when he is at idle it no longer over heats. The shroud cover the entire radiator and you still retain a stock look.

Also Hank great info.

70SS454
05-13-2012, 09:43 AM
My fan shroud covers the entire radiator and my fan blades are completely covered by the shroud.

Bowtie-Bri
05-13-2012, 09:33 PM
Another thing to check out would be the clutch fan if it's been replaced before.
There is 3 different clutches available, standard, heavy duty and severe duty(trucks).
Cars with big blocks use the heavy duty ones. If it has the standard duty one, this can cause it to run hot. Some people have used the one for trucks, but it is alittle noisier than the heavy duty one. It's one more thing to check out.
Good luck!

70SS454
05-14-2012, 07:07 PM
How can I tell if the fan clutch is bad?

carpoor
05-16-2012, 05:46 PM
Two things... thermostat? What temperature is it? Could it be stuck open or closed? And, what condition are the hoses in? They might collapse when it gets hot.

Ms Grumpy
05-16-2012, 07:49 PM
Any luck yet ?

Hank70SS
05-17-2012, 07:39 AM
Two things... thermostat? What temperature is it? Could it be stuck open or closed? And, what condition are the hoses in? They might collapse when it gets hot.

Grab a hold of the fan blades, engine off of course and try to spin the fan, should spin but should have resistance. Also try to move a blade front to back, look for worn out bearings in the clutch assembly. Open the hood when the engine is cold. Start it up and you should hear the fan 'roar' for a second or two. If it's engaging properly when the engine gets hot you should also be able to hear a change in the amount of noise from the fan. Let the engine idle and get hot, should hear when the clutch engages.

If it spins easily by hand or you don't hear it engage it needs to be replaced. Hayden 2747 HD clutch is the best choice.

What type of fan? Is it a stock 7 blade fan? Carpoor brought up a good point. The lower hose can collapse when hot if it doesn't have a spring inside to keep it in shape. If the the thermostat was stuck closed the engine temp should continue to climb from the time you start it until it's way overheated. That doesn't mean the thermostat couldn't be bad, not opening and closing as it should. Stuck open, that won't cause a problem, except the engine might never come up to temp. It's a myth that stuck open or no thermostat doesn't allow the coolant to stay in the engine long enough to cool it. It just doesn't work that way. The more cool water you can force through the engine the more it will cool. They make high volume water pumps for engines that have a cooling problem, more cool water, lower temps.

70SS454
05-19-2012, 09:15 AM
Good info. I appreciate the help. I have been working alot and have not had time to dig into it anymore. I will in a week after several business trips this next week. The motor warms at a normal rate when air is warm or cold. Temp usually stays around 200-220 even at stops unless you get caught at a long light then it climbs. I check the fan clutch, replace thermostat (just incase), and check for the spring. I know the hoses are in good shape.

70SS454
05-19-2012, 07:27 PM
Ok, I do have the springs in the upper and lower radiator hoses. I also do have the stock 7 blade fan. It does spin freely but has some resistance. It will turn about two blade widths. I do however have some play in the clutch if I try to move the fan in a motion from the radiator to the motor.

Hank70SS
05-20-2012, 08:17 AM
May be time to just go ahead and replace the clutch if there is play in the bearings. The Hayden 2747 clutch can be picked up at most auto parts stores. A rad flush may help also. Since you're in Tx, you don't need to use much antifreeze, mostly distilled water. Good luck.

70SS454
05-21-2012, 03:14 PM
Thanks, I'll see what I can find.

70SS454
05-26-2012, 02:42 PM
I ordered and received a new Hayden fan clutch and 180 degree thermostat. Should fix it. Ill install it when I get a break from work. Thanks for the help!

jpekarek
06-11-2012, 01:54 PM
A couple of people have mentioned timing. That is extremely important to engine temp. More than people think.

70SS454
08-23-2012, 09:56 AM
Timing was dead on. Replaced fan clutch and thermostat.mall hoses are fairly new and are not collapsed. Motor still runs 200-210*. It's still gets warmer at a light...230-235*. That new Hayden fan clutch is pretty dang loud. I don't like it

fleming23
08-23-2012, 10:13 AM
I just glanced at the thread but it seems from reading that you are only having issues at low speed/idle?

If so, please take the time to read through my thread and all the different things I tried to get my car to run cool at idle. It was great at cruise but as soon as I would stop for more than 5 minutes it would start creeping up.

There are a lot of tips in my thread and an eventual fix for my situation. Not sure if yours will be the same but there are likely to be things you can try if you have not already.

http://www.chevelles.com/forums/showthread.php?t=384474&highlight=

If you can spend the $40 to try the same fan I did, it might be worth your time. I took the car out yesterday and with my new gauge I could watch the water temps fluctuate from 160 to 164 and back.

Hank70SS
08-31-2012, 11:36 AM
Timing was dead on. Replaced fan clutch and thermostat.mall hoses are fairly new and are not collapsed. Motor still runs 200-210*. It's still gets warmer at a light...230-235*. That new Hayden fan clutch is pretty dang loud. I don't like it

What exactly is dead on for the timing? The old GM specs, which really weren't advanced enough?

70SS454
09-02-2012, 07:41 PM
Hank,
My buddy checked it for me, he is a big Chevy big block guy. We followed your thread advice. The timing was already set at 16 if I remember correctly.

Fleming23, I will have to look through your thread.
Dan

70SS454
09-02-2012, 08:10 PM
Could my water pump be not working well enough?

70SS454
10-08-2012, 07:56 AM
Drove the chevelle yesterday...50* day and car stayed at 210* all day.

Hank70SS
10-08-2012, 12:11 PM
Could my water pump be not working well enough?

Could be, how about the radiator? Does it look like it's 40 years old, could be plugged and lot allowing good coolant flow.

You said you don't like the Hayden clutch because it's so noisy. You didn't get a severe duty clutch did you? They are noisy and all you should need is the heavy duty.

Try making the idle mixture a little richer. Turn the adjustment screws counter clockwise at least 1/2 turn, see if the idle temp stays closer to driving temp.

Also, are you sure your temp gauge is accurate? Does your buddy have an infrared thermometer to check the engine temp.

70SS454
10-10-2012, 03:25 PM
Radiator is not original and I had it checked out. The shop said it was good to go.
The Hayden clutch that I installed was the one that was suggested (heavy duty). It sounds like it is even on on the highway on a cool day. I hear it over the motor. I don't think it ever kicks off. I need to idle the motor from cold to warm on the drive and pay specific attention to it.
The mixture is already pretty rich. You can smell the richness in the exhaust. I also had the mixture looked at by a local hot rod shop and they said its where it should be.
I am not sure if the gauge is correct. I will look into the infra red thermometer. What part of the engine do you shoot it at? I drove it again yesterday. Outside air temp was 60*. When I was moving, temp sat at 210*. After idling for a min or so, it still jumps to 230 and then drops as soon as the car moves.
Ya know, that just made me think....at night, at idle my lights are dimmer than if the rpm's come up slightly. I wonder if that voltage drop at idle could be affecting the temp gauge? Causing the reading to change at idle. I think that's prob not it but I still wonder.

Hank70SS
10-10-2012, 04:27 PM
Okay, had to go back and read the entire thread. You've replaced the fan clutch, thermostat, rad was checked out, base timing is at 16*, hoses are good. No vacuum leaks, it was mentioned, hope you checked that out. Not a lot left.

Only other thing I can think of is the vacuum advance. Is it working? Timing and engine RPM should jump up when it's connected, compared to disconnected with hose to carb plugged. Also where is it connected to the carb, near the base or up above the throttle plates? If it's up top I would move it down to a fitting near the base of the carb.

If you use a infrared thermometer check a few different places, front of head, lower on the block, center of head on the side. Then temps will vary some but should give you a good idea of what's going on.

70SS454
10-11-2012, 10:05 AM
I'll check that Hank. That's for your help.
Dan

John
10-16-2012, 03:37 PM
I personally at this point would be wondering about the water pump and radiator.

Ms Grumpy
10-16-2012, 05:34 PM
Hank, there are a few infrared thermometers out there. Do you have one that you suggest ?

Hank70SS
10-16-2012, 05:42 PM
Hank, there are a few infrared thermometers out there. Do you have one that you suggest ?

Not really, like you said there are quite a few. Fortunately the internet let's you find reviews on just about anything or maybe someone else has a suggestion.

70SS454
10-18-2012, 01:15 PM
I am actually thinking about replacing the water pump. It never hurts to have a new one and it could be the culprit.