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Discussion Starter · #1 ·
I have a 63 Chevy running a 1994 Chevy 350 TBI – less than 1000 miles on a create motor, upgraded to a alloy High Flow Water Pump and installed an old BeCool Radiator I had in an old El Camino that cooled a 327

New Engine added a 2 months ago, starts and runs great, drove is 150 miles to the desert one Saturday ran great radiator leaked and got hot, fixed cap added more coolant drove home no issues over 300 freeway miles.. (That was my test drive on the engine.. With three motor bikes in the back)



Lately around town it over heats for short trips – 10-15 minutes around town
I thought about head gasket.
1- Oil is still a beautiful gold color
2- no water or sludge build up at the top of the rocker cover.
3- No bubbling in radiator when running without cap (Until it over heats)

I build the fan shroud from 1/2 steal and installed a Perma-Cool Fan approx 3000 cfm Fan sits 1.5 inches from Radiator however I fabed sides around fan to create pressure.



- Yes I checked it works and it really pumps air through (see video)

It sucks air I just feel it may not be enough

The radiator is mounted rather high, I do have two Alloy Oil coolers in front, but there is a good gap between the radiator and the oil & trans cooler

I thought I must be getting to much re-circulation of heat form the engine so
I fabricated a shield to make sure the air was coming from the grill, it actually made it worse



It seems every time I drive it a short distance pressure builds up and pushes water into the overflow which means I am always adding 300 ml (About a small water bottle)

Other info:
- Removed thermostat (San Diego never below 50 degrees anyway)
- New Top Hose
- Check water is flowing (Yes it is)
- High Flow Alloy Reverse Water pump (SKIP WHITE BRAND) - no idea if that is good

My current options
1- Buy a new bigger Alloy radiator with fan & shroud - $4-600
2- Remove lower Cross member and lower Radiator 4 inches
3- Try an old Radiator I have sitting around

I am just lost and hoping I have missed something easy on this build cause my truck needs to be driven..

 

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Was it overheating before or after you took out the thermostat? I had always been told that the thermostat was there to also slow the water down as it is pumped through the system. With out it, the water doesn't stay in the radiator long enough to cool effectively (cool being a relative term) or stay in the engine long enough to draw off the heat.

Just a suggestion...I'm sure that there are those here with a lot more knowledge on the subject than I have...But it's a start.

Oh, and Nice looking truck by the way!
 

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Discussion Starter · #3 ·
Was it overheating before or after you took out the thermostat? I had always been told that the thermostat was there to also slow the water down as it is pumped through the system. With out it, the water doesn't stay in the radiator long enough to cool effectively (cool being a relative term) or stay in the engine long enough to draw off the heat.

Just a suggestion...I'm sure that there are those here with a lot more knowledge on the subject than I have...But it's a start.

Oh, and Nice looking truck by the way!

Thanks... I have never tested engine with Thermostat

I put the engine together late one night and did not have a new Thermostat to I just skipped it. YES i have heard the same thing however I have not had issues with flow before and I have two other v8's with no Thermostats
 

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Thanks... I have never tested engine with Thermostat

I put the engine together late one night and did not have a new Thermostat to I just skipped it. YES i have heard the same thing however I have not had issues with flow before and I have two other v8's with no Thermostats
First off, nice truck....as McGyver said, try a T-stat, 180 degree, it will slow the water flow down sense you put in a high volume pump, you need more radiator time to cool it....I run a Champion 3 row, stock shroud and fan 180 t-stat on a 350/350/3.73 gears runs at 180 all the time even in 105 ambient heat in traffic...
 

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Discussion Starter · #5 ·
First off, nice truck....as McGyver said, try a T-stat, 180 degree, it will slow the water flow down sense you put in a high volume pump, you need more radiator time to cool it....I run a Champion 3 row, stock shroud and fan 180 t-stat on a 350/350/3.73 gears runs at 180 all the time even in 105 ambient heat in traffic...
I threw a thermostat in tonight .. will take for a spin in the morning.. thx again
 

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heating up

When the motor get warm it will push out the fluid into the overflow container, & pull it back in when it starts to cool. Is your container to small to hold the overflow. Your container must always have a reserve so it won't suck air into the radiator & the hose must be tight & no kinks. Bad gauge Maybe ? Does the car roll freely No brake drag Front disc not releasing all the way. Timing ? The middle of the fan should be at the edge of the shroud.What the lbs rating on you cap ? My two cents worth.

Stepsider65
 

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Well we haven`t heard back from him, maybe a good thing....
 

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Discussion Starter · #8 ·
Well we haven`t heard back from him, maybe a good thing....
no luck .. added thermostat over heated in 15 min ..

the confusing bit is that i had a build up of pressure and let about 1 cup of water from radiator into overflow..

will order a new rad tomorrow and try that ...
 

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Discussion Starter · #9 ·
When the motor get warm it will push out the fluid into the overflow container, & pull it back in when it starts to cool. Is your container to small to hold the overflow. Your container must always have a reserve so it won't suck air into the radiator & the hose must be tight & no kinks. Bad gauge Maybe ? Does the car roll freely No brake drag Front disc not releasing all the way. Timing ? The middle of the fan should be at the edge of the shroud.What the lbs rating on you cap ? My two cents worth.

Stepsider65
I upgraded to a 25lbs cap as the 9 lbs was leaking
 

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Just a few ideas for recap...!
1). Does your motor over heat a idle (stopped) as well as on the highway (cruising)? If only at idle, more than likely you do not have enough low speed air flow (fan). If both, you need to test further.
2). Check your total timing, make sure your mechanical and vacuum advance are working properly. I would suggest total timing be between 32°-36° and all in by 2500rpm (vacuum advance disconnected at this time). If you have vacuum advance check to see how much it adds at idle and cruise rpm (I would suggest 10°-12° vacuum advance max). Timing will cause heating problems.
3). Use your timing light on each wire at the spark plug, it will tell you if spark is getting to the plug (light will flash), a miss can cause over heating.
4). Pull the plugs keeping them in order as to which cylinder they came from and examine them. The plugs will tell you a lot about your motor’s condition and keeping them in order will show which cylinder is suspicious.
5). While the plugs are out do a compression test, verify all cylinders are within 10% of each other and compression is sufficient to support combustion. If you have two adjacent cylinders with lower compression (especially 3&5, 4&6 on SBC), usually this indicates a head gasket, you can squirt a little oil in these cylinders and re-test their compression to see if the rings are a problem (the oil will raise the compression by momentarily sealing the rings).
6). While the plugs are out, check valve adjustment. Poorly adjusted valves can cause low compression and heating problems.
7). Check the air/fuel ratio, a lean motor runs hot. Some smog check stations will test the air/fuel ratio reasonably for you.
8). Check the flow rate through your radiator, with the cap off, warm your motor to thermostat opening while watching the flow, when the thermostat opens you should see a significant change in water flow. Put the cap on and feel the upper and lower hoses (careful hot), the upper hose should feel firmer than the lower. If both feel firm, you probably have too much restriction, check for a clogged hose or passage.
9). If you suspect an exhaust blockage, un-cap your headers and run to see if it corrects problem.
10). Bottom hose have a retention spring in it to prevent it from collapsing.
11). Vacuum leaks around intake or carb.
 

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Discussion Starter · #11 · (Edited)
Totally stocked this give me tons of things to check.. I am banging my head really appreciate it ..

Just a few ideas for recap...!

1). Does your motor over heat a idle (stopped) as well as on the highway (cruising)? If only at idle, more than likely you do not have enough low speed air flow (fan). If both, you need to test further.

Freeway is fine ... 185-195 idling or low speeds are the only time i have issues

2). Check your total timing, make sure your mechanical and vacuum advance are working properly.


Checked timing reset to zero with Timing bypass wire disconnected, turned off reconnected runs at idle at about 26 degrees

I would suggest total timing be between 32°-36° and all in by 2500rpm (vacuum advance disconnected at this time). If you have vacuum advance check to see how much it adds at idle and cruise rpm (I would suggest 10°-12° vacuum advance max). Timing will cause heating problems.

The engine is a TBI version with advance controlled by ECU. I am not sure how to adjust, Manual says set to zero with timing bypass timing disconnected. it adjusts with temp and use of ping sensor.

3). Use your timing light on each wire at the spark plug, it will tell you if spark is getting to the plug (light will flash), a miss can cause over heating.

each seems to be firing

4). Pull the plugs keeping them in order as to which cylinder they came from and examine them. The plugs will tell you a lot about your motor’s condition and keeping them in order will show which cylinder is suspicious.

They have less than 500 miles on them





5). While the plugs are out do a compression test, verify all cylinders are within 10% of each other and compression is sufficient to support combustion. If you have two adjacent cylinders with lower compression (especially 3&5, 4&6 on SBC), usually this indicates a head gasket, you can squirt a little oil in these cylinders and re-test their compression to see if the rings are a problem (the oil will raise the compression by momentarily sealing the rings).

1 -7 are all at 141-144 (8 is a nightmare to remove due to engine offset)

6). While the plugs are out, check valve adjustment. Poorly adjusted valves can cause low compression and heating problems.

7). Check the air/fuel ratio, a lean motor runs hot. Some smog check stations will test the air/fuel ratio reasonably for you.

I did rebuild the Throttle body and replace springs seals etc (I have another TBI sitting around may change just to test)

8). Check the flow rate through your radiator, with the cap off, warm your motor to thermostat opening while watching the flow, when the thermostat opens you should see a significant change in water flow. Put the cap on and feel the upper and lower hoses (careful hot), the upper hose should feel firmer than the lower. If both feel firm, you probably have too much restriction, check for a clogged hose or passage.

I have pretty good water flow .. through the radiator at least it seems to flow well Posted video here


9). If you suspect an exhaust blockage, un-cap your headers and run to see if it corrects problem.

I have headers running into a Y and a 3 inch Flow Sound Exhaust still sets off car alarms when I drive past packed hondas

10). Bottom hose have a retention spring in it to prevent it from collapsing.

Bottom hose is 2 inch and seems okay

11). Vacuum leaks around intake or carb.[/QUOTE]
 

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Oz....looks as if you are running lean, ( hotter ) even with a TBI plug color should be light tan..lets see what Charlie has to say about plug color....in case I`m wrong on this..!
 

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Discussion Starter · #14 · (Edited)
really lean or not been in very long. To lean will melt pistons. Be real carful here
Thank you

Plugs only have a few hundred miles on them .. 3-500 at most.

I got up this morning and removed the throttle body and replaced it with an old none that was on a working truck 6 months ago.



Still seemed hot so I check my build notes and it seems like I had not been running an 02 sensor in the headers which I added when I rebuilt the TBI unit.

I disconnected the 02 sensor and temp seems to have leveled out at 205 on idle for 25 min (previously it would be hot idling in 10 min.

I did find a fair bit on Gas on the Throttle body around and under the fuel pressure regulator even though it had not been driven in 20 hours, I am guessing I messed something up in the rebuild even though it is pretty straight forward..

Something else to throw in my parts bin

I am going to see if I can get air/fuel checked so i do not mess it up

406Rich & Charlie ... beers are on me if you guys make it to San Diego any time..
 

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Thank you

Plugs only have a few hundred miles on them .. 3-500 at most.

I got up this morning and removed the throttle body and replaced it with an old none that was on a working truck 6 months ago.



Still seemed hot so I check my build notes and it seems like I had not been running an 02 sensor in the headers which I added when I rebuilt the TBI unit.

I disconnected the 02 sensor and temp seems to have leveled out at 205 on idle for 25 min (previously it would be hot idling in 10 min.

I did find a fair bit on Gas on the Throttle body around and under the fuel pressure regulator even though it had not been driven in 20 hours, I am guessing I messed something up in the rebuild even though it is pretty straight forward..

Something else to throw in my parts bin

I am going to see if I can get air/fuel checked so i do not mess it up

406Rich & Charlie ... beers are on me if you guys make it to San Diego any time..
Hope you get it figured out, once you do make a plug run...open highway, take it up to minimum 80, hard throttle, slip in neutral, kill the engine immediately, when you coast to a stop start pulling plugs and look at them, sand colored or light tan...then your set...or most any smog shop can plug their snifer in and tell you your air fuel ratio, you want 12.8 to 13.4.
 

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I have a 63 Chevy running a 1994 Chevy 350 TBI – less than 1000 miles on a create motor, upgraded to a alloy High Flow Water Pump and installed an old BeCool Radiator I had in an old El Camino that cooled a 327

New Engine added a 2 months ago, starts and runs great, drove is 150 miles to the desert one Saturday ran great radiator leaked and got hot, fixed cap added more coolant drove home no issues over 300 freeway miles.. (That was my test drive on the engine.. With three motor bikes in the back)



Lately around town it over heats for short trips – 10-15 minutes around town
I thought about head gasket.
1- Oil is still a beautiful gold color
2- no water or sludge build up at the top of the rocker cover.
3- No bubbling in radiator when running without cap (Until it over heats)

I build the fan shroud from 1/2 steal and installed a Perma-Cool Fan approx 3000 cfm Fan sits 1.5 inches from Radiator however I fabed sides around fan to create pressure.



- Yes I checked it works and it really pumps air through (see video)

It sucks air I just feel it may not be enough

The radiator is mounted rather high, I do have two Alloy Oil coolers in front, but there is a good gap between the radiator and the oil & trans cooler

I thought I must be getting to much re-circulation of heat form the engine so
I fabricated a shield to make sure the air was coming from the grill, it actually made it worse



It seems every time I drive it a short distance pressure builds up and pushes water into the overflow which means I am always adding 300 ml (About a small water bottle)

Other info:
- Removed thermostat (San Diego never below 50 degrees anyway)
- New Top Hose
- Check water is flowing (Yes it is)
- High Flow Alloy Reverse Water pump (SKIP WHITE BRAND) - no idea if that is good

My current options
1- Buy a new bigger Alloy radiator with fan & shroud - $4-600
2- Remove lower Cross member and lower Radiator 4 inches
3- Try an old Radiator I have sitting around

I am just lost and hoping I have missed something easy on this build cause my truck needs to be driven..

Why the reverse flow water pump? The LT1 engines were reverse flow because the heads were built that way .The TBI motors should be standard flow like most SBC engines. Something to think about...
 

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Discussion Starter · #17 ·

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Discussion Starter · #20 ·
thought I would provide an update .

Borrowed an air fuel ratio gauge off a buddy it showed that it was green to orange - his gauge did not measure exactly but seemed okay..

I ordered 2 new 14 inch eBay plastic fans $40 made a new shroud from scratch with my brake...

Running a different throttle body - with injectors that i cleaned with 9v battery and carb cleaner

I also installed a new pressurized purge tank,instead of an overflow

O2 Sensor still disconnected (i forgot about it until just now)

THE GOOD NEWS

I drove it in traffic for 90 minutes today 80 Degrees outside (Drove it hard, lots of burns out and short hard bursts)

The temp gauge did not get above 200 and for the first hour, it actually cooled off sitting at traffic lights instead of getting hotter..

I call it good .. thanks for all the help..

I would post pics but it looks like Photosuckit have locked all my sharing pics..
 
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