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TR3b water pump

Moss Motors
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Jimm57 Avatar
Jimm57 Jim M
Apex, NC, USA   USA
Water pump was leaking on my TR3b. Ordered replacement 4 vane Classic Gold from Moss. It came and is much different. New vanes are .5" where the old one is .68". Have been told that I need a Hi Flo pump. Anyone know where to get and a P/N? See attached pix. Thanks!

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
I'm pretty sure Moss sells uprated pumps. I bought one from TRF, but never got around to installing it.

Make sure the pulley is a tight fit on the shaft. If you can push it into place with your fingers, consider a new pulley or using Loctite to improve the fit. Otherwise, in spite of the key and nut, the joint will eventually fail.

I was lucky, the electric fan housing caught the pulley with no further damage. I hate to think what would have happened with a stock fan!

I replaced that bolt with a stud, which IMO makes things a lot easier. Otherwise, make sure you have the bolt in the right hole before installing the pulley! (IIRC, the stud is the same as the rocker shaft studs.)



Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

ArtL Avatar
ArtL Art Liefke
Kings Park, NY, USA   USA
I looks like the vanes on the new pump are just too short. If the end clearance between the vanes and the housing is too much, then the pump will be very inefficient, especially at low engine speeds. Read this thread about that problem and about "uprated" pumps.



Art


Beer is proof that God loves us and wants us to be happy. - Benjamin Franklin

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CJD john durant
Southlake, TX, USA   USA
Wow. Welcome to the world of really bad repro parts. I bought from TRF, and the impeller was correct, but I had to re-drill the mis-aligned mounting holes! The pump before that was Moss, and the pulley rubbed against an abnormally large boss on the pump casting, causing a constant "chirp" as I drove. Then I rebuilt a pump, only to find the Brit Vict shaft seal was wrong, so the pump blew anti-freeze all over my fresh restoration. Then there is the pulley issues, where many new pumps will not mount an original pulley. So, definitely buy a pulley from the supplier you use to ensure it will fit.

Multiply the issues above times the several hundred parts that went into my restoration and you may just get a glimpse of my frustration with the current parts available.



John
Southlake, TX

'55 TR2

twomanytriumphs Avatar
twomanytriumphs Gold Member Kyle Darby
Kelso, WA, USA   USA
1965 Triumph TR4 "My Baby"
1966 Triumph 2000 MkI "Bessie"
1970 Triumph GT6+ (MkII) "The Princess"
1977 MG MGB
Doesn’t Dutchman rebuild original pumps? I try to hang onto originals until someone wants one to build. Kyle.

ckeithjordan Avatar
ckeithjordan Gold Member Keith Jordan
Shawnee, KS, USA   USA
In reply to # 1592912 by twomanytriumphs Doesn’t Dutchman rebuild original pumps? I try to hang onto originals until someone wants one to build. Kyle.

Yes, they do. I had them do the water pump on my TR3 last year. Excellent job, price and turnaround.



Keith

1957 TR3 TS20447LO (2017-)
1962 TR3B TCF1183L (1979-1982)
1966 Spitfire 4 Mk.2 (1972-1975)

andy303 Avatar
andy303 Gold Member Andrew Blackley
Chardon, OH, USA   USA
In reply to # 1592912 by twomanytriumphs Doesn’t Dutchman rebuild original pumps? I try to hang onto originals until someone wants one to build. Kyle.

Looks like a good idea. He replaces the stock impeller with a vaned one to make it "better than new" :
http://water-pump-rebuilders.com/triumph-water-pumps.html


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Fred Winterburn Avatar
Ripley, ON, Canada   CAN
Exactly! Apparently the spec is 75 thou end clearance and that's how most went together with a standard gasket thickness. Absolutely way too much clearance and the pump will not pump at idle speed with that kind of clearance. That clearance is with the standard pump and the bronze impeller as shown. The Moss offering would make that clearance much larger and the effect is not linear. That Moss pump would be useless and wouldn't pump until the rpm was near redline. The correct end clearance for an efficient pump should be 7.5 thousands of an inch, not the 75 thou spec (or even higher with the Moss pump). On the old original pumps the impeller could be adjusted on the shaft to correct the end clearance, but some of the aftermarket pumps this is not possible. On the County brand pump I am using, I added a spacer washer (77 thou) riveted in place to make up the end clearance since I couldn't budge the impeller. I experimented with various gasket thicknesses until I achieved 7 thou. It really has to be less than 20 thou or you no longer have a proper pump. Adjusting the end clearance makes a huge difference and without the adjustment the engine coolant is only moved by thermosyponing at low rpm. I'll bet if most people adjusted the end clearance they could get rid of the electric fan they just installed that enhances thermosyphoning. I'm nearly convinced that the 7.5 thou end clearance that I know works and was probably specced by the original engineers somehow became 75 thou in print and subsequently in production. No need for extra vanes, just adjust the end clearance and the standard pump is terrific. Fred

uote=ArtL,1592731,1592764]
I looks like the vanes on the new pump are just too short. If the end clearance between the vanes and the housing is too much, then the pump will be very inefficient, especially at low engine speeds. Read this thread about that problem and about "uprated" pumps.
[/quote]


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Spacer to reduce end clearance from 80 thou to 7 thou with County brand pump.JPG

andy303 Avatar
andy303 Gold Member Andrew Blackley
Chardon, OH, USA   USA
I agree that the end clearance of he impeller to the body of the pump is important, but I believe that the number and the shape of the vanes is even more critical. It is a difficult problem as engineers design pumps to operate at a fixed rpm for optimal efficiency whereas on an automobile engine the rpm obviously varies. Suffice to say the OEM impeller design with four rectilinear vanes is crude and cheap to produce. Any impeller with curved vanes is going to be superior. Beware making the clearances too small as thermal expansion also occurs.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Moving more water around is never going to compensate for lack of air movement through the radiator. My fan doesn't even come on until the coolant leaving the radiator is around 190F; which will never happen if the coolant flow is low.



Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

Fred Winterburn Avatar
Ripley, ON, Canada   CAN
Well actually more coolant flow does help a lot because it maximises the effect of what little air flow is going through the radiator. The delta T is lower, but the cooling rate is far greater with increased coolant flow. I spent a large portion of my life operating large scale cooling systems of all kinds (nuclear power plant) and increasing pump flow contributes in a major way. With the Morgan, the rad fan is really far removed from the radiator and barely pulls any air through at idle and the rad is only 2/3 the size of the TR rad, yet my modification worked. The reason it worked is because the cooling system no longer had to rely on thermosyphoning for its cooling method at idle and low rpm operation. The amount of air being pulled through the rad even with the poor system employed by Morgan and even with the smaller radiator is sufficient providing there is forced coolant flow. An electric fan in the absence of forced coolant flow enhances thermosyphoning which is why they work, and on an engine working hard but at low speed where the capacity of the radiator becomes smallish, then they help too, which is partly why modern cars employ them. Fred

In reply to # 1594376 by TR3driver Moving more water around is never going to compensate for lack of air movement through the radiator. My fan doesn't even come on until the coolant leaving the radiator is around 190F; which will never happen if the coolant flow is low.

Fred Winterburn Avatar
Ripley, ON, Canada   CAN
I've only tested the flow of the straight impeller variety off the car run with an electric drill, but I'll bet the old straight impeller design pushes more water at low rpm. The curved impeller probably pushes more water at normal driving rpm, but that isn't where you need the most flow as the flow with the straight impeller design is very high already if the end clearance is adjusted, with plenty of margin. Idle and low rpm is the most critical. As a point though, it doesn't matter which vane style is chosen: The end clearance is the most important factor with these pumps in getting proper flow. On some large industrial pumps, a one thou change in end clearance can be several PSI, so imagine how important it is with these small diameter pumps. You are right about thermal expansion and the other point not mentioned is the condition of the bearings. They can't be too sloppy or there will be rubbing. Having written that, comparing other cars I've owned, the end clearance has been small and even with a bit of bearing wear I haven't seen evidence of scoring when I've replaced the pump. Usually it gets noisy first just from bearing vibration and I know it's time to change the pump. Fred

In reply to # 1594373 by andy303 I agree that the end clearance of he impeller to the body of the pump is important, but I believe that the number and the shape of the vanes is even more critical. It is a difficult problem as engineers design pumps to operate at a fixed rpm for optimal efficiency whereas on an automobile engine the rpm obviously varies. Suffice to say the OEM impeller design with four rectilinear vanes is crude and cheap to produce. Any impeller with curved vanes is going to be superior. Beware making the clearances too small as thermal expansion also occurs.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1594410 by Fred Winterburn Well actually more coolant flow does help a lot because it maximises the effect of what little air flow is going through the radiator. The delta T is lower, but the cooling rate is far greater with increased coolant flow.
Sorry, I don't buy it. If there is no delta-T across the radiator, then moving hot water around faster does nothing for cooling.

And if the coolant flow is inadequate, one of the symptoms will be a larger delta-T across the radiator.

The old chain analogy fits well here. To move heat from the cylinder head to the atmosphere, the heat has to follow several steps. If one step isn't working, it doesn't matter how strong the other links are. Moving coolant around only transfers heat from the inside of the cooling jacket on the engine, to the inside of the tubes on the radiator. If that heat doesn't get transferred from the radiator tubes to the air, it doesn't matter how well it gets transferred into the tubes.

And since heat only flows downhill (from hotter to colder), moving coolant faster doesn't help once all the surfaces in contact with the coolant are the same temperature. It's like trying to fill a tank by emptying a bucket in, then scooping the same bucket back out.

There is also no appreciable thermo-syphon effect, even with the fan running. To prove that, just try letting the engine idle with the fan belt off and the fan running. If the pump isn't spinning, the engine overheats very quickly.

Now, I'll admit I'm not familiar with the Morgan and it's problems. Maybe it's different and does get enough air convection past the radiator that it doesn't need more airflow. Maybe it won't overheat with a broken fan belt. But a TR3 sure does!



Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild



Edited 1 time(s). Last edit at 2019-02-05 07:33 AM by TR3driver.

Fred Winterburn Avatar
Ripley, ON, Canada   CAN
I did not state that there would be no delta T across the radiator with increased flow, I meant that it would be lower than if the flow is low either by low coolant flow from an inefficient pump or by thermosyphoning. You are right though that if there is absolutely no flow then there won't be a delta T (kind of obvious) and the engine will overheat very quickly. After a hard run, my engine would thermosyphon briefly until some boiling started to occur and that completely stops the thermosyphon due to the parasitic pressure robbing that steam gives (same phenomenon as vapour lock). I could have installed an electric fan as many do to improve the thermosyphoning, but fixing the pump was the better route. By the way, I'm pretty sure that is a TR3 engine in my car! So yeah, I think it applies to this forum! Fred
In reply to # 1594416 by TR3driver
In reply to # 1594410 by Fred Winterburn Well actually more coolant flow does help a lot because it maximises the effect of what little air flow is going through the radiator. The delta T is lower, but the cooling rate is far greater with increased coolant flow.
Sorry, I don't buy it. If there is no delta-T across the radiator, then moving hot water around faster does nothing for cooling.

And if the coolant flow is inadequate, one of the symptoms will be a larger delta-T across the radiator.

There is also no appreciable thermo-syphon effect, even with the fan running. To prove that, just try letting the engine idle with the fan belt off and the fan running. If the pump isn't spinning, the engine overheats very quickly.

Now, I'll admit I'm not familiar with the Morgan and it's problems. Maybe it's different. But I am very familiar with the TR3 and if I'm not mistaken, this is a TR3 forum.

Fred Winterburn Avatar
Ripley, ON, Canada   CAN
Randall, I missed this when I first read your response this morning. You wrote:

"The old chain analogy fits well here. To move heat from the cylinder head to the atmosphere, the heat has to follow several steps. If one step isn't working, it doesn't matter how strong the other links are. Moving coolant around only transfers heat from the inside of the cooling jacket on the engine, to the inside of the tubes on the radiator. If that heat doesn't get transferred from the radiator tubes to the air, it doesn't matter how well it gets transferred into the tubes."

What you wrote sounds reasonable, but it isn't true. If the radiator air flow is low, increasing the coolant flow simply utilizes what is there better and means the air is heating up more as it is pulled through the rad. An analogy in humans is for people with bad hearts or lungs. If you have both, you are in trouble. If you have a bad heart and your lungs are good, you can generally get enough oxygen to survive by breathing heavily. Conversely if your lungs are poor and your heart is good, it will beat faster to provide the required blood oxygen, Same is true for cooling systems. It is NOT a chain with the weakest link determining the outcome. One can compensate to a degree for the other. Fred

In reply to # 1594416 by TR3driver
In reply to # 1594410 by Fred Winterburn Well actually more coolant flow does help a lot because it maximises the effect of what little air flow is going through the radiator. The delta T is lower, but the cooling rate is far greater with increased coolant flow.
Sorry, I don't buy it. If there is no delta-T across the radiator, then moving hot water around faster does nothing for cooling.

And if the coolant flow is inadequate, one of the symptoms will be a larger delta-T across the radiator.

The old chain analogy fits well here. To move heat from the cylinder head to the atmosphere, the heat has to follow several steps. If one step isn't working, it doesn't matter how strong the other links are. Moving coolant around only transfers heat from the inside of the cooling jacket on the engine, to the inside of the tubes on the radiator. If that heat doesn't get transferred from the radiator tubes to the air, it doesn't matter how well it gets transferred into the tubes.

And since heat only flows downhill (from hotter to colder), moving coolant faster doesn't help once all the surfaces in contact with the coolant are the same temperature. It's like trying to fill a tank by emptying a bucket in, then scooping the same bucket back out.

There is also no appreciable thermo-syphon effect, even with the fan running. To prove that, just try letting the engine idle with the fan belt off and the fan running. If the pump isn't spinning, the engine overheats very quickly.

Now, I'll admit I'm not familiar with the Morgan and it's problems. Maybe it's different and does get enough air convection past the radiator that it doesn't need more airflow. Maybe it won't overheat with a broken fan belt. But a TR3 sure does!



Edited 1 time(s). Last edit at 2019-02-05 05:18 PM by Fred Winterburn.

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