Anything else to do when changing a head gasket?

[mikehaugen]

I wonder if that can cause the tractor to run lean. Seems like it stalls either because its too lean or sucking air. Can running lean . It run hot?

I would think so, but I'm not sure how lean a diesel will actually run?

 

[Topher265]

...snip... so I traced the fuel lines back to the tank. Found the fuel pump and, lo and behold, there was another inline filter between the tank and the fuel pump. But of course there would be. Just makes good sense. I bet he's clogged up. But I think I'm gonna get some line and bypass him just to make sure. Then I can get everything in one order.

Thoughts?

It sounds like you found a very likely cause.

I wonder if that can cause the tractor to run lean. Seems like it stalls either because its too lean or sucking air. Can running lean . It run hot?

Yes, running lean increases temperatures in the combustion chamber. This is compounded in this situation because the cooling system capacity is rather small (2 quarts!?) so it's hard for the system to get rid of excess heat. This is why it is possible to damage pistons if running super lean... the heat can actually melt pistons or parts of them.

I would think so, but I'm not sure how lean a diesel will actually run?

Diesels run leaner than gassers to begin with, sometimes as lean as 120:1 (air:fuel) in the right circumstance on the right engine (that lean it would be at idle). Technically, gasoline engines have the most complete burn at 14.6-14.7:1. Yet max power from a gasser is on average between 12.0-13.5:1. Gasoline engines have come a mighty long way once you look at a Gasoline Direct Injection (GDI) engine in terms of how lean they can run. A carb'd engine might get away with 15:1, where a GDI can do around 60:1.

 

[mikehaugen]

Diesels run leaner than gassers to begin with, sometimes as lean as 120:1 (air:fuel) in the right circumstance on the right engine (that lean it would be at idle). Technically, gasoline engines have the most complete burn at 14.6-14.7:1. Yet max power from a gasser is on average between 12.0-13.5:1. Gasoline engines have come a mighty long way once you look at a Gasoline Direct Injection (GDI) engine in terms of how lean they can run. A carb'd engine might get away with 15:1, where a GDI can do around 60:1.

I guess what I was asking was more along the lines of how lean (relative to "optimum" mixture for given fuel) will a diesel run? My thinking is that a gas engine is more forgiving, but it's just an assumption.

 

[Lobanz]

Here's Mr Kubota's weak stream from the fuel pump.

 

[Coyote machine]

Too lean, sucking air = not enough fuel: runs hot, boils coolant, etc. So YES!

 

[Topher265]

Here's Mr Kubota's weak stream from the fuel pump.

Wow.

That's awful. I imagine bypassing that filter will solve your problems. It's barely getting fuel at all.

 

[Lobanz]

Wow.

That's awful. I imagine bypassing that filter will solve your problems. It's barely getting fuel at all.

Actually the dealer had one in stock, so I will just change it. Will see about cleaning out tank while I'm at it, but doesn't look bad poking a flashlight in it. Will have to empty it anyway. Got a little extra fuel line at the dealer in case I have to replace some. I wonder if that restriction would kill the lift pump. We'll see.

 

[Topher265]

Actually the dealer had one in stock, so I will just change it. Will see about cleaning out tank while I'm at it, but doesn't look bad poking a flashlight in it. Will have to empty it anyway. Got a little extra fuel line at the dealer in case I have to replace some. I wonder if that restriction would kill the lift pump. We'll see.

Excellent. Lots of restriction would make life harder on the lift pump, so I would think overall it's life may be shorter but you may be luck enough that it lives for a while longer .

 

[Lobanz]

Wahoo!

It was the hidden rear inline fuel filter. Man was it dirty back there. Piles of dirt on the floor now. Took it all apart and cleaned everything. Took gas tank completely off and cleaned it. I could not even blow through the old filter. Replaced it and flow is very good. The little lift pump will spray diesel several feet out of the loosened banjo fitting on the injector pump. Mowed quite a bit with my flashlight in my mouth. Didn't bog down at all in high dew covered grass with dull blades. The only time it struggled at all was if the mower deck could not discharged the grass fast enough and it clogged a little. Changing fuel filter may have helped the temp a little, but not much ( I've read that diesels actually wont run hot if run too lean -- they just won't run at all). But it did not overheat or anything. No coolant loss. The temp meter still reads higher than I like but it plateaus off at a point and stabilizes there just a little below the hot white line. I think the temp sensor is just reading a bit high. Need more load testing to see how it behaves now that its fuel system is back to normal. Hopefully just a few more little things and Mr Kubota can be discharged from the hospital.

 

[Coyote machine]

Xcellent! Now you're beginning to see the big picture. Clogged primary fuel filter causing lack of fuel delivery to lift pump/IP and injectors, of which all suffered in one way or another. Lean fuel delivery causing overheating when tractor being worked hard with dull bladed mower and high grass, etc.
How tractor ran at all is beyond understanding, but I'd bet you were saving big time on fuel use!

 

[Lobanz]

Xcellent! Now you're beginning to see the big picture. Clogged primary fuel filter causing lack of fuel delivery to lift pump/IP and injectors, of which all suffered in one way or another. Lean fuel delivery causing overheating when tractor being worked hard with dull bladed mower and high grass, etc.
How tractor ran at all is beyond understanding, but I'd bet you were saving big time on fuel use!

Yes. I was thinking about that -- how all these systems are interrelated: cooling, fuel, air, lubrication, etc. Seems like on smaller engine like this, there may be less margin for error -- especially when your cooling system only holds 2.2 QUARTs. The tiny cooling system has to be in perfect working order and nothing else can cause any extra heat.

I could be wrong, but, I'm not convinced that a diesel engine can overheat by running too lean. There is no throttle body to limit the air flow, so it's always gulping as much air as possible -- there is always an excess of oxygen in the combustion chamber during normal running conditions. Black smoke indicates incomplete combustion (i.e., too much fuel, or too little air), so it seems that if it ain't smokin', then it's getting full combustion. So, the impact of being starved for fuel would be loss of power and, eventually, stalling (i.e., so little fuel that combustion does not produce enough energy to overcome load), but WITHOUT black smoke. This jives with the fact that when my mower had the fuel restriction, there was no black smoke when it stalled under light load. The reason why there is black smoke when a sudden load is encountered is that the governor somehow senses the load (drop in RPMs but no drop in throttle position?) and squirts in more fuel resulting in a temporary over fueled condition. In a short time, the RPMs come up and the governor is satisfied and backs off the fuel and the smoke goes away. This is also the reason that there is a little black smoke when I punch the throttle even under "no load". By punching the throttle, I've told the governor that I want to increase engine RPMs. The "load" is just the inertia of the engine parts that take energy to being them up to speed (flywheel, etc, maybe the whole tractor if I'm driving). If there is constant black smoke, it would mean that there is a constant condition of too much fuel for the air being taken in, meaning that either the air intake is restricted, or that the load is too much for the engine to handle (governor is squirting in as much fuel as it can but RPMs are not coming back up), or something is malfunctioning or ain't adjusted right causing either too much fuel or incomplete combustion (governor adjustment, injection pump adjustment, injectors not spraying right, injection timing adjustment, maybe other things). Is this a correct understanding?

 

[Topher265]

Yes. I was thinking about that -- how all these systems are interrelated: cooling, fuel, air, lubrication, etc. Seems like on smaller engine like this, there may be less margin for error -- especially when your cooling system only holds 2.2 QUARTs. The tiny cooling system has to be in perfect working order and nothing else can cause any extra heat. Correct, as the cooling system capacity goes down, so does your margin for error. Your lubrication system also performs a good deal of cooling as well.

I could be wrong, but, I'm not convinced that a diesel engine can overheat by running too lean. It would take a combination of things but it is possible. The more I thought about it, the more I realized your specific situation shouldn't cause the overheating from just lack of fuel...but that lack was certainly causing your stalling/lack of power. There is no throttle body to limit the air flow, so it's always gulping as much air as possible -- there is always an excess of oxygen in the combustion chamber during normal running conditions. True. Black smoke indicates incomplete combustion (i.e., too much fuel, or too little air), so it seems that if it ain't smokin', then it's getting full combustion. True. Just be aware Exhaust Gas Temperatures -EGTs- are a better indication of how well a diesel is running, but basically you're right. So, the impact of being starved for fuel would be loss of power and, eventually, stalling (i.e., so little fuel that combustion does not produce enough energy to overcome load), but WITHOUT black smoke. True.. This jives with the fact that when my mower had the fuel restriction, there was no black smoke when it stalled under light load. The reason why there is black smoke when a sudden load is encountered is that the governor somehow senses the load (drop in RPMs but no drop in throttle position?) and squirts in more fuel resulting in a temporary over fueled condition. Sort of. The throttle input stays the same, but the RPMs drop, meaning same fuel delivery but less air...resulting in temporary rich. Governor should be able to reduce the fuel input so the imbalance of fuel:air is closer, then increase the fuel back to what is commanded by the operator. In a short time, the RPMs come up and the governor is satisfied and backs off the fuel and the smoke goes away. This is also the reason that there is a little black smoke when I punch the throttle even under "no load". By punching the throttle, I've told the governor that I want to increase engine RPMs. The "load" is just the inertia of the engine parts that take energy to being them up to speed (flywheel, etc, maybe the whole tractor if I'm driving). Correct. It's corrected very quickly because there is very little adjustment needed. If there is constant black smoke, it would mean that there is a constant condition of too much fuel for the air being taken in, meaning that either the air intake is restricted, or that the load is too much for the engine to handle (governor is squirting in as much fuel as it can but RPMs are not coming back up), or something is malfunctioning or ain't adjusted right causing either too much fuel or incomplete combustion (governor adjustment, injection pump adjustment, injectors not spraying right, injection timing adjustment, maybe other things). Is this a correct understanding? I'd say your understanding is very good.

See Bold comments above

 

[Lobanz]

See Bold comments above

Cool. Thanks Topher!

I did some more load testing. Smoothed out some dirt for a new pasture seedbed by pulling a chain link drag (with some non-trivial weights on it) around with the Kubota mower for quite a while -- couple hours at least. Didn't overheat. It settled out about the same place -- about 1/8" below the top (hottest) white line. This was somewhere around 206-209. Head and radiator (near top hose input) were always similar -- within a degree or two. Block temp was more in the 211-215 range. Oil filter temp was a little less than the block. But each surface is going to be a little different with these infrared gizmos.

Now, if I really push it I can get the temp up to the white line. I was full out bush hoggin' for a while ["thrashing" it ] with dull blades and got the temp up to the top white line -- radiator temp of 219. Wanted to see that the top white line temp was. 219 seems like it's bordering on the danger zone. Seems like a good reading for the top white line. Let it cool down and after about 4 minutes it came back down to about 190. Let it cool down real good before shutting it off. It will cool back down to about 180 (thermostat opening temp) just sitting there at about 1/2 throttle. Seems to cool better at higher RPMs with no load -- more fan speed I guess.

But no boiling over. No coolant loss. Seems to behave pretty well. Does the temp sensor seem OK to you guys? EDIT: Tech at tractor parts place said he would start getting nervous with temps over 225. He also said that temp sensors CAN read wrong and that it sounds like mine might be reading a little high.

Just a few more things to do. I have a problem with the starter. The little lever that pushes the gear against the flywheel is made of plastic. And I think my ignition switch will sometimes stick on -- I've caught it doing this a couple of times. Causes the plastic lever to heat up and deform. Replaced plastic lever once already. Have new ignition switch and lever on the way. Maybe that will fix it.

Yanmar has not exhibited any problems. Box bladed the pasture for quite a while with no trouble. Want to try it plowing. It's never done that before. I've always borrowed my neighbors tractor, but now I have a single bottom plow I want to test out.

 

[Topher265]

Lobanz,

I just posted this in another thread and it made me think of your issue. Have you used your infrared thermometer to check the temps across the entire radiator? You could have possibly a plugged section of the rad.

Also, it might be worth it to install an electric "pusher" fan on the other side of the radiator that comes on as it nears the top end of the temperatures. You can run it with a simple single-throw switch ("on/off") or you could go as far as installing a thermal switch that closes (turns on) at 200F to 212F...like this. It'd require a bit more wiring (the thermal switch would be wired into the control side of a relay, which would turn on the current side where the fan is wired) and it's the safer option so you can protect the tractor. You could fine-tune when it comes on by changing thermal switches.

I'd prefer to see your temps around 190 to 200 max. Pushing it to 211-215 in the block and 219 at the radiator still concerns me and I think it needs to come down from there. The more you get it down to normal, the better off you'll be.

I'd say you may want to install an oil cooler as well. Because the tractor somehow has such a low coolant capacity (2 quarts is flat-out crazy to me), it is depending on the oiling system to aid it's cooling. All engines use the oil to also cool parts, but in your case I believe the oil plays a much more significant role. Installing a cooler should provide you a lot of benefit. Some oil coolers also have an electric fan that will turn on/off as well...helping cool the oil more effectively. I'd also suggest you run a synthetic to fight the breakdown from high heat better, as you are breaking down conventional oil faster (if you run regular oil). Depending on where your oil filter is, you could also install some fins on it to help a little there too.

 

[sparkyrasmus]

I'm resetting the head on my B275 McCormick. I've asked around about gasket sealant and have responses from different shops - about 50/50 response. Some say - DON'T USE SEALANT others say (equally vehemently) Use Copper Coat. What do you folks think? The tractor uses a BD144 engine with pre-ignition cups in the head. It is not a clearance head.

 

[Lobanz]

I'm resetting the head on my B275 McCormick. I've asked around about gasket sealant and have responses from different shops - about 50/50 response. Some say - DON'T USE SEALANT others say (equally vehemently) Use Copper Coat. What do you folks think? The tractor uses a BD144 engine with pre-ignition cups in the head. It is not a clearance head.

I don't know nearly as much as some here, but EVERYTHING I read says to follow the instructions in the service manual or head gasket instructions to a tee -- at least as far as the head gasket is concerned. I'm pretty sure that my service manual explicitly said not to use anything.

 

[Mike in VT]

Pardon me if this sounds stupid - I've only just started reading this thread, and haven't read every post. But, have you cleaned the air side of the radiator? My B2400 was overheating badly, and I tried several things before thinking to blow out the radiator fins with an air nozzle. Turns out they were plugged up with "fluff" from years of mowing. Once they were cleared I've had no more problems with overheating.

 

[Lobanz]

Pardon me if this sounds stupid - I've only just started reading this thread, and haven't read every post. But, have you cleaned the air side of the radiator? My B2400 was overheating badly, and I tried several things before thinking to blow out the radiator fins with an air nozzle. Turns out they were plugged up with "fluff" from years of mowing. Once they were cleared I've had no more problems with overheating.

Yeah. We spray it off before each use. Helps keep it clean. I think this is probably necessary because the cooling system is so small (2.2 quarts) that any issue with it will cause problems. We had is tanked last year, but that wasn't it. I think this mower's cooling system is just too small.

 

[jack72138]

Use the straight edge of a framing square to check the mating surfaces of the head and block to see both are
flat, otherwise you get to do the job again. If not flat, need a machine shop to grind the offending part.
This is not your problem, but I've had trouble with a Kohler Command gas engine overheating and the "oil sentry" (pressure) switch shutting off the ignition forcing you to wait for it to cool down. Drove 26 mi. round trip to buy some gas without ethanol additive. Presto, no more overheating! Jack Brehmer

 

[sd455dan]

Yeah. We spray it off before each use. Helps keep it clean. I think this is probably necessary because the cooling system is so small (2.2 quarts) that any issue with it will cause problems. We had is tanked last year, but that wasn't it. I think this mower's cooling system is just too small.

is there a radiator with more cooling passages that will fit that tractor,
I have heard of some people installing ford replacement radiators (2000-3000models) in some of the small chinese tractors . and the increase in cooling was dramatic.

i have had some radiators coored out in the past for my muscle cars and when that did not achieve the desired cooling a new hd radiator and possibly adding an electric fan always did the trick..

The idea of adding an external oil cooler is a good idea to especially if you can get good airflow and or a fan blowing through it. it is another way to pull more heat out of the engine, it may help pull the temps down.

I just mowed 15 acres with the rhino and a 6 ft. brush bull on a 95* day non stop and the engine never broke 195* the ford runs the same, i believe you should keep trying to get the temps down some. my:2cents: