Its getting hot, damn hot. Radiator and fuel problem

[sqrlnts]

Long post with as much info i can think of. Thanks in advance for your help!

Couple problems with the truck as the temperatures rise to 110 plus here in Phoenix. Daily driving home from work in the heat of the day my truck is vapor locking. Have also noticed the radiator tends to allow fluid to escape the cap rather than enter the overflow once I park.

The truck runs and drives perfectly in the morning with AC going and even ok up to about 105 degrees outside, no vapor lock, 190 max water temp, AC is blowing the entire way as its already 90 degrees at 8am.

My commute is 4 lane surface streets approx 10 miles in stop and go traffic, 45 MPH speed limit. The more red lights I catch the more pronounced the problems are. The water temp hovers very near 215-220 at the warmest just before I get home. I am running the AC the entire way. Again, this seems to be a recent issue with the severe heat driving home after work. It runs fine in the morning and has also done fine all winter long.

What I know and have done so far.
The stock '73, 350 is timed at 32 degrees.
Ceramic coated headers, 2.5" exhaust dumped in front of rear axle.
recently added a 1/2" wooden spacer to the Quadrajet carb.
Aluminum Edelbrock RPM intake
I have ensured the rubber fuel line is not against anything hot.
Recently replaced the fuel filter
newer upper and lower radiator hoses
2 year old Champion 3 core AL radiator
1 year old 16lbs radiator cap
1 year old 16" Maradyne electric fan with shroud.
Flex-A-Lite fan speed controller. Fan runs at 100% when AC is on.
2 year old sending unit and sock in tank.
2 year old Aluminum fuel line running along the inside frame rail, no return line
I recently insulated the carb gas line from the mech pump to the carb.
I also added 3' of insulation on fuel line just prior to the fuel pump.
Newer 180 degree thermostat.
2 year old radiator overflow tube into bottle, need to check rad neck orfice for blockage.


What i don't know
Water pump condition. I know its pumping fluid at idle in the driveway.
Fuel pressure when hot. No FP gauge installed.
Radiator cap was replaced a year ago but not tested.
Have not read spark plugs.

Again, thanks to any and all who can help. Feel free to ask questions. Here is a picture cause I know they help to visualize things.

[geezer#99]

You're timed at 32 but what's your initial timing?
You have an overflow bottle but is it a return system?
What temperature thermostat?
Do you have a vented gas cap.
Where's your pcv?
Got a pic of your fan, rad for us?
Any restrictions in front of your rad?
What other mods? Like cam, compression etc?

[Speedbumpauto]

GM started using a 3 line mechanical fuel pump for that exact reason in the mid 70's. The third line is a return to keep the fuel pump cooler. If you have provisions at the tank for a return line, that would do nothing but help. Also, in my experience, those engines like around 38 degrees or so of timing but I don't think that's the root of your problem. Don't be afraid to put a 1" phenolic spacer under the carb if you have room. I also installed a manual override switch on my fan so on some days I could turn it on and get ahead of the heat curve before the sender turned it on. On our killer AZ days it can be pretty effective for a while. That's if your AC doesn't turn it on as soon as the AC is activated. A last thing that would help is a cold air intake that would keep the carb from getting the really hot underhood air and get just the pretty hot Phx air. That would take more work and I think the 3 line pump is your simplest, best first option.

[fabguy]

Got a pic of your fan & shroud?

[Dunenutt]

I had exactly the same problems with my 69. First I ditched the electric fans. Installed a 19" 6 blade fan with a severe duty clutch. 1" phenolic spacer under the carb. Installed DEI slip on heat sheild on the fuel line, from the carb to just under the cab. Added an electric low pressure pusher fuel pump near the tank, and Edelbrock manual pump. Added a B&M engine oil cooler. Removed the trans cooler from radiator, and added coolers to the front. See page 8 of my build. Runs at 180* in 112* heat. Just took it to the brothers show, 777 miles in 100+ heat with no issues. Did it last year in 122 heat, and she hit 190* for a while. Good luck!

[Dunenutt]

BTW mine is tuned with wide band air fuel mixture gage. and timed correctly too. You may want to start there. I missed where you said that you have not read plugs...

[_Ogre]

first off... 215*-220* is not running hot, especially when the outside temps are over 100*
water boils at 212* at sea level and 1 atmosphere
every 1 psi pressure you add brings your boiling temp up 3 degrees
with a 16 lb cap you add 48 degrees to your boiling temp of straight water
50/50 antifreeze will add another 16 degrees of boiling protection to water
212*+48*+16*=276* at your current mix and pressure you won't boil over until 276 degrees

i am not recommending you run your truck at 276*, just saying you are no where near over heating
your truck, oil, wiring and feet would never tolerate those temps
if your running a stock radiator with a top tank you really don't need an overflow tank, just keep the level over the core
cross flow radiator needs an overflow tank to keep the top of the core full
if your not pulling the overflow coolant back in on cool down you have the wrong cap, it needs to be a vented cap
that said; i have a stock style radiator and overflow tank, i had the wrong cap initially that would not pull the coolant back

if you run a full system and rise in temp will bleed thru the cap, simple physics
you'll need the right cap to pull coolant back in

at 110* outside temps you don't need to add much heat to vapor lock
try speedbump's ideas: 3 line pump (never saw one, may have to google that), phenolic spacer and cold air intake
though 110* air is not exactly cold, it is cooler than your under hood temps
if your fuel line is running parallel and close to your exhaust, try to get some separation with a heat shield or space
double check your timing and don't run more than 50/50 antifreeze or try 100% water
fan w/shroud is good not much you can do there, i too turn my ac on and see temps drop
plus it helps the drivers disposition

[Speedbumpauto]

Airtex part # 40986 is the 2 line pump and #40987 is the 3 line pump. Interchangeable in the parts books. In the "day" we had to ask the customer "two line or three line?" when they came in for a pump. You can imagine how that went at times.

[OrrieG]

Ethnol fuel??? I have had two vehicles that vapor locked at 105+ air temps because of it. I worked as a mechanic at the Union Station at 24th and VanBuren out by the airport in the mid 70's. Most over heating then was bad cap or hose connection letting air into the system. It looks like you have done all the obvious stuff, try switching to real gas and see if it helps.

The drive you describe is the reason we left after school and headed north, none of the commuter freeways had been built, and I got tired of spending 3 hours a day in my car. I also worked for a civil engineer that did site staking and remedial engineering (fixing the problems the office guys made). We started work at 4am so we could quit at noon.

At the time I had my 59 in original 6/4speed configuration, I added AC and it did fine. So did my first 64 Chevelle and 68 Camaro I had at the time.

[sqrlnts]

Wow, you guys are awesome and Happy 4th!!

Originally Posted by geezer#99

You're timed at 32 but what's your initial timing?
You have an overflow bottle but is it a return system?
What temperature thermostat?
Do you have a vented gas cap.
Where's your pcv?
Got a pic of your fan, rad for us?
Any restrictions in front of your rad?
What other mods? Like cam, compression etc?

Without getting into a big timing discussion, i will just say i don't worry too much about initial timing, just total all in at ~2800 RPM. If I had to hazard a guess I would say 10-15 degrees.

Just one overflow tube to a bottle. The tube goes to the bottom of the bottle.
Non Vented gas cap.
PCV is in pic below, the one above is a little old.
Fan pics below, no restrictions in front of rad or condensor.
stock '73 long block, HEI, RPM intake, and 4BBL Quadrajet.

Originally Posted by Speedbumpauto

GM started using a 3 line mechanical fuel pump for that exact reason in the mid 70's. The third line is a return to keep the fuel pump cooler. If you have provisions at the tank for a return line, that would do nothing but help. Also, in my experience, those engines like around 38 degrees or so of timing but I don't think that's the root of your problem. Don't be afraid to put a 1" phenolic spacer under the carb if you have room. I also installed a manual override switch on my fan so on some days I could turn it on and get ahead of the heat curve before the sender turned it on. On our killer AZ days it can be pretty effective for a while. That's if your AC doesn't turn it on as soon as the AC is activated. A last thing that would help is a cold air intake that would keep the carb from getting the really hot underhood air and get just the pretty hot Phx air. That would take more work and I think the 3 line pump is your simplest, best first option.

I have provisions on the sender for a return line just not on the pump. I have tons of room for a spacer. Do you think the 1" plastic spacer would outperform the wood spacer?

I found out something interesting today. Our temps are down today, way down probably 80 degrees this morning. When I floored the truck several times I noticed after about 3 seconds it starts to stumble, like its running out of fuel. This is very repeatable, did it probably 3-4 times.

Originally Posted by fabguy

Got a pic of your fan & shroud?

See below Fabguy.

Originally Posted by Dunenutt

I had exactly the same problems with my 69. First I ditched the electric fans. Installed a 19" 6 blade fan with a severe duty clutch. 1" phenolic spacer under the carb. Installed DEI slip on heat sheild on the fuel line, from the carb to just under the cab. Added an electric low pressure pusher fuel pump near the tank, and Edelbrock manual pump. Added a B&M engine oil cooler. Removed the trans cooler from radiator, and added coolers to the front. See page 8 of my build. Runs at 180* in 112* heat. Just took it to the brothers show, 777 miles in 100+ heat with no issues. Did it last year in 122 heat, and she hit 190* for a while. Good luck!

I agree the electric fan isn't pulling the air a clutch fan would. My issue is space as you can see below. I am considering replacing the fuel pump based on my WOT experience listed above. I wonder how much heat load would be removed from the radiator by installing the remote trans cooler? Does your electric pusher pump run all the time? Are you running a return line from the fuel pump?

Originally Posted by Dunenutt

BTW mine is tuned with wide band air fuel mixture gage. and timed correctly too. You may want to start there. I missed where you said that you have not read plugs...

Pulled the plugs, pics below. I have had carb issues in the past I believe they are solved but have no idea what my AF ratio is.

Originally Posted by _Ogre

first off... 215*-220* is not running hot, especially when the outside temps are over 100*
water boils at 212* at sea level and 1 atmosphere
every 1 psi pressure you add brings your boiling temp up 3 degrees
with a 16 lb cap you add 48 degrees to your boiling temp of straight water
50/50 antifreeze will add another 16 degrees of boiling protection to water
212*+48*+16*=276* at your current mix and pressure you won't boil over until 276 degrees

i am not recommending you run your truck at 276*, just saying you are no where near over heating
your truck, oil, wiring and feet would never tolerate those temps
if your running a stock radiator with a top tank you really don't need an overflow tank, just keep the level over the core
cross flow radiator needs an overflow tank to keep the top of the core full
if your not pulling the overflow coolant back in on cool down you have the wrong cap, it needs to be a vented cap
that said; i have a stock style radiator and overflow tank, i had the wrong cap initially that would not pull the coolant back

if you run a full system and rise in temp will bleed thru the cap, simple physics
you'll need the right cap to pull coolant back in

at 110* outside temps you don't need to add much heat to vapor lock
try speedbump's ideas: 3 line pump (never saw one, may have to google that), phenolic spacer and cold air intake
though 110* air is not exactly cold, it is cooler than your under hood temps
if your fuel line is running parallel and close to your exhaust, try to get some separation with a heat shield or space
double check your timing and don't run more than 50/50 antifreeze or try 100% water
fan w/shroud is good not much you can do there, i too turn my ac on and see temps drop
plus it helps the drivers disposition

Ogre, thanks for your input. I agree that 220 is not a danger. I found that my radiator overflow nipple on the neck was plugged with scale. I think this explains why I was pushing fluid out of the cap. I am heading to a friends house to try and test my cap. Does everyone think the caps with the red pressure relief valve are reliable? Would this type of cap allow the coolant to be pulled back into on cool down?

Originally Posted by OrrieG

Ethnol fuel??? I have had two vehicles that vapor locked at 105+ air temps because of it. I worked as a mechanic at the Union Station at 24th and VanBuren out by the airport in the mid 70's. Most over heating then was bad cap or hose connection letting air into the system. It looks like you have done all the obvious stuff, try switching to real gas and see if it helps.

The drive you describe is the reason we left after school and headed north, none of the commuter freeways had been built, and I got tired of spending 3 hours a day in my car. I also worked for a civil engineer that did site staking and remedial engineering (fixing the problems the office guys made). We started work at 4am so we could quit at noon.

At the time I had my 59 in original 6/4speed configuration, I added AC and it did fine. So did my first 64 Chevelle and 68 Camaro I had at the time.

I have searched high and low for ethanol free fuel. Outside of trying race gas it seems its not available in the valley anymore. Phillips 66 is listed as carrying it in town but they are all out of business. I usually run 87 octane from where ever. I recently filled the tank with 91 octane from 76 station. Have noticed no difference.

Here are some more pictures from this morning as requested. I am no plug whisper'er, what do you think? They are from L to R, cylinder 2, 4, 6, & 8.
You will also notice my belt setup is ummmm unique? This is due to wanting the compressor on the PS and the Alt on the DS. Belts are tight but not optimal.

[Speedbumpauto]

Phenolic is a preferred insulator because it's more stable than wood when compressed and around liquids. The big thing I saw was your overflow bottle needs a vent, at least from what I saw in the pics. The commercial ones have two lines coming out. One for coolant flow in and out of the radiator and it stubs off at the bottom of the tank and the other for vent/overflow which extends from the bottom to about 3/4 the way up the tank. I think your system is getting an air lock and forcing the coolant out the cap. I don't really think it's contributing much to your problem but it's nice when you can just look in the overflow tank and check your coolant level without disturbing the system. Plugs don't look bad to me.

[Dunenutt]

Plugs look OK, but that radiator neck looks pitted. The rubber seat on cap needs to seal on that ridge in the neck.

No return line, and the pump runs with ignition on.

[sqrlnts]

Originally Posted by Speedbumpauto

Phenolic is a preferred insulator because it's more stable than wood when compressed and around liquids. The big thing I saw was your overflow bottle needs a vent, at least from what I saw in the pics. The commercial ones have two lines coming out. One for coolant flow in and out of the radiator and it stubs off at the bottom of the tank and the other for vent/overflow which extends from the bottom to about 3/4 the way up the tank. I think your system is getting an air lock and forcing the coolant out the cap. I don't really think it's contributing much to your problem but it's nice when you can just look in the overflow tank and check your coolant level without disturbing the system. Plugs don't look bad to me.

Thanks, my overflow bottle is home made! Its an old plastic tea bottle. I have a 1/8" hole drilled about 1" down the neck. Also the hole in the overflow bottle cap doesn't seal real tight to the hose going through it so am hoping this will suffice. My previous overflow tube was one of the cheap stainless cylindrical types that constantly pissed fluid out because it was too small.

Originally Posted by Dunenutt

Plugs look OK, but that radiator neck looks pitted. The rubber seat on cap needs to seal on that ridge in the neck.

No return like, and the pump runs with ignition on.

Radiator neck is pitted, I actually think this may be due to the cheaper Champion materials used in Chinatown. I tested my radiator cap at the parts store. It tested to around 10lbs. I asked the guy for replacement and immediately tested it in the store. The first cap tested to 12lbs, the second was 13lbs. The last one tested to 14lbs so I purchased that one.

Also just installed a fuel pressure gauge and going for a little ride. Will report out fuel pressure.
Also checked my fuel tank cap, it is vented.

[sqrlnts]

Alright, I think I have narrowed it down a bit. Fuel pressure just after starting from cold is 6psi. After driving for 15 mins and getting to operating temperature the fuel pressure gauge never moves off of 0psi.

I either have a bad pump or my fuel is vaporizing. Going to change the pump because I have no idea how old it is or how to tell if fuel is vaporizing in the lines....

More to follow

[mr48chev]

I see the tank vent coming off the tank and heading to the top of the photo, where does it go and what is on the end of it?

If the engine goes up to 215/220 in heavy traffic and then drops right back to 190 once you get to moving good it's an air flow problem. Possibly that particular fan isn't moving enough air. That setup looks great but how much air does it actually move when the truck is sitting still?

[sqrlnts]

Originally Posted by mr48chev

I see the tank vent coming off the tank and heading to the top of the photo, where does it go and what is on the end of it?

If the engine goes up to 215/220 in heavy traffic and then drops right back to 190 once you get to moving good it's an air flow problem. Possibly that particular fan isn't moving enough air. That setup looks great but how much air does it actually move when the truck is sitting still?

Mr48chev, I am hoping that is not my tank vent because that rubber line goes to my fuel pump via a new aluminum line.
I was told the lines from top to bottom were
1. supply line
2. vent line
3. filler neck vent line

The fan moves a decent amount of air. Its "rated" at 1660 cfm. If I put my hand in front of the grill ~12", I can feel the fan pulling air through. Is it enough i am not sure.

I have talked with a local hot rod friend, he thinks my fuel pump (or fuel vaporizing) problem may be causing a lean condition which is causing the engine to run hotter than it should. Good news is he has a tailpipe sniffer so when I get the new fuel pump on I plan to sniff the exhaust to see where the AF ratio is.

So far the new radiator cap is holding fluid.

[sqrlnts]

found answer to blocking the return port, bad idea. Please disregard.

[fabguy]

Originally Posted by mr48chev

If the engine goes up to 215/220 in heavy traffic and then drops right back to 190 once you get to moving good it's an air flow problem. Possibly that particular fan isn't moving enough air. That setup looks great but how much air does it actually move when the truck is sitting still?

I had a similar problem and replaced my 16" elect. Fan and installed 2) 10" fans. I also added a hinged door so that when I am driving it allows more sir to flow through radiator. I have a 160* thermostat in my engine and mine runs at around 160-170 on 100* days. Although I don't have AC in my truck. Btw, I used SPAL fans on mine also which made a big difference.

[mr48chev]

Originally Posted by sqrlnts

Mr48chev, I am hoping that is not my tank vent because that rubber line goes to my fuel pump via a new aluminum line.
I was told the lines from top to bottom were
1. supply line
2. vent line
3. filler neck vent line

You have one plugged off that should be the VENT line that vents the tank to the outside air WHEN YOU RUN A NON VENTED CAP hate to shout but the answer is totally obvious. Your tank is not vented to the outside and you can run until it creates a vacuum in the tank then the engine quits because the pump is pulling against the vacuum. The vent hose to the filler neck only vents the filler neck when you are filling gas so the tank doesn't barf gas back on you through the neck. It does not vent the tank when you are running down the road if you have a NON VENTED cap. Put a line on that vent tube and either run it up in a stake pocket with a little filter on it to keep dirt from getting in or run it to the front and vent it though one of those Charcoal canisters of a 70 something and I think that will solve your fuel problem.

[sqrlnts]

Originally Posted by fabguy

I had a similar problem and replaced my 16" elect. Fan and installed 2) 10" fans. I also added a hinged door so that when I am driving it allows more sir to flow through radiator. I have a 160* thermostat in my engine and mine runs at around 160-170 on 100* days. Although I don't have AC in my truck. Btw, I used SPAL fans on mine also which made a big difference.

Hey Fabguy, what kind of a hinged door are you referring to? My truck will also run at 170 without A/C on a 100* day. sorry, couldn't resist....

Originally Posted by mr48chev

You have one plugged off that should be the VENT line that vents the tank to the outside air WHEN YOU RUN A NON VENTED CAP hate to shout but the answer is totally obvious. Your tank is not vented to the outside and you can run until it creates a vacuum in the tank then the engine quits because the pump is pulling against the vacuum. The vent hose to the filler neck only vents the filler neck when you are filling gas so the tank doesn't barf gas back on you through the neck. It does not vent the tank when you are running down the road if you have a NON VENTED cap. Put a line on that vent tube and either run it up in a stake pocket with a little filter on it to keep dirt from getting in or run it to the front and vent it though one of those Charcoal canisters of a 70 something and I think that will solve your fuel problem.

Hey MrChev, I don't mind if you yell, I am used to it at my age. I think I understand what your saying but I am running a vented cap?? I do plan to install the new pump with proper return line tomorrow.

Didn't work on the truck today, wife wanted to go to Payson and enjoy the cooler weather. Before we left I jumped on Craigslist and found these, picked them up for a song!! Spears are a little Haggard but pretty good otherwise.

[_Ogre]

i see a lot of rusty mess on your shroud, are you running any antifreeze

[sqrlnts]

Originally Posted by _Ogre

i see a lot of rusty mess on your shroud, are you running any antifreeze

I am only running a 25% antifreeze mixture. The engine was old and crusty but the radiator was new. I did make the initial mistake of filling the truck with tap water. I have since flushed that out and filled it with distilled. Didn't do myself any favors on that one.

[sqrlnts]

Ok, new 3 port pump is installed. I also did the following
Ran a rubber return line outside the frame.
Slit a 3/8 ID fuel line and wrapped it around the entire Aluminum fuel line
wrapped the PS exhaust tube from the collector to the muffler.

Started the truck and it had 9PSI. After it warmed up the gauge went to 0. Funny thing is the truck is running great, did several WOT runs and did not experience any bogging or cutting out.

True test is tomorrow's drive home from work.

[OrrieG]

I'd get another gauge and add 25% more coolant. Not only does in keep things from freezing it raises the boiling point in pressure systems.

[Speedbumpauto]

The down side of adding more antifreeze % is it becomes a less effective coolant, straight water being the absolute best. Most of us here don't worry too much about the freezing thing and I believe 20-25% is an effective corrosion inhibitor. I shoot for 20% on my hot rod stuff and add a jug of water wetter, although I'm not sure that stuff isn't in the snake oil category.