Team Camaro Tech banner
Cancel
Create thread New Garage Forums

'68 350 SBC Running Hot?

Jump to Latest
1 - 20 of 58 Posts
G

GlacierBlue68

· Registered
Joined
·
62 Posts
Discussion starter · #1 ·
Hey all,

This may be me being OCD, and a lack of knowledge, but I was wondering if this is worth looking into.

I have noticed that at times, when in traffic on normal temp days (50-70* ambient), my temp gauge starts to rise past 180 up to 190-195. Because I'm in the city and do a lot city driving, I sit in traffic quite often. Now, as soon as I start moving again, the temp gauge drops back down to 180, but I know that if I didn't move and get air flowing the temp would continue to creep.

I know very little about what the PO did to this car, it was purchased less than a year ago from a local dealer, but here is what I know in terms of the cooling system:

- 3 core aluminum radiator (can't find a make/model, may be a cheap aftermarket part)
- 2 electric fans (1 larger 1 smaller, these are right up against the rad)
- New water pump
- Overflow coolant bottle and clear tubing
- There is no shroud on this setup

I have never seen the car get over 200*, but again I have also not let the car sit idling for more than a few minutes to find out. I don't want to start throwing parts at it if this isn't a problem, but wanted some advice if this is normal or not. I would think that once the engine hits operating temp, the stat opens, engine gets cold coolant and would maintain the same temp regardless of whether I am moving or not.

Thanks in advance.
 
#2 ·
A shroud will most likely help. It acts as a funnel . The fans will then pull air through the radiator and across the engine. Others will most likely chime in .
 
Save
Reply Quote Like Like
#4 ·
It would be nice to know what temperature the T-stat is....a 195 "should" maintain 190-200 IF everything is in proper operating condition.

Things that can effect running temps….

*Timing
*Running lean
*Air bubble in system

(done any work lately ?)
 
Discussion starter · #5 ·
I had it at the shop I bought it from in the fall, they had to put a new carb on it (edelbrock) and make a few other adjustments to the A/F mix. They adjusted the timing and the firing order, because the previous mechanic had messed things up pretty badly. However, this temp creep is not a new problem, it was like that day 1.

The radiator drain plug was leaking and I had to slide a new o-ring on it, but I'm not sure if that would've introduced air into the system, maybe?

Here is a shot of the current setup, like I said, I think this was a cheap route for cooling.

Image
 
#6 ·
Discussion starter · #7 ·
Is there a shroud I could potentially purchase to improve the airflow?

I was afraid that the current setup was near useless, just looks wrong.

As for the t-stat, is there a way to tell what temp it is set for? I want to say that the stock t-stat's for these cars was a 195, but I'm not 100% on that.
 
#8 ·
I would go back to the basics. Factory style clutch fan, and factory shroud. . You are not that far off from what it shy be running at.
 
  • Like
Reactions: bill3337
Save
Reply Quote Like Like
Discussion starter · #9 ·
Code:
I think he took off the original clutch fan because it ate up the shroud. I almost put this car through a wall the first week I owned it because the mounts were starting to go. If you made a left turn, and gunned the accelerator, the engine would physically move in the bay, probably an inch or so. It would in-turn pull the throttle linkage and the car would floor itself.

The mounts were original, and one of the first items that were replaced. I'll bet that since he never swapped them, the first time it happened it probably ate up his original parts too.
 
#11 ·
If you made a left turn, and gunned the accelerator, the engine would physically move in the bay, probably an inch or so. It would in-turn pull the throttle linkage and the car would floor itself.
Click to expand...

That is exactly what happens when a original mount breaks. Most newer mounts are interlocked so even if the rubber tears it cannot raise like that.
 
Save
Reply Quote Like Like
#13 ·
scblucam said:
That is exactly what happens when a original mount breaks. Most newer mounts are interlocked so even if the rubber tears it cannot raise like that.
Click to expand...
I'll beg to differ on this. I've had interlocking mounts break on me twice. 1st time was from a dead stop at an intersection turning left. I ended up doing 2 doughnuts in the intersection before I could get to the ignition and shut it down. 2nd time was a couple months ago, not as drastic as the 1st time but same outcome.. Went to a prothane mounts instead.

https://www.amazon.com/gp/product/B002P8VHO8/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
 
#14 ·
First item on the bill is replace both engine isolators wit the newer style, aka, interlocking. You don't need a sudden WOT and run into somebody else.
Onto the temp, remember, the gauge is NOT calibrated, and only an indicator.
The thermostat controls the minimum temperature, the dissipation of heat method determines operating temp.
Other contributing factors for heat is the location of the gauge sensor - if in the manifold crossover along with thermostat, temp will be less than a sensor in the cylinder head, its closer to the heat source, the combustion chamber.

GM designed the gauge markings as the 10 o'clock mark, first mark left of center, is 180°; 12 o'clock mark, center mark, is 210°, 2 o'clock mark, first mark right of center, is 240°.
In the picture shown, I agree with others, poor set-up, one reason is I see a large potential for recirculating heated air about the rad/fan set-up. As the present fans pull air through radiator and exits, this heated air can, and probably does, get pulled through again through the radiator, until the Camaro moves forward giving cooler air. Remove the fans and go back to OE design of mechanical fan, minimum five blade, it can be a fluid fan, and a shroud. Good item seen is a smaller water pump pulley compared to crankshaft pulley, meaning coolant and fan will spin faster than crankshaft. But, remember, the faster the medium being pumped, whether the coolant or air, the less time for the transfer of heat.

Yes, thermostat can be checked for opening temp in a large pan of water, suspend the stat into water, and have a known good thermometer reading water temp.
Set stove on high and observe thermometer and thermostat. Stat opens at stamped temperature. Stat fully open at 10° above.

Assemble Camaro, and see what happens. An engine running 200° is not a problem. I have a '88 454 C3500 truck I bought new. It ran at 230° plus with a 195° stat. Three different dealers for the same problem - too hot.
First question from all three was "Is it puking?" "No, it is not." " This is normal."

So, if she runs a little warm, it's okay.
 
#15 ·
I'd dump the electric fans in favor of the stock system. It's proven to work very well.
The e-fans you have are not adequate and are poorly installed. The wiring visible in the picture posted is a mess and is likely to cause other problems.
 
  • Like
Reactions: bill3337
Save
Reply Quote Like Like
Discussion starter · #16 ·
Everett, thank you for the thorough write-up, very informative stuff.

Unfortunately, I don't have a stock setup for the temp reading, what I do have is this:

Image


I found where the temp gauge sender is hooked into the block and it is right by the t-stat. I also like the idea of going back to stock, doesn't seem like an impossible task either. Would the stock setup work with the existing rad or would I also need to replace the rad too with a stock one?
 
#17 ·
You should be able to go back to stock with what you have now.

OR

Get a proper E-fan like Vegas posted or a Mark VIII fan.

The set-up you have now IS your issue. You're only moving air in those 2 spots Vs. the whole radiator.
Think about it this way... you cooling system acts like it's the size of a dinner plate.
 
#18 ·
I love e-fans. They’ve been used on virtually every new car for the last 20-30 years.

Why? Because they work better than mechanical fans. At idle the mechanical is moving less air the at rpm. Well that’s backwards as you need more CFM from the fan idling in traffic than at speed. Electric moves 100% of the rated CFM at low and high rpm.
 
Discussion starter · #19 ·
Thank you all for the advice on this.

FYI, this car doesn't have any performance mods, it's a bone stock (newer) 350 SBC from a different machine, and is actually geared at 3.11 to be more street/highway friendly. That said, going back to stock I feel would be a better move and probably cheaper too.

I am thinking that going with the following would work?

- Hayden 2747 clutch
- Hayden 3618 fan
- 23" fan shroud

This is what the current fan spot looks like:

Image


Going back to stock would keep me under $200, a lot less than an e-fan setup alone. Would this work? Would I need a spacer or any other mounting hardware? Thank you again for all your knowledge, this forum is awesome.
 
#20 ·
There's a lot of good suggestions posted here. You don't have a big problem. You just need to pull more air in stop and go. Either get those fans off the radiator and into a shroud or get an OEM shroud and fan combination. Either will most likely solve your problem.
 
  • Like
Reactions: LeeC
Save
Reply Quote Like Like
1 - 20 of 58 Posts
About this Discussion
57 Replies
15 Participants
Last post:
GlacierBlue68
Team Camaro Tech
posts
2.4M
members
90K
Since
1998
A forum community dedicated to 1st generation Chevy Camaros owners and enthusiasts. Come join the discussion about performance, builds, restoration, modifications, classifieds, troubleshooting, reviews, and more!
Full Forum Listing
Explore Our Forums
Bench Racing Engine Body Shop Performance Brakes, Suspension & Steering