☺cooloing questions☺

[west]

 my new engine runs very hot and i'm not sure why.so i have a few questions.
but first,here are the stats.
it is a newly built 360 9to1 with 75 miles on it.aluminum heads
the timing is set at 35 degrees
the radiator is a freshly flushed oem type.

The temp gauge has gotten to 215 but the coolant didn't seem as hot as the motor plus the radiator wasn't under pressure.shouldn't it have been?it also seems to get hot faster when its driven as opposed to idling.
when i pull the rad cap off i see movement but not sure if its enough.how do i tell?

I was thinking of buying an infared temp gauge to determine if the engine is hotter than the coolant because i thought the heat was related to a timing issue but now i'm not sure.should my coolant temp be close to temp of my engine?

so i guess im looking for ideas on how to diagnose my problem,how do i tell whats causing the heat?
Also,how important is a fan shroud when the car is moving?i know i need one but didn't think it would make much diff whem moving forward.

Assume i know nothing,you wouldn't be far off.

[satellite65]

If the engine heats up when sitting still or moving slowly and cools down as speed increases it's probably an air flow problem. You would be looking at the fan, fan clutch, fan shroud (very important item that usually gets tossed  ) and how deep the fan sits in the shroud. Should be about 1/2 way between the blades. It could also be a pump issue, running to slow due to underdrive pulley, loose belt, etc.

You stated that the engine heats up when moving. Could be a radiator issue (not large enough), lower rad hose collapsing (does it have the coil in it?), timing issue (not enough advance and/or coming in too late), fuel mixture issue (too lean).
What mix of coolant do you use? 50/50 should be the max. too much anti freeze will make it run a little hotter.
You also said the rad wasn't under pressure. I'm not quite sure what you mean. What pressure cap are you using (I run a 14-16 lb.)

Also....and this may sound stupid but, are you sure the gauge is accurate? You may just be chasing ghosts. And 1 more thing, it's a fresh motor and may still be a little tight. Give it some time to loosen up a bit.

I'm sure there are other things to look for and I may have missed a couple....some of the other (more knowledgable) members might chime in and we'll both learn something

[west]

thanks for the reply,my lower hose is dented a little,i plan on getting the spring but didn't think it was enough to be a problem.
as far as timing,i dont know how to tell when the advance kicks in or how to adjust it.
the car seems to run fine.
50/50 coolant.and what i meant by pressurized is should'nt the upper rad hose be stiff and the cap under pressure when its that hot?mine wasn't.
i'm going to hook up another gauge but i can tell the engine is really hot,you can feel it.
any ideas on if a infrared temp gauge will help?

[Capt Jack]

it could tell you if the gauge is malfunctioning.  also if the engine is really hotter than the radiator, which would lead me to believe the coolant isnt flowing.

the lower hose is important.  without the coil, those can collapse very easily when theyre old and restrict flow to almost nothing, even at a high idle...which would explain a lot

its odd for the cap not to be pressurized and may very well be a big part of the problem.  I'd replace it outright.  cheap insurance.
also, verify the thermostat is facing the correct direction.  should be able to do that just removing the hose.
let us know

[nothingbutdarts]

any ideas on if a infrared temp gauge will help?

  I use one all the time @ work! Get one with the laser beam to help line up what your trying to get a temp. of a bit more accurate.


  What deg. thermostat are you running? Flex fan, factory steel fan or viscus fan? Shroud?

 The radiator hoses should have been quite hard if there was pressure built up in the cooling syst. Sometimes a closed syst. radiator cap will not seal. Is the cap new? Is there a spring loaded steel cap in the center of the rubber on the end that goes into the radiator? The cap is used to pull coolant back into the radiator as it cools down when you have a recovery tank. Sometimes this center cap won't seal properly and therefor not let pressure build up as it needs too. If it's not building pressure than the boiling point of the A/freeze mixture will be low. (not good) 

[satellite65]

Well, first change the lower rad hose (or install the spring). That could very well be the root cause so change it and rule it out. When the RPM's come up the pump can suck the hose closed.

Timing- you said it was set at 35*. Where? At idle or at 2000-2500 RPM's? Changing the advance curve involves putting in lighter springs to make the advance come in sooner or heavier ones to make it come in later. Changing the total advance may involve some grinding. You didn't say what dizzy you had so it's hard to go into detail. Let's not get ahead of ourselves here.
Set timing to 35* @ 2500 RPM's. Then back off the revs to idle and check timing again. If your anywhere in the 10* to 14* range you're real close and I wouldn't sweat it too much. You said the car runs fine so you're probably in the ballpark. You could try tweaking the timing up a bit (and re-adjust the idle speed) and see if it helps. No pinging? No problem.

Yes. At 215* I would expect some pressure in the system. That's what led me to ask if your gauge was any good. I can't say as to whether or not the I.R. meter is going to tell you anything because I've never used one on an automobile engine but if you got one...............

One more thing. Your carb. What is it? Are you running it out of the box? It might need to be jetted up a bit. Need more info.

[west]

everything is new except the rad which i had used before and was flushed.
i think the thermostat is a 180,it's in right.
I do have some short comings like the flex fan and lack of a shroud but i'm pretty sure its not the cause.

my next step is to put a spring in the hose,and try another gauge.

how do i determine if i'm getting enough flow through the system?

[satellite65]

With the cap off you would see the coolant moving but it doesn't move fast at idle. as the revs come the coolant should move a little quicker.
I just thought of something. It's a smallblock. There's a bypass hose between the water pump and intake manifold (I think) and if my memory serves me correctly they are a royal pain in the ass to install. Check to see that it's not kinked.

[west]

the timing was set at 35 deg@ 3k rpms.are you saying it should go to 10-14 at idle?
i dont think it does.does this mean i need lighter springs?its a mallory unilite no box.
the carb is an out of the box holly 700.i had planned on taking it to a guy with a dyno to tune it but i cant even get it to his shop.
I appreciate all the help,it looks like i have a few things to fix and I'll try again.

[west]

here are some pics:
here is the dented hose,too much?

stupid design:

[satellite65]

I honestly don't think your timing is too far off, if any. That's fine tuning stuff and probably not causing your problem. Check all the obvious stuff first. Also check your gauge against a known referance ( your infrared - aim it at the top of the radiator or right near the engines temp sending unit). You may not have any problem afterall. What are you using as a gauge now and what sending unit? I don't know if aftermarket gauges work accurately with the factory sender.

[NYrr496]

What diameter is that fan? And where is your shroud?

I have a Raytec laser spot infra red non contact thermometer. It is one of the most valuable tools I own. You can watch the thermostat open, check the temp of the bypass and even check the diff across the radiator. You will absolutely solve your problem with one.

[west]

17" fan and I've been looking for a shroud for weeks.can't plunk $160 on a new one and don't want to buy an aftermarket one unless i'm positive it will fit.I also wasn't sure if i was going to need an aluminum rad so i didnt want to buy a shroud that wouldnt fit later.thats why i was wondering how important they are when driving.
I know some of these parts are not ideal and need to be upgraded but $ is low and I used what i had when i could.

[satellite65]

"and if my memory serves me correctly they are a royal pain in the ass to install."
My memory sucks. The one on the /6 is the hard one. (did my dads a few months ago). I don't see any real serious issues. Yeh, Ya got a little kink in the lower and bypass hoses but honestly, I've seen worse. The fan could be a little closer to the radiator and you need a shroud but that's going to show up at idle or in traffic so I don't think it's too much of an issue.

Check out the gauge before you rip hair out of your head.

BTW, Great looking engine. I like the serpentine belt setup. Could we get a full engine view?

[west]

o.k. so tomorrow is a spring in the hose,a different gauge and an infrared meter to play with.
I will post my findings,I really appreciate the help.thanks

[satellite65]

Engine looks great. It's 12:25 here in NY. I'm going to sleep. Let us know how you make out.

[ucdcrush]

I've (tried) running without a shroud as well with various flex fans, didn't work for me at all, the idle temps kept creeping up in the 225+ range. The fan simply isnt' going to pull enough air through the radiator which offers a restriction.. it's "easier" to pull the hot air from around the fan itself.

I finally put a junkyard shroud on, and a clutch fan, and have not gotten over 205 after driving then sitting idling. I still have more trimming to do on my junkyard shroud to make it ideal since the fan/shroud position is not good (fan blades too far in the shroud). During my trip to the yard, I found lots of 26" wide mopar radiator shrouds on various v8 mopars over the years. I have a summit alum radiator with a 22.5" core surface, and the shroud that ended up fitting the summit radiator (almost like it was made for it) was from a Ford aerostar.

[NYrr496]

Wow, Ford Aerostar... That's good to know.

[ksdartguy]

I just popped for the mopar resto shroud.
Herbs parts. $160 shipped. Wish I had looked for the aerostar.
Rick

[west]

i just found out that napa doesnt stock the hose spring by itself.
so it looks like i have to wait for a trip to the junk yard

[ucdcrush]

Here's a pic of the aerostar shroud. I still have more trmming to do, but in the upper drivers side, there was a big pocket where the fan blades were pushing hot air back through the front of the rad (the shroud is designed with the fan offset towards the passenger side, good for mopars..), so cutting that part back solved the problem. There are still some pockets that im planning to cut out too. I know its not ideal because there is lots of space between the edge of the fan and the shroud, but so far it seems to be cooling good.

[Thin White Duke]

You might have some RTV hanging up in the thermostat or thermostat bad.  Just use the gasket and don't worry with the RTV.

[west]

that chrome therm housing was a pain.
i had to grind it smooth to keep it from leaking,the rtv was a must.
but if it was stuck closed the upper rad hose would be stiff,right?
and i am getting some movement of water,just not sure if its enough.

[oldkimmer]

..........R your pullies under drive?...........that flex fan is useless........u still need a shroud...........kim.......

[PureGTS]

  There's a few things I noticed:

1) Get the timing down to the afore mentioned 10-14 BTDC (I've found 10 - 12 to be about spot on.)

2) If you have lightweight springs in the dizzy this WILL cause you grief in a street application as the advance comes on too quick. Too much advance at the wrong time and it overheats.

3) a 700 seems a bit light for a 408 (I use a '70 440 AVS on mine, but I have a 780V/S on the shelf) especially when you consider a 340's best friend is a 750. You said at idle it comes up slow but at driving RPM's 'it get hot'. The carb may be jetted too low causing it to lean out. The main jets are on line and metering the fuel at higher RPM's. Lean it out and you'll get excess heat too and quickly

4) A shroud will help and in your case looks absolutly needed! To get the fan to work without a shroud it has to be really close to the radiator. So close that if your knuckles don't bleed from rubbing against the radiator core while installing the fan bolts...  it is too far away.

5) The theremostat issue, I think at this point, it has been talked aboput enough. But does the thermostat have a air bleed in it? If not drill a 1/8Th inch hole next to the outlet in the thermostat. This will help purge the air in the system when filling it up and driving. At 1/8th of an inch it doesn't have the capacity to do any harm but it will dump air quickly.

6) Did the cooling system purge the air pocket that gets trapped in the heads? I would think so due to the miles you say you have driven, but if everytime it gets hot you don't get the air out it could still be trapped in there. Long shot I know, but worth checking.

7) Loose the chrome thermostat housing. If the fool thing NEEDS silicone to seal up it won't take much pressure, when it does come, to pee all over your clean engine. I had one, just like your's, and I couldn't get it to seal up no matter how many times I sanded and filed at it. I just thought a cast iron housing would be tacky on a $300 electric water pump. But I refused to let a $10 part stop me from racing. I painted it black and on it went, no more leaks. Besides the aluiminum ones tend to deacy after a while anyway.


The pic doesn't show what, if anything, is in front of the radiator (A/C, the biggest tranny cooler ever made, etc.). I added A/C to my car and the combination of the A/C AND a oversized trans cooler does have an effect. Even though I increased the radiator to a 4 row design with a shroud. Before the A/C was active it ran fine never getting above 180*. Now with the A/C, it is pushing the limits. Fortunately, I don't need the monster tranny cooler as it only has a light stall and is meant for more street duty than all out performance.

9) Off topic - I'd use two - 6 lines from the regulator to each end of the carb instead of one - 8 to feed both ends. Not real critical but it would have better flow. Of course, if it works for you, with no pressure drop, forget I mentioned it.

This should keep you busy for a while...  Make sure you let us know what you do find. Just in case we are all wrong and you find something we never thought of.

[west]

i bought an infrared temp meter at napa for $60 on sale,grainger had em for $95,
anyway it's a cool tool and fun to play with.
with this i was getting readings 30-35 degrees cooler than the gauge.i put it on the block,heads,waterneck and intake next to the sending unit.
this gave me more confidence to run the engine longer.i drove it ten miles and the gauge maxed out at 235 and i got readings about 195-200 with the infrared.

as satellite said it was the gauge.when i built the new motor i bought the wrong sending unit forgetting they need to be calibrated for my gauge .
my timing was also off,it seems to run a little cooler now.
so hopefully with a new sending unit,shroud and hose spring i should be dialed.
I really appreciate the solid advice from all you guys.

GTS:
1. i got my timing closer but i think it still needs some tweeking,stay tuned
2. its not a 408 its a 360,i hope to get the carb worked out on the dyno
3.you got a shroud laying around?I'm searching...
4. i'm ditching that therm. housing the next time its comes off.
5.my fan is 1 5/8" away from the rad,you still think it's too far or was it just the pic?
6.as far as the fuel lines,are you saying i should run 2 separate feed lines to the carb from the reg. instead of sharing one?is that neded on a small motor like this?

[satellite65]

Yay! What do I win?
Seriously, glad you got it figured out. I've found that it's always best to shoot for the obviuos (cheap) stuff first before tearing into anything thats too involved. You would be kicking yourself in the ass if you changed out $700.00 worth of parts only to find out that it was a $10.00 sensor causing all your woes. You should still put the spring in the lower hose and get a shroud but at least you're on the right track.

I gotta get me one of them IR thermometers. I could get a lot of use out of one of those in my line of work. I'm surprised I haven't bought one yet after all these years.

[NYrr496]

I bought one when I was servicing emergency generators. It turned me into a cooling system troubleshooting guru overnight.  Now, my current job is in a building and when the regular engineers get too busy, I'll help out with ccold or hot calls. I walk into an office with the Raytec and the office women always put their hand up and say see how cold I am. It's amusing.

[74swinger]

The shroud is super important.  Think about it for a minute.........engine running at 180 idling, non-shrouded fan pulls in air (but not through the rad) at around 140, engine warms up to 190, non-shroud fan pulls in air (but not through the rad) at around 150, etc, etc etc.  If you had the shroud, then the fixes are much different.

I have run many SBDs in my life, and the fan shroud really, really helps on a street car.  Put this item in (either factory or aftermarket) and everything will settle down.

My advice to all others, don't toss the OEM stuff, try to make it work.

[satellite65]

Idling, moving slowly, crawling along in traffic, etc. Probably doesn't do very much once the car is up to speed, air's going to move through the radiator whether it wants to or not. Unless the radiator is all caked up with crap, but I certainly don't think thats the case with your car.

[73swinger]

thermostat in backwards?