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Cooling issues.....

daveSanborn

daveSanborn

Active Member
Don't underestimate the stupid stuff when you're troubleshooting a heating/cooling issue.
Click to expand...

Famous last words......

I need a sanity check....

347 motor/19x16 Griffin double core AL radiator (19x16 is just the finned surface area, not including the side tanks)/16 lbs. radiator cap/Flex fan (but it's a real strong "flex", the fan doesn't flatten out easily)/SPAL 14" pusher on the front of the radiator wired to come on at 190, off at 175.

When I start the car up in the AM, the radiator is almost full and the overflow bottle is full to it's "cold" level. In 85-90 degree temperatures, I can drive 6 miles on the highway (no stoplights) and the temp gauge barely moves off of 100 degrees. Oil pressure is good at a steady 60 pounds while driving.

Once I get into town and start hitting some traffic/stop lights, the water temp hovers around 160 and oil pressure drops to around 50 (warmer/thinner oil). I can drive at 160-180 all day long, but when I slow down/stop and sit at a light, the temp climbs to 190 and the oil pressure drops to around 20 at idle.

After the car is fully warmed up, like on the way home from a drive, I'll sit at the top of the driveway and do some 4000 rpm 30 yard launches (it's a County road with no other cars in sight). After the first launch, I'll notice the water temps up to 190-200 while I'm backing up to launch again. Second launch, while backing up water temp is 210. Oil pressure is great with RPMs, but down around 20 at idle. Third launch, while backing up I'm still sitting at 210-215, but now I notice a puddle of anti-freeze at the launch point. ???

I pull down my long driveway and upon getting out notice a nice clean trail of anti-freeze going all of the way up the driveway (150 yards?). Engine off in front of the shop with the temp gauge at 210.. slowly climbing to 215 area, I pull the hood and the overflow bottle is full and I can hear the coolant "boiling?" within the system (engine/radiator/hoses).

A couple hours later, the overflow is empty and pulling the radiator cap reveals that I've lost some coolant (obviously as there was a nice line of coolant going all of the way up my driveway from the drain line on the overflow bottle).

Is this normal? Or not?

Do I need to try an 18 pound radiator cap?

What effect is not having a fan shroud having on all of this? I realize that without a fan shroud, the mechanical fan is less efficient, but will it reduce the coolant temps at low RPM? Remember that I have a pusher fan on the front that's already running once I'm up to temperature. I thought the pusher fan would take care of things during unshrouded low RPM mechanical fan situations?

With the custom sized radiator (it's a couple inches shorter in height than a standard '66 size radiator), procurring a shroud worth installing is out of the question (unless someone here can point me to some custom sized shrouds). I'm thinking I'll have to get out the metal brake and bend up some tin, fire up the welder and make a custom shroud. After getting it pretty close to perfect and painting it, I could have a couple weekends tied up in it..... and I'd rather not do this unless it's unavoidable.

Thoughts?
 
Oil pressure at 20 on idle is normal during cruise. It sounds like your "leak" is coming from the overflow and at cool down sucking back into rad. leaving overflow empty. I'm sure you know this already which brings you to the stat question. Where is your timing set at on this beast? Low(er) timing at idle and lack of fan shroud will definitely pull the temp up.

WTH am I doing? I'm trying to diagnose THE Dave Sanborn's problems. Edit/delete
 
A couple more questions.....

I'm presently using a 16 lb. radiator cap. What benefit is there to switching to an 18 lb. cap? Will the increase from the additional 2 lbs. of cap resistance stop/slow the coolant from entering the overflow bottle by a significant amount?

TIA
 
It will slow it (18 lbs of pressure) but how much is hard to determine. Need to find out what kind of pressure your cooling system is making. Those consistent hard launches definitely builds the pressure and an 18lb cap may only reduce overflow by a minimal amount. The nice thing is, a new cap is a cheap way to find out.
 
The nice thing is, a new cap is a cheap way to find out.
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Yeah, that's what I'm thinking too. It'll be a LOT easier than building a custom fan shroud, that's for sure....

I'll pick up a new cap here in a minute, drive the car this afternoon and let you all know how it effected the situation.
 
Well..... I'm not sure I fixed all of the problem, but I fixed part of it.

Instead of switching from a 16 lb. cap to an 18 lb. cap..... I noticed there was a 20 lb. cap and figured I'd try it. I'm no longer dumping coolant and the engine seems to be running cooler.... I'm just not sure what effect running a 20 lb. cap will have on the system over the long haul.... it seems like an awful lot of pressure.

Instead of devising a "home-made" shroud for the mechanical fan, I'm looking at replacing the mech. fan with an electric Zirgo fan rated at 3000 CFM..... but.... I already have an electric pusher on the front (rated at 1800cfm?) and I'm thinking that the slower fan on the front may reduce the efficiency of the higher rated puller fan. Thoughts?
 
I don't think you'll have any problems with the 20lb cap as long as everything is tight. Someone with more knowledge can chime in on that one. The biggest problem with running the two fans, as you've noted, will be the "interference". A pusher running half the capacity of the puller will, IMO, make the puller less efficient. Actually, a pusher even turned off will disrupt the airflow causing an inefficient puller. The first thing I would do is contact the manufacturers of the gaskets and see what their tech dept. says. A hose blowing ain't jack compared to a gasket. If the gaskets can handle the pressure, use a 20lb cap with a puller and leave the pushin' to the bedroom.
 
Nope, still have problems....

I was driving around today and ran into a highly modded 5.0. We hit about just about every red light through town together. There was no street racing, but some spirited shifting and RPMs. After I pulled into the office parking lot and was idling through it, I noticed my temp gauge was up around 210. I parked the car and she spit approx. 1 quart of fluid out of the full overflow bottle.

The radiator is just not getting enough cooling air pulled through it at low speed/RPMs.

I've been looking at the below two electric fans.... one has a black plastic housing and the other a chromed plastic housing. I spoke with the manufacturer yesterday and both fans are identical other than the appearance of the housings (same motor, same fan, same output). Summit has some of the details screwed up on their on-line store, but one thing is certain, for $100 less, I'll take the chromed housing one. I ordered it a few minutes ago.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=HFM%2DZFBC16S&N=700+320174+115&autoview=sku

http://store.summitracing.com/partdetail.asp?autofilter=1&part=HFM%2DZFU16S&N=700+320174+115&autoview=sku
 
Actually I think I know the solution. Take that teardrop hood, cut a hole, and mount the new fan on top. Then install the hood. You just need a little more fresh air!
 
Timing is set right at 10 degrees BTDC (with the SPOUT disconnected of course).

I ran into a fella last weekend with a '66 and a teardrop hood... it doesn't really look as bad as I thought it would on the car..... his car, not mine. I mentioned that I had a "spare" TD hood and he asked a couple questions about it. I may move that thing out of my garage yet.

Behind the TD hood is a spare FB back glass. I know the minute that hoods gone, that glass is going to get bumped/broken.
 
Yep. Glass will all of a sudden be in the way. 210 is not bad if that is your idle temp. Just take your temp gauge and rotate the numbers to read 180 at idle. If the new fan doesn't work your only option may be a shroud. Hopefully someone else with more experience can offer up a solution. Another week and I'll be training for MBB so will not offer any technical advice.
 
My understanding of pusher fans are (1) they are not as efficient as puller fans, and that is under debate, and (2) they actually block air flow at speed due to the presence of the fan blades, whether they are turning or not.

The addition of an 18 lb or 20 lb radiator cap will eventually cause something else to fail in the cooling system, most likely a radiator weld joint or a hose to come off. These old cars were designed for 13 lb systems.

I would recommend going to a high flow puller fan and a lower pressure cap. Something is not right with 18 or 20 lb caps, and all you're doing is masking the true problem.
 
I would recommend going to a high flow puller fan and a lower pressure cap. Something is not right with 18 or 20 lb caps, and all you're doing is masking the true problem.
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Randy,

I couldn't agree with you more. I ordered a high CFM fan and I'm going to remove the mechanical fan and plumb the new fan in as a puller. In so doing, I'll remove the lower CFM pusher fan and use one of the radiator caps in my now extensive collection to reduce the pressure.

I'm more convinced than ever that the root of the problem is the shroudless mechanical fan.

When at cruise RPM on the open road, the temp stays at or below 180. It's only when I slow down that the problem surfaces. Leading me to believe that there's not enough cooling air going through the radiator at low RPM/low speed conditions.

The new fan should be here in a couple of days and I'll let you'all know how it works out.
 
Dang Randy, where you been? Have you been lurking around laughing at me the whole time? With Dave's engine being a fresh build, would an 18/20 lb cap cause that much of a problem? I could see an older engine but am curious concerning a "fresh" engine.
 
I'm getting a little nervous about this temperature situation...

I think I may have royally screwed the proverbial pooch, matter of fact, I know I screwed it up!

Background....

The one piece frame that the car rides on has the radiator support/crossmember about an inch too high to run a traditional radiator. I found this out after I ordered a new Griffin a few months ago and the top of the radiator was too high... preventing the hood from closing.

In my rush to get a "shorter" radiator, I cut some corners.... maybe too big of corners. I bought a Griffin custom sized crossflow radiator that's 19" wide and 15" tall (the surface area not to include the side tanks). When I went to connect the lower radiator hose from the EFI motors reverse rotation water pump to the radiator, the narrower size of the radiator put the lower hose directly in line with the PS pump pulley. There was no way in hell a hose would fit onto the radiator and not interfere with the pulley. So what's a guy to do? At the time, this was the only obstacle preventing me from starting and driving the car after 8-9 months of a "frame-off" build.

To make this radiator "work"..... I cut off the driver side lower outlet, welded the hole closed and re-mounted the lower outlet tube over to the passenger side. Now.... it's a crossflow radiator but with the oulet pipe below the inlet pipe. In hindsight, I don't think this was a very good idea....

Think about it for a second.... the radiator has side tanks, not upper and lower tanks as a traditional/stock radiator would. Once the thermostat opens and coolant enters the radiators passenger side inlet pipe, the coolant is dropping straight down through the side tank and gettng sucked out the passenger side oulet pipe. There's no reason for coolant to circulate through the radiator.

I'm such a dumbass. My new 3000 CFM puller fan arrived today, is sitting on the front porch waiting to get installed.... and it's not going to do a lick of good.

I found this radiator and am going to order it pronto!

http://store.summitracing.com/partdetail.asp?autofilter=1&part=FLD%2DFHP20%2D93MU&N=700+4294908331+4294908282+4294924761+4294840126+115&autoview=sku

Where the stock radiator was too high at 19", this ones a little shorter at 17.5" and will fit heightwise just fine.

Where the Griffin (that I butchered) had the lower outlet right in line with the PS pump pulley, this one is much wider, placing the outlet pipe to the outside of the pulley. I'll be able to use a stock 5.0 lower hose to connect the radiator to the engine.

I've spent the last 48 hours racking my pea-sized brain on this cooling issue and the stupid modification to the radiator outlet pipe just hit me like a ton of bricks! No wonder the cars not cooling properly! Once coolant actually starts flowing through the radiator.... and not just the side tank... this problem should disappear.

Okay, now I have a question or three....

Should I just leave the unshrouded mechanical fan in place for now and see how it does with a "real" radiator?

.... or stick to my plan and dump the existing 1700CFM pusher and the mech. fan and install just the 3000CFM puller that's still sitting in it's unopened easily returnable box?

....also, my mechanical water temp sender is currently screwed into a water passage on the rear of the intake. I've heard this isn't the most accurate mounting point on 5.0 intakes. The one front port on the lower intake is occupied by the "190 on/175 off" thermostat for the pusher fan. I'd like to install another sender port onto the cooling system, but where is the best place (other than drilling a hole into the BBK lower intake)??? I've used "sleeves" before that mount into the lower radiator hose, but I noticed that Autometer makes an adapter sleeve for the heater hoses also. These are the "sleeves" I'm referring to:

Radiator hose sending unit adapter:

http://store.summitracing.com/partdetail.asp?autofilter=1&part=ATM%2D2283&N=700+115&autoview=sku

Heater hose sending unit adapter:

http://store.summitracing.com/partdetail.asp?autofilter=1&part=ATM%2D2280&N=700+115&autoview=sku

As I see it..... either the lower radiator hose or one of the heater hoses should be an accurate coolant reading. Thoughts?

Oh and Duane, BP and anyone else going to MB, the less I hear about this down there, the better. You can call me an idiot, but try not to include specific examples such as this.
 
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