Ever seen this before?
 

I have heard of it happening, but never actually seen it...

Was driving the Camaro (pretty hard) yesterday, when I noticed the temp gauge was pegged. Pulled over to diagnose... the radiator was not that hot, but the motor was cooking.

Limped it home the 2 or 3 miles, coasting with the motor off as much as possible. In doing so noticed there was no heat from the heater either.
The radiator fans were blowing cold air, but the motor was very hot.

I could only come up with there was no coolant circulating. But the pump was running as normal. No noise, no wobble, no leaking. I removed the belt & the pump pulley spun just like before, smoothly with no noise or looseness. This is a Stewart water pump, supposedly the best pump made.

I called Stewart this morning. I was told their pumps make so much water pressure at high rpm’s that it can sometimes shear the impeller. They only see it happen once or twice a year.


2 hours later…..

http://i1113.photobucket.com/albums/...6/IMG_1498.jpg

http://i1113.photobucket.com/albums/...6/IMG_1499.jpg

Just something to keep in mind for those that run at high revs for extended periods.
This occurred while street driving, with some 2nd & 3rd gear blasts. My rev limiter is set at 6000 rpm's.

I've never seen this before, and wouldn't have believed it if I didn't see it myself.

The fix is Stewart is upgrading my pump to a Stage 4, which has a larger shaft, and a CNC billet impeller. Cost is about $150 to do so.

Just FYI...


Bill

Yes. A lot of circle track guys buy zillion dollar engines and put a $5 water pump on the front of it. They don't last. Wouldn't have thought that a Stewart pump would do that however. Looks kind of rusty. You run straight water?

Have you ever seen this
 

Yes. I was running a similar sheetmetal pressed
impeller on the Pantera that was a ford racing unit
It had a short nose so helped with clearance issues
Broke one then welded the curved portion on another but it failed
also. Both times racing (7000 rpm). Found out many ford gt
guys and kit car cobras were having the same issue
Switched to a flow cooler pump with a cast impeller with no
issues for several years now. Sheetmetal can't take the rpms

Bob

I was surprised by the rust too. I have had the car about 15 months. I use only 50/50 (in Minnesota), but maybe the previous guy(s) used water only, as that was in Texas.
Stewart has 4 levels of pumps... Levels 1 & 2 use the stock impeller, level 3 uses an "improved" sheet metal type that is more durable, and level 4 has their own design billet impeller.

Thanks for the head's up. I'll have to look at what's on my engine, which is an older pump that actually says "Howard Stewart".

As an aside, I spent a couple days with Howard Stewart at a test for work. He is a seriously smart and cool dude. At that time, he had already sold the pump business and was making some custom parts for the team we were working with. I told him that I ran one of his pumps and he got a big grin like I was saying nice things about one of his kids.

"Cool dude"...hahaha.
I love guys that see a need for a better mouse trap, develop the new trap, and create a business. THAT is what hot rod/ entrepreneurship is all about.

I had my motor apart all winter and repaired/ replaced, or cleaned up everything I touched, including the water pump. But I never thought to take the back cover off to inspect the impeller. I felt how the bearing spun, saw no evidence of leaking, and just cleaned it up.

Oh well, live & learn.


Bill

I bet a lot of stuff doesn't like 7000 rpm for long!

Ever seen this
 

Actually 7000 rpm is really not that bad
I have several buddies in Norcal Shelby that
track the hell out of their cars.. the ones that
keep things at 7000 and change springs once a year
seem to have no issues.... A few have tried to push
beyond the 7000 limit and then things seem to break
more often.. my motor is about 10 years old.. I run
3-4 track events a year and can tell you the motor
sees 7000 on almost every shift... but it has all the good
things inside... I do worry things are getting a little worn now

Bob

Ever seen this before
 

I also know that the motors I have babied
seem to break a lot more than the ones I
run as hard as I can.. not sure why

Bob

When you baby a motor, God breaks your parts as punishment for not driving correctly. You have to sacrifice your tires and abuse the everlasting p!ss out of your car to make God happy.

It has also always seemed when you break in a new motor or car or bike easily, it ends up being a pooch. Those that hammer the hell out of them right from the start usually have the fast sh!t. Like you, not sure why.



Bill

Ever seen this before
 

Very true about hammering motors.. Pantera with
a fresh motor 10 years ago went on the trailer, off
the trailer and onto the race track.... never had any
other motor run over a year and 1/2

Bob

That whole break in thing is old school back when rings were different and tolerances for motors were different. Nowadays - the rings are "seated" by the time you've degreed the cam... and with roller cams - we've eliminated the face/lobe mating... Pretty much anymore - you install a motor - fire it off and go racing.

Good information. I always thought the sheet metal ones looked cheap, but never thought about fatigue cracking like that. I guess they probably don't pump as efficiently, but have nothing really to back that up, other than it doesn't look like much like a turbo scroll.

I agree 100%. It doesn't make sense, but it still seems to me the guys who beat on their cars, have faster cars.
FWIW, this is not the only instance my experiences/ beliefs make no scientific or logical sense. How about those "lucky" people who win all the time playing pull tabs/ slot machines/ or drawings? Or get great hand after great hand playing blackjack or poker? Makes absolutely no sense. Me? I NEVER win. Of course, I very seldom play. Hmmm, maybe that's why.


Bill

The story gets another chapter.
I got the upgraded stage 4 Stewart pump back, put the car back together, and took it for a ride. Got maybe 5 miles on it, and jumped on it in 2nd gear. Ran it up to maybe 5 grand. A minute later, noticed the gauge was at 210. Pulled to a side street & popped the hood. Was greeted to a motor covered with anti-freeze, and a gusher spraying from the pump. When it slowed down, I could see it had blown the gasket for the rear plate of the pump.

Another 2 hour disassembly (I'm getting good at it) revealed this...



http://i1113.photobucket.com/albums/...6/IMG_1508.jpg

My motor builder had tried to warn me NOT to run a thermostat, especially with the upgraded pump, saying we don't need one, and it is too restrictive. He says we control water temp with the electric fans, and the thermostat needs to go.
The pump obviously made so much pressure, something had to give. I have no other idea how to eliminate the pressure other than to ditch the 'stat.
I made a new gasket, glued it in place with Hi Tack, and put it back together. this time WITHOUT the stat. Drove it about 5 miles, it ran up to about 180, the fans kicked on, and dropped it back to about 170 (where they are set to turn on & off). So far, so good.

Of course now I'm gun shy, gonna stay close to home until I get a few more miles under my belt.
In the meantime, I hope I don't get a ticket for inattentive driving while fixating on the temp gauge!

I hope this is the end of the story....


Bill

Lots of folks seldom, if ever, look down at their gauges while driving, so good for you, for catching this in time...again. High rpm's and thermostats usually don't mix. I found that running a restrictor in my water neck, not a thermostat, made my cars run cooler, because it kept the water in the radiator a tad longer, thus giving the water more time to cool. This was not on street engines, but race engines at high rpm's. Something to think about when summer temps arrive here shortly. Don't you hate it when your engine builder is right?

HAHAHA. I sure do. He is the smartest (engine) guy I know. But in his late 60's, he is also pretty old school. And very opinionated. The F/I thing is just a little too new fashioned for him. He still contends the carburetor is a better way to go. It is simpler, smarter, & easier to tune. I think in the hands of a capable tuner, the FI is hard to beat, especially on a street car.


Bill

I'm going to disagree with your engine builders opinion of controlling the temp with the fans, while that will work at low speed in traffic, it will not work when moving at highway speeds with airflow through the radiator. Fwiw I have a 750+ hp enine that spins to 8K and it cools just fine with a stock GM pump and 195* thermostat. Imho there's no need for fancy high flow water pumps, running the engine too cool is not good for it either. Ideally you want it warm enough to get the oil to get to 212* to boil out the condensation.

My builder's opinion/experience is way more complex than what I typed above. I didn't want to type a long diatribe, and most don't want to read it. I don't claim to know all he does, but he agrees you need oil temp. But oil temp runs considerably hotter than water temp, and (in his opinion) you don't need or want that much water temp.
A little more info... My motor has about 11.5:1 static C.R., and the cam timing provides for about 220 lbs cranking compression. I use 92 octane gas. I have a 6 speed & 3.55 gears, so in "touring" mode, I am at about 1500 rpm at 65 mph. Another factor is I can sometimes get stuck in traffic on a 90 degree day, and with a black car, want to be able to run the A/C. (What is the point of having A/C if you can't use it?) With this setup, we want to control the temperature as much as possible. His biggest concern is detonation. And I think we can all agree that higher combustion temps lead to detonation.
My car has the Vintage Air Frontrunner system, which comes with the Stewart pump. Do I need it? I don't know, but as long as it was engineered that way, I will run it if I can.
My motor is new, with more static & way more dynamic compression. I also have a new larger radiator with larger fans. And now the "new" pump. Dialing this in is a learning experience for me. I have always run a 'stat in my cars, and read years ago you needed the restriction the 'stat provides to create higher pressure in the block to prevent hot spots from locally boiling coolant in the heads. I had installed it with the new pump, but it obviously didn't do well with that restriction. I can control the fans with my ECU, and (so far) it seems to work well.
Drove about 60 miles on Saturday... it ran at 150 in 55 degree weather, and about 165 when it warmed up to 75. Drove it about 50 miles yesterday in 80 degree weather, sometimes with the A/C on, and it never went over 180. I am very happy when the gauge is under 200.
Time will tell about the city vs. highway speeds, and 90 degree days with A/C. But so far, so good.

And thanks for weighing in!


Bill

The thermostat has nothing to do with pressure.... it's on the inlet side of the pump, therefore it would create a vacuum if anything, but will cavitate before it creates much vacuum. I think you simply had a faulty water pump. From the temps you posted, you're overcooling the engine imho, these engines are designed to run hotter than the old school sbc/bbc.

Tim,
I have a BBC....534 C.I. (.250" stroked 502)

Doh.... I guess I should've realized that from the pictures. :sieg:
150* is too cool imho, what are your oil temps at that temp?

I can't honestly answer that. i don't have an oil temp gauge.
My C-6 Z06 had a temp gauge, and it took FOREVER for the oil to get hot. Who can drive for 30-45 minutes to warm the oil every time before they lean on it?
My procedure has always been (right or wrong) to warm the engine up by driving gingerly for at least 10-15 minutes and make sure the coolant is up to temp. before jumping on it. And usually longer than that. My driving is more short acceleration blasts than autocross type driving. I may run it through 2 or 3 gears, than back off.
Is the oil up to temp? I highly doubt it. But I think it would take longer for the oil to get to full temp than I'm always willing to wait. FWIW, I've never had an engine failure. I think overall I'm easier on my motor than most guys.
All this discussion led me to do some 'net research. I found a very interesting site about motor oils. It has is a series of articles that are very enlightening.

I highly recommend this...

http://www.bobistheoilguy.com/motor-oil-101/


Again, thanks for the input...


Bill

Ever seen this
 

My old mustang (Chet's now.. that runs with Greg Weld)
had an oil to air cooler out front... it would take about
two laps on the race track before the Oil temp gauge
would lift off the stop that was at 140
My Pantera has a water to Oil Cooler and it not only
cools the oil but also helps it warm up quicker... very
good to have when you autocross on a cold day

Bob

Cool to hear from another Minnesotan. I am no expert but I would sooner drill some little bypass holes in the t-stat as opposed to run without one altogether. The thermostat will get you up to temp quicker and high flow stats will have minimal resistance. I think Milodon are pre drilled with a tiny bypass.

Anyway, can I ask what your 5th and 6th ratios are? ...and rear tire diameter?

Robert,
I would rather run a stat too, but given the circumstances, I won't, at least for now. My stat had (3) 3/16" holes drilled in it. It still blew the gasket out of the back of the pump. And it was wide open both times when I took it out of (the still hot) motor. Considering the mess it made & the work involved to fix it, I am going to run w/o the stat & closely monitor the temp. If it heats up in a normal fashion, and runs in the same range as it did with the stat, I am comfortable with that.
My T-56 has a .74 5th gear, and a .50 6th. I have 335/30-18 BFG Rival tires, which are advertised at 25.9" tall.
Where in Central Mn are you located?

Bill

I see what you mean on the T-stat. Since you can't determine if the gasket or cover could have been mishandled, compromised by being unclean mating surfaces etc that lead to failure I understand your decision. I can't help but wonder if that could not have been the case on the rebuild however.

I am in Monticello.

The reason I asked about gearing is I sourced a 12 bolt last summer with 3.55 that originally belonged to a '69 Z-28. I wanted it to still be 3.73 but someone had changed it.
My trans is a TUET11009 /Tremec T56 Magnum, a "close ratio" with a 2.66 1st, .80 5th, .62 6th gear. I am in perpetual build purgatory.

I have done some math or I should say used Tremecs website calculators and really just was curious if 6th will be usable as some people have told me it won't be. Or, at least one engine guru (also old school) told me that it will load up running off idle out of power band or too low on torque curve at cruise rpm etc...

Forgive the thread highjack, and granted you have BIG BBC torque on tap, but could you comment toward this? How do you like it and does this sound like a silly worry?

I'm only going to weigh in here with some food for thought. I'm not trying to make a point - or start any arguments.


There are LOTS of cars running around that are far more powerful than what this motor is (not saying your's isn't powerful)... and these motors get RACED and raced hard.... which means that they're being spun up and held there for long periods of time... AND they're running thermostats. Including my race Mustang and Lotus.

Water only builds up pressure when it meets resistance (over simplified)... so I'd be looking at the flow of the radiator or the bottom hose being sucked closed (lacking the internal spring that is in place to keep it from doing that)... or some other simple issue that is restricting the flow other than the thermostat.

Robert,
You have deeper 5th & 6th than I do, and the same rear end gear, so you will be running a little higher rpm than me, but not by much.
We built my motor with torque in mind, for use with the 6 speed. It will cruise at 14 or 1500 rpm ok, but we had to drop the advance to 17 degrees there to completely eliminate detonation at that high load/ low RPM situation. And, I have fuel injection, so we could tailor the fuel & timing for cruising as well. In my case, I can run in 6th, but only at about 65 mph or higher. When traffic dictates slowing below 65, I have to drop to 5th. Frankly, I'd be just as happy with a 5 speed, but that's because I usually don't drive at 70 or above as I am in the metro area most of the time.
You didn't mention what motor you're running, so I can't comment on how it will work, but it will need some torque to pull 6th gear. As long as it isn't cammed too wildly, you'll probably be fine. Depending on what you plan to use the car for, you can always drop to a 3.73 rear gear, but gives you a pretty low 1st, and closer shifts all the way up. I'd start where you are, and see how you like it.
I also had a C6 Z06 and didn't use 6th very much on that either. I viewed it as high speed/ low noise/ fuel economy gear.
BTW, I am in Maple Grove, so close by.


Bill

Any updates on this beast Bill?

A friend had the same issue you are having with a 540 BBC and front runner system. Because of the design of the front runner system they have to use a low profile Stewart water pump. He tried everything thermostats, radiator, etc. and nothing solved his issue until switching out to a Edelbrock Hi-Perf water pump. Took a little grinding on the pump to fit but the problem was solved. As a result the theory is the Stewart water pump used with the front runner system just does not move enough volume to properly cool a hi-perf BBC. Hope that may help.

While we haven't had any really warm weather yet, in 80 degree weather, the car runs exactly between 170 & 180 deg water temp... right where the fans are set to come on & off. A/C makes no difference. The stat is out, and it warms up at very near the same rate it did with the 160 stat.
All seems fine, and I'm leaving it this way unless really hot weather & A/C presents a problem.



Bill

Interesting. Would love to know the flow differences between the Stewart & Edelbrock. I'm sure both companies have tested this, and I'd bet they'd both claim to work better.
I have always read Stewarts are the strongest pumps on the market, but they'll print anything you want in ads.


Bill

Greg,
I somehow missed this post (for a month). As usual, I agree 100% with what you say.
I have thought long & hard about other restrictions. I have springs in BOTH hoses. I have a new BeCool rad, the largest one they make. I even wondered if there was a defect in it that restricts flow, but the rad temp is consistent when checked with a temp gun. FWIW, the system holds pressure for days.... if you release the cap, it releases pressure 4-5 days after last driven.
I read a very detailed article about cooling system issues YEARS ago written by someone very credible (maybe Smokey) that said a 'stat is NECESSARY to build pressure in the block. This pressure prevents the hot spots (in the heads or low flow areas in certain blocks) from localized boiling, which further prevents cooling in that area. It made perfect sense.
I have ALWAYS run a stat, and it bothers me a little not to have one now. But as long as all is running well, the car heats up normally, and it runs at level temps, I am happy.


Bill

just wanted to say that the cap regulates pressure. It will release over pressure. What cap are you running and does the hose for your overflow hit the bottom of the bottle? Have the cap tested at any shop.

I always run a thermostat, never had any issues.