Engine Compartment Cooling (1 Viewer)

[Downey]

1. If engine was pushed back too close to firewall you will always over heat. Heat radiates out back of engine, hits fire wall, and bounces right back into the engine. 2. 350’s run hotter than smaller c.i. engines, anything under 200 degrees is a happy day with a 350. Keep in mind some smog devices keep the engines running 209-220 degrees all day long. 3. An electric fan will never create the hurricane in the engine compartment to blow out the heat, you need the engine horse power to do that. Last Chevota I had used an 18” inch, 7 blade, heavy pitch GM air conditioning fan on a clutch- -I didn’t even need a fan shroud with this set-up.

 

[troutbum4]

with that same set up, I have experienced the same issues, finally have it pretty much under control. Mine was set up w an electric fan, changed that out to a larger one, replaced radiator w a bigger one, insulated fuel lines, and added a spacer under the carb. The last 2 helped greatly w the starting issue when hot. I've also used coolant additives that are supposed to help run things a bit lower and run coolant mix at a bit lower than 50/50. Also wrapped the headers. At some point I would like to replace the headers w coated ramshorns, though think that may be more for my comfort inside the cab than lowering engine temps.

 

[brooklyn]

When I was running a V8 (with electric fan), I upgraded the radiator, put the mechanical fan back with a shroud and put an upgraded water pump (was supposed to increase flow) and did the thermostat— no longer ran hot, which it only did on the hottest days. Wasn’t running headers. My problem was solved — I did check timing as well.

I tend to be a fan of ripping everything out to solve problems and starting with components I have researched.

My engine position was okay based on the folks I consulted.

 

[ceylonfj40nut]

Got to a mechanical fan. Those electrical fans dont work. Your brakes are likely unrelated to the heating issue.

 

[rlong]

1. If engine was pushed back too close to firewall you will always over heat. Heat radiates out back of engine, hits fire wall, and bounces right back into the engine. 2. 350’s run hotter than smaller c.i. engines, anything under 200 degrees is a happy day with a 350. Keep in mind some smog devices keep the engines running 209-220 degrees all day long. 3. An electric fan will never create the hurricane in the engine compartment to blow out the heat, you need the engine horse power to do that. Last Chevota I had used an 18” inch, 7 blade, heavy pitch GM air conditioning fan on a clutch- -I didn’t even need a fan shroud with this set-up.

Everything Jim says here! (for posterity), I'm far less an expert, but started V8 conversions in the mid-late 70's (all just freinds) and have seen the too close to the firewall issue several times. On my never ending project below, I went too far forward (current state) becaue of this concern BUT misjudged adaquate space for mechanical fan with (gm) oem fan clutch. (I'll tweak it back a little once back at it) These two make the biggest difference... and if thier wrong you end up chasing your tail to some degree or another. (And a vote for cast manifolds! I want it "icy moderate" under the hood).

 

[OrangeCrush496]

170 to 200 isn't hot. My 1st 40 runs around 160-170 normally and on long climbs it'll get close to 200. It has a 160 tstat.
I made a fan shroud and properly positioned the straight steel fan 1/2 way into the shroud as is should be. I ran fenderwell headers for decades b4 going to ramshorns manifolds. At the beginning I had cooling problems with a high hp 350, then adapted a shroud which helped a lot. Now the engine is more stk and runs cool.

You might try adding aluminum or metal sheet metal to the open corners so the electric fan can pull air from those areas/corners, like @peesalot mentioned. The metal needs to be spaced away from radiators core, so the fan can pull air. At 1st you could cut and tape cardboard there and see if it helps. Does it have a heater, is there a reason it's not hooked up? I not 100% convinced the heat is effecting the clutch, the headers are above the slave. Below is also the fsm instructions on clutch adjustment. Pedal height, pedal play, rod adjustment. Pedal play is when the slave rod start to move and slight Pedal travel.

View attachment 3886645View attachment 3886656

Thanks for this its very helpful. The diagram and your description helped me understand about those open corners. I will try the cardboard option just to see how much difference it makes, and see about adjusting the clutch. That would be awesome if an adjustment could correct that.

My FJ doesnt have a heater. I feel stupid asking....but should there be one?

 

[peesalot]

Mine 40 does not either, I never run a full top so heater is mute point.

 

[pb4ugo]

Is your 40 an import or US-spec? If your 40 is a US-spec 40 it should have a heater. A heater isn't necessary, but it adds to the cooling capacity. We need more pics of the vehicle, mainly because we like to see them. Looking at your pics, they are several things I would eventually clean up. You should be able to keep it cool running the stk radiator with a mechanical fan. Some have gotten away with electric fans, but as others have mentioned you might have to add some creative band aids to keep it cool.

Does it have drum brakes?

 

[charliemeyer007]

Way back in the day I'm talking early 70's my buddy drove his dad's Hudson Hornet sorry I don't remember the year, they had 3 or 4 of them. Anyway pulling a long grade it would run hot - but if we turned the heater on it would not boil over. Yea running the heater inside when its 105 outside sucked but it was way better than walking.

There are coolants that claim to move more heat than water. Some folks say the aluminium radiators also do better at moving heat.

 

[OrangeCrush496]

Mine 40 does not either, I never run a full top so heater is mute point.

Is your 40 an import or US-spec? If your 40 is a US-spec 40 it should have a heater. A heater isn't necessary, but it adds to the cooling capacity. We need more pics of the vehicle, mainly because we like to see them. Looking at your pics, they are several things I would eventually clean up. You should be able to keep it cool running the stk radiator with a mechanical fan. Some have gotten away with electric fans, but as others have mentioned you might have to add some creative band aids to keep it cool.

Does it have drum brakes?

The shroud was a genius idea...it kept the temp 10-20 degrees cooler! Never once got over 170. Obviously need to make a more permanent setup, but this showed how much of a difference it will make!

I dont know if its an import or not. I think theyre drum brakes...here's a few more pics from random pics

 

[pb4ugo]

Your brake issue could be with within the drum brakes. You probably need to pull the wheels and drums and take a look at them. Stk FJ40 drum brakes are old and antiquated. They don't self adjust, so periodically they will need to be adjusted. You need to make sure nothing is leaking and the star wheels can turn. Someone mentioned checking for the return spring under the dash.

 

[3_puppies]

the front axle appears to have a disc caliper

 

[sogncab]

How old is the brake and clutch fluid? If it's old and contaminated with water, it's possible it's getting hotter than clean fluid.

This was my first question as well

 

[Rodger1957]

Using the thermometer...How would I tell if there are areas that arent transferring heat? And what does it mean if there are? Sorry...I'm a nooob.

You need one of those point and shoot thermometers. There should be fairly equal heat across the radiator, if you’ve got cold spots it’s because that part of the radiator isn’t doing its job.
Flushing doesn’t get them clean, the tanks need to come off and the tubes rodded to do the job right.

 

[OrangeCrush496]

This was my first question as well

These are all good questions about things I havent event looked at yet. I bought it in 2022 and Since then I've had to reinstall the camshaft, replace the distributor, rebuild the transfer case, replace the starter motor, replace the ignition switch, fusable links, and a host of minor things like swapping the battery, etc, etc ,etc. I bought myself a project

 

[sogncab]

I bought myself a project

It's a 50 year old vehicle. Just how it goes.

 

[WILLD420]

A few things.

The coolant temps of the engine have little to do with the problems you are facing. There could be numerous reasons some of these things are happening and each will need to be chased out.

Hard starting when warm. How hard? Like crank and crank, play with the throttle and crank some more then it will light off?

First thing. What is your starting procedure? Are you pumping the gas or just hitting the starter and hoping it will catch?

That looks like and Edelbrock 1406 style carb. They are good, but all carbs are a heat sink. Modern gas doesn't like heat, but it's not as bad as the old stuff was. Still, an open element air cleaner, a 200 degree engine, a carb with no heat shields and possibly too high of float levels can make them boil the gas into the intake. If it puffs a black cloud on hot starts without you pumping the pedal, I would be looking at fuel boil over out of the bowls into the vents and flooding while it is sitting there. If it doesn't puff black smoke and you have to crank it 50 revolutions to get it to fire while pumping the pedal, you need to make sure your accelerator pump is working and adjusted right, as well as making sure you are getting full voltage to the ignition system while cranking and that you don't have a weak ignition issue when it gets hot.

What kind of ignition system do you have? HEI's are notorious for heat sink issues with the module. There is also the issue of the intake manifold on that motor. That looks like a single plane intake. They aren't the best for drivability at low rpm and starting ease. If you have points and an external coil, you need to make sure all of that is up to speed or it will be a hard starter as well.

Brakes not Returning:

Sounds like a soft line is collapsing, or you are getting the lines hot and the fluid is boiling, thus expanding, or you have an issue with a hard-part like a proportioning valve or a residual valve somewhere in the system. Deal with the heat first, then you can fine tune into some other areas. Do some research on what others have worked through on braking issues and you may have a common problem that others have identified and fixed.

Brake and Clutch Fade: = Heat

Those are fenderwell headers. They will concentrate heat in areas that Toyota never meant to be hot. They will radiate that heat into the clutch and brake system. Only cure is to either swap them out for a style that dumps out the center away from all those things, or make up some heat shielding and keep the radiant heat away from things. The header wrap will help, but without airflow, and direct shielding, you are still going to have heat soak. I love fenderwell headers, but they do require some finesse to keep the side effects at bay. Manifolds will probably help your issue, but they have drawbacks as well. They can cause lot of radiant heat soak issues in the cylinder heads and you will see a pretty substantial loss in HP and MPG by going back to a log style manifold. You just have to work through the compromises to see what fits your style best.

Radiator Shrouding:

There is a reason the OEM's use a lot of baffling and shielding around radiators in modern cars. You have to do everything you can to keep the hot air from doing a u-turn and getting back into the radiator. Just about the worst thing you can do is hang an electric fan right on the radiator like most people do. Your setup is very typical of a bad one. You are only getting the cooling of the radiator within the circle of the built in shroud on that fan. That cardboard you are putting on there is basically keeping the hot air from getting sucked backward, through the radiator and doing a u-turn, to go back through where the fan is pulling on it. It will help, but it won't fix it like the proper shrouding will.

Nice looking rig. Just needs the typical "un-hotrodding" things done to return the driveability that the oem's spend a lot of time dialing in.

 

[ceylonfj40nut]

A few things.

The coolant temps of the engine have little to do with the problems you are facing. There could be numerous reasons some of these things are happening and each will need to be chased out.

Hard starting when warm. How hard? Like crank and crank, play with the throttle and crank some more then it will light off?

First thing. What is your starting procedure? Are you pumping the gas or just hitting the starter and hoping it will catch?

That looks like and Edelbrock 1406 style carb. They are good, but all carbs are a heat sink. Modern gas doesn't like heat, but it's not as bad as the old stuff was. Still, an open element air cleaner, a 200 degree engine, a carb with no heat shields and possibly too high of float levels can make them boil the gas into the intake. If it puffs a black cloud on hot starts without you pumping the pedal, I would be looking at fuel boil over out of the bowls into the vents and flooding while it is sitting there. If it doesn't puff black smoke and you have to crank it 50 revolutions to get it to fire while pumping the pedal, you need to make sure your accelerator pump is working and adjusted right, as well as making sure you are getting full voltage to the ignition system while cranking and that you don't have a weak ignition issue when it gets hot.

What kind of ignition system do you have? HEI's are notorious for heat sink issues with the module. There is also the issue of the intake manifold on that motor. That looks like a single plane intake. They aren't the best for drivability at low rpm and starting ease. If you have points and an external coil, you need to make sure all of that is up to speed or it will be a hard starter as well.

Brakes not Returning:

Sounds like a soft line is collapsing, or you are getting the lines hot and the fluid is boiling, thus expanding, or you have an issue with a hard-part like a proportioning valve or a residual valve somewhere in the system. Deal with the heat first, then you can fine tune into some other areas. Do some research on what others have worked through on braking issues and you may have a common problem that others have identified and fixed.

Brake and Clutch Fade: = Heat

Those are fenderwell headers. They will concentrate heat in areas that Toyota never meant to be hot. They will radiate that heat into the clutch and brake system. Only cure is to either swap them out for a style that dumps out the center away from all those things, or make up some heat shielding and keep the radiant heat away from things. The header wrap will help, but without airflow, and direct shielding, you are still going to have heat soak. I love fenderwell headers, but they do require some finesse to keep the side effects at bay. Manifolds will probably help your issue, but they have drawbacks as well. They can cause lot of radiant heat soak issues in the cylinder heads and you will see a pretty substantial loss in HP and MPG by going back to a log style manifold. You just have to work through the compromises to see what fits your style best.

Radiator Shrouding:

There is a reason the OEM's use a lot of baffling and shielding around radiators in modern cars. You have to do everything you can to keep the hot air from doing a u-turn and getting back into the radiator. Just about the worst thing you can do is hang an electric fan right on the radiator like most people do. Your setup is very typical of a bad one. You are only getting the cooling of the radiator within the circle of the built in shroud on that fan. That cardboard you are putting on there is basically keeping the hot air from getting sucked backward, through the radiator and doing a u-turn, to go back through where the fan is pulling on it. It will help, but it won't fix it like the proper shrouding will.

Nice looking rig. Just needs the typical "un-hotrodding" things done to return the driveability that the oem's spend a lot of time dialing in.

I have the headers you are running. I don't have brake issues. Maybe SC does not get as hot as TX. Tried everything with electric fans. Did not work. The shroud test you did was great idea. With the cardboard flat faced on the radiator, you are pulling air from the fan area only. To get air flow through the whole radiator those flat faced areas need to have a 1-2” space between radiator and shroud, which means you fac needs to move back some. Rip it on the highway on a hot day for about 30 mins to see if it will stay cool. My other concern was that it would get hot when on the trail. Looks like you have room to add a mechanical fan. Have someone build you a shroud. Summit has a great shroud kit that can be easily fitted.

 

[pb4ugo]

@WILLD420, good eye on the single plane manifold. I would ditch that. Single planes are designed for high rpm/hp wide open throttle applications. A dual plane would be a better choice and offer lower rpm torque and better drivabilty on the street and trail. I never paid attention to the manifold, because there's so many other things I would want to change or clean up in that engine bay.

As I mentioned earlier, I don't care for electric fans, but if the op wants to try and make it work, we can only make suggestions to make it work better. Looking at the pics, it appears there is a frame around the rad that allows the cardboard experiment to stand off the rad core by about an inch or more, which allows the fan to pull air from the whole core. If the circular part of the fan shroud housing is up against the core, I would suggest maybe drilling holes in the side of that shroud where enclosures were added to eliminate air restrictions or space that part of the shroud away from the core so it can pull air the whole enclosed core.

As i mentioned b4, I ran fenderwell headers for decades, at 1st i had overheat issues with a high hp sbc, after some cooling refinement it was kept in check. It wasn't a result of the headers. I constantly hear the f/w headers create a problem with heat. The only problems I had with them was constantly tightening header bolts and replacing header gaskets. The exhaust would periodically hit trail obstacles because the exhaust was outside the frame rails and create leaks. When I went to ramshorns, I immediately had cooling problems. I found the manifolds were huge heat generators, plus I went from dual exhaust to single. A more refined fan shroud and properly positioned aggressive mechanical fan fixed that.

 

[OrangeCrush496]

A few things.

The coolant temps of the engine have little to do with the problems you are facing. There could be numerous reasons some of these things are happening and each will need to be chased out.

Hard starting when warm. How hard? Like crank and crank, play with the throttle and crank some more then it will light off?

First thing. What is your starting procedure? Are you pumping the gas or just hitting the starter and hoping it will catch?

That looks like and Edelbrock 1406 style carb. They are good, but all carbs are a heat sink. Modern gas doesn't like heat, but it's not as bad as the old stuff was. Still, an open element air cleaner, a 200 degree engine, a carb with no heat shields and possibly too high of float levels can make them boil the gas into the intake. If it puffs a black cloud on hot starts without you pumping the pedal, I would be looking at fuel boil over out of the bowls into the vents and flooding while it is sitting there. If it doesn't puff black smoke and you have to crank it 50 revolutions to get it to fire while pumping the pedal, you need to make sure your accelerator pump is working and adjusted right, as well as making sure you are getting full voltage to the ignition system while cranking and that you don't have a weak ignition issue when it gets hot.

What kind of ignition system do you have? HEI's are notorious for heat sink issues with the module. There is also the issue of the intake manifold on that motor. That looks like a single plane intake. They aren't the best for drivability at low rpm and starting ease. If you have points and an external coil, you need to make sure all of that is up to speed or it will be a hard starter as well.

Brakes not Returning:

Sounds like a soft line is collapsing, or you are getting the lines hot and the fluid is boiling, thus expanding, or you have an issue with a hard-part like a proportioning valve or a residual valve somewhere in the system. Deal with the heat first, then you can fine tune into some other areas. Do some research on what others have worked through on braking issues and you may have a common problem that others have identified and fixed.

Brake and Clutch Fade: = Heat

Those are fenderwell headers. They will concentrate heat in areas that Toyota never meant to be hot. They will radiate that heat into the clutch and brake system. Only cure is to either swap them out for a style that dumps out the center away from all those things, or make up some heat shielding and keep the radiant heat away from things. The header wrap will help, but without airflow, and direct shielding, you are still going to have heat soak. I love fenderwell headers, but they do require some finesse to keep the side effects at bay. Manifolds will probably help your issue, but they have drawbacks as well. They can cause lot of radiant heat soak issues in the cylinder heads and you will see a pretty substantial loss in HP and MPG by going back to a log style manifold. You just have to work through the compromises to see what fits your style best.

Radiator Shrouding:

There is a reason the OEM's use a lot of baffling and shielding around radiators in modern cars. You have to do everything you can to keep the hot air from doing a u-turn and getting back into the radiator. Just about the worst thing you can do is hang an electric fan right on the radiator like most people do. Your setup is very typical of a bad one. You are only getting the cooling of the radiator within the circle of the built in shroud on that fan. That cardboard you are putting on there is basically keeping the hot air from getting sucked backward, through the radiator and doing a u-turn, to go back through where the fan is pulling on it. It will help, but it won't fix it like the proper shrouding will.

Nice looking rig. Just needs the typical "un-hotrodding" things done to return the driveability that the oem's spend a lot of time dialing in.

Thank you so much for taking the time to type all this, and for offering your valuable expertise! I'm going to reply in sections, by problem.

Hard starting when warm. How hard? Like crank and crank, play with the throttle and crank some more then it will light off?

I push the accelerator all the way to the floor. Crank for 5-7 seconds, then wait 10 minutes if it doesn’t start.

First thing. What is your starting procedure? Are you pumping the gas or just hitting the starter and hoping it will catch?

When car is hot, I push the accelerator all the way to the floor and turn the ignition 5-7 seconds. When its cold, I just turn ignition and it fires right up.

That looks like and Edelbrock 1406 style carb. They are good, but all carbs are a heat sink. Modern gas doesn't like heat, but it's not as bad as the old stuff was. Still, an open element air cleaner, a 200 degree engine, a carb with no heat shields and possibly too high of float levels can make them boil the gas into the intake. If it puffs a black cloud on hot starts without you pumping the pedal, I would be looking at fuel boil over out of the bowls into the vents and flooding while it is sitting there.

There isn't a major cloud of smoke on hot start, but I recall seeing smoke that's not present on cold start. I will pay attention next hot start.

If it doesn't puff black smoke and you have to crank it 50 revolutions to get it to fire while pumping the pedal, you need to make sure your accelerator pump is working and adjusted right, as well as making sure you are getting full voltage to the ignition system while cranking and that you don't have a weak ignition issue when it gets hot.

This statement got my attention because I think it describes what I'm experiencing.

as well as making sure you are getting full voltage to the ignition system while cranking and that you don't have a weak ignition issue when it gets hot.


Some additional info that indicates this is happening:

When I use a jump starter, the car fires up almost immediately so it seems part of the issue is voltage. Over time I replaced the battery , and the starter motor…and the problem improved somewhat…but its still a problem. l

What kind of ignition system do you have? HEI's are notorious for heat sink issues with the module. There is also the issue of the intake manifold on that motor. That looks like a single plane intake. They aren't the best for drivability at low rpm and starting ease. If you have points and an external coil, you need to make sure all of that is up to speed or it will be a hard starter as well.

Attached is a pic of the coil.