Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part MAY's Ride of the Month Challenge!

1 - 20 of 63 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter · #1 ·
New guy here looking for some advice.
Have fixed same problem for other guys but cant fix my own. Built my car from just a body so I have no BEFORE reference. Just mix of performance parts.
I have a efi stroker 331 (crate motor) with vintage air ac. From the time i got this car on the road 8 years ago it will overheat in traffic ONLY at idle with AC on and over 95 degrees.
Can be 100 degrees and ac off its fine. Can start moving at any point and temp will go down to normal until stopped again in traffic. Driving down the road is between 180 to 190.
Can ride it hard and temp will stay below 190.
After 225 degrees is when i shut the air off and it will cool its self right back down.
Now the history- started out with milodon high flow pump and high flow thermo stat. Electric fan and shroud. Aluminum 24 in. Radiator . Swapped 180 thermo about 5 times, Then went to Flex a lite Mechanical fans working my way thru 3 different versions up to 7 blade ( no clutch)
Then changed to new aluminum 2 core 1 in. Tube radiator and changed water pump to flowcooler style. Still no change. Replaced all hoses again (bottom hose is not collapsing) changed pulley sizes, even readjusted clearance between condenser and radiator. Had ac pressures checked. Started my way thru 3 electric fans 2400 cfm to 3000 and now running contour fan swap. No change. Changed idle mixture up and down, changed timing, flushed block and radiator numerous times never saw anything come out. Checked gauge multiple times. (Have 2 temp gauges- 1 dash 1 on efi. Even changed oil pump to make sure i was oiling properly.
Appeartly there is something i missed cause it still doing it. Any suggestions?
 

·
Registered
Joined
·
5,138 Posts
Sounds like you've spent a ton of money trying to solve this problem! I would look into a timing issue at idle and I'm sure others that know about this issue will respond. I've spent a ton of money myself to solve weird issues on my Mustang. Just not your issue. You seem to be determined to fix it!
 

·
Registered
Joined
·
36,555 Posts
I don't see a 7-blade thermal clutch fan on your list. If that can cool a CobraJet with AC, it should do for you.
 

·
Registered
Joined
·
5,355 Posts
Describe how the electric fan operates. What is the trip temperature? Have you verified it? Sitting idling in the driveway and up to temp, fan on or off? Puller or Pusher fan and is the orientation correct?
 

·
Registered
Joined
·
4,911 Posts
The cheapest solution is probably moving... ;o)



When it overheats, if you rev the motor to say 2k while at a standstill, does it drop the temp? I'm thinking you may have a ratio issue with your pulleys. See what the lowest RPM that keeps it cool is, if it works then do the math to get the right pulley ratio.


In a proper situation, a 195 thermostat temp will do nothing to help this situation - open is open after the temp has been reached...
 

·
Registered
Joined
·
5,629 Posts
...or turn the heater on when the needle climbs.:wink:

I have seen the higher * t-stats help with the small rads until it gets into a runaway situation. A low temp becomes the same as having none at all although with a good 24" rad I think it should never reach runaway temps without a bigger problem.
Good idea about raising the RPMs as it get warmer but I dont know if it helps by flowing more water or moving more air. With it only happening at idle on a hot day with the AC on its minor and might not really be a problem outside the mind at all. GM seems better at putting actual numbers on the gauges, a C3 I had 210 was the middle, yellow warning about 230+ and red wasn't until nearly 250*. That has always stuck with me and confirming on other cars with an extra gauge poor running doesn't happen until about 250, iron is tough and can generally handle it, then after that detonation which I think is the real killer from overheating. Lucky Ive never had an aluminium engine or heads overheat I guess.

The simplified logic I picture it as time in the rad helps lower temps. Without being able to quote numbers or % of * drops from top to bottom of rad I just see it as this: With a low temp t-stat the coolant leaves the engine sooner then through the rad, back into the engine quicker, then a shorter time back up to temp then back into rad through the rad quicker to engine and back up to t-stat temp quicker. So with a higher *stat water leaves engine into rad and brings in water that is cool enough(ideally) to not be at temp before the top of the engine and restrict at the stat which slows flow so water is trapped in rad longer so its drops * more. then when it opens again that cooler water takes longer to reach temp so the stat closes thus letting the next cycle of water stay in the rad longer again so that the trip back up to full open temp takes longer once again.
Thats my story and Im sticking to it:yoho:
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #9 ·
Motor is a 87 5.0 block stroke out to 331 using standard rotation pump (both times) you can see flow across top of radiator with cap off,looks normal like any other I've seen.I have tried different timing settings at idle and afr and tested. It either idle bad or made no difference. Motor seems very happy at 15 base.
Have tried puller electric fan(s). All have been full shroud. Mechanical from flexalite that they said was for idling to pull more air.Currently contour set up. Wired right,pulls strong currently with a cooling components fan controller ss-2. Comes on 185ish for low and then high at 195 ish. With ac on fan comes on high anyway.
Doesn't matter if you try to raise rpm while at idle doesn't cool until moving or ac off.
Currently 1 to 1 ratio on pulleys-cvf beast serpentine kit.
Before was overdriven by 1.2 with march pulleys (i believe).
Even using trans cooler to keep out of radiator. Also went as far as lining front of grill/support to only allow air to go thru radiator ( boy, do i catch some air at 80mph)
Used all the brands of local auto parts water wetter additives. Currently 65ish/35ish water/antifreeze mix.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #10 ·
When it happens it slowly gets to 210 increasing more rapidly to 220 and then like its counting up by 2 from there and then i chicken out and turn off ac. Highest ive seen was 235 and motor started running bad (open air filter to engine bay)
 

·
Registered
Joined
·
1,631 Posts
If the overheating only occurs at idle with the a/c on I can think of only two reasons (there are probably more).
First, turning the a/c on is somehow messing with the electric fan, but that doesn't apply as you have the same problem with a mechanical fan.
Second, the a/c is somehow messing with the timing. Check your timing at idle with the a/c on and off and see if there is a change.

Good luck. And keep us informed.
 

·
Registered
Joined
·
2,468 Posts
In a proper situation, a 195 thermostat temp will do nothing to help this situation - open is open after the temp has been reached...
His point remains the same. A 220*-230 isn’t over heating but a 235 would be too hot. This is common in nearly every “over heating” thread where the running temp is under spec (which is where the proper thermostat comes into play) and the high temp is still within spec though at the higher end. A point that is missed on these type threads is if the drivability is impacted. In many cases there is no impact in drivability (though in this case it appears there is under some conditions) it’s only the driver being concerned with thinking the vehicle is out of range when it isn’t.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #13 ·
Have tried checking timing with ac on/off stays the same at 15 base.
I say highest ive seen is 235 because that where i chicken out not that thats where it stops. It will keep going.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #14 ·
I even tried one of those filters in upper radiator hose (pointing correctly) and never got more than one or two tiny crumbs here and there. Finally just left it out.
 

·
Registered
Joined
·
2,468 Posts
Stopping at 235 (or before boil over) good call. Without looking at the specs 15 sounds a bit high as a base. I’m used to using 10 or so (0 on my smogger 67) but I don’t have your engine. Are you checking with the distributor vacuum line disconnected?

I’d have a thermal image shot of the engine to look for hot spots since it looks like you’ve tried quite a lot. That may narrow it down.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #16 ·
Distributor locked out, no vacuum, running fitech efi now. (Had edelbrock carb before with same results).
Good point on thermo scan. About the only thing i havent done is look over with temp gun.
 

·
Registered
Joined
·
2,468 Posts
A temp gun will give you an idea of what’s hot at the surface though an image will delve deeper into it. I don’t know what it costs for a shop to do as I’ve used mine. Could be you’ll need to calculate some pulley ratios specifically for your config.

Here’s a shot of how an imager can help vs a temp gun alone for me solving a cooling issue in my 67 289.

https://forums.vintage-mustang.com/...7-coupe-bringing-back-driver.html#post9937505
 

·
Registered
Joined
·
5,292 Posts
The item in the link may help once you are moving, but probably not while sitting still. I used a similar one on my FF Cobra and it cured the the cars' over heating problem.

1967 1968 MUSTANG RADIATOR/GRILLE MASK
 

·
Registered
Joined
·
5,629 Posts
I have tried different timing settings at idle and afr and tested. It either idle bad or made no difference. Motor seems very happy at 15 base.
.
Running rich=running cooler.
If you can take a few degrees timing out without it making a difference you should try that to see if its enough before the summer ends. If you happen to have a Duraspark ignition there might be some different boxes you could coax some tricks out of.

When it happens it slowly gets to 210 increasing more rapidly to 220 and then like its counting up by 2 from there...
Thats what i mean by runaway-the coolant can't shed enough heat in the rad so its hotter and hotter each time it enters the engine and thus hotter when it reaches the stat, in this case an upward spiral. You are in open loop as is by 195 and have been in constant flow long before 210. It can be delayed or even prevented.

Distributor locked out, no vacuum, running fitech efi now.
.
Another AHA!

Still, in the grand compromise of an analog car cutting off the AC at times is to me a minor inconvenience.
 

·
Premium Member
Joined
·
6,642 Posts
Still, in the grand compromise of an analog car cutting off the AC at times is to me a minor inconvenience.
Is there some sort of switch made that would automatically turn the AC off when the engine reaches a certain temp, ie. cut the AC off at 225*? Not curing the problem I know, but this would make sure it never overheated.

Not sure, but it may just continuously cycle according to where the "kick back on" temp would be set...

Allen
 
1 - 20 of 63 Posts
Top