SBC Rapid engine heatup (1 Viewer)

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Magnolia, TX
I've got my SBC hooked up and running but I've noticed that it seems like it heats up pretty fast. My engine temp (according to my coolant gauge is between 195-210) while in park. I haven't been able to drive it at any speeds yet to see what that will do as far as bring the temp down but it just seems like it heats up really quick w/in 2 minutes or so. Does that seem normal? I'm letting it cool down and will time how long it actually takes to heat up. I'm running a mech. fan w/ shroud, med. duty fan clutch, & reverse flow h20 pump (serpentine). If this is normal then great, just want to make sure I haven't missed something.

When I did my engine break in, I ran it for 20 minutes (in park) @ 2000 - 2200 RPM. I had a box fan blowing into the radiator and my temps stayed w/in the 195-210 mark.

Nick
 

Elbert

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no..it should not heat up that fast. Make sure your radiator fan matches up with the serpentine drive...I assume it does, but if you are running and old shool fan with a serpentine drive ....you might have an issue. your radiator fan, serpentine setup , to include the water pump, and fan clutch all have to be of the same "setup".

Off hand it sounds to me like the thermostat might be in upside down. Assume you are running a 4 core radiator? Or there is some issue with the water pump.

at cold start I would say my SBC take maybe 10min or so to get to temp... I'm running electric fans, so I have no air flow across the radiator until the fans come on.
 
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I have reverse flow fan, clutch, and water pump. All are brand new. I am running a new 19x26 griffen aluminum radiator. The one thing I never checked on this motor was the thermostat.

Nick
 
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How's the timing?

When I installed my new dizzy I set it to TDC, as close as I could find it anyway. I don't have / couldnt find any timing marks on my motor. It almost seems like it could you a fine tune on the timing. It is TBI so I have some computer controlled timing going on but my initial timing may need to be adjusted. I just bought a OBDII cable to check my codes to see if I'm running rich / lean.

Ken, I'll get some pictures.

Nick
 
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Here are a few shots of my engine compartment. Excuse my zip ties and stray wiring, they are temporary until I get everything where I want it:

IMG_5740.jpg


IMG_5739.jpg


IMG_5738.jpg


Nick
 
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Enola, PA.
Are you sure your sending unit matches your gauge?
If so, I sounds to me like you have a 195 thermostat installed. Your system is working or it wouldn't stop at 210. Pull the thermostat and see how it acts.
When you crank the motor is it slow like the initial timing is too far advanced? Check your plugs to be sure there is no detonation going on.
 
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We had similar issues when we cranked up our Ramjet.

1st fix was to get a reverse flow fan matching the rotation of the waterpump to actually pull air into the radiator, not push it back toward the front of the vehicle. :doh: Double check that.

2nd fix was to move our sensor from the top front of the "intake manifold" (sensor located just under the air filter, left side) where we deduced there was a bit of air pocket/cavitation going on and the coolant was perhaps flash steaming. While the gage would top out, the motor was obviously not overheating. You may need to get a heat sensing "gun" to validate/debunk your gage reading.

We have nearly 2,500 miles on the motor now, with no overheating issues.

Good luck
Pictures 036.jpg
 
Joined
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We had similar issues when we cranked up our Ramjet.

1st fix was to get a reverse flow fan matching the rotation of the waterpump to actually pull air into the radiator, not push it back toward the front of the vehicle. :doh: Double check that.

2nd fix was to move our sensor from the top front of the "intake manifold" (sensor located just under the air filter, left side) where we deduced there was a bit of air pocket/cavitation going on and the coolant was perhaps flash steaming. While the gage would top out, the motor was obviously not overheating. You may need to get a heat sensing "gun" to validate/debunk your gage reading.

We have nearly 2,500 miles on the motor now, with no overheating issues.

Good luck

Where did you move your sensor to? Mine is at the top portion of my intake manifold. My fan is a reverse flow fan from flex a lite.

Nick
 

alex e

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make sure fan is in the shroud at the proper depth as well.....SEARCH for Jim from Downey's treatise on this very subject or PM him here.
 
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wow, that engine compartment is clean, but, paint your headlight buckets. I had a similar issue on mine and it turned out to be the thermostat. I installed a 180 F thermostat and it hasn't given me any problems since.
 

1Fine40

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Might try a gauge like I have on mine...keeps the electronic one honest! Here's a pic.

Cheers!
Mark8p1C.jpg
 
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You may have a blocked oil line, bad oil pump, clogged pickup (wrong pickup like I did once) or perhaps filter is choking flow?

Might want to double check the oil flow before anything else. Put a mechanical pressure gauge in by distro, and anywhere else you can. I'm using a remote oil filter and allows me to check before/after filter.

10 psi/1000 rpms is a rule of thumb.
 
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Quote:
Originally Posted by centerlineseal
We had similar issues when we cranked up our Ramjet.

1st fix was to get a reverse flow fan matching the rotation of the waterpump to actually pull air into the radiator, not push it back toward the front of the vehicle. :doh: Double check that.

2nd fix was to move our sensor from the top front of the "intake manifold" (sensor located just under the air filter, left side) where we deduced there was a bit of air pocket/cavitation going on and the coolant was perhaps flash steaming. While the gage would top out, the motor was obviously not overheating. You may need to get a heat sensing "gun" to validate/debunk your gage reading.

We have nearly 2,500 miles on the motor now, with no overheating issues.

Good luck


Where did you move your sensor to? Mine is at the top portion of my intake manifold. My fan is a reverse flow fan from flex a lite.

Nick
We put it in the driver's side head, between the first two cylinders, from the front.​
 
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Fan depth is close, ideally the shroud ends right in plane with the farthest forward portion of the fan. Have you hot bled the coolant system? Pull the cap, start it, let it run to temp and circulate, watch for bubbles. However, my bet is it has a 195 thermostat in it. If it bothers you run a 180.
 

Elbert

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temp sender on the intake will read about 10 degrees hotter than one in the OEM factory drivers side cylinder head location...3rd option would be to use passenger side cylinder head.

Timing on a TBI is.... unplug brown wire to set "base timing" which is 0 degrees at TDC.. TBI engine is real senstive to this setting. Adjust to 0 degrees.... Then plug brown wire back up and the ECM will then control timing. Don't know where you brown wire is on the engine swap but on a GM truck is normally on the firewall right near the passenger side cylinder head.

I agree it potentially sounds like you have a 195 thermostat... TBI engines will run with with 180F. I have a 91 TBI 350 K1500 for a few years with 180F...ran fine.

I Still don't think your truck should heat up that fast though.

Pay attention to the rotation of the fan. What you think is reverse flow etc....does not necessarily align with the way in wich flex-a-lite lists their products.

I had a 6 blade flex-a-lite radiator clutch fan on my truck....the first one they sent was designed to rotate the opposite direction. Just check that...should be easy to test for air flow. I think your fan looks right though..from the pic.


Normally if you have issues with timing the truck is really hard to start, runs like crap, pops and spits, and may backfire up through the throttle body.

DO you have any trouble codes set?
 
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make sure fan is in the shroud at the proper depth as well.....SEARCH for Jim from Downey's treatise on this very subject or PM him here.

My fan is about half in and half out of the fan shroud w/ about 3/4" all the way around between the fan and shroud.


wow, that engine compartment is clean, but, paint your headlight buckets. I had a similar issue on mine and it turned out to be the thermostat. I installed a 180 F thermostat and it hasn't given me any problems since.

I know, I know. I really forgot to do it and then installed them and now it sticks out like a sore thumb. On the list of things to do. I may pull my thermostat and put in a 180. I have no idea what is in there.
 
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Messages
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You may have a blocked oil line, bad oil pump, clogged pickup (wrong pickup like I did once) or perhaps filter is choking flow?

Might want to double check the oil flow before anything else. Put a mechanical pressure gauge in by distro, and anywhere else you can. I'm using a remote oil filter and allows me to check before/after filter.

10 psi/1000 rpms is a rule of thumb.

I'll add another gauge, maybe by the filter. My electrical gauge reads about 50 psi and is plumbed from by the dizzy.

Quote:
Originally Posted by centerlineseal
We had similar issues when we cranked up our Ramjet.

1st fix was to get a reverse flow fan matching the rotation of the waterpump to actually pull air into the radiator, not push it back toward the front of the vehicle. :doh: Double check that.

2nd fix was to move our sensor from the top front of the "intake manifold" (sensor located just under the air filter, left side) where we deduced there was a bit of air pocket/cavitation going on and the coolant was perhaps flash steaming. While the gage would top out, the motor was obviously not overheating. You may need to get a heat sensing "gun" to validate/debunk your gage reading.

We have nearly 2,500 miles on the motor now, with no overheating issues.

Good luck


Where did you move your sensor to? Mine is at the top portion of my intake manifold. My fan is a reverse flow fan from flex a lite.

Nick
We put it in the driver's side head, between the first two cylinders, from the front.​

Thanks, I'm going to move it there and put in a mech gauge on the intake manifold and see what my difference is in the reading.

Fan depth is close, ideally the shroud ends right in plane with the farthest forward portion of the fan. Have you hot bled the coolant system? Pull the cap, start it, let it run to temp and circulate, watch for bubbles. However, my bet is it has a 195 thermostat in it. If it bothers you run a 180.

I didn't hot bleed the system like you described. I ran it, then turned it off and added a little coolant to it. I'll run it and watch for bubbles and add coolant.

temp sender on the intake will read about 10 degrees hotter than one in the OEM factory drivers side cylinder head location...3rd option would be to use passenger side cylinder head.

Timing on a TBI is.... unplug brown wire to set "base timing" which is 0 degrees at TDC.. TBI engine is real senstive to this setting. Adjust to 0 degrees.... Then plug brown wire back up and the ECM will then control timing. Don't know where you brown wire is on the engine swap but on a GM truck is normally on the firewall right near the passenger side cylinder head.

I agree it potentially sounds like you have a 195 thermostat... TBI engines will run with with 180F. I have a 91 TBI 350 K1500 for a few years with 180F...ran fine.

I Still don't think your truck should heat up that fast though.

Pay attention to the rotation of the fan. What you think is reverse flow etc....does not necessarily align with the way in wich flex-a-lite lists their products.

I had a 6 blade flex-a-lite radiator clutch fan on my truck....the first one they sent was designed to rotate the opposite direction. Just check that...should be easy to test for air flow. I think your fan looks right though..from the pic.


Normally if you have issues with timing the truck is really hard to start, runs like crap, pops and spits, and may backfire up through the throttle body.

DO you have any trouble codes set?

I set the base timing when I installed my new painless TBI wiring harness and did as you described w/ the base wire and IAC module. My fan is listed as a reverse rotation fan and I can feel that it is pulling air into the engine compartment. My engine fires right up but does backfire if I give it a heavy pedal from idle. I have to go back and adjust my ECM idle settings after adjust my rocker arms and idle set screw. I'm leaning towards thermostat needing to be changed to a 180 and adjusting my timing maybe just a bit.
 
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I moved my temp sensor to the side of my block as recommended and that really dropped my temperatures. I timed it and it took about 6 minutes at idle to get to 180* and I must have a 180* thermostat because it as soon as it hit 180 it dropped to about 155 or so. This was a drastic change in temps from my previous placement in the intake manifold to the side of the block (drivers side between cylinder 1 and 3). Thanks for the suggestions.

Nick
 

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