Overheating Issues, Perplexed

[Rick Yeager]

What should the difference in temperature readings with an Infra Red Thermometer when the termperature from the lower hose is subtracted from the the temperature of the upper hose on a good running radiator? I read one place that it should be above 40 degree F but this seems a little small to me. If this were known, one could readily know if the radiator was the major problem after the engine was warmed up and the fan running. What do you all think?

Thanks, Rick

[Eljaro]

Are you absolutely sure that P/N 8805 Victor Edelbrock water pump is what you have and is for counterclockwise rotation? I have read of mislabeled waterpumps. Most pumps are for clockwise rotation. Also make sure to get the air out by unscrewing the temperature sensor on top of the intake manifold next to where the thermostat housing is and with the stopped engine wait till water comes out there.
Maybe I am reiterative on this, but having the wrong waterpump is after all what you have tried the only option left coming to my mind.

[elmariachi]

Originally Posted by Andrew Teal

I think someone else said how inportant it was to shroud the front also so all the air goes thru the rad. I put on the biggest fan i could get for got how much it flows. The pipes should be coated to cut down on radant heat. Also you really need a oil cooler and a seven qt. oil pan. which cuts down on heat. I run Amsoil oil and there coolant.

I am running ceramic coated headers and pipes and the front is completely shrouded on sides and bottom. I am using an 8 quart Armondo road race pan and though I don;t have an oil cooler, it is not going to solve this problem because a.) the oil is not heating up past the coolant and b.) Having an oil cooler will not help when sitting still (unless I add fans to it too.)

Originally Posted by Eljaro

Are you absolutely sure that P/N 8805 Victor Edelbrock water pump is what you have and is for counterclockwise rotation?

Yes, absolutely positively without any shadow of a doubt, its an 8805.

[bran3b]

This may have already been explored or ruled out but I had a similar overheating problem caused by a lean condition, mine was a damaged fuel line but could you have a lean idle circuit that is causing the overheating? I spent 2 summers fighting my problem talking to experts all the time but until I found the fuel problem nobody suspected the A/F mixture.

[elmariachi]

Based on the spark plugs, if anything I am right on a idle and slightly rich at mid and WOT.

Thanks,

Jim

[vettestr]

You have been methodical and seem to have a firm grasp on how everything is built or needs to function. I went back to the beginning to re-read all that has been done. Many good suggestions have been added by the gang but you are in the same place so back to basics.

Ron Davis is local for me and taught me a few tricks or system checks. All coolant systems works best under pressure and a magic number seems to be 12.5 PSI as the MIN. and that is easy to verify (a fuel pressure gauge works great). As a tool only install a gauge in the manifold somewhere as a system check. Use water and additives to lube as well as an anti-corrosion agent as I don't agree with the 100% coolant suggestion but water for test period will work fine. You tested T-stat and all flow related items but pressure will be a sanity check. This leaves the engine and it runs well with good looking plugs but a lack of timing would not show up under tests you mentioned. You mentioned No Pinging etc... I know you verified timing against the marks but go 1 step more. I would be tempted to roll in initial timing until it rattled or bumped against starter then check to see what timing marks are showing again as a sanity check. If you have 45* you know the marks are wrong somehow, you could do a piston TDC stop and check marks that way too???? Your A/F ratio looks good and engine runs good but if timing marks are off by 20+ degrees retarded you may not know it on a new install and that would be easy to miss.

The waterpump and pulleys were covered, I use 15% overdriven as the minimum and 20% is even better for pulley ratio. You can look for more issues with fans and all that but if it overheats at hi-way airflow with shrouding on the inlet side and any fan working on puller side I would suspect engine caused issue. How about some new photos of rad inlet/outlet sides with shrouding?

[DAVID GAGNARD]

El;

I've used thermostats just like the ones in your photo.. While the gold one on the left may be the best flowing, I've had the worst luck with them.... I've had the best luck with the el-cheapo Auto Zone ones in 180 degress like the 2 on the right, I would also suggest 4, 1/8 holes in the thermostat flange......I always test them before installing them in water just as you did and let them cycle 3 or 4 times just to be sure..... had one last year that opened and closed perfectly the first time and on the second cycle as it was closing it closed "off center" and was stuck at about 25% open...

Was has me puzzled is the "boiling" back of the water in the expansion tank, that ain't good........

On my Mustang, I run the 180 thermostat with 4, 1/8 holes and an 17inch diameter electric fan (curved blade, they work better than straight blades I've found) with a manual on/off switch....On the highway I never have to turn on the fan, the car will run 180 degrees as long as I'm going 40 mph or more no matter the outside temp. In city driving I leave the fan on and it may creep up to 185 in prolonged stop/go traffic, but that's about it....

I'm running a 351-W and a larger radiator than you have,so we're not comparing apples to apples here....

My radiator and motor combined hold somewhere between 3 and 4 gallons, I think.....

I would try the water restictor instead of a thermostat, just to eliminate the thermostat, it's a quick and easy change, as well as a smaller water pump pulley or larger crank pulley....

I'm like vettestr, I'd like to see some pics of the front of the car as well as from inside looking at the back of the radiator.....

Something just doesn't add up.....Your set-up should work without any problems as I've seen smaller radiators/fans and the cars ran o-k temp. wise...........

I don't recall seeing it, but are you running a puller or pusher fan??both????Pusher fans in the front may look peroid correct, but actually can restrict airflow,a puller, shrouded fan on the rear are the most efficent and when off, will not restrict airflow nearly as much as a front mounted pusher fan........

David

[Blas]

Just a thought...
Assuming the fans are in the engine compartment, they should be "pulling" air into the engine area...

[elmariachi]

Originally Posted by vettestr

Ron Davis is local for me and taught me a few tricks or system checks. All coolant systems works best under pressure and a magic number seems to be 12.5 PSI as the MIN. and that is easy to verify (a fuel pressure gauge works great).... I know you verified timing against the marks but go 1 step more. I would be tempted to roll in initial timing until it rattled or bumped against starter then check to see what timing marks are showing again as a sanity check. If you have 45* you know the marks are wrong somehow, you could do a piston TDC stop and check marks that way too????How about some new photos of rad inlet/outlet sides with shrouding?

We are testing the cooling system pressure this afternoon and checking for combustion gasses in the coolant. But talk to me more about the timing issue. When I left the dyno we had a timing mark on the balancer with 18 initial and 18 in the advance, total 36. I have since gone up to 20 initial based on changing to the 750 Mighty Demon with 18 additional advance, total 38 by 3k rpms. I am using the aftermarket timing pointer that came from Professional Products with the balancer. It mounts at the 11 o'clock position in the OEM holes and PP says its suitable. So there should be no issues there right? How could timing not be right in this scenario?

Originally Posted by DAVID GAGNARD

El;

I've had the best luck with the el-cheapo Auto

Was has me puzzled is the "boiling" back of the water in the expansion tank, that ain't good........

I would try the water restictor instead of a thermostat,

I'm like vettestr, I'd like to see some pics of the front of the car as well as from inside looking at the back of the radiator.....

I don't recall seeing it, but are you running a puller or pusher fan??both???? David

Originally Posted by Blas

Just a thought...
Assuming the fans are in the engine compartment, they should be "pulling" air into the engine area...

Ordered the restrictor package. I have reinstalled the NAPA t-stat that opened the widest and closest to 180*. Didn't drill more holes, trying to change only one or two things at a time. Refilled with distilled water, headed to the radiator shop for testing. Fan is a 3600 cfm Zirgo puller. Shroud is a JEGS aluminum trimmed to fit tightly and made for 16" puller fans. More pics later today but here's the shroud:

[DAVID GAGNARD]

El;

Your on the right track checking the cooling system. The puller fan and shroud could be a problem as I see it in the photo, all the air must past thru the 16" diameter hole where the fan is located, and since the fan itself is shrouded, I don't think you need that real nice aluminum shroud, that could be your problem.....I would remove the aluminum shroud and try it again.....

On my street car as well as my racecar, I use a puller fan similar to yours (slightly larger),but no other shroud other than the one with the fan....At highway speeds, you should have enough airflow to keep the motor cool and as I see it, the shroud would force all the incoming air thru the small 16" diamter fan hole!!!!!!!!!!!!!!!!!!

As to the timing that vettestr aluded to, simple check is to bring # 1 piston to TDC and see where your pointer is in relation to the timing marks on the damper, that would check/eliminate that as a cause...

David

[vettestr]

Originally Posted by elmariachi

We are testing the cooling system pressure this afternoon and checking for combustion gasses in the coolant. But talk to me more about the timing issue. When I left the dyno we had a timing mark on the balancer with 18 initial and 18 in the advance, total 36. I have since gone up to 20 initial based on changing to the 750 Mighty Demon with 18 additional advance, total 38 by 3k rpms. I am using the aftermarket timing pointer that came from Professional Products with the balancer. It mounts at the 11 o'clock position in the OEM holes and PP says its suitable. So there should be no issues there right? How could timing not be right in this scenario?

Hey THE,
You do have fact she was run on the dyno to confirm timing is correct but in the world of Hot Rods who knows. With aftermarket covers, bolt on pointers not to mention distributor in and out a few times all is possible. I am sure not questioning anybodies abilities or smarts, throwing ideas out over the net only. I have seen 4 ways the marks can be wrong and just want to eliminate the possibility $hit happened.

You know what sounds right or more important what way off sounds like. Reach up and grab a handful of distributor and throw an extra 10 or 15 degrees in her as a sanity check only. Blirp the throttle off idle and listen for crisp response or a lazy lay-down response. Set the initial timing by ear and get it to rattle a little under load of lugging the engine ( put in 2nd gear when you should be in 1st gear and let engine pull a little) all at low safe RPM's . Set it by ear to a few degrees below where it wants to rattle and it bumps against the starter when hot, not hard or long enough to hurt anything of course. Then when you find that point check to see what the timing marks are telling you. If the numbers show about what you would expect great, if not you need to find out why. Either way it is fast, easy and cheap way to eliminate a lot of weird but possible problems.

I know it should be and probably is right but a lack of advance would sure cause this grief. A quick double check is what I was suggestion to just take a bunch of things out of the picture since you have done the normal stuff.

[mr0077]

El, David is right, the shroud you have is compounding your cooling problems, take it off. In general (with electric fans), the air should flow through the whole radiator when moving and get pulled through the electric puller fan when idling. A tapered shroud (which you don't have room for) might let air move through the radiator and through the fan, but at speed the air hits the flat surface and it just blocks air flow.
On timing, if you have the timing too retarded, it will overheat, particularly at idle. When the mech and vac advance come in at higher revs it will "solve" the problem a bit, but you would likely know something was wrong, 'cause the car would run like a dog if it was that far retarded. Still worth checking...

[elmariachi]

Originally Posted by mr0077

El, David is right, the shroud you have is compounding your cooling problems, take it off. On timing, if you have the timing too retarded, it will overheat, particularly at idle. When the mech and vac advance come in at higher revs it will "solve" the problem a bit, but you would likely know something was wrong, 'cause the car would run like a dog if it was that far retarded. Still worth checking...

Okay guys, removing the shroud will back me up one notch to where I was last weekend. Car will run great and cool down the road, but will not cool well at slow speeds or idle. Can I safely advance the timing beyond 20*???

So....

Once I remove this shroud my car runs great at 180* down the road, no knocking/pinging/dieseling at shut-down. Car heats up to 110C if left sitting still long enough.

I am headed to do the coolant eval.

[CobraEd]

If the timing is retarded the engine will run very hot. Check to ensure that your aftermarket pointer is right. Also make sure your fan is wired right and is pulling, not pushing.


.

[DAVID GAGNARD]

Originally Posted by elmariachi

Okay guys, removing the shroud will back me up one notch to where I was last weekend. Car will run great and cool down the road, but will not cool well at slow speeds or idle. Can I safely advance the timing beyond 20*???

So....

Once I remove this shroud my car runs great at 180* down the road, no knocking/pinging/dieseling at shut-down. Car heats up to 110C if left sitting still long enough.

I am headed to do the coolant eval.

Since your main problem is stop/go traffic, add another fan just like the one you have in the rear, but to the front of the radiator, pushing........I did this on my street car for parades, I added a 12" fan (cause I had one)(I'd go bigger,at least 16") and reversed the wiring so it pushed thru the radiator, helped tremedously while doing 45 minute to one hour parades on the Forth of July when the outside temp was 100 degrees!!!!!!!!!!!!!

Put the puller fan to one side and the pusher fan to the opposite side of the radiator and I think you'll be fine is city driving.......

Your radiator is not as large as I would like to see, but that's all you can use on your car, so you need to increase low speed airflow, the only way is to add more fan/fans........

Looking back, your radiator is the same as both my cars,cept mine are 28" wide instead of 27" like yours, not enough to worry about..... I would suggest putting the 16" fan you have in the front, pushing and get a 17" fan like in the picture I posted and put it in the rear pulling, that with a change of pulleys and you should be good to go.........

BTW: put the front fan on a manual switch and use as needed.....Not sure how your prsent fan is wired,but I keep mine on manual switchs, I don't trust those automatic switches to come on.......

David

[mr0077]

Interesting tidbit of trivia on shrouds...during development of the C2 Corvette (the Stingray), the engineers found that the big block cars would overheat at high speeds. On that car, the air came through two openings below the front of the car, went up then back down through the radiator (that was leaned back at the top similar to some Cobras), then straight back toward the motor-driven fan. Because of the long nose and the engine setback, it had a shroud that was about 10" at the top and about 26" at the bottom. The engineers found that at high speeds the fan acted as a plate and would restrict air flow between the radiator and the fan. They came up with two fixes, one was shroud flaps that were pressure operated and the other was shroud flaps that were thermo operated...in either case, the flaps would open up to let air OUT of the shroud when needed for air flow and better cooling. Both ideas were nixed by the bean counters as unnecessarily expensive and complicated...

[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.

[DAVID GAGNARD]

El;

You've tried a whole bunch of things and some have helped and some have not, that's part of the process,been there/done that.....

I think your going about it the right way and I have been going over this in my mind and it's starting to get "personal" with me.

So far, you've done pretty much all the recommend "fix's" cept the pulley and a different fan.......pretty much the same results, so I'm gonna box up that crappy pulley and a fan and send to you to try....

The fan is 1/2 of a factory dual fan set-up off some Mitsubishi car I picked sometime ago at a body shop. The actual blades are 16"s in diameter and the whole thing is about 18"s in square.I cut it in half and used one half on my engine run-in stand, all I have is a small aluminum Griffin radiator (old) on the stand, maybe 24"s wide total. I ran my 331 race motor on it for a total of 3 hours a while back, with the longest continous run time of 1 hour at varouis rpms and it never,never got above 180.......On the race car I have a 17" or 18" electric fan (Spal, I think) but a bigger radiator and it does the job. I think it is a 3600 cfm fan, but the Mitsubishi fan will blow that and at least half that again if not more, it's a freakin hurricane when on, I'm guessing at least 5000 cfms...

It's worth a try and by switching the hot/ground wires, you can make it a puller or pusher....

E-mail me your mailing address at

cda351@bellsouth.net

and I'll get it out to you in the next day or two.....if it works, pay the shipping and it's yours.......
As I said, it's starting to get personal with me and I want to see it fixed as bad as you, been in the same situation before and I know it ain't no fun going for a drive wondering when it'll get hot and always watching the temp gauge!!!!!!!!!!

David