743 Issues

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DEGER

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Joined
Jan 12, 2016
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3
Apologies for the double post... I picked up a 743 a few months ago. It always smoked a bit when starting up(dark), I just chalked it up to an old diesel... Last week after 5 minutes of use, I turned it off and heard the rad bubbling. The next day I added fresh coolant. A couple days later i was running for a few minutes and the engine quit., then I heard the coolant jug spitting out coolant and bubbling. Had it towed to a shop and they said the entire engine was full of coolant! Shop said the injectors were plugged and that caused it to quit, not the temp luckily. Head gasket? Thermostat? water pump? They're quoting $1200 just to take out the engine and diagnose what it needs and then go up from there, saying it'll likely be $4k after all is done. I picked it up for $4000 and am prepared for some work, but is this a typical issue? Are there other underlying issues usually? Is there anything else I should be doing at the same time to ensure it runs well going-forward? Any help or insight would be appreciated.
 

Bobcatdan

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May 3, 2012
Messages
1,684
I'd say it overheated, cracked the head and hydro locked the engine. Anybody who knows these machines should know that. Also said mechanic should be able to remove the engine in about an hour. Depending on engine condition, replacement of the would be about $1500 in parts if I recall right. Personally not being a fan of 40 series, unless you can do the work, dump it. $4000 is about max vavle for the unit so to turn around and stick another $3000 isn't my way of budgeting.
 

mmsllc

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Dec 29, 2015
Messages
715
I'd say it overheated, cracked the head and hydro locked the engine. Anybody who knows these machines should know that. Also said mechanic should be able to remove the engine in about an hour. Depending on engine condition, replacement of the would be about $1500 in parts if I recall right. Personally not being a fan of 40 series, unless you can do the work, dump it. $4000 is about max vavle for the unit so to turn around and stick another $3000 isn't my way of budgeting.
Overheating CAN and DOES happen with out warning. BUBVBLING is usually a sign of severe overheating as the coolant is then BOILING!! The most common reasons are usually pretty obvious; leaks that cause low level, fans not turning because of belt issue, insufficient air across coolers due to fan clutch / drive issues, stuck thermostat causing too little fluid able to pass through, scale build up in system due to incorrect coolant type, ETC. If you do repair this engine, DO replace a lot of these cheaper parts to help prevent this from ever happening again. Having the radiator taken out & Boiled clean is a super smart move as well. Replacing coolant hoses is another cheap idea that will help, too. As for value or if you should repair this machine, that will be a decision that only you can answer. If you can find a 751 or 753, that runs, it might be best to part it out to help regain some of your lost $4000 purchase price. Someone once told me that life gives you the test first, then teaches you the lesson second. It makes it difficult to get it right every time.
 

Tazza

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Dec 7, 2004
Messages
16,829
Overheating CAN and DOES happen with out warning. BUBVBLING is usually a sign of severe overheating as the coolant is then BOILING!! The most common reasons are usually pretty obvious; leaks that cause low level, fans not turning because of belt issue, insufficient air across coolers due to fan clutch / drive issues, stuck thermostat causing too little fluid able to pass through, scale build up in system due to incorrect coolant type, ETC. If you do repair this engine, DO replace a lot of these cheaper parts to help prevent this from ever happening again. Having the radiator taken out & Boiled clean is a super smart move as well. Replacing coolant hoses is another cheap idea that will help, too. As for value or if you should repair this machine, that will be a decision that only you can answer. If you can find a 751 or 753, that runs, it might be best to part it out to help regain some of your lost $4000 purchase price. Someone once told me that life gives you the test first, then teaches you the lesson second. It makes it difficult to get it right every time.
Bubbling was probably a cracked head, it is exhaust gasses being blown into the water jacket. When it quit, the coolant was probably hot enough and under pressure pushing it through the cracks and into a cylinder.
As Dan mentioned, a running engine will run you about 1-1.5k, if you have the gear, you could do the swap your self.
 

Fefanatic

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Joined
Dec 14, 2015
Messages
42
Bubbling was probably a cracked head, it is exhaust gasses being blown into the water jacket. When it quit, the coolant was probably hot enough and under pressure pushing it through the cracks and into a cylinder.
As Dan mentioned, a running engine will run you about 1-1.5k, if you have the gear, you could do the swap your self.
$4k max value? I've done the research and they are generally selling for $6500. to $9k depending on condition. Yes, you probably can buy one for $4k but it will be like the unit the OP is having problems with. $4k will get you a hurt machine. You can pick up a used engine for around $1500.00. A couple of hours to change out and you are back in business. Look around and you can find the parts you need without paying all those extra dollars. Ebay is a good source for parts.
 

rodbuilder

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Joined
Mar 6, 2015
Messages
236
100% - you have a cylinder head problem. 1. Crack. 2. Blown gasket If you have any mechanical experience working on it is just as easy as working on your car - except for the lack of room. The ONLY thing different is the fact that a diesel is an interference-type engine, so there's NO room for error when adjusting the valves, or setting cam timing. You won't have to mess with the injector pump, so you can write that off! Look on Ebay for a head and replace the whole thing. I've seen them there for as little as $300-$400......NEW. NOTICE: If you buy a rebuilt head you need to know how much they milled off of it to surface it, so you can order a gasket with the correct thickness. .010" off the head equals a .010" thicker gasket. You can buy a decent 743 for $4500-$5000 if you look around, so don't step on your weenie by spending more on it than it's worth!
 

rodbuilder

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Joined
Mar 6, 2015
Messages
236
9 grand for a 743 Bobcat?!!!!! If you'd pay 9 grand (or even EIGHT!) for a 743 Bobcat, give me a call. I have a big bridge in New York city that I want to sell you!!!!! Here's a BRAND NEW head you can buy for just $350, including shipping. http://www.ebay.com/itm/1902-1702-Bobcat-743-Bare-Cylinder-Head-Kubota-v1702-brand-new-/161956008469?hash=item25b5549215:g:yFUAAOSw14xWKnWl&vxp=mtr He can use his old valves and springs and have a local machine shop grind the seats and valves and put it all together for about $150-200. Any more than that and you're getting ripped off for that 4-banger valve job.
 

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