Overheating Issues, Perplexed

[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

[DAVID GAGNARD]

Here's picture of my racecar radiator/fan set-up.... use the exact same thing on my street car....The racecar fan is 17" diameter and the street car fan is 19" diameter..... as you can see, plenty of room for airflow at highway speeds with or without fan running......

I think the new shroud is the problem........

[Monster]

I have been reading through this thread and wanted to correct some of the information and provide some of the solutions that have worked for my FE in trying to resolve this same problem.

Note: Your problem as has been mentioned appears to be air flow at lower speeds. Your fan & shroud appear to be fine at 3600CFM and the diameter does not seem to be an issue at 16". I would suggest checking or lowering your fan relay settings, using a manual switch when you get into traffic and reducing your T-stat to allow more cooling margin and possibly adding pushers to help at lower "city" speeds.

I started to write my findings and then I found the article that applys and provides the tech data (though it was written for Jeeps it did a better job than me). cooling article

here's another article on "coolant" coolant article

Bottom line that worked for me:

-25% "coolant" mixture (note that water is best for disapating heat but it has a lower boiling point which can be raised under pressure (pressure cap) and with the addition of some "coolant" below 50%

-Shrouded fan (I have a Blackmagic 16" 2800CFM) note that CFM is more important than fan diameter

-Manual Fan switch (used in traffic conditions since the "automatic" Blackmagic temp control is a contact type bulb on core and does not come on until the temp is at 200 which doesn't switch on the fan early enough to provide fast cooling

-Pusher fans. These provided an extra 5deg cooling as well as faster cooling

Edelbrock waterpump- the CNC design does provide better balanced cooling in an FE, less cavitation (turbulance at impeller) and did reduce operating temps 10deg.

160 T-Stat- contrary to the article I've found that a 160 provides an extra operating margin for cooling with no downside, I did add a single 7/32 hole.

13lb Rad cap- I've seen folks using 15lb+ but had some concerns about that much pressure and my older expansion tank (see below)

Results are that since making all of these updates to my cooling system my car (FE 500hp) runs at 170 highway and 180city and on hotter 90deg days in city in stopped traffic for 20+ minutes it may get to 195deg. I've been running these updates for 15K miles without any cooling issues......except for a recent pinhole that developed in my expansion tank due to age

good luck,
Mike

[767Jockey]

I think David and Mr0077 have it right. The problem isn't that you added a shroud, it's the size and shape of the shroud that you added that is causing you the problem. Long story short, from the looks of the picture you posted, the rear surface of the shroud is much too close to the back of the radiator, effectively blocking all airflow through the radiator except for the area ahead of the hole for the fan. Effectively, you now have a radiator that is 16" in diameter, the rest of it has blocked airflow.

It was explained to me once that a shroud is in effect a huge sealed plenum behind the radiator. The puller fan creates an area of low pressure in the plenum, which draws air in through the front of the radiator while at less than highway speeds to balance the high pressure in front with the low pressure in back. If the plenum is not large enough (the shroud is too close to the radiator) there is not enough airflow to pull the air through the areas where the shroud is too close to the radiator, so the only airflow you get via the fan is straight through the area directly in front of the fan. This also blocks ambient airflow through the rest of the radiator at highway speeds. This would seem to hold water in your case since now not only is your low speed and stop and go overheating problem still there, but the shroud is also blocking airflow at highway speeds since it has blocked all airflow through the areas where the shroud is too close to the radiator.

Put another simpler way, there are two ways to block airflow through a radiator - you could put a piece of cardboard in front of it., or you could mount the same piece of cardboard tightly behind it. Either way, you cut off airflow through the radiator. In effect you have mounted a piece of cardboard with a 16" hole in it behind your radiator. The shroud needs to be bigger with regard to depth, creating a plenum for air to move. Sorry for the rambling, writing is not my forte, hopefully you get the concept of what I am trying to say. Good luck.
Doug

[elmariachi]

Originally Posted by 767Jockey

I think David and Mr0077 have it right. The problem isn't that you added a shroud, it's the size and shape of the shroud that you added that is causing you the problem. Sorry for the rambling, writing is not my forte, hopefully you get the concept of what I am trying to say. Good luck.Doug

Well its definitely part of the more recent problems. In order to keep some process to this, I am only making a couple changes at a time. Here is what I have done (which essentially backs me up one step to before the shroud):

1. Drained all the coolant from the radiator.
2. Removed the 180* hi-flow t-stat and replaced it with the 180* NAPA shown in the upper right of the earlier pic. I actually installed it, then pulled it and added 3 more holes per David's instruction.
3. Filled it up with distilled water only up to the half level mark in the expansion tank.
4. REMOVED THE SHROUD.

I fired it up and it warmed up as usual, though it warmed up a bit quicker this time I assume due to the air pockets in the engine and the 3 extra holes in the t-stat. To make the most of my available time, I didn't wait around and see how hot it got. Once it was at 80C/175F I headed out to the radiator shop. Its only a mile from me so I took a longer route of about 5 miles. The car stayed at 180* the whole trip except at two lights, where each time while sitting it got up to 90C/195*.

The radiator guy tested it for combustion gases in the coolant said there were NONE. Hallelujah, that shi!!y news could have ruined my day and my career as a backyard FE builder completely. He said he couldn't add much else without having the radiator out to test it, but he did say it appeared to him that the radiator was not able to handle the engine heat. But he also said it could be fan or water pump. He agreed the fan apperas to be driving LOTS of air.

So I took it out and ran it for about 10 miles and it never got over 185-190*, except at one redlight where it went up to about 90C/195F. When I pulled back in to the drive I parked it and let it idle. Over the course of the next 4-5 minutes it slowwwwllllyyyy climbed back up to 105C/220F, which is when I decided to start hosing down the radiator to cool it off. That dropped it back to 90C/195F, and I killed it. I will burp it but based on prior burps in the sessions before adding the shroud, I am not optimistic

I did try using a small shop fan in the nose and it didn't seem to matter. I may get a bigger box fan and try it tomorrow.

So that's where we are, right back to where I was when it was suggested I needed a shroud. I agree with the comments that THIS shroud is not designed to solve my problem, its too close tho the back of the radiator, as was proven above.

By the way, I called PRC this morning (they built this radiator.) Out of 130 Hurricanes sold, they have not had anyone come to them with this problem. They suggested water pump or fan flow. Need to get a new IR gun so I can do some spot temp checks on the radiator face for them.

EDIT1>> That gurgling in the radiator was likely because the expansion tank was too full or that hi-flow t-stat. Its not doing that at all now, its flowing normally through the tank at half level.

EDIT2>>>I appreciate the remarks about the timing. I am going to check that over again for the hundredth time tomorrow, and may giver her another 4 degrees base from 20 to 24 just for the hell of it and see what happens.

[DAVID GAGNARD]

Good news, your eliminating one thing at a time and seeing some progress........

Check with Edlebrock or Stewart/Warner or any other aftermarket water pump manufacter and see what they advise for pulley sizes and overdrive/underdrive %'s!!!!!!!!!!!!!!!!!!! I think you'll see the recommend minimum 15% to 25% overdriving the water pump to the crankshaft speed.....Could be your next step....

If you have an extra fan laying around, try mounting on the front and see if it helps, bet it will....


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.

[vettestr]

I was off line while a few posts came in... David G is right about a TDC on piston and look at marks. I just find it easier to listen for rattle but either way.

007- I am not sure being retarded some amount on a new build would be that easy to know/catch. Maybe it would just run that much quicker as it is all new to him??

I agree the shroud does look restrictive but should work great at an idle???