Ever seen this before?

[69hugger]

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…..





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

[Che70velle]

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?

[Panteracer]

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

[69hugger]

Originally Posted by Panteracer

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

[Panteracer]

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

[69hugger]

Originally Posted by Che70velle

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?

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.

[Graham08]

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.

[69hugger]

Originally Posted by Graham08

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

[Panteracer]

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

[DavidBoren]

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.