Bobcat 753 - Pulled engine, fixing leaks and fan drive.

[colson04]

Some weekends, goals and reality don't align. I got the back end of the machine all buttoned up Friday evening. Saturday morning, I go out and start filling fluids. Get to the coolant, and after about 6 quarts I hear gurgling from down near the engine somewhere. Start tracing coolant lines and find leak at thermostat housing. Got a loose bolt. Get wrench on bolt and realize its pretty loose, and won't snug up. Crap. Remove hydraulic filter housing for better access and find a stripped bolt hole in thermostat housing. Family time took over Saturday afternoon so I got back to it today. I have a metric helicoil set already. Get ready to drill and realize my drill bit plus right angle drill is too long and I cant get straight on to drill the hole because of the chassis. Drill length plus drill head has to be under 5" to get aligned to hole to drill it straight. Looking for an 8.25mm stub drill bit. Of course, anyone open on Sunday doesn't carry specialty bits like that. I called a machinist friend, he's going to check his cabinet of drill bits tomorrow for me.




Some family stopped by unexpectedly this afternoon so I shut down this project for the night day and visited instead.

 

[willie59]

Tough spot for a heli coil. Remember, gotta have room for the tool to install the heli coil as well. Another option, worth a try, and if it doesn't work you can always go back to the heli coil. Use a metric stud, set the stud in the thermo housing using red loktite, give it plenty of time to cure, red loktite is some pretty strong stuff. Once that's set, install the outlet and instead of using a gasket use permatex "the right stuff" one minute grey RTV. The RTV makes a bond on it's own so you don't have to torque down the stud nut as much as you would have to using a gasket, and between the loktite stud and the RTV you'll likely have to bust that connection with a chisel next go around. And most cooling systems typically are 7 to 14 psi so pressure isn't really an issue. Make sure you clean the glycol well from the components first, that $hit is slick as snot.

 

[Welder Dave]

A retaining compound may be better than red locktite. Another other option might be to use a longer bolt with a nut on the back of the housing. Loctite makes a stripped thread repair kit too that might be good for a thermostat housing that doesn't need a lot of torque.

 

[56wrench]

In those situations i cut down a drill bit as needed, re-sharpen and carry on. I have multiple sets of drill bits, so, no problem. However i only use the cheap bits for that

 

[DMiller]

In those situations i cut down a drill bit as needed, re-sharpen and carry on. I have multiple sets of drill bits, so, no problem. However i only use the cheap bits for that

Have several made just as that from over the years.

 

[colson04]

In those situations i cut down a drill bit as needed, re-sharpen and carry on. I have multiple sets of drill bits, so, no problem. However i only use the cheap bits for that

I realized that late last night that I could just as well cut off the one I have and keep this project moving forward. For whatever reason, cutting off the one I have to do the task I need never crossed my mind until I was laying in bed. Probably because I never had to do that before, but I'm certainly capable of doing that.

Tough spot for a heli coil. Remember, gotta have room for the tool to install the heli coil as well

I double checked, my helicoil install tool is under the 5" length so I can get it in there. I had not thought about a stud, but I don't know of there's enough material there for a stud to bite on.

 

[willie59]

I had not thought about a stud, but I don't know of there's enough material there for a stud to bite on.

Doesn't have to be fully confident thread material there, Loktite fills gaps and makes a bond to the metal. We have two very old Gehl DL-10 telehandler forklifts. Don't get me started how much I hate those machines, but here we are. One of the things I dislike about them is the steering tie rods, ball joints, and tie rod ends are waaaayyyyy too undersize. I have to keep tie rods and ball joints on the shelf because they have a propensity to snap. Enough of that, another problem they have is the tapered tie rod end stud comes loose, next thing you know it's wallowing around in the hole in the steering knuckle. Over time it makes that tapered hole in the steering knuckle wonky and egg shaped, nothing will keep them tight like that. My latest solution, which so far seems to be working, I have a machine shop make me some bushings that are straight on the OD, but tapered like the tie rod end stud on the ID. I bored the hole in the steering knuckle with a carbide tipped annular cutter the size of the OD of the bushing, stopping 1/8" before I busted out the bottom of the hole to give me a stop when inserting the bushing. Used Loktite 7649 primer in the hole and on the OD of the bushing, then applied Loktite 638 high strength retaining compound to the bushing and in the hole. Slipped the bushing in until it hit the stop at the bottom of the hole. Let it sit for days just to insure a good cure. Dropped the tapered tie rod end in the hole, nutted it tight, did two of those on that machine. That was last August, the machine has been out on jobsites since, with our bunch of iron workers who could destroy an anvil with a wet corn cob and those bushing haven't budged. That's on the stress of a tie rod end on a telehandler, that thermostat connection on you engine is miniscule stress/torque compared to that. Sometimes a Loktite repair works wonders. I can't say that it would work for you, but it would be easy to try, and like I said, if it doesn't work you can always go to plan B helicoil repair.

 

[colson04]

I won't be far from Ace tomorrow, I can see if they have a metric stud in the hardware section.

 

[crane operator]

any auto parts store should have a manifold stud selection.

 

[Welder Dave]

Would putting a nut on the back of the housing be an option? If you have some thread left or could run a tap so the same size thread could be used, I'd try the Loctite retaining compound with a stud or even the Loctite thread repair so you could use the standard bolt.

 

[DMiller]

I have used Cat Supplied Epoxy/Metal that is drillable and machinable made bad days better on those machines requiring new structure to fasten. Devcon produced it then Cat quit carrying under their label and we used Devcon in place. Stuff was extraordinary but a damn short shelf life.

 

[colson04]

Had a busy week of demo and prep work for a bathroom remodel, so this sat all week, again.

Currently, its waiting on red threadlocker to set before putting it all back together. I couldn't find any automotive studs that had the right length/spacing, but the local Ace had metric threaded rod. I think I probably could have just bought a longer bolt. The original bolt only engaged the top 10mm of threads in the hole. The aluminum boss is 20mm thick, and threaded all the way through.



@Welder Dave The only thing stopping me from using a nut under the boss is access. It's already tight accessing the top, and worse squeezing fingers underneath that spot. I looked into that as an option before going with @willie59 suggestion. I could barely get my finger tip in there, let alone anything bigger.

 

[colson04]

All back together. Off to celebrate my Grandmothers 78th birthday now. Then to finish under the cab tonight.

 

[DMiller]

On the way to healed!!

 

[colson04]

I didn't get any pictures, but the Bobcat made smoke today! A long afternoon of sorting out little things. Routing wiring harness, adjusting linkages, filling fluids, replacing case drain filters, priming fuel system, etc. Finally got to the point of hitting the key. A bit of cranking, more bleeding of the fuel system, and vroom! She purrs like a Kubota should. I didn't run it long, getting late and kids have a school night. I did a cursory glance for any leaks during the short run, but I haven't spotted any yet. I don't expect leaks, but given the amount of hoses I disconnected, I wouldn't be surprised if there's a dribble somewhere. For now, it runs. I still have to adjust my neutral setting on the hydrostat, but that will be easier to do now that I can lock the arms out of my way.

Looking forward to having this back in use. A customer just called, asking if I could swing over and grade his private drive. I think I'll put a couple hours on it at my place before I venture too far from home with it.

 

[willie59]

Get the machine on stands with the wheels off of the ground to adjust drive neutral. If you attempt to do it with the wheels on the ground you'll just be wasting your time.

 

[colson04]

Get the machine on stands with the wheels off of the ground to adjust drive neutral. If you attempt to do it with the wheels on the ground you'll just be wasting your time.

I remember, you mentioned it earlier in this thread. I'll have it on stands and get the front wheels off before attempting it.

 

[DMiller]

Great to hear another project finds completion, need to be gathering funds as we speak to build up a Track Loader or a tracked Skid loader purchase. Really need several pieces of heavier machines to get what needs done finished around here.

 

[Welder Dave]

Great to hear another project finds completion, need to be gathering funds as we speak to build up a Track Loader or a tracked Skid loader purchase. Really need several pieces of heavier machines to get what needs done finished around here.

No AC's though. Too bad you weren't close or you could borrow mine.

 

[DMiller]

Yeah, nothing Orphaned.