TR2/3/3A TR3 Uprated Water Pump?

[RedTR3]

I will be replacing my TR3 water pump and would like to get some advice as to whether the "uprated" water pump sold by Moss offers any real advantage or is it just hype?

 

[Moseso]

As near as I can tell, the stock pump works fine -- and more coolant flow (if the uprated pump actually delivers that) won't help you if there are other problems in the system.
1) It's gotta be clean.
2) Front air deflector in place!
3) I think uprated fan is more important than uprated water pump -- electric, or the yellow plastic one, or a real "tropical" TR3 fan.
4) Proper skirted thermostat, or some other flow restriction on the bypass pipe.

 

[angelfj1]

As near as I can tell, the stock pump works fine -- and more coolant flow (if the uprated pump actually delivers that) won't help you if there are other problems in the system.
1) It's gotta be clean.
2) Front air deflector in place!
3) I think uprated fan is more important than uprated water pump -- electric, or the yellow plastic one, or a real "tropical" TR3 fan.
4) Proper skirted thermostat, or some other flow restriction on the bypass pipe.

I agree (as usual) with Moses. However, we are going with an upgraded impeller.

 

[Don Elliott]

I have heard it said and seen it written that the up-rated pump will create such a high flow rate that the hot water entering the radiator is never there long enough for it to cool down. The "theory" is that the hot water goes back into the engine hot and doesn't cool down the overheating problem.

I can't say that this is true or false. I have never seen a report where someone has compared his standard pump with the up-rated pump. Results before versus results after.

Frank, we'd all love to see what you discover after you run your new 6-bladed pump in the "Grey Lady". It will only be the "after test", but at least it may shed some truths about the theories circulating. Pun intended.

I know that my pump still has the original bronze impeller that came with the car 51 years ago. 20 years ago during the restoration, I bought a new water pump and noticed that the impeller was cast iron (not brass or bronze) and it was smaller on the outside diameter and the 4 straight vanes were not as high. I assumed that this impeller would just stir up the coolant and that there would be lots of lost flow so I put my original impeller into the new pump. At the same time, my neighbour with the lathe turned a new shaft for me out of stainless steel and in 100,000 miles since then, I have had no issues with it.

The new 6-bladed pump will really be an improvement over the repro pumps with the inferior cast iron impeller, but mine works fine till I stop in traffic for more than 5 minutes at which time, I flip the switch to turn on my electric cooling fan and a minute later, while still stopped in traffic, the temperature has come back down to normal.

 

[angelfj1]

The new 6-bladed pump will really be an improvement over the repro pumps with the inferior cast iron impeller, but mine works fine till I stop in traffic for more than 5 minutes at which time, I flip the switch to turn on my electric cooling fan and a minute later, while still stopped in traffic, the temperature has come back down to normal.

I hope that you are right. With a fresh engine we really didn't believe a pump upgrade was necessary. However, we went with this design because the new (repro) impellers looked so bad. The castings were very rough and the impeller width was less than the originals as you have stated.

 

[NickMorgan]

I recently purchased a new pump and I asked around before I bought it. The consensus was that if the rest of the system is OK there is no need for an uprated pump. If there is a problem with the cooling system then the pump may mask it for a while, but really you should sort out the rest of the system if you want it to be reliable.

 

[angelfj1]

I recently purchased a new pump and I asked around before I bought it. The consensus was that if the rest of the system is OK there is no need for an uprated pump. If there is a problem with the cooling system then the pump may mask it for a while, but really you should sort out the rest of the system if you want it to be reliable.

Nick: Even though we are starting with a fresh-end engine, we went with the upgraded pump (from the UK) because we knew that this person sold a quality item, we had seen demonstrated a few years back (at Stoneleigh). We actually had started with a standard replacement from one of the big three here in the states and it belonged in only one place. The bin. :madder:

 

[TR3driver]

I have heard it said and seen it written that the up-rated pump will create such a high flow rate that the hot water entering the radiator is never there long enough for it to cool down. The "theory" is that the hot water goes back into the engine hot and doesn't cool down the overheating problem.

I can't say that this is true or false.

I can. It's nonsense. Heat transfer is heat transfer, no matter what the flow rate is. Yes, each cc of water gets cooled less. But there are more ccs flowing per unit time. The overall cooling in the radiator depends only on the temperature of the water in the radiator (assuming all the other variables like air temp & flow, etc. remain the same); and a higher flow rate will ensure that the radiator remains closer to the temperature of the engine (ie hotter).

Then the question becomes, how much improvement can one expect from a higher flow rate. It's an asymptotic effect; if the water could move fast enough to keep the entire radiator is the same temperature as the engine, then more flow would make no difference at all. This can be estimated by comparing the radiator inlet and outlet temperatures. If the outlet is cooler than the inlet, then more flow would dissipate more heat.

I held one of each pump in my hands the other day, pondering if I wanted to try the 6-vane version. The original impeller has considerably larger blades and I find it hard to believe that smaller vanes work better at low rpm. The original has been said to suffer from cavitation problems at high rpm; and probably does for the racers who are turning over 5000 rpm for extended periods of time. The redesigned impeller would have far fewer problems with cavitation due to it's smaller (and more) blades, plus the curvature of the blade.

Ultimately, I put back the original pump (which appeared to be in perfect condition, implying no cavitation). The backflush with water mixed with air plus blocking the bypass appears to have done the trick; the engine actually runs a little on the cool side now. So the experiment with the 6-blade remains on the shelf for another day.

BTW, some early versions of the 6-blade pump did not have clips to locate the shaft in the bearings. That made it easy to move the shaft slightly when installing the pulley, which would cause the seal to leak. I doubt there are any of those left on anyone's shelf (except mine); but it still wouldn't hurt to be careful not to apply force against the bearings when installing the pulley.

 

[70herald]

Randal you summed it up pretty well.

There has been allot of debate on these uprated pumps on other sites as well. A few other objections have been raised

1. The rotor is Aluminum. This is probably allot easier to machine, but is will not last nearly as long as a proper bronze or iron rotor. Any corrosion problem will attack the rotor first.

2. SOME of the "uprated" pumps sold by major vendors have the vanes BACKWARDS relative to the direction they are rotated! Ironically they may still pump better than the original but that is kind of incompetent!

 

[trfourtune]

All,
You don't get the increase in flow that you might think you will get. All the flow has to go past the thermostat (restriction). The thermostat plays a major part in the flow rate through the engine. What you should get is more flow but also HIGHER coolant pressure in the block and head. This is very, very beneficial. Hot spots in the head cause local boiling (you don't even see this but happens all the time in the head) but this is reduced because of the increased coolant pressure. This helps reduce detonation. In my mind, I would never use the old pump (and i live in Canada!).
IMHO
Rob

 

[RedTR3]

Sounds like there is a leaning toward the uprated unit but it is close...Now it turns out that a major supplier has just put the uprated pump on sale for $80 so there is not much for me to lose in trying it.

Assuming that I order it, I will report back here after installation as to the results. Thanks!

 

[TR3driver]

In my mind, I would never use the old pump (and i live in Canada!).

Yeah, it's just amazing how these engines have survived 50 YEARS with so many things terribly, horribly wrong with them!