Bobcat 721 Renovation Project Commencing

Well, I just signed a check to buy a Bobcat 721 with various attachments. I have not succeeded in locating manuals yet, and I will need them. I have no experience with diesels or hydraulic systems yet. Any other Bobcat 721 diesel owners want to pow-wow and share information? Bobcat 721 Renovation Status ======================= * need manuals! Is ebay my best option, or the $9.95 download PDF option I see on some websites? * how to reach the battery when not running? Perhaps jumper cables aren't too hard to reach the battery. * apparently 10W-30 is good for 40 to 95+ degree days (any hotter or colder, and I'll wait for better weather) * dipstick shows oil is milky (presumably hasn't been changed in too long, and has water/decomposition setting in) * too much juice in the pan under the motor (probably has multiple things leaking oil / hydraulic fluid) * green wire to console/circuit panel not connected to anything, another wire cut, but hour meter looks untouched/unmodified and reads less than 1,500 .. maybe even possible, since owned by a homeowner for many years * need one tire: 10x16.5 I presume * all but one ram needs resealed; how many specialty tools will I need to reseal these myself, or better to find a hydraulic shop? * LPS has very few parts specifically listed as compatible with 721 .. worries me .. maybe even basic parts are going to be impossible to find? * fasthose website seems to have just about any hose I might need * plumbed for auxiliary hydraulics, but only 10gpm (attachments included: auger, backhoe, forks, bucket) * some hydraulic lines have been replaced, but others are clearly needing replaced * I've seen and bookmarked the topic about the "hidden" bronze filter: http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=13739 * going to need a lot of "self etching primer" What else should I consider cleaning first? I am still digging through the old topics, and finding gems of wisdom like easter eggs Thanks guys! Thanks OldMachinist! Cheers, GM

Post lots of pictures!!! Looking forward to hearing and seeing your progress!!

SkidRoe said:

Post lots of pictures!!! Looking forward to hearing and seeing your progress!!

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First off, get it clean. Work out where any leaks are or badly rusted/cracked points. Get it running (if its not already doing so). Get the oil changed pronto! You will need multiple flushes to get it right.
As already stated, pictures, lots of them

Tazza said:

First off, get it clean. Work out where any leaks are or badly rusted/cracked points. Get it running (if its not already doing so). Get the oil changed pronto! You will need multiple flushes to get it right.
As already stated, pictures, lots of them

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Pictures ... good idea. I just moved .. which is why I need the Bobcat .. have to find my camera now. > First off, get it clean. Yeah! Pictures after cleaning should help locate leaks/cracks/problems. I was thinking about gently using my pressure washer (electric/medium pressure) with a wide spray nozzle. What areas should I avoid spraying with water? Anything non-obvious need to stay dry at all cost? Roger .. I was thinking about how to get out all the milky oil. So maybe I use cheap 10W-30 in the engine (not the semi-synthetic) for the first 10? 50? hours, and then swap it out early, along with another new oil filter. Hopefully I don't have to also do multiple flushes of 10W-30 in the hydraulic system .. that is a lot of gallons and $$$.

SkidRoe said:

Post lots of pictures!!! Looking forward to hearing and seeing your progress!!

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SkidRoe: I just noticed your signature .. "wood splitter". I can drool over that attachment

gmoon said:

SkidRoe: I just noticed your signature .. "wood splitter". I can drool over that attachment

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There aren't really any no go areas for spraying with water. The on;y problem area is bearings, especially alternator ones. As long as you get it hot to evaporate the water they will be fine.
The milky oil, where is it? just the engine or hydralics too?

Tazza said:

There aren't really any no go areas for spraying with water. The on;y problem area is bearings, especially alternator ones. As long as you get it hot to evaporate the water they will be fine.
The milky oil, where is it? just the engine or hydralics too?

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> The milky oil, where is it? just the engine or hydralics too?
I observed the milky oil on the engine dipstick. I have not checked the hydraulic reservoir/etc. yet. I will check this weekend, when I start working on getting the Bobcat and attachments hauled home. They are still on the original owners property. I'm clearing a spot in my small barn for her new home.

Do you think its safe to hookup the backhoe attachment and leave it connected while transporting the Bobcat on a trailer at speeds up to 45mph on paved roads?

FYI, I discovered NAPA has a handy online tool to lookup various fuel/oil/hydraulic filters for many makes and models, even including the Bobcat 721 with the Deutz diesel engine.

gmoon said:

> The milky oil, where is it? just the engine or hydralics too?
I observed the milky oil on the engine dipstick. I have not checked the hydraulic reservoir/etc. yet. I will check this weekend, when I start working on getting the Bobcat and attachments hauled home. They are still on the original owners property. I'm clearing a spot in my small barn for her new home.

Do you think its safe to hookup the backhoe attachment and leave it connected while transporting the Bobcat on a trailer at speeds up to 45mph on paved roads?

FYI, I discovered NAPA has a handy online tool to lookup various fuel/oil/hydraulic filters for many makes and models, even including the Bobcat 721 with the Deutz diesel engine.

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FYI, for temperatures above 40 degrees F, from various websites/posts of other owners/models, it appears several fluid options are ok for these older Bobcats like 721. Walmart, Costco, and auto-parts stores are said to have one or more of these in stock for about $8 to $12 per gallon, depending on type/brand/size of container:

1. Mobil 1 full synthetic 15w/50
2. AW46
3. 10W-30 SE (Small Engine oil)
4. 10W-30 HDEO (heavy duty engine oil)

Probably makes a bigger difference in how often the fluid and filters are changed than which specific type of oil is used?

gmoon said:

FYI, for temperatures above 40 degrees F, from various websites/posts of other owners/models, it appears several fluid options are ok for these older Bobcats like 721. Walmart, Costco, and auto-parts stores are said to have one or more of these in stock for about $8 to $12 per gallon, depending on type/brand/size of container:

Mobil 1 full synthetic 15w/50
AW46
10W-30 SE (Small Engine oil)
10W-30 HDEO (heavy duty engine oil)

Probably makes a bigger difference in how often the fluid and filters are changed than which specific type of oil is used?

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A 721 would have Deutz 411D air cooled diesel so for the engine oil to be milky there has to be water getting in the crankcase from some outside source. I would change the oil before trying to run it in case the crankcase is over full with the added water. A over full crankcase can blow the crankshaft seals out.
http://www.bobcatstore.com/category...e3qPbheMc38Ke3qOc3aQch4Mbi0.2?categoryId=1460

OldMachinist said:

A 721 would have Deutz 411D air cooled diesel so for the engine oil to be milky there has to be water getting in the crankcase from some outside source. I would change the oil before trying to run it in case the crankcase is over full with the added water. A over full crankcase can blow the crankshaft seals out.
http://www.bobcatstore.com/category.html;jsessionid=0a06662030d8c6b21f27de8343469b4c8d592206b6a3.e3qPbheMc38Ke3qOc3aQch4Mbi0.2?categoryId=1460

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OldMachinist> .. for the engine oil to be milky there has to be water getting in the crankcase from some outside source.
I was thinking the same thing. It has been sitting outside in the rain (dry for recent months) in California for who knows how long, but still shouldn't be access for water into the crankcase. Well, I'll start with the cleaning and oil+filter change, and go from there.

gmoon said:

SkidRoe: I just noticed your signature .. "wood splitter". I can drool over that attachment

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Hi gmoon, The splitter is a unique inverted one that we cooked up ourselves. It splits transversely. You drive up to the block and drop the splitter down over top of it. You can then use it as tongs to reposition the block for your next cut; no need to get out of the cab. I guess I should take and post some pictures of it.

SkidRoe said:

Hi gmoon, The splitter is a unique inverted one that we cooked up ourselves. It splits transversely. You drive up to the block and drop the splitter down over top of it. You can then use it as tongs to reposition the block for your next cut; no need to get out of the cab. I guess I should take and post some pictures of it.

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SkidRoe: Hi gmoon, The splitter is a unique inverted one that we cooked up ourselves. It splits transversely. You drive up to the block and drop the splitter down over top of it. You can then use it as tongs to reposition the block for your next cut; no need to get out of the cab. I guess I should take and post some pictures of it.

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Yep, that sounds perfect .. actually sounds much better than the commercial 30 ton vertical units I have seen. I have large rounds weighing 50 to 100+ pounds that must be split multiple times. Interested in building another one ? :;

gmoon said:

Yep, that sounds perfect .. actually sounds much better than the commercial 30 ton vertical units I have seen. I have large rounds weighing 50 to 100+ pounds that must be split multiple times. Interested in building another one ? :;

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I took some pictures last night and I will post them in "Attachments" forum in the next couple of days.
I will talk to Pops about building another one. We are in Southern Ontario, Canada; it sounds like you are in California. Shipping may be significant $$'s.
My e-mail address is in my profile, shoot me an e-mail if you are serious and we can talk off-line.
Cheers,
SR

SkidRoe said:

I took some pictures last night and I will post them in "Attachments" forum in the next couple of days.
I will talk to Pops about building another one. We are in Southern Ontario, Canada; it sounds like you are in California. Shipping may be significant $$'s.
My e-mail address is in my profile, shoot me an e-mail if you are serious and we can talk off-line.
Cheers,
SR

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Ok, I am just going to keep posting bits of information for the Bobcat 721, as I discover them. The information exists in other posts on this website, the manual, and other websites. Credit goes to the numerous other authors. I'm just collecting information for the 721
NAPA filter parts (circa 2011) for Bobcat 721:
* $29 Air Filter https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL2276_0006473389&An=0
* $13 Fuel Filter (Gold) https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL3195_0271551452&An=0
* $84 Fuel Filter Base https://www.napaonline.com/Catalog/...eyword&Nty=1&Dn=0&D=3195+filter&Dk=1&Dp=3&N=0
* $11 Part 1551 (10 micron) Transmission/Hydraulic Oil Filter .. 3 to choose from .. which one(s)? https://www.napaonline.com/Catalog/...eyword&Nty=1&Dn=0&D=1551+filter&Dk=1&Dp=3&N=0
* $22 Part 1758 (25 micron) Hydraulic Oil Filter https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL1758_0006481006&An=0
* $5 Oil Filter (Gold) https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL1342_0192950064&An=0

gmoon said:

Ok, I am just going to keep posting bits of information for the Bobcat 721, as I discover them. The information exists in other posts on this website, the manual, and other websites. Credit goes to the numerous other authors. I'm just collecting information for the 721
NAPA filter parts (circa 2011) for Bobcat 721:
* $29 Air Filter https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL2276_0006473389&An=0
* $13 Fuel Filter (Gold) https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL3195_0271551452&An=0
* $84 Fuel Filter Base https://www.napaonline.com/Catalog/Result.aspx?Ntt=3195+filter&Ntk=Keyword&Nty=1&Dn=0&D=3195+filter&Dk=1&Dp=3&N=0
* $11 Part 1551 (10 micron) Transmission/Hydraulic Oil Filter .. 3 to choose from .. which one(s)? https://www.napaonline.com/Catalog/Result.aspx?Ntt=1551+filter&Ntk=Keyword&Nty=1&Dn=0&D=1551+filter&Dk=1&Dp=3&N=0
* $22 Part 1758 (25 micron) Hydraulic Oil Filter https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL1758_0006481006&An=0
* $5 Oil Filter (Gold) https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=FIL1342_0192950064&An=0

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As an experiment, I have converted one section of the Bobcat 721 manual (the Deutz engine section) to text searchable Google Docs (online) format:
Searchable online Bobcat 721 Deutz Engine Manaul
Anyone can edit the text and add notes. The conversion process from an image to English text is not perfect, so there are a few minor flaws, but the original page images are shown first. Anyone can use their web browser and edit/fix the minor typos. The Google document revision history shows who made which edits. Feedback appreciated.

gmoon said:

As an experiment, I have converted one section of the Bobcat 721 manual (the Deutz engine section) to text searchable Google Docs (online) format:
Searchable online Bobcat 721 Deutz Engine Manaul
Anyone can edit the text and add notes. The conversion process from an image to English text is not perfect, so there are a few minor flaws, but the original page images are shown first. Anyone can use their web browser and edit/fix the minor typos. The Google document revision history shows who made which edits. Feedback appreciated.

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I would certainly go for a 15W40 engine oil. Mobil 1 would be fine as would Amsoil or Shell Rotella T.

donald73d said:

I would certainly go for a 15W40 engine oil. Mobil 1 would be fine as would Amsoil or Shell Rotella T.

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Yeah, it only holds a gallon in the engine, so using pricier oil isn't a big deal. Good to hear someone else mention 15W-40. I've never even noticed this weight before, but the temperature ranges seem better suited for when I would actually use it. Maybe even 20W-40, if I can find HDEO rated.
However, the 17 gallons in the hydraulic system really adds up, so I need to do some careful shopping. I'm planning on changing it twice in a short time period. After I reseal the rams, change it once, then use it a while, and change it again to flush as much of the old as possible out of the system. Anyone ever tried the fluid lab tests for older Bobcats (about $37 per fluid sample)? I did this for a 1990's JCB backhoe, and got some very helpful information back about problems with the machine.

gmoon said:

Yeah, it only holds a gallon in the engine, so using pricier oil isn't a big deal. Good to hear someone else mention 15W-40. I've never even noticed this weight before, but the temperature ranges seem better suited for when I would actually use it. Maybe even 20W-40, if I can find HDEO rated.
However, the 17 gallons in the hydraulic system really adds up, so I need to do some careful shopping. I'm planning on changing it twice in a short time period. After I reseal the rams, change it once, then use it a while, and change it again to flush as much of the old as possible out of the system. Anyone ever tried the fluid lab tests for older Bobcats (about $37 per fluid sample)? I did this for a 1990's JCB backhoe, and got some very helpful information back about problems with the machine.

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I see Chevron diesel-application 15W-40 5 gallons for $70:
http://www.tractorsupply.com/motor-oil/chevron-delo-reg-400-le-sae-15w-40-5-gal-pail-8307058
I see Traveller diesel-application 15W-40 5 gallons for $55:
http://www.tractorsupply.com/motor-...fleet-15w-40-diesel-engine-oil-5-gal--8040070
The Traveller-branded oil above certainly claims to be "good" for diesel tractor engines, listing numerous specifications it meets/exceeds.
Also the Shell Rotella 15W-40 5 gallons for $65:
http://www.tractorsupply.com/motor-oil/shell-rotella-reg-15w40-oil-5-gal--0830675
What do you think?

gmoon said:

I see Chevron diesel-application 15W-40 5 gallons for $70:
http://www.tractorsupply.com/motor-oil/chevron-delo-reg-400-le-sae-15w-40-5-gal-pail-8307058
I see Traveller diesel-application 15W-40 5 gallons for $55:
http://www.tractorsupply.com/motor-oil/traveller-reg-premium-all-fleet-15w-40-diesel-engine-oil-5-gal--8040070
The Traveller-branded oil above certainly claims to be "good" for diesel tractor engines, listing numerous specifications it meets/exceeds.
Also the Shell Rotella 15W-40 5 gallons for $65:
http://www.tractorsupply.com/motor-oil/shell-rotella-reg-15w40-oil-5-gal--0830675
What do you think?

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gmoon, wondering if you are still on here and would be willing to share your experience with the 721. I came across your posts when you were starting to restore and I am contemplating a purchase of a 721 and wondering how yours turned out and if you would recommend the machine in general. Also anything to look for specifically when purchasing one. Appreciate it.