SBC Cooling Saga...can anyone offer a good suggestion I haven't tried yet? - Page 3 - Hot Rod Forum : Hotrodders Bulletin Board
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  #31 (permalink)  
Old 07-01-2008, 01:22 PM
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Quote:
Originally Posted by ScoTFrenzel
RE Malc's pictures post # 23.

The full shroud works for pulling air across the entire core when the fans are running, but
that shroud blocks ram air flow through the radiator at highway speeds. But that might not be a problem if the radiator is big enough.

I have plans to install flap type doors in the lower part of the shroud, at the moment it runs at 180º-185º which is way better than the 220º it used to run and all the idle problems that came with it.
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  #32 (permalink)  
Old 07-01-2008, 01:29 PM
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Flaps...

Quote:
Originally Posted by malc
I have plans to install flap type doors in the lower part of the shroud, at the moment it runs at 180º-185º which is way better than the 220º it used to run and all the idle problems that came with it.
Malc, I've heard of free-floating flaps installed on aluminum shrouds that will open when air is moving through the radiator at highway speeds, but will actually stick closed when the car is not moving and the fans are going. I'd like to see pics when you have done it, and hear how it goes!

Chuck
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  #33 (permalink)  
Old 07-01-2008, 03:04 PM
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Don´t hold your breath, while it is planned I have other stuff to do,
the car is taking the back seat for awhile.
The fan shroud is now a part of the rad so I have to take both out at the same time, you´ll see there is´nt much room in there ´tween motor and fans.
This is my plan.
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  #34 (permalink)  
Old 07-01-2008, 03:08 PM
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SBC Cooling

I know you said timing is "spot on" - but, I have found that a LOT of SBC cooling issues are timing related - static timing (at idle, Vac hose disconnected) may be "spot on", but how about the advance curve? AND - especially for a hiway cruiser - the Vac advance has to be working really well. Try disconnecting your vac advance hose at idle - if RPM drops, it is most likely working and you can disregard this message - plugging hose back in should increase RPM. If this does not happen, then you have found a part (maybe not all) of your problem.

Now disconnect the vac hose again - rev it up and see if the mech advance is working too.

SBC's are notoriously sensitive to timing and show their displeasure on the heat gauge

Is there any chance that it is running too lean? (Vac leak, etc)

Just fishing for ideas here
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  #35 (permalink)  
Old 07-01-2008, 03:24 PM
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Hi Chuck,
I had a similar problem on my 351 Cobra after I replaced the electric motor my single blade Flex-a-lite fan. The engine got to operating temp and got hotter as I drove it. I brought it home and found that the plug on the electric motor was reversed. I took a sheet of paper and put it in front of my grill and the paper blew off. I reversed the wires and the paper stuck to the grill. My next drive the temp never went above 180. I also switched my coolant to the waterless Evans and have been pleased. Hope your problem is as simple as mine was, just check and see if your fans are ''pulling air'' through the radiator and not pushing.
Good luck,
Everett.
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  #36 (permalink)  
Old 07-01-2008, 03:54 PM
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Lean???

Quote:
Originally Posted by Dave57210
I know you said timing is "spot on" - but, I have found that a LOT of SBC cooling issues are timing related - static timing (at idle, Vac hose disconnected) may be "spot on", but how about the advance curve? AND - especially for a hiway cruiser - the Vac advance has to be working really well. Try disconnecting your vac advance hose at idle - if RPM drops, it is most likely working and you can disregard this message - plugging hose back in should increase RPM. If this does not happen, then you have found a part (maybe not all) of your problem.

Now disconnect the vac hose again - rev it up and see if the mech advance is working too.

SBC's are notoriously sensitive to timing and show their displeasure on the heat gauge

Is there any chance that it is running too lean? (Vac leak, etc)

Just fishing for ideas here

I'm actually trusting my mechanic here that he did/checked all the timing issues, frankly, apart from what I actually noticed. As to running lean, I don't smell fuel save when the choke is engaged, but there IS a slight noise from the driver's side rear of the engine (at around the exhaust manifold) that disappears after a few minutes of operation...that may be something, it may not..I dunno.

I've run an ad in the local Craigslist to find if someone will diagnose and fix the problem in return for my '89 Honda Nighthawk..I'm being flooded with emails, but I have to sort 'em out to see who may be trustworthy...

Chuck
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  #37 (permalink)  
Old 07-01-2008, 03:56 PM
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Pushing and pulling...

Quote:
Originally Posted by Everett II
Hi Chuck,
I had a similar problem on my 351 Cobra after I replaced the electric motor my single blade Flex-a-lite fan. The engine got to operating temp and got hotter as I drove it. I brought it home and found that the plug on the electric motor was reversed. I took a sheet of paper and put it in front of my grill and the paper blew off. I reversed the wires and the paper stuck to the grill. My next drive the temp never went above 180. I also switched my coolant to the waterless Evans and have been pleased. Hope your problem is as simple as mine was, just check and see if your fans are ''pulling air'' through the radiator and not pushing.
Good luck,
Everett.

Thanks for the post, Everett...both fans are indeed pulling, and pulling strongly...i was most paranoid about that when I had 'em installed. What kind of coolant is that you're talking about...I've not heard of it. How well has it worked???


I've just checked online..it ain't cheap, but I may try it anyway...at $33 a gallon, uses no water, so I'd need 5 gallons AND flush all the water from my system. Given what the website says, it may just be a 'go!'

Chuck

Last edited by cmk59; 07-01-2008 at 04:16 PM. Reason: Incomplete
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  #38 (permalink)  
Old 07-01-2008, 06:08 PM
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Check your lower radiator hose and make sure it is not collapsing when you are having the heat problem. I have had that happen and it restricts the flow through the engine and back out to the top of the radiator. I did a flush and fill, new stat and cap only to find the hose collapsing. Just an idea and easy to check.
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  #39 (permalink)  
Old 07-01-2008, 06:36 PM
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Not there, either...

Quote:
Originally Posted by 48ChryslerRodder
Check your lower radiator hose and make sure it is not collapsing when you are having the heat problem. I have had that happen and it restricts the flow through the engine and back out to the top of the radiator. I did a flush and fill, new stat and cap only to find the hose collapsing. Just an idea and easy to check.

Yup...already checked that one. There's good circulation; both hoses (new) are full and piping hot. I make sure that every time I have the system changed / topped up that it's run cap-off for 15-20 mins to bleed the air out, too. I'm getting great circulation...it's the heat that's the issue...
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  #40 (permalink)  
Old 07-01-2008, 06:41 PM
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Quote:
Originally Posted by cmk59
1968 Impala Custom, 275/327, TH400, dual exhaust with 'h' pipe. New suspension, engine still stock save for water pump and t'stat.
Your main problem ... is ... in my opinion
THAT you have removed the original good shroud and belt driven fan.


( photo taken from the internet ... )

General Motors spends tons of time and money engineering their cars to run cool ... why does people think that they can make it BETTER ??? with some aftermarket electric fans.

Install the shroud back on and the proper belt driven ... and the correct 195 range thermostat and be done with it ...

Deuce ... Moderator

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  #41 (permalink)  
Old 07-01-2008, 06:43 PM
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Quote:
Originally Posted by cmk59
I've run an ad in the local Craigslist to find if someone will diagnose and fix the problem in return for my '89 Honda Nighthawk..I'm being flooded with emails, but I have to sort 'em out to see who may be trustworthy...

Chuck

Wish I was somewhere near you. I'm outta work at the moment and looking for stuff to keep me busy....(just installed a disposal in my sink tonight )

I would be on that deal like stink on a skunk!
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  #42 (permalink)  
Old 07-01-2008, 08:35 PM
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Really?

Quote:
Originally Posted by Deuce
Your main problem ... is ... in my opinion
THAT you have removed the original good shroud and belt driven fan.


( photo taken from the internet ... )

General Motors spends tons of time and money engineering their cars to run cool ... why does people think that they can make it BETTER ??? with some aftermarket electric fans.

Install the shroud back on and the proper belt driven ... and the correct 195 range thermostat and be done with it ...

Deuce ... Moderator


Geez, Deuce...I hadn't thought of THAT one. I kinda figured that even with my three (yes, 3) college degrees that maybe GM had known what they were doing...oh, wait, they didn't always[I], even in those halcyon days!!! Besides, I didn't just willy-nilly remove perfectly good components... they were shot and needed replacement.

Just give me some credit for doing some decent research and not pushing the panic button right off the bat! I ran with the OE setup for 3 years before the old girl developed her 'issues.'

I went with the dual electrics because it was a matter of economics. The fan AND clutch were shot (fan coming apart at the rivets), and it was going to cost as much to replace them as to get the two electrics (on sale at that time). So if you were going to replace a bad one with a (potentially) better one, why wouldn't you?

BTW, the only t'stats listed for my 327 / TH400 at O'Reilly, AutoZone, Pep Boys, Raceway and Impala Bob's are a 160 and a 180, so I don't know where 195 came from...and believe me, I've looked and asked for 3 solid years. No one has even been able to tell me what the normal op temp for this engine/application is yet.

IF someone could tell me (with any degree of authority - meaning: show me in print) what the temp my engine should be on a 90 degree day, and it was 195-205, I might believe them. Might. But when the gauge reads 220 within 15 minute of operation with a puny 160 t'stat in it, and pegs 250 with the AC on ... and I'm no mechanic, but I have run a motor pool worth $225 million in the USAF ... I'd say that, if anything, I indulged in needless overkill and something else must be wrong.

Chuck
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  #43 (permalink)  
Old 07-01-2008, 08:39 PM
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I wish you were closer, too!

Quote:
Originally Posted by Holder350
Wish I was somewhere near you. I'm outta work at the moment and looking for stuff to keep me busy....(just installed a disposal in my sink tonight )

I would be on that deal like stink on a skunk!

I appreciate that...even though I've specified that the mechanic must buy all parts and do the work locally, folks have come out of the woodwork. I'm hoping I can either find someone who has a good OE fan and clutch to try that route with the original shroud, or will have a large sheet of aluminum to fab me up a shroud for the dual electrics.

Then again, if you wanna travel to OK and do the work here, I'll give ya room and board! What tools I don't have, I'll get / borrow.

Chuck
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  #44 (permalink)  
Old 07-01-2008, 09:45 PM
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you say you ran the stock setup for 3 years without trouble?

Seems strange that this happened all of a sudden.

I hate to sound stupid but are you 100% that the gauge is correct?

Is it puking water out of the overflow?

.....the original Tstat had a small hole in it to bypass water by the stat, Hondas use a bleeder screw below the water neck. If theres no water on the stat it will not open.

You know more about what has and hasn't been done, I'm just grasping at straws here to try and give some ideas!

Also... I dont know how your mechanic flushes the system out......but I always take the upper hose of the rad, start it up and let it warm up, all the while keeping the radiator full. (thru the upper hose inlet)

when the engine temp hits the Tstats temp water will start POURING out of the upper hose. I then let it run till it the water coming out of the upper hose is clear.....

This lets you know that the entire system is clean, plus because the water must go thru the rad, engine and the Tstat.....you know if its flowing adequately.
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  #45 (permalink)  
Old 07-01-2008, 10:07 PM
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Quote:
Originally Posted by cmk59
Hello, all!

I notice overheating is a hot topic (bad pun) here, but I wanted to dive in with my woes and see if anyone can figure out what I haven't yet. The history:

1968 Impala Custom, 275/327, TH400, dual exhaust with 'h' pipe. New suspension, engine still stock save for water pump and t'stat. Still gets 15 mpg +/= city, so she's still doing ok there.

BUT, she has a cooling problem from Aitch Eee Double Hockey Sticks I can't figure out or fix. For 2 years, the idiot light came on intermittently, but could find no trouble. Added an Auto Meter gauge with probe inserted in lower center of radiator, but this showed actual NUMBERS that freaked me out...well over 290 degrees, w/o the A/C on!

SO, I did the following, in order (rather, my Goodyear guy did it):
1. Back flushed the coolant;
2. Put in a (tested first) 180 deg. thermostat;
3. Added an Impala Bob's 4-core Desert Cooler radiator, along with auxiliary external coolers for the engine oil and trans fluid;
4. Put dual 16" electric fans on said radiator, mounted 1/8" from the core (no shroud of any kind was provided with the fans..they mount on dual rails that span the radiator left to right).

STILL had high temps as described! Now, I added:

5. 160 degree thermostat;
6. 40 GPM hi-flow water pump;
7. All new hoses inside and out;
8. New heater core (thanks to the water pump);
9. Went broke converting the A/C to the new refrigerant.

And still the problem persists. It takes the car just 15 mins or so to get up to 180 when the ambient temp is 85, but after that it just climbs to about 205-210. If I use the A/C, the temp gauge pegs out and coolant spews out the overflow!

As we all know, the cavernous interior of a '68 Full-Size Chevy takes awhile to cool, but I can't risk using it anymore. I'm fed up and broke, and the only thing I HAVEN'T replaced is the condenser, which seems fine.

What next?
What's the normal op temp for my engine anyway?
Do I need to replace the condenser with something new anyhow?
Should I try to make a shroud of my own out of rubber, etc, to cover the inboard areas of the radiator not covered by the fans?

Please help me...I hate to sound pathetic, but I can't deal with this any more, and need a positive fix!

Chuck
Norman, OK
Holder350 sorry that was not me I had a Mustang being towed in, and I had to be outside, letting the driver know how to back up the driveway. His son had asked to use my computer, and I told him to minimize what I had on it.. Sorry again.

Last edited by carsavvycook; 07-02-2008 at 12:16 AM. Reason: wrong wording
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