Don Jr. Posted March 12, 2019 Share Posted March 12, 2019 Hi, Have pulled the entire water pump assembly apart except for the impeller. Got the gear off in front that drives the assembly and drove out the associated pins. My problem is getting the pin that holds the impeller in out from the worn shaft. I drilled a hole above the spot where the pin protrudes out from the impeller on the back side. Could not see any other way to drive it out of the impeller. Made a punch that would fit the hole but am now at a point where it will not move back any more. Assume this pin is about 1 1/2 inches long and if so I have 1/2 inches to go to clear the shaft. Any tricks to get the pin out?? Also do I need to replace all the pins with new pins if available or can I use roll pins to secure things. Thanks Link to comment Share on other sites More sharing options...
TonyAus Posted March 12, 2019 Share Posted March 12, 2019 The original method of holding the impeller to the shaft is a number one taper pin (standard taper of 1/4" per foot). In theory you should be able to drive it out easily from the rear. However, the pin may be rusted in place. I managed to remove mine by tapping the pin at both ends after applying heat and WD40. You will note that the pin is slightly offset to the shaft. I suspect that originally the impellers were individually drilled and pinned. Therefore a replacement shaft should, in theory, be drilled to suit your impeller. Being a bit of a perfectionist I made up my own shaft and taper pin, reaming the impeller and shaft to suit. The pin was then driven in with a little Loctite for good measure. I'm not sure that using a roll pin in this location is a good idea given the alternate heating and cooling cycle which may degrade the spring in the pin. You might consider using a plain pin riveted over at both ends. In any event the tapered hole in the impeller would need to be drilled parallel to suit the pin. Link to comment Share on other sites More sharing options...
Don Jr. Posted March 12, 2019 Author Share Posted March 12, 2019 O.K. Great info. Did not try heat but have a torch setup and will give it a go!! I was able to drive it in a bit at first then tried backing it out. Did this a few times .It went so far then stopped dead. Did not realize it is a taper pin but makes sense. Other pins looked like straight pins then ends mushroomed over. Thought impeller pin was the same. Thanks for the info. Will post how I make out. Link to comment Share on other sites More sharing options...
Don Jr. Posted March 12, 2019 Author Share Posted March 12, 2019 Hi, Just got the pin out. It fought me all the way. I heated the impeller 3 times gaining a little each time. Cannot understand how the pin was installed originally as I had to relieve the end of one of the of the impellers with a Dremel tool to allow the pin clearance to come out. I will braze the part I relieved after installation and braze the hole I made at the other end where I used a punch to remove it. Now I can order the new shaft. Another question. Some folks are talking about a chromed shaft. Is that what I am supposed to buy? Also hearing about using PTFE packing instead of graphite to keep shaft from being cut up. Any thoughts on this?? Link to comment Share on other sites More sharing options...
Ron Lawson Posted March 13, 2019 Share Posted March 13, 2019 Marine grade stainless Steel is the way to go Link to comment Share on other sites More sharing options...
Spinneyhill Posted March 13, 2019 Share Posted March 13, 2019 (edited) I think when made, they just pushed the impeller on in a jig to get the end float right then "drilled a hole" through the boss on the impeller. Orientation didn't matter. They just wanted a hole for the pin. A roll pin is not good. For one, there isn't much steel in it so if there is any corrosion, it won't last. Secondly, it is open to corrosion along its entire length inside, so it won't last. A solid pin is only available to corrode on the ends and maybe a tiny amount along the shaft. Taper pins are used in many applications, including holding mechanical clocks together. As far as trying to drill a non-diametral hole to match the impeller, don't bother. It is very, very hard to set it up. I tried, it went nearly alright, but not quite right. I showed to a friend who owned a machine shop; he said drill a hole at 90o. Edited March 13, 2019 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
Don Jr. Posted March 13, 2019 Author Share Posted March 13, 2019 O.K. Thanks for the explanation. Appreciate it. Link to comment Share on other sites More sharing options...
Don Jr. Posted March 13, 2019 Author Share Posted March 13, 2019 The marine grade Stainless steel 316 series. It contains Moly so that explains things better. Will look into it. Again thanks for the info update. Link to comment Share on other sites More sharing options...
FLYER15015 Posted March 13, 2019 Share Posted March 13, 2019 3 hours ago, Don Jr. said: The marine grade Stainless steel 316 series. It contains Moly so that explains things better. Will look into it. Again thanks for the info update. Don, To make a new shaft I would use 316 SS rather than 304. because it does contain moly, which gives it strength. You should also look at 17-4 ph SS as that is what Mercury Marine makes their salt water boat props out of, and correctly machined it will give you a "mirror" finish. Plus it is stronger than 316, and cheaper too. Just my $.02 Mike in colorado 1 Link to comment Share on other sites More sharing options...
TonyAus Posted March 13, 2019 Share Posted March 13, 2019 10 hours ago, Spinneyhill said: I think when made, they just pushed the impeller on in a jig to get the end float right then "drilled a hole" through the boss on the impeller. Orientation didn't matter. They just wanted a hole for the pin. A roll pin is not good. For one, there isn't much steel in it so if there is any corrosion, it won't last. Secondly, it is open to corrosion along its entire length inside, so it won't last. A solid pin is only available to corrode on the ends and maybe a tiny amount along the shaft. Taper pins are used in many applications, including holding mechanical clocks together. As far as trying to drill a non-diametral hole to match the impeller, don't bother. It is very, very hard to set it up. I tried, it went nearly alright, but not quite right. I showed to a friend who owned a machine shop; he said drill a hole at 90o. On the contrary, it is possible to drill an offset hole. The method I used was to turn up a taper pin which entered the taper entrance hole and just touched the shaft. This pin was centrally drilled through 7/64", forming a guide for a drill of the same size to attack the shaft without skidding off course. Holding the tapered guide in the lathe chuck was achieved by drilling and taper reaming a piece of aluminium rod into which the guide was driven. After drilling through the shaft the guide was removed and the hole enlarged with a #24 drill (to suit a #1 taper). The larger drill followed the smaller hole perfectly. You could use a similar technique to drill for a parallel pin - just drill out the taper in the impeller and make up a parallel guide. Of course the job should be carefully set up in a drill press and securely fastened to the table before attempting to drill. BTW, the pin I used was turned up from stainless steel to avoid future rusting. Link to comment Share on other sites More sharing options...
Spinneyhill Posted March 14, 2019 Share Posted March 14, 2019 (edited) To start the hole, use an end mill. It doesn't skid sideways. As you say, it is possible, but not for the beginner like most of us. I am struggling to understand your method! I think my learner status was one of the reasons Filip said to drill another hole at 90o. It is also not economic for most of us to pay someone to spend the time. Well done you, though! Edited March 14, 2019 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
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