Pump housing crack above test port

[Dave G9N]

I have recently rebuilt a 2N pump and shortly after installing it I found a leak near the test port. The mounting bolts were tight, so it didn't seem to be a leaking gasket. I thought that I might not have tightened the plug well enough, since I don't like to over tighten plugs. It didn't feel tight, so with a load on the lift to put some oil pressure on the leak, I snugged it up. It leaked faster. I snugged a little more which opened up the crack enough to see the problem.

This You tube video provides a good picture about 13 1/2 minutes in. The crack in the video is nearly identical to the one in my pump. The solution in the video was to have the crack TIG welded. You tube video showing TIG repair at 60 sec

My question is whether it might work to sleeve the hole with a threaded stainless steel tube without welding the crack.

The picture shows the crack location and a drawing of the stainless steel sleeve available from McMaster.

The crack is only loaded by the hydraulic pressure and the wedging action of the plug, which is probably worse than the hydraulic pressure. The sleeve would extend into solid metal , so the crack should not be under any load after the repair.

I would drill and tap 2" into the hole, then drill out the last half inch so the hollow tube would extend well past the crack. The tube would be cut off and threaded internally for a plug. The wall is too thin to thread the ID where the OD is threaded, so the plug has to be more than 1 1/2" from the end of the tube. The oil passage up to the pump would have to be drilled through the tube after installation.

This post was edited by Dave G9N on 12/26/2023 at 09:15 am.

 

[JMOR]

No wedging action of #11, as it is straight thread just like a bolt. If someone did use a 'wedge' shape plug like NPT, that is likely the cause of the crack.

 

[Dave G9N]

(quoted from post at 07:32:01 12/26/23) No wedging action of #11, as it is straight thread just like a bolt. If someone did use a 'wedge' shape plug like NPT, that is likely the cause of the crack.

hanks, something to look for. I looked, and no, having just looked, it is not an NPT pipe plug. Straight threads do produce some lateral force, but as you say, nothing like a pipe thread. Enough to open the crack even if it is not enough to cause the crack. The crack was not visible until the plug was tightened. The strangest thing in the picture is liquid water and bare ground in Minnesota on December 26. That is more unusual than a cracked pump housing.

Now that I look at it, the muffler touches the aluminum casting. That can't be good. It is possible that the crack was at least partially caused by overheating.

At this point, the root cause is not my issue. It could be 75 years of fatigue cycling. I have read that Ford eventually gave up on the aluminum castings because they cracked, but it didn't say where.

I don't know how long the muffler has been touching there, but since I didn't change the mounts, I think it was like that when I bought it around a year ago. I don't know how hot it got, but heat is not good for aluminum. The paint was applied after the pump was rebuilt. It is not discolored, but has only a few minutes of running time. I didn't notice any sign of overheating before, and with the fresh paint, any signs of overheating have been obliterated. I will get the muffler off the test plug.

I think I might go ahead with the threaded pipe repair. It should help to drill out the end of the crack to keep it from propagating, and the pipe should prevent the hydraulic pressure from loading that area of the casting.

 

[JMOR]

(quoted from post at 13:14:42 12/26/23)

(quoted from post at 07:32:01 12/26/23) No wedging action of #11, as it is straight thread just like a bolt. If someone did use a 'wedge' shape plug like NPT, that is likely the cause of the crack.

hanks, something to look for. I looked, and no, having just looked, it is not an NPT pipe plug. Straight threads do produce some lateral force, but as you say, nothing like a pipe thread. Enough to open the crack even if it is not enough to cause the crack. The crack was not visible until the plug was tightened. The strangest thing in the picture is liquid water and bare ground in Minnesota on December 26. That is more unusual than a cracked pump housing.

Now that I look at it, the muffler touches the aluminum casting. That can't be good. It is possible that the crack was at least partially caused by overheating.

At this point, the root cause is not my issue. It could be 75 years of fatigue cycling. I have read that Ford eventually gave up on the aluminum castings because they cracked, but it didn't say where.

I don't know how long the muffler has been touching there, but since I didn't change the mounts, I think it was like that when I bought it around a year ago. I don't know how hot it got, but heat is not good for aluminum. The paint was applied after the pump was rebuilt. It is not discolored, but has only a few minutes of running time. I didn't notice any sign of overheating before, and with the fresh paint, any signs of overheating have been obliterated. I will get the muffler off the test plug.

I think I might go ahead with the threaded pipe repair. It should help to drill out the end of the crack to keep it from propagating, and the pipe should prevent the hydraulic pressure from loading that area of the casting.

our picture of repair tube isn't clear enough for me to read the TPI, but it doesn't look like 1/2-20, which was the factory test port plug.

 

[Dave G9N]

(quoted from post at 10:52:32 12/26/23) your picture of repair tube isn't clear enough for me to read the TPI, but it doesn't look like 1/2-20, which was the factory test port plug.

he threaded tube has a 1/2-13 thread on the OD. the plan is to drill about 2 1/4 deep with a 27/64 bit, then thread the hole for the 1/2 -13 thread. Then drill the threads out of the last 1/2" of the the casting to 1/2" to match the unthreaded portion of the tube. 27/64 should just clear the existing threads in the tapped portion of the hole, so I have a built in drill guide.

The ID of the tube is 11/32 (.34375), and my thread table says that the drill size for M10 x 1.25 is 8.8mm (0.3465), which is close enough to the ID (no drilling, I can just tap). I could go with a 7/16 but the hole size for 7/16 are .368 and 3.91 for 14 or 20 tpi and I don't like drilling stainless, so 7/16-20 is more trouble than it's worth.

The threads on the OD and ID can't overlap because the wall thickness is insufficient.

Hollow Threaded Stud
18-8 Stainless Steel, 1/2"-13 Thread, 4" Long
https://www.mcmaster.com/94624A127/

Alternative, more drilling and tapping involved, larger hole in casting, cutting more threads on OD:
Internally Threaded Connecting Rod 5/8" OD
18-8 Stainless Steel, 1/2"-20 Thread Size, 3" Overall Length
ttps://www.mcmaster.com/7417N57/

/7417N68/ 6" could be cut so threads don't overlap.

This post was edited by Dave G9N on 12/26/2023 at 01:18 pm.

 

[HFJ]

Spare the duct tape, spoil the job.

 

[Dave G9N]

(quoted from post at 16:00:55 12/26/23)

Spare the duct tape, spoil the job.

urprisingly enough, it didn't work this time. Maybe a few more wraps around the entire center section?

Yer right though, not welding is just plain cheap and lazy. Ya still gotta waller out the hole after welding and I figgered why not just waller without the light show?

Edit: Good joke, no complaint.
If, as I expect, this is a common failure mode that often results in the scrapping of the pump housing, the supply of good used parts is diminishing rapidly as a result. I don't think anyone is making new ones. There is a reason to look for an inexpensive and effective repair that is within the capability of most shade tree mechanics.

I had hoped that someone here would have seen similar repairs and would have some experience to pass on. If not, I'll give just it a try. I'm 71, so I'll find out if it's bad. If it's good, I won't.

TIG welding may be the way to go, but I don't know how many of us have a TIG welder, and forking over $100 for a 1 1/2" weld is about the same as the used but not abused replacement pump that I bought. Either approach will require some machining to restore the hole for the plug. Drilling and tapping aluminum or cast iron is easy, as is threading. Drilling and tapping stainless steel, not so much, unless the 18-8 grade they use is 303, which is likely to be the case. 303 has manganese sulfide stringers running through it which break the chips and lubricate the cutting tool. The rest of the 300 series are a bear to work with hand tools.

Stainless steel was surprisingly less expensive than carbon steel for these parts. Stainless is also more compatible with aluminum for corrosion and thermal expansion than carbon steel. Compatible and 'more compatible' are very different, and in this case not as different as 'more compatible' and incompatible. Steel fasteners get along well enough with the aluminum in most tractor environments anyway. Just stay away from salt water.

This post was edited by Dave G9N on 12/26/2023 at 09:29 pm.