v8 cooling

[was a 75]

i have a 350 chev in my 75 ute and went with the orig radiator and mounted a thermo to it. first drive it was hovering between 200-220. im thinking its too small a setup and maybe junking it and getting a tray mounted radiator. what are these worth and does anyone in the ipswich area do them? thanx

[hulsty]

Tried an engine fan and a good shroud?

[crankycruiser]

I'd be doing as hulsty suggested and putting a real engine fan on it b4 u get too excited. No matter how good a thermo is it will never match a engine fan

[75 cruser]

i run a v8 in a 75 with the standard 2h diesel raditator and a engine fan and its never over heated, try a engine fan and a shroud for sure

thanks rob

[gingerbreadman]

very first thing is verify your gauge with either another gauge or infa red gun to know if your actually in the 220 range .lets check to see if you have used the original toyota temp sender on your chev block/head or have you wired your gauge onto a chev sendor?..they will not communicate correctly.

mate 200-220 is not catastrophic in a chev but its up there and i wouldnt want it tipping 220 . i know modern engines run around the 220 mark for fuel injection but not a gen 1 ,2 and getting it to hover around the 185-195 range would be better. I see your in ippy or somewhere around there and it has been very hot of late so 200 in a chev is going to be quite common. 200 in summer generally means it will run 180 in winter so what can we do to fix this temp.... i have a few chevs and i have them all running around the 190 range max but in saying that they all have fairly decent 3 or 4 core radiators so is the toyota 2f radiator up to it i would love to know?

the obvious thing to me to do is check if its a fan problem or radiator/timing/thermostat etc problem.....so is it reaching this high temp at highway/cruising speeds or when your idling at lights/driveway. if it sits at a reasonable temp at idle with the fan on than its not the fan . when cruising your fan should not even be on and if it is its doing nothing as hitting air when driving 60klms/h or higher is going to overpower any thermofan so we can look elsewhere other than the fan as well for things like a collapsing lower radiator hose , or a thermostat that may be faulty , thermostat that does not have a 1/8 hole drilled in the plate to expell air,timing too advance or even retarded for that matter.normally i would also include a naturl airflow restriction but on a cruiser im yet to see that I am interested to hear what thermofan your using as well and if it has a shroud?

if you put your hand in front of your radiator and you cant feel the air being drawn through than its not sufficient .i use 1x16 inch spal mounted directly to the radiator and they seem to be doing the job...maybe post a pic of your setup from the engine side bud and we might be able to pick some problem spots?

[hulsty]

when cruising your fan should not even be on and if it is its doing nothing as hitting air when driving 60klms/h or higher is going to overpower any thermofan so we can look elsewhere other than the fan

I used to think that too (may not be applicable for all vehicles) till I had a overheating problem at 100km/h even on fat ground. Turned out to be a dud viscous coupling, cant hear the fan running but it must be doing something at those speeds even if it is only a small contribution.

[gingerbreadman]

when cruising your fan should not even be on and if it is its doing nothing as hitting air when driving 60klms/h or higher is going to overpower any thermofan so we can look elsewhere other than the fan

I used to think that too (may not be applicable for all vehicles) till I had a overheating problem at 100km/h even on fat ground. Turned out to be a dud viscous coupling, cant hear the fan running but it must be doing something at those speeds even if it is only a small contribution.

the only contribution it has at those speeds is restricting the natural airflow...stick your head outside at 100kmh , you think a fan can compete with that?

[hulsty]

when cruising your fan should not even be on and if it is its doing nothing as hitting air when driving 60klms/h or higher is going to overpower any thermofan so we can look elsewhere other than the fan

I used to think that too (may not be applicable for all vehicles) till I had a overheating problem at 100km/h even on fat ground. Turned out to be a dud viscous coupling, cant hear the fan running but it must be doing something at those speeds even if it is only a small contribution.

the only contribution it has at those speeds is restricting the natural airflow...stick your head outside at 100kmh , you think a fan can compete with that?

Then how did only changing the viscous clutch fluid stop my overheating at 100km/h ??

[Zuri92]

the fan will still suck air through, even though the car is doing 100, the air doesnt go through the rad that fast, it gets turbulence etc and a fan thats running well can still draw on the air coming through the rad. fans are important reguardless of speed.

[gingerbreadman]

when cruising your fan should not even be on and if it is its doing nothing as hitting air when driving 60klms/h or higher is going to overpower any thermofan so we can look elsewhere other than the fan

I used to think that too (may not be applicable for all vehicles) till I had a overheating problem at 100km/h even on fat ground. Turned out to be a dud viscous coupling, cant hear the fan running but it must be doing something at those speeds even if it is only a small contribution.

the only contribution it has at those speeds is restricting the natural airflow...stick your head outside at 100kmh , you think a fan can compete with that?

Then how did only changing the viscous clutch fluid stop my overheating at 100km/h ??

because the stock clutch fan attaches to the water pump pulley, it can cause belt slip on the pulley when the fluid or fan is in poor condition.

[gingerbreadman]

the fan will still suck air through, even though the car is doing 100, the air doesnt go through the rad that fast, it gets turbulence etc and a fan thats running well can still draw on the air coming through the rad. fans are important reguardless of speed.

At cruise speed no ,air will only flow if there is a pressure differential. This is a really important point to grasp – air doesn’t pass through the radiator just because the car is moving forward. Instead, there needs to be a higher pressure in front of the radiator and a lower pressure behind it – that is, a difference in pressure.

for an example imagine that the engine bay is sealed off top and bottom. (In most cases it is sealed off at the top by the bonnet, but there are usually openings around the engine to allow air to flow out under the car - but here we’ll think about a car with a totally sealed engine bay.)
Without any escape route, the engine bay soon ‘fills up’ with air, until the pressures either side of the radiator become equal. Now, no more air will flow through the radiator.Air can only flow through a radiator as fast as it can be expelled . Some cars like a corvette with its side vents or typically higher 4wd,s with more ground clearance can expell the air faster increasing air flow but a fan alone on the low pressure side of a radiator cant. A Cruise speed of only 50kmph is about all the high pressure most family cars need/have to create that DIFFERENCE in pressure.

[DIRTY ROCK STAR]

as said above.
engine fan and shroud will fix it up.

[was a 75]

thanx for the input. gingerbreadman it was a 2h truck so has the 2h radiator. its an efi 350 ramjet. stuart warner gauge wired into the chev block, with the sender that came with the guage. i will try post some pics, hopefully they work. i ditched the stock fan and shroud in favour of a thermo so i can turn it off for creek crossings basically. my original viscous coupling setup also crapped itself and it took a long time to work out why it was overheating. changed everything including a new radiator. when we worked out it was the coupling we chucked it and lathed up a solid spacer that ran the fan all the time. overheating fixed. no good for creek crossing tho.[img][IMG]http://i850.photobucket.com/albums/ab64 ... G_1104.jpg[/img][/img][img][IMG]http://i850.photobucket.com/albums/ab64 ... G_1105.jpg[/img][/img]

cheers

[WICKED]

Too many [img] codes

[was a 75]

photo rookie! thanx for that.

[gingerbreadman]

my biggest question is still if your having issues at slow speeds or at highway speeds as thats 2 entirely different sets of troubleshooting.
....from the way you talk how it overheated prior with the shoddy clutch fan but was ok with the solid fan im guessing its only at low speeds? if thats true this is an easy fix..

your pictures look ok to me. being picky i would say your bar and winch does restrict some natural airflow but not enough to cause any big dramas.

here is a list on what i would do depending on what your answer is to low or highspeed cooling...........

1) ..make sure your wiring is correct on the fan, sometimes if in reverse polarity a puller fan spins as a pusher fan
2)..i like ramjets and nearly bought that set up once but thought it was too expensive...are you sure its tuned properly?
3)..what coil and distributor or you using?
4)..are you around the 34-36 degree mark ? if not whats your total timing and initial timing?
5) this could be a big one..is your radiator sealed well?..by that i mean is the air possibly finding a path of less resistance around or under your radiator rather than going through it?

of course some of these things would depend on if its low speed overheating or high speed OR BOTH so thats important to know. i have no trouble sitting on 185 with a fan just like yours. i cant see if its a spal or not ( looks similar) but if its at least 2400 cfm it should do the job as its covering almost all of your radiator. even though its hardly noticeable that fan actually does have a shroud. building a bigger shroud is bit of a trade-off as they will help your fan pull air through a broader area but will normally restrict natural airflow some what. with fans like we have i have seen people add a section of sheeting around the outer edge of the minimum shroud that is there just to stop the fan from pulling air (hot air) from the backside of the radiator. i have even seen some thermo fans come with the parts to stop this.

here is one of my setups which is much like yours. im sure we can solve this and have you running sub 200 eventually

[was a 75]

cool. i got another thermostat off a mate tonite so i will try that 1st tomorow. its a brand new crate engine and from memory i thought i read somewhere they have 3 tune modes. not sure, but maybe the timing is a bit out? tackle that next. the dizzy and coil are ac delco units that came with the engine.

sitting there idleing the temp gradually gets higher and higher till it sits between 200-220, but when i drive it and its warm if i put my foot into it up the gears that is enough to make the temp go soaring instantly. it actually went past 220 today so i shut down straight away and the overflow bottle was overflowing. not so cool idleing everywhere with all that power!

[Zuri92]

reguarding the pressure difference thing..... do you relyse that with the fan drawing on the air behind the radiator it is causing a low pressure situation, between the fan and radiator, allowing the higher pressure air at the front of the radiator to pass through, so with the fan working properly the pressure on the fan side of the rad will be lower than if it were not, therefore increasing airflow and therefore cooling.

see how i just used your evidence of how i was wrong to prove that i was right. fact of the matter, a properly functioning fan is always beneficial, and guess what, the manufacturers designed the fans to work in such a way for a reason and that reason is as simple as this..... it works

[brooksy]

It will always work more efficiently with a shroud & in many cases is designed with a shroud in mind. I agree with the idea of the shroud reducing back turbulant hot engine air. I think with the nature of our 4wds having winches & lights restricting the factory designed airflow point makes for a stronger necessity to direct the cool air & make it more uniform via some sort of shroud.
just my thoughts



brooksy

[gingerbreadman]

reguarding the pressure difference thing..... do you relyse that with the fan drawing on the air behind the radiator it is causing a low pressure situation, between the fan and radiator, allowing the higher pressure air at the front of the radiator to pass through, so with the fan working properly the pressure on the fan side of the rad will be lower than if it were not, therefore increasing airflow and therefore cooling.

see how i just used your evidence of how i was wrong to prove that i was right. fact of the matter, a properly functioning fan is always beneficial, and guess what, the manufacturers designed the fans to work in such a way for a reason and that reason is as simple as this..... it works

I will simplify it for you...
if your at cruise speed and you need to turn on a fan to try and get your temp down then your cooling system needs attention

[gingerbreadman]

cool. i got another thermostat off a mate tonite so i will try that 1st tomorow. its a brand new crate engine and from memory i thought i read somewhere they have 3 tune modes. not sure, but maybe the timing is a bit out? tackle that next. the dizzy and coil are ac delco units that came with the engine.

sitting there idleing the temp gradually gets higher and higher till it sits between 200-220, but when i drive it and its warm if i put my foot into it up the gears that is enough to make the temp go soaring instantly. it actually went past 220 today so i shut down straight away and the overflow bottle was overflowing. not so cool idleing everywhere with all that power!

sweet as 75 ,before you install your new stat be sure to hang that thermostat off a piece of wire in a saucepan and bring the water to boil. check to see if it opens as normal once the water starts to get hot. Definatly (if it doesnt already) drill a single 1/8 hole in the flat part of the thermostat so when you fill your coolant into your radiator the air in your block can pass through the hole that you drilled and coolant can fill the entire system. once the coolant comes up to the full level normally wait a minute and refill ( it takes a little while for that coolant to come through the hole)

220 is about when i would shut down as well. It sounds like you can most likely rule out your fan if its overheating in both cruise and idle. At cruise there is abundant airflow if your radiator sides are sealed well and there is no airflow restrictions so i hope for your sake its as simple as the thermostat ( i have seen plenty of duds)

did you get your crate motor from eagle?

[was a 75]

turns out the thermostat was cactus. i tried the boil the water thing with the other thermostat a couple times and couldnt tell if it was opening or not. so i put a new gasket on and ran it without any thermostat. results were driving round without the the thermo fan off and as much revs as i want it sat on 165. sittin there idleing with the fan on it was sitting at 175-180.

my next question would obviously be do i need to run one or not? it had a 180 one in it. cheers

[was a 75]

oh, i got the engine through grant from brisbane engine balancing at capalaba.

[gingerbreadman]

yes mate definatly run one. a 180 would be the best for a chev. I run a 160 stat in one motor as its bombed pretty hard and i like to have a little bit of a bumper before i need to turn on my fan but sometimes in winter i even run a 190 to keep the temp up on other cars...for best economy and to burn of moisture residue in your oil i have read that a temp of 185-195 is best in our motors. i bet your loving that ramjet torque now

[was a 75]

rito. i will get a new 1 asap. thanx heaps for all the help. few more mods and it will be time to play. cant wait.