Overheating Issues, Perplexed

[elmariachi]

The restrictors and new IR gun arrived yesterday and we are going to do some temp testing today and I will be trying the restrictor tomorrow. CC user "Patrick" has been kind enough to lend his opinion in a number of one-on-one emails with me with regard to timing and carburation tuning. Patrick was of the opinion that 20* base was possibly too much initial timing and that could have been contributing to the additional heating. We have backed it off from 20 initial to 16* base + 21 advance and tuned the Demon accordingly. I won't say the carb is running exactly right yet or that I've sorted out the ideal curve, but I am confident that the timing was contributing the to build-up of some of the heat. And the car idles at 1000 rpms albeit very lopey due the high lift cam using the current mixture tuning. Today we are going to idle it in the heat and see to what extent it overheats, and that will give me a chance to take some temp readings on the radiator face.

One of my biggest gripes about CC is that, unlike several other forums I frequent, there are so many threads started by people who never care enough to come back and "close the book." That will not be the case here; however this ends up will be detailed here for those that can benefit later.

Thanks, more to follow.

[67FEfastback]

I've been dropping in on this thread from time to time.
I'd say to keep methodically going through everything.

Different car, but similar problems. Fortunately I had a pressure tester to help as well.
FE 1st boiled over. (new rad-high flow 'stat)
Added an expainsion tank
pressure tested the system
fan clutch had failed - replaced that
pulled the 'stat it had stopped opening (brand new Mr gasket)
tested the rad cap = NFG not holding pressure.

Put it all together
No more boil overs
Still hot at traffic lights, heats up when spirted on the freeway
Added twin elect. pushers
Better but it's still winter / spring.
Have a new BB aluminum raditor to go into the car, in a couple weeks.

[elmariachi]

Originally Posted by 67FEfastback

I've been dropping in on this thread from time to time.I'd say to keep methodically going through everything.

Thanks for the encouraging words. We just did some temp testing, 1000 rpm idle, outside temps about 85F and 50% humidity, hot midday sun, light breeze, hood up. Temps rose slowly through about 15 mins idling up past 90 finally to 100*C. At 100*C, the IR gun says temps at the radiator intake pipe is 205*F and at the lower opposite corner at the exit pipe its 195*F, only 10* difference. Not nearly enough I'd say. We shut her down at 100*C so I don't yet know what she would climb to following the tuning exercises.

Engine bay temps on intake and carb are around 165-190 with IR gun with dash gauge showing 100*C. Oil pressure is good (25 psi) at idle and oil temps were around 95*C/205F.

I am tired of wrenching so I am going to get in the pool and take her to the Saturday night hot rod drive-in tonight and enjoy her. Restrictor testing tomorrow.

Thanks,

[ERA Chas]

El,
X 2 about the 'close the book' guys!
And the guys who ask for help, get serious responses and never revisit the thread they started-much less appreciate the help they got. Makes me hate helping out if the guy doesn't care enough to reply whether the instructions helped or not and post results.
Off my soapbox now and bought more popcorn seeking your very detailed and helpful methods at solving this common problem.
Thanks from me.

[DocDirk]

Will have the very high CFM fan in by Tuesday and hope to post some running results on Wednesday... There is very little I haven't done that's been described in this wonderfully detailed thread except the last ditch option of moving my transmission and oil coolers off to the side of the radiator to optimize incoming air temps...hope not to have to!

I'll keep you posted though on Thursday my 16 y.o. and I are taking her on her maiden voyage to Arizona and back to mid Calif...hope to find a few stretches of Route 66 still driveable.

Regards,

Dirk

[67FEfastback]

Aluminum rad will get installed in a couple weeks. Much thicker than the old one.

[coinop101]

My 427 side oiler runs best between 190 - 210 F . Also installed
1- Edelbrock hi flow Rad. Pump
2- Hi Flow Thermostate
3 Like 90 % anti freeze / coolent
4- 2800 CFM puller fan .
5- Flushed Radiator
6- Removed rear hood gasket to allow heat to excape .
Big blocks do run hot .
Peter

[razerwire]

Something to think about also, my bennett car has stainless steel headers with full polish stainless side exhaust, there is a lot of radiant heat in engine bay and off side pipes , cools off quicker than steel exhaust when shut down, but I can feel heat in foot boxes and side of car when running. Motor is 427 f.e. 1965 block and heads, cast iron, runs 185 to 190 degrees. The csx car has HPC coated headers and side pipes. The finish is ruff almost like velcro. The reason is to cut under hood and side exhaust temp. The dry sump tank is in right fender above exhaust and even with shield and heat barrier ,coating was needed to keep from overheating oil. Motor is 468 f.e. Kroyer/Shelby block and heads, 670 h.p. , runs 80 degrees c. You can feel the diff in under hood and side exhaust temp. You would have to work real hard to burn leg, there is that much diff. The Bennett car you don't want to get close to for 10 to 15 min after shut down.

[elmariachi]

The restrictor testing has begun. The largest of the 3 in the kit is installed. I drove it tonight and it behaved just as before, cool down the road, temps rising to 90-95C at average timed red lights, then up to 100C sitting in the driveway idling. I'll install the smallest restrictor tomorrow eve.

I do want to mention that as a result of the tuning and timing last week, the overall time to temp rise at lights and when idling is slower than before, but I still fear that if I were to let it sit and idle it would eventually melt down. Not going to try it to find out.

[edwhite7]

I noticed in the original post you stated that you had the bypass hose installed. I had this exact problem and it went away after I plugged the bypass and started running water wetter. I am sure others will disagree but I am convinced that the engine is to far from the radiator and the pump will bypass rather than pump through the radiator at idle. I also drilled some 1/8 holes in the thermostat to help it bleed air through the system and installed an overflow tank.

[elmariachi]

Originally Posted by edwhite7

I noticed in the original post you stated that you had the bypass hose installed. I had this exact problem and it went away after I plugged the bypass and started running water wetter. I am sure others will disagree but I am convinced that the engine is to far from the radiator and the pump will bypass rather than pump through the radiator at idle. I also drilled some 1/8 holes in the thermostat to help it bleed air through the system and installed an overflow tank.

I have tried the t-stat holes, no dice. But the notion of the bypass allowing water to recirc is interesting. Are you saying that the bypass is keeping water from being pumped into the expansion tank and on into the radiator?

[edwhite7]

For me the holes were just to keep air from collecting behind the t-stat. It is designed to sense water and air can cause the temp to go way high before it finally opens. After it opens it can then regulate normally. This tends to happen in cars with t-stats mounted at the top of the system, they collect air. I believe that the bypass is keeping the water from being pumped through the expansion tank and then the radiator. It is just to far and easier to bypass. I am sure that there is a good reason for the bypass but my car will overheat in traffic with it connected. If I sat more than two or three minutes at idle I would turn the heater on and after it passed 220 F I would have to shut it off and leave the fans running. I would bump it over without starting to get new water into the heads until the temps came down. Those were the days, water wetter made a big difference and now I never think about it. The car has been on the road more than 20 years and has never overheated.
I originally cut through the existing hose and worked it off without removing the pump. I was able to slip some hose caps on and clamp them with worm clamps. After I was convinced that it worked I removed the pump and plugged the ports with some pipe plugs.

[vector1]

http://www.stewartcomponents.com/Tech_Tips.htm

[undy]

El,

Do me a favor, get a volt meter and read your puller fan voltage at the fan relay outlet or fan motor (better) with the engine up to temp, at idle with the usual accessories on. Take a new reading with the headlights on too. Let me know what you find.

The highest CFM puller fan will pull like poop if it's run in an extreme under-voltage condition. The "typical" replica wiring harness is marginal at best for hi-amp fans (inadequate conductor sizes). Also, a lot of alternators struggle to put out 10 to 15 amps at idle.

I think you'll end up discovering the only way you're going to improve things is raising the air CFM across the "full face" of the radiator at idle. Your "tight to the radiator" shroud isn't helping things either.

Dave

[danc30]

I still say nix the glycol. Go with straight water and a bottle of water wetter. Mine runs about 15-20 degrees cooler like this.

Water cools a lot better than glycol........

Dan

[elmariachi]

Shroud was already removed. I'll check the voltage again and reply back later this eve, but it was 13.1 when I checked last weekend. Dan, I had already drained the coolant/water mix and gone with straight distilled and water wetter as you mentioned on the Hurricane forum. I was hopeful, but alas, no change.

[CHANMADD]

Originally Posted by edwhite7

I noticed in the original post you stated that you had the bypass hose installed. I had this exact problem and it went away after I plugged the bypass and started running water wetter. I am sure others will disagree but I am convinced that the engine is to far from the radiator and the pump will bypass rather than pump through the radiator at idle. I also drilled some 1/8 holes in the thermostat to help it bleed air through the system and installed an overflow tank.

I would go with this answer as the solution!!

[Monster]

It appears that you have not applied the suggestions from a number of folks that have been through this issue, that your issue is AIRFLOW and that your problem appears to be an issue with the design of the shroud that you previously had installed. (not pulleys, t-stat,timing etc.)

Shroud's are a critical component in cooling, just look at any modern car. Not installing one reduces the effectiveness of your cooling system (especially at low speeds)

From SPAL:
The efficiency of your cooling system depends on the following factors:
Radiator core size (the size of the radiator inside the tanks where the cooling tubes and fins are located.) This space determines the diameter of the fan.
Space required for a cooling fan. Our High Performance cooling fans require 3.5-4.5-inches in depth (from the radiator core to the fan motor cap). This distance may be shorter if the cooling fan can be offset on the Radiator to clear the water pump.
Radiator material and number of cores. An aluminum radiator is more efficient than a copper radiator.
If a shroud is utilized: For the most efficient system a shroud should be utilized. The shroud forces the fan to pull air across the entire radiator core area, opposed to a fan without a shroud that pulls air only across the diameter of the fan.

Currently, without a shroud, in traffic (lower speeds) you do not have sufficient airflow going through your radiator. Air is only being drawn through the area directly in front of your puller fan. The area of your radiator according to what you posted earlier is approx. 393.75sq.inches and you have an 16" fan (201sq.in) which calculates to approx. 51% coverage/draw through your radiator.

As Olddog, 767jockey and Brettco observed the design of your "old" shrould appears to be an issue (not allowing sufficient draw). By increasing the space between the shroud and radiator to a minimum 1" at the outside edges and tapering to 2" at the fan you will increase the draw through the entire radiator which will improve airflow/cooling at both low and high speeds.

Try this, what do you have to lose at this point.

good luck,
Mike

[danc30]

I have the same radiator and fan set up as he does. I do not have a shroud. I have one of KC's big and nasty 482's and it hasn't gone north of 100C in the hot Florida sun and it was 95 last weekend when I took it out to the beach.....

I have the bypass hose hooked up just as it was when Keith built it, I have a 180 thermostat for a Ford with no holes drilled in it, straight water and a bottle of water-wetter.

I do have Cool-Flex hoses top and bottom, maybe that's it.

I believe it's in the engine set up myself. Waterpump, timing, T-stat, etc.

JMHO.....

I hope you can get this issue resolved though. It's probably something really simple and easy, you just need to find it.

Dan

[elmariachi]

Originally Posted by Monster

It appears that you have not applied the suggestions from a number of folks that have been through this issue, As Olddog, 767jockey and Brettco observed the design of your "old" shrould appears to be an issue (not allowing sufficient draw). By increasing the space between the shroud and radiator to a minimum 1" at the outside edges and tapering to 2" at the fan you will increase the draw through the entire radiator which will improve airflow/cooling at both low and high speeds.
Try this, what do you have to lose at this point.good luck,Mike

Mike, you might want to re-read this entire thread again. I have applied or am planning to try EVERY recommendation made except for going to 100% coolant and plugging the bypass valve. The prior is not even worth trying and the latter is on the list to be tried. I have been very systematic in my approach and SOME of the suggestions were tried repeatedly before I even made the first post. With regard to the flat aluminum shroud, it was installed as one of the things to try and solve the INITIAL overheating problem. After installing it, it caused more problems by making temps rise even while the car was moving. But after removing it, we are back to the original problem, which is the car is fine while moving and overheats slowly when is sitting still for more than 5 minutes. We did try spacing it back 1" and that made no difference, but that could be due to this shroud's design.

I recognize that this thread is getting long and some of you don't want to read it all. Just so everyone is clear on where we stand and what i am doing next in sequence:

**The car runs great and stays cool (180-185*F) while moving. The JEGS aluminum shroud screwed that up, both installed almost touching the back radiator surface and spaced 1-1.5" back from the radiator's back surface.

** The car slowly begins to overheat when sitting still for any period longer than 2-3 minutes. If I don't start moving, it will eventually hit 210F*+.

** The hottest I have let it get is 215F. Not going beyond that.

** I have backed off the initial timing from 20* to 16* and re-tuned the carb. Based on the plugs and vacuum gauge it is tuned correctly, but we won't know for sure until I get the cooling issue fixed and go hit the chassis dyno.

I am currently trying various sizes of restrictors, as recommended. Next step will be to try and plug the bypass as recommended. I am also chasing a smaller diameter water pump pulley, as recommended. Last steps will involve a different shroud/fan combo and finally, a new high-capacity radiator.