The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1960 - 1966 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 04-08-2017, 03:16 PM   #1
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Overheating when driving and gas tank building up pressure

Almost done with my 66. I've taken it on a few test drives and it starts to overheat when on the highway (got up to 230) and it isn't even hot here in Texas yet. It will sit at idle and the electric fan will cycle just fine. I have a newly rebuilt 350, new aluminum 2 row radiator with a single fan mounted on an aluminum fan shroud from Brothers Trucks. I have the Fitech efi with the fuel command center. The timing has been double checked so it is not that.

The other thing that is happening I'd the under bed fuel tank some how becomes pressurized. It starts to bow out on the top and bottom. I have a tanks Inc vent on it and can see capers coming out of it, but it can't keep up. I have to remove the gas cap to release the pressure. The fuel command center has a return line. I pulled it and is doesn't seem to have enough pressure to pump up the tank.

Any advice would be much appreciated.
Attached Images
 
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-08-2017, 03:47 PM   #2
The Rocknrod
Moderator

 
The Rocknrod's Avatar
 
Join Date: Aug 2011
Location: China Spring, TX
Posts: 7,280
Re: Overheating when driving and gas tank building up pressure

What temp gauge are you using and where did you get the sender?
The Rocknrod is offline   Reply With Quote
Old 04-08-2017, 03:56 PM   #3
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

Actually I have two. One is in the intake manifold and it came with the Fitech system. I was using the display to watch the temp. The second one is in the drivers side heat and goes to the dash. No numbers but goes all the to the red line.
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-08-2017, 03:59 PM   #4
blown240
Registered User
 
blown240's Avatar
 
Join Date: Jan 2011
Location: CA
Posts: 772
Re: Overheating when driving and gas tank building up pressure

Are your fans ON all the time? Or are you having your Fitech control them?

Fans on all the time can cause overheating on the freeway...
__________________
'61 Panel - Helms Bakery Truck - Daily Driver - FOR SALE
blown240 is offline   Reply With Quote
Old 04-08-2017, 04:02 PM   #5
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

The Fitech is controlling it, I don't think it turns it off, but I could be wrong.
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-08-2017, 04:04 PM   #6
The Rocknrod
Moderator

 
The Rocknrod's Avatar
 
Join Date: Aug 2011
Location: China Spring, TX
Posts: 7,280
Re: Overheating when driving and gas tank building up pressure

The gage (assuming it's a 66) will read high if it doesn't have the correct sender.
https://www.lectriclimited.com/elect...ing-unit-87590
Also see: http://67-72chevytrucks.com/vboard/s...d.php?t=525139
The Rocknrod is offline   Reply With Quote
Old 04-08-2017, 04:09 PM   #7
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

That's what I thought, but the Fitech digital read out was also indicating that is was at 230, I don't think bouth would be reading wrong.
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-08-2017, 04:08 PM   #8
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

depending on what pressure cap you have and coolant mixture you can run at 230 without a problem.
If it is getting hotter on the highway it could mean an air flow problem and sometimes it can mean a bottom rad hoce collapsing. is the bottom hose a wire reinforced hose or just rubber.
ron
padresag is offline   Reply With Quote
Old 04-08-2017, 04:16 PM   #9
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

but 230F is not really a problem as I mentioned. what pressure cap and coolant mixture are you using? I also don't know what a Fitech is.
ron
padresag is offline   Reply With Quote
Old 04-08-2017, 04:27 PM   #10
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

This is Fitech efi system I have.
http://fitechefi.com/products/30003/

Not sure about the cap, it came with the aluminum radiator from Brothers. I remember that it says champion on the cap. I believe it's just a 50/50 coolant mix. I'll have to check the lower house, but I think I remember the spring being in it.

Could it be the fan not letting the air flow properly at highway speeds?
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-08-2017, 04:44 PM   #11
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

water boils at 212 degrees F normally at sea level without any pressure. they more than likely supplied you rad with at least a 13# cap and you have a 50-50 mix. for every # lb pressure that you add to the system you will raise the boiling point 3 degrees F. a 13# cap will raise the boiling point 39 degrees. a 50/50 will raise the boiling point another 18 degrees F, add 212 + 39 +18 =269 Degrees, your system will not reach boiling point until 269 degrees. 230 is not a problem. this is why they installed idiot lights in vehicles instead of temp guages.
ron
padresag is offline   Reply With Quote
Old 04-08-2017, 04:53 PM   #12
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

re your fuel tank you are having a venting problem somehow. when gas gets hot it expands. if you system is drawing fuel from the tank and it is not vented the fuel being drawn causes a vacuum and can cause the reverse action; causing the tank to indent. with your injection it must have a return line. you say that there is a vent on the tank; are you sure that it is working. is your gas cap vented, if not I would try a vented cap
ron
padresag is offline   Reply With Quote
Old 04-08-2017, 05:04 PM   #13
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

I'm using this vent.
http://www.tanksinc.com/index.cfm/pa...prod/prd98.htm

I can see the vapors coming out of it. I have an under bed tank with a pop up cap. I looked and couldn't find one that was vented.
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-08-2017, 05:05 PM   #14
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

By the way thank you for your input guys.
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-08-2017, 05:25 PM   #15
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

if you had of installed a 3 or 4 core rad it more than likely would have run cooler as you are running a greater volume of water. the main reason for raising the pressure of radiators was due to the use of smaller rads and smaller openings in the grille areas years ago.
ron
padresag is offline   Reply With Quote
Old 04-11-2017, 09:44 PM   #16
Port&PolishMan
Registered User
 
Port&PolishMan's Avatar
 
Join Date: Mar 2017
Location: Etowah, TN
Posts: 210
Re: Overheating when driving and gas tank building up pressure

Quote:
Originally Posted by padresag View Post
if you had of installed a 3 or 4 core rad it more than likely would have run cooler as you are running a greater volume of water. the main reason for raising the pressure of radiators was due to the use of smaller rads and smaller openings in the grille areas years ago.
ron
I haven't read all the way through , but My 350 has a Desert Rated Rad in it and
I'm still up at 210-215 then it goes back down to 185 and Up again in Traffic

I'm putting in a Precision Stat , those Respond Faster and Hold Temps more Evenly .

4 Row for Sure , in Texas - Dam Hot there .
Also I - like to Note - with 2 Core - Your Pushing Water through it to Fast .
I'm sure You could - Tweak it - By going to Under Drive Pulley's ,180 Precision Stat , & Pusher Fan ..

Last edited by Port&PolishMan; 04-12-2017 at 09:29 PM.
Port&PolishMan is offline   Reply With Quote
Old 04-08-2017, 05:32 PM   #17
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

Believe that it was 63 or 64 that they raised the pressure in the cooling system of these trucks from a 7# to a 14# pressure system and a 16# pressure with a/c. so there had to be reasons for that
ron
padresag is offline   Reply With Quote
Old 04-08-2017, 10:28 PM   #18
shp4man
Registered User
 
shp4man's Avatar
 
Join Date: Oct 2016
Location: San Diego, CA
Posts: 557
Re: Overheating when driving and gas tank building up pressure

Don't know if it will help, because my truck is a stock six cylinder with the Harrison radiator still in there. Anyway, it would have some wild temp fluctuations and get hot on the freeway. It had a 160 degree thermostat in it.
Looking at parts catalogs, GM recommended a 195. I was skeptical, but put in a decent quality 195, and it seems to be fixed.
__________________
Everybody has to believe in something. I believe I'll have another beer.
shp4man is offline   Reply With Quote
Old 04-08-2017, 11:11 PM   #19
lumpy63
Registered User
 
lumpy63's Avatar
 
Join Date: Apr 2016
Location: san diego ça
Posts: 121
Re: Overheating when driving and gas tank building up pressure

If I understand correctly your truck will sit and idle without overheating? But on the freeway it runs too hot? The cooling fan basically becomes useless over 30 mph as the incoming air overtakes the fan. This could be a case of insufficient cooling system capacity ,or miss matched parts..I have seen people put serpentine counter rotating water pumps on standard rotation sbc's double check your cooling system.
lumpy63 is offline   Reply With Quote
Old 04-08-2017, 10:25 PM   #20
urmyboyblue
Registered User
 
Join Date: Feb 2015
Location: Montevallo, AL
Posts: 272
Re: Overheating when driving and gas tank building up pressure

1. Is the fan pulling air thru the radiator? It needs to based on how it is mounted- if it pushes from the rear, it will lose efficiency at speed due to the incoming air from the front being pushed by the fan.
2. Does the FITech show you AFR? If so, what is it showing at cruise?
3. What fuel pressure are you running at?

Do a little research- I read that the fuel command systems were causing issues for some people.
urmyboyblue is offline   Reply With Quote
Old 04-09-2017, 12:55 PM   #21
61K10
Registered User
 
61K10's Avatar
 
Join Date: Feb 2012
Location: pleasant valley--placerville ca
Posts: 3,039
Re: Overheating when driving and gas tank building up pressure

you have a flat piece of metal covering the rad with just a hole for the e-fan. with the fan on at speed, it actually blocks the air through the rad. try turning the fan off, and see if any difference. As Lumpy63 say's, could be something else.
__________________
1961 chevy K10

my build is------------61K10 build
61K10 is offline   Reply With Quote
Old 04-09-2017, 04:44 PM   #22
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

I'm beginning to think I have a combination of problems with regards to the overheating. I read this
http://www.tanksinc.com/index.cfm/pa...ode=prod/prd98.
I called Brothers where I bought the radiator from to see I'd they had any specs on the row size, they did not. So it is possible that it is undersized. I do have a solid piece of aluminum used as the shroud with only a hole for the fan which is on the engine side of the radiator. I'm pretty sure the fan does not turn off at speed. It is controlled by the Fitech system (it doesn't monitor speed) and the A/C switch.

I found this link about the Fitech fuel command center.
http://fitechefi.com/tech-posts/go-e...with-pictures/
I'm going to try this adjustment and see if it helps the build up of pressure. Some people were having fuel come out of the return line, but I just have vapor coming out of mine. I have a tanks Inc vent installed on the fuel tank under ther bed. I added a "T" to the return line just before it enters the tank. Is it possible that I am getting a vapor lock since the warm gas vapor coming from the engine is blocking the vent? Should I have the vent on a separate line?

Once again, thanks for all the feedback, I really appreciate it.
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-09-2017, 05:02 PM   #23
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

http://www.tanksinc.com/index.cfm?pt...id=-1&mode=cat
ron
padresag is offline   Reply With Quote
Old 04-09-2017, 05:18 PM   #24
Adam1966C10
Registered User
 
Adam1966C10's Avatar
 
Join Date: Nov 2015
Location: Cypress
Posts: 39
Re: Overheating when driving and gas tank building up pressure

That is the way I have it mounted. There is a "T" right in the return line before the inlet nipple. Is it possible that having it in the return line before the tank is not letting the vent work properly?
__________________
1966 Chevy C10 short bed stepside
Adam1966C10 is offline   Reply With Quote
Old 04-09-2017, 06:02 PM   #25
padresag
Registered User
 
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
Re: Overheating when driving and gas tank building up pressure

Quote:
Originally Posted by Adam1966C10 View Post
That is the way I have it mounted. There is a "T" right in the return line before the inlet nipple. Is it possible that having it in the return line before the tank is not letting the vent work properly?
should be in the tank as that is what you are venting. when your vehicle is running that line is returning to your tank. if there is product in the line, it will not vent against the incoming fuel. it will vent after you shut the engine off as fuel will not in the line.
your vent hose should steadily rise also and not have a dip in it as it has in the illustration
ron
padresag is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 11:45 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com