Ill try to post a photo. Was cleaning out under cab and noticed one bolt was missing from the pump mount. Another was hanging half out of the hole. Pulled it out and end was broken off. The other two bolts are still tight. Anyone ever see this happen and why?
Serial number ?
I'm trying to see the markings on the heads of the bolts and don't see anything to determine if they are grade five or grade eight bolts. If they are metric I think they should have something like 10.8. Can you confirm that?
Vibraaaaation would be my guess.. are those flat washers or lock washers?? are they thick enough to actually tighten up or are they bottoming in the housing?? They look like "blind holes" & don't actually go into any fluid type of area or there would be fluid running from the bolt holes.. Heres an old/odd trick.. get a straw from the kitchen or from a fastfood place in the morning/lunch.. OR use a scribe.. Remove one of the "good" bolts & run the straw down the hole till it bottoms & pinch it w/your finger & hold it up to the bolt & see if the bolt is to long, washer to small or you have PLENTY of room for it to tighten up w/o a fatter washer.. Maybe put some BLUE Loctite on the threads & FIND OUT what the actual tightening torque is..
That's interesting. I wonder if its an issue with the steel bolts in an aluminum housing? 257B is gotta be around 10-15 years old now. Could just be from years of vibration.
Bad thing I see is from checking on SIS it appears that the only parts available for this pump are the input shaft seals! Hopefully if it has to come apart to get the broken bolt(s) out any seals(orings) can be matched up by a good hydraulic shop. I know I would be looking close at the broken bolts to see if there were signs of corrosion from the galvanic reaction between the steel and aluminum. I would not reuse any of the bolts no matter how good they look and if there is even the slightest signs of corrosion I would be using some good grease on them when installing.
I plan on removing the pump and replacing all bolts with a stronger bolt and use some blue thread locker. They are metric and I don't see any corrosion on the one hanging out. Will report back after removing pump.
The bolts are 10.9 metric ... equal to a grade 8 . You could go up to a 12.9 equal to a grade 9. The broken end will tell a lot of the "WHY" Progressive fracture means a fatigue break
Agree that a close look at the broken end of the broken bolt is very important to understand the reason for the failure. If you can get a good clean close-up hopefully someone here can identify the cause of the failure. Just off the top of my head it seems strange that if this pump is working with half of the bolts either missing or broke and does not appear to be leaking it seems like the problem was related to those two bolts alone. If I understand the information in SIS this is the "high flow" pump. Is it possible your application does not make use of this pump?
This is a standard flow pump. The bolts are metric and are Identified as "JD 10.9" Looks like the bolts screw into the steel pump mounting flange. I will remove and get the broken ends out.
Here is a link to some pictures of failed bolts might help to understand what caused them to fail. https://www.google.com/search?q=bol...TwzbvWAhXl1IMKHbaoA5UQ7AkIQg&biw=1280&bih=586
No point putting a higher grade bolt in, if you pull it to higher than specced torque (about 50-55nm for a 10 mm 10.9,) you just risk ripping out an alli thread. Correct torque and blue loctite, and if the thread is okay it'll be okay.
Thanks for the info. I ordered 4 new ones from McMaster Carr. No one locally had any long enough. Now I need to see if I can get this pump off without getting a oil bath.
A little blurry but here is the broken end of bolt,
That pic didn't help much. Your finger is clear enough to make out finger prints... Move the end away from the camera lens.
Looks like a lot of extra threads ,how much thread left in the hole
Got both out and replaced them all. Broken pieces were about 1/2" long.
Were they bottomed out ? If not how much extra room was there