1931 water pump testing

[avantey]

Please teach me a little more, this time on water pumps. I want to test the pump on the '31 Hupp to see if that is part of the overheating problem. How are pumps specified? By volume (gpm) and rate (@rpm) or just by one of these? Where can I find that spec- a period MoToRs or Chilton manual? How can I bench test when I know the spec?

The car runs hot, overheated within fifty miles every ride. The engine rebuilder says the block and head are so clean he did not boil it out. When I got the car I had an old time radiator shop clean it and repair some leaks he found. He said it flowed 'good' but never did a measure. The water pump did have significant play in the shaft from lack of packing (I fixed that early on) but very little shaft end play. When I opened up the pump housing it was not worn excessively but I wondered if the flow was bypassing the impeller behind it due to the play.

Really not sure where to look but the engine is back end of January. I want to reinstall it for a late spring tour so I need to fix the hot problem. If the block is good, the radiator is good I am not sure what else is left besides the pump. Thanks for any help, the knowledge here is amazing.

That is why I keep asking-

[Owen_Dyneto]

Rough rule-of-thumb; double the clearance between the impellor and the casting and you quadruple the loss in pumping efficiency.

[Ben Bruce aka First Born]

Bill, I may be wrong, but in my opinion, if the radiator was not taken apart, i:e, tanks removed, and rodded out, one cannot be sure it is clean. Almost everyone who has had the same problem as you has traced it to the radiator.

Ben

[trimacar]

Well, my son calls me Captain Obvious, Defender of the Already Known, but I'll point something out....is the radiator painted? If your "old time radiator shop" knew what they were doing, then it's possibly painted with correct radiator paint. Some people paint the radiator with regular enamel paint, which dramatically reduces heat transfer on surfaces.

In the real old days (when I first restored my 1931 Chevrolet), radiator paint was a special thick paint that you thinned with gasoline before lightly spraying on.....now it can be bought in spray cans, the last I got was from Eastwood.

It also concerns me that you took up play in the water pump with packing. Packing is meant to seal, not to be the bearing surface. Are you getting any foaming of coolant? Look to your water pump sucking in air if so.

My Pierce was blowing coolant out the overflow, particularly if you were running at higher rpm and let your foot off the gas.....I took a freeze plug the same outside diameter of the inside diameter of the upper hose (return to radiator), drilled a 5/8 inch hole in the center, inserted, and that solved the problem and car runs cool......not meaning to start a debate of flow rates, just telling you what I did....

[Graham Man]

When I put my 1933 Graham back into service my cooling system was in the same shape as yours. I was running a little hot but not bad. I installed an in house water filter (5 micron, available at any hardware store) in my heater circuit (heater inside the car). The junk it cleaned out was amazing, and the car keeps running cooler the more I drive it. I have changed the filter twice, the first time it was almost plugged. I am planning on transferring the system to all my cars, just clean them out and then remove it. I have not had any problems melting plastic in the filter, I checked all the components they are good to about 325F. The best part is all the parts together were about $35, filters are about $2.

PS I would pull the radiator and boil it out, if you have not. My radiator guy in his 80s said not to rod it out, you will only make leaks. I figured after doing radiators for over 60 years it was good advice.

[avantey]

Once again you all are proving how good the help is here. Like Graham Man the old timer who did this radiator for me had been in business all of 60 years and this was actually a job the new shop owner called him back in for, since he was new enough to be unsure with it.

Trimacar- It is painted but I believe it is the old thin style black. It has that sheen to it and is not at all thick on the fins, weldmarks on the tank are easily visible, etc. I am questioning my analysis/solution with the packing. I think I will tear it down again since your comment makes sense. The packing is "packed" via a large screw from the top of the unit- you remove it, put in graphite string or whatever, and screw the screw in to push the material around the shaft. I think if you put in enough the packing ends up acting as a poor bearing and the shaft would feel more true (at least at first). Or the shaft is loaded to the side away from the screw and feels better. Like I said- I am going to tear it down again after all this help and look more closely.

FirstBorn- Like you I am a little suspicious of the term used- "it flowed good" can cover a range of opinion with an old timer's experience. I found out today there is a radiator shop in Rochester that can flow test, etc. and will probably end up there for better testing.

OwenDyneto- This housing is a two piece with a flat backing plate you remove to rebuild the unit. How can I measure the impeller to plate distance with it opened up? I do not have surface plates, height indicators, etc. to work with. With the back cover off I suppose I could use a straightedge across the back face of the front half and my verniers in depth mode to get fairly close but would that be close enough?

Again, thanks to everyone for the help! It has given me a lot more to work with and think about.

[Owen_Dyneto]

OwenDyneto- This housing is a two piece with a flat backing plate you remove to rebuild the unit. How can I measure the impeller to plate distance with it opened up? I do not have surface plates, height indicators, etc. to work with. With the back cover off I suppose I could use a straightedge across the back face of the front half and my verniers in depth mode to get fairly close but would that be close enough?

I can't quite visualize the assembly from your words, but you might try this. Stick a wad of modeling clay or putty on the back of the impellor; install the pump and then remove it and see how much the putty or clay has flattened. Same concept as determining valve to cylinder head clearance on flat head engines.

[avantey]

I took some time yesterday and reopened the fuel pump after these conversations. The shaft feels good when turning by hand with no visible diametral play or end play. I used my measuring method with a straightedge and verniers to measure the gap from the impeller back to the rear cover. Depending on rotation of the impeller, it has small pits and any play I was getting .108-.111 clearance. Is that too much gap? The depth of the impeller in the housing is set by the cross pinned pulley on the front so I do not know how to change this clearance if it is too big.

With the pictures below: This shows how I crudely measured the clearance. The straightedge replicates the rear cover and the measure minus the SE thickness is the gap. Not real accurate (and even harder trying to one hand it with for the camera!) but it gives some idea of what I am asking about. Picture #3 shows the flat rear cover removed. The last pic shows the pump from the front with the large packing screw at the top. I may try the putty method too, that is basically plastiguage on growth hormones!

Thank you,

Bill

[Graham Man]

OK maybe a dumb question but it looks like a belt drive pump, are you sure the belt is not slipping? These old belts are sometime hard to have sized correctly and the can slip without making ugly noises. The other question is do you have a thermostat, and/or should you?

[37_Roadmaster_C]

Bill,

I am no expert on automotive water pumps, but .100 clearance in a small industrial pump would mean it is junk, wore out, kaput etc... I would try to check with an old time pump repair shop and get their opinion. They might not know about automotive pumps but a pump is a pump and the effencies are directly related to tolerance and clearance.

[Owen_Dyneto]

I'm not familiar with your particular water pump but typical gaps between impellors and end plates are about 0.010 - 0.015" or about one-tenth of what you're measuring. I would think the pump efficiency would be absolutely terrible.

[HarryJ]

Check the timing.

[avantey]

OK, haven't had a chance to respond here so here we go!

Graham Man- I can't tell if the belt was slipping as the engine is out. When driving it last fall the generator (on the same belt) was working fine with steady output but that is the best gauge I can give you.

37RdmrC- I will try to find an old time pump guy in the area but I do not know of any right off.

OD- your numbers are frightening! I have a scrap pump if you are correct but it could go a long ways to explain the overheating gradually getting worse with driving.

Harry J- I can't check the timing as the engine is out for rebuild. Running last fall it seemed fine. Started right up, ran right along at 50mph with no breakup, loss of power on hills and idled well. I used to have tons of overheat problems on my Model A Ford and finally understood it was almost always a timing issue. Learned the quirk to timing that car and it is now a dream to drive, losing maybe a pint of water in 400 miles week of touring. And most of that is from the water pump packing nut dripping if I do not see it. When I put this Hupp back together setting the timing will be a priority and my first time doing a dual point setup.

I should have the radiator test results today and have it back tomorrow so stay tuned. They only steam them out now with soap injected in the process. Not sure if I like that, rather they boiled it, but I guess that is not EPA/NYSDEC friendly anymore. They also only use a 70/30 solder today at best. He says most of the time on newer stuff it is 60/40 but the low lead solder soes not flow well enough for their liking. The original solder was probably 90/10, I have a little bit left on one roll.

Thanks everyone for all the help. I learn a lot here, just wish I knew enough to help others but the knowledge base here is way above my contribution level!

[Friartuck]

In reading this thread, I don't see where Owen's suggestion of using clay or other soft material between the impeller and the flat plate was performed and measured (plasti-gage on hormones). Given the impeller distance is set via a pin and the shaft doesn't have much end play, the dimension should be taken with the gasket taken in account. You may have to build up the impeller base (silver solder or maybe powder coated??) and sand/file to the right dimension.

[Curti]

Does your engine have a water distribution tube behind the water pump? The engine will over heat if the tube is missing, plugged or installed up side down. Some engine builders do not remove this tube, and clean the block with the tube installeed and go away thinking they did a good job. My feeling is the overheating problem you are expierencing is related to crud in the engine and radiator, and not the pump. I would think that your radiator is a honeycomb 'type' which cannot be rodded out. A new core consistant with the original design to maintain authenticity may be in order. Go to the water distribution tube first.

[avantey]

I may not have been clear on my efforts with this heating problem. Since I am having the engine rebuilt I do not want a continued overheating problem so I am trying to preemptively hit all the causes. Here is where things stand:

The block was clean enough my builder decided not boil it out. Still not sure about not cleaning it out now, especially the head, but I trust him and his experience. Part of this is because when I got the car I removed the side water jacket cover. I found the distribution plate behind it had dissolved and packed tightly around the last two cylinders. I cleaned all of this area out, remade the plate in SST per Hupp factory print and reassembled. I think this is the Hupp version of a water tube Curti is talking about.

I also took out the radiator and had it checked, repaired and cleaned at that time. I have now had it at a shop this week who checked it again. They flushed it and steamed it, can't boil it anymore with EPA, etc., and said the flow is now way better than at first. However I do have a small leak issue where the honeycomb core meets the top tank. They could not get to it to repair it so I had a friend who is a good restorer look at it too. He said I was better off trying a sealant than trying to get heat in where the leak is as it would probably cause more problems rather fix things. Another friend has offered a radiator epoxy he got in St. Louis during the Great Race. It is an external application but it helped his race car a lot and it was running very high temps without leaks the rest of the race. I may look at this more.

The pump is just another possible cause I am checking out. My thinking is that even with other things working well if the coolant can't move thru fast enough it will still overheat. So I want to be sure I understand the possible issues with the pump such as bypass, inefficiency, cavitation, etc. I know my measures were approximate due to crude capabilities but the good part was I left half the gasket there when I measured thinking about that. The other half went with the removed cover but the whole gasket was only .010-.020 thick I bet.

The last part of the system I can think of is the lack of a thermostat and I have not brought that up here at all. Guess I have now though. With no thermostat the coolant should circulate faster which mean less time in front of the radiator correct? This would mean higher water temps in the return flow to the block. How much hotter and how bad an effect would this have?

Again I am trying to be be proactive and protect my new engine. So all of this help here has been great and taught me a lot that I appreciate. I've said it before- the collective knowledge here is amazing and since I am very firm in my restoration vs modification desires I usually get some needed advice here. A lot of other folks tell me to change things but I like to try to keep my cars original so it helps to understand the theory too.

Thank you to all-