Overheating - Chevelle Tech
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post #1 of 44 (permalink) Old Jul 21st, 19, 12:36 AM Thread Starter
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Overheating

OK. I've read several threads on this subject at this forum and I have a feeling that you guys have heard this story a few times and there may not be an answer to this but I'm at my wits end on this and grasping for straws.

Problem is that within ~ 20 mins of driving, coolant temp will approach 230 degrees (I will pull over, stop and let it cool down before proceeding). Here's what I've tried:
- New large Griffin aluminum radiator with 2 large electric fans that come on @ 185 degrees. Also installed larger alternator to go with new fans.

- New thermostat.

- New coolant temp gauge and sensor.

- New overflow bottle.

- System has been drained, vacuumed out and new 50/50 mix anti-freeze put in.

- Using the radiator cap that came with the new Griffin radiator.

- If I can get car on freeway and up to 60 mph, no overheating problems.

- Been tuned up as well as can be expected I think.

- Not sure about the water pump. The engine is a rebuild and not sure if the water pump is new/used/good. Engine is a 454 thats been stroked out to a 496 with Isky racing cam. Aluminum intake manifold and headers with Holley 4 bbl.

Now, I have broken the alternator fan belt twice by stomping on the gas and the temp pegged (over 250 degrees). Both times I went about a 1/2 mile before pulling over because I didn't realize it until I looked at the temp gauge and it was pegged. Fixed the belt problem by installing a heavier duty alternator mount. I mention this because I'm not sure that maybe I might have broken something by doing this and it's causing the overheating problem. Don't know.

Any suggestions about the next thing to try?

Couple questions: - I live in Hawaii, do I really even need a thermostat? And am curious, is the thermostat gap smaller than the coolant hoses because the cooling system is supposed to be choked down because you want the coolant to go a little slower?

- I'm guessing water pump is working because you can see the coolant flowing in the radiator and that water pumps either work or they don't. But, would it be wise to get an 'upgraded' one?

Thanks for any help.

Ben.

1970 Chevelle SS (clone)
454 cid (496 stroker)
Holley 4 bbl 750 cfm
Muncie M21 (Hurst shifter)
Long tube headers
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post #2 of 44 (permalink) Old Jul 21st, 19, 1:01 AM
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Re: Overheating

What kind of fans and are you running a shroud?

Do you know the model number of the radiator?

Do you have to keep adding coolant?

Are you running a bypass hose between the water pump and the manifold?

Are you running a heater?

What's your timing set at? Running a vacuum advance?

Have you always had this issue or did it just pop up one day?

It wouldn't hurt to see some pictures of your set up.

The whole breaking belts thing has me thinking you may have an issue in that area. Ever hear the belts squealing?

Yes you should run a thermostat. You can run a restrictor in place of the thermostat, but the engine will come up to operating temp more slowly causing additional wear and may not reach sufficient temps to burn off condensation in the oil. Leading again to more wear. As a test you can remove the thermostat and see if it helps. If it does, you may have a thermostat issue or a flow issue.
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post #3 of 44 (permalink) Old Jul 21st, 19, 1:31 AM
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Re: Overheating

Ignition particulars may help.
Do you have a bypass hose and/or heater hoses installed?

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post #4 of 44 (permalink) Old Jul 21st, 19, 1:42 AM Thread Starter
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Re: Overheating

Thx for response:

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
What kind of fans and are you running a shroud? Got fans with new radiator, and yes shroud covers most of the radiator; model below.

Do you know the model number of the radiator? It's a Griffin CU-00006 ($1k) from Summit.

Do you have to keep adding coolant? No. And have yet to see it leak anywhere.

Are you running a bypass hose between the water pump and the manifold? No. Don't know what this is. Should I have this?

Are you running a heater? No heater, in fact, it's been disconnected.

What's your timing set at? Running a vacuum advance? Timing is 8-10 degrees, yes vacuum.

Have you always had this issue or did it just pop up one day? I only have 700 miles on the new engine so it's still kinda new.

It wouldn't hurt to see some pictures of your set up. 2 attached.

The whole breaking belts thing has me thinking you may have an issue in that area. Ever hear the belts squealing? No, but I think we fixed the breaking belt thing by putting in heavier duty mount on alternator and that seems to have fixed that.

Yes you should run a thermostat. You can run a restrictor in place of the thermostat, but the engine will come up to operating temp more slowly causing additional wear and may not reach sufficient temps to burn off condensation in the oil. Leading again to more wear. As a test you can remove the thermostat and see if it helps. If it does, you may have a thermostat issue or a flow issue.
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1970 Chevelle SS (clone)
454 cid (496 stroker)
Holley 4 bbl 750 cfm
Muncie M21 (Hurst shifter)
Long tube headers
Tuxedo Black - black interior
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post #5 of 44 (permalink) Old Jul 21st, 19, 2:52 AM
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Re: Overheating

It will be tough to fault the new Griffin Radiator and that type of shroud. Top of the line parts there as long as you are running Spal fans and not some Chinese knock off. If they are not Spals, I would invest in the highest flow Spals available if you get no results from what's posted below.

Check and adjust your timing for max possible without hard starting or detonation. It will probably be in the 16-18 initial range with the vacuum advance disconnected. I see an HEI w/vacuum advance. Hook up your vacuum advance to manifold vacuum. If you can get us your initial timing with the vac disconnected, with the vac connected and your all in timing at 2800 we can offer suggestions. Running retarded will cause your engine to run hot as will running too lean.

Some guys will get by not running a bypass hose on a big block, If I were you I would try to run one. Temporarily move your fan switch to one of the other positions or into a head. Install a new thermostat 160- 180, I prefer 180 and it should work well with a functioning cooling system. EMP Stewart type is best all around. https://www.summitracing.com/parts/e...make/chevrolet. But I would be happy if you just replaced what you have to eliminate that as an issue.

If that doesn't work I would throw a high flow pump at it. You may have an impeller issue. You may be able to feel it if you remove the belt and spin the pulley by hand.

All in all it looks like a first class set up. If it's holding water and you don't keep adding coolant, then your head gaskets are probably ok. If you have to keep adding coolant, I would run a radiator pressure test to rule out blown head gaskets. Keep an eye on your oil and the inside of you cap. Watch for rising oil level or gray watery deposits.

If you can supply your timing specs we can determine if that could be cause for your issues.

Last edited by DUTCH MAX HEADWORK; Jul 21st, 19 at 3:10 AM.
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post #6 of 44 (permalink) Old Jul 21st, 19, 8:40 AM
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Jeff
 
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Re: Overheating

I'd remove the electric fans and use the clutch fan. Not only will it cool better, it will take all that extra work off the electric system..
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post #7 of 44 (permalink) Old Jul 21st, 19, 12:32 PM
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Re: Overheating

Noticed that you have no overheating issues at freeway speeds. Thats telling me there may be a problem with your fans or the fan control circuit.

Ed

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post #8 of 44 (permalink) Old Jul 22nd, 19, 1:41 AM Thread Starter
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Re: Overheating

Not sure what the fans are but they are advertised at 1734 cfm per fan. I 'assumed' that would be ok.
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post #9 of 44 (permalink) Old Jul 22nd, 19, 1:53 AM
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Re: Overheating

Quote:
Originally Posted by chevyhawaii View Post
Not sure what the fans are but they are advertised at 1734 cfm per fan. I 'assumed' that would be ok.

Griffin uses spal fans on their shrouds. They should work for your application if functioning properly at there full output.

I couldn't find your setup at first, then lucked on it......https://www.summitracing.com/parts/g...le?prefilter=1

As far as suggestions, posts 2 and 4 is all I have at the moment.

Last edited by DUTCH MAX HEADWORK; Jul 22nd, 19 at 2:20 AM.
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post #10 of 44 (permalink) Old Jul 22nd, 19, 9:43 PM Thread Starter
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Re: Overheating

I have a friend who really does all the heavy lifting with my car so I'm kinda quoting him here on timing info: starting timing is 8 degrees, with an idle timing of 14 and total of 28. He couldn't get it to start good cold with any more than that and now he's looking into a better vacuum advance pod.

Thermostat is an edelbrock 160 degree high flow one.

And, again, thanks for your respones. I thought I could put 'like' tags on posts but doesn't seem to work, maybe I need newer version of the site.
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post #11 of 44 (permalink) Old Jul 22nd, 19, 9:48 PM
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Try bumping it up to 20 at idle. Then add vacuum. May make a big difference. Check to verify that your timing marks are correct.
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post #12 of 44 (permalink) Old Jul 22nd, 19, 10:05 PM
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Re: Overheating

What distributor are you running?

Your just jealous because you can't hear the voices!

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post #13 of 44 (permalink) Old Jul 22nd, 19, 10:27 PM
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Re: Overheating

Quote:
Originally Posted by LevonH View Post
Try bumping it up to 20 at idle. Then add vacuum. May make a big difference. Check to verify that your timing marks are correct.
Check to verify that your timing marks are correct

I agree, not running enough timing. Start at 20 then work your way down 2 degrees at a time until she still starts fairly easily.

I'll take a stab and say that engine will probably like 16-18 degrees initial with 36 total without the vacuum and will respond well to a vacuum can that adds 10 degrees under vacuum. You have no vacuum at start up, so you still start at 16 degrees initial until the vacuum builds and pull in more advance.

The tough starting may not entirely be timing related, check your battery and clean/check your terminals.

I still think you should add the bypass hose. I can't count the times guys have come with overheating issues and gone through the whole speil, just to finally install that hose as a last straw attempt and find success.
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post #14 of 44 (permalink) Old Jul 22nd, 19, 10:29 PM
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Ditto^^^^^

Levon Hovagimian
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Current Engine VortecPro 460 (513 HP) Original is resting
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post #15 of 44 (permalink) Old Jul 23rd, 19, 1:00 AM
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Re: Overheating

Whats in Front of the Rad / Grill Side ? Big old A/C Condenser ??
Pic would be good

And that Rad with Dual Row 1.25" Tubes & Efans/Shroud looks good to me if the Efans are SPALs

Not having any Heater Hoses or a Bypass Hose is not good

Sounds like Timing like others have mentioned
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