JD LX178 blowing black smoke

[genynnc]

When you mean towards the driver, you’re referring to pushing it towards the back of the mower correct? I just tried tapping/gently pushing all the linkages towards the back of the mower - no change. Interestingly enough, I got a coolant leak now. Any thoughts why it randomly popped a coolant leak by the radiator?

Another thing to note is that it cranked for a long time after the spark plug change to get started. And just as it was catching, I think there were a couple of puffs of white smoke (couldn’t tell it was dark and overcast outside), which then reverted back to the black smoke and the rough idling.

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Driver's side, as in a car (sorry that wasnt clear)... if you are looking toward the front of the mower... you would kneel down by the left, front wheel... find that metal plate where throttle/choke attach... and push on all the linkage toward the right side of the machine.

You said you changed the carb... did you get the governor adjusted/ put back correctly?

As for the coolant leak... probably radiator needs some work if it's not a head gasket (which sounds like some of your symptoms could resemble that but not the black smoke... and if your oil isn't milky then... should be fine on that front.)

If it's the radiator... find a good radiator shop and have it fixed. People who cannibalize parts from non functional machines have the parts (like a radiator)... but you'll overpay big time.

I highly doubt Kawasaki still sells this radiator. And if they did it would be big money anyway.

IF you don't have a radiator shop nearby AND there's not a reasonable one listed on ebay/ craigslist/ marketplace... I would just look for a complete engine from a used LX 178/ 188... and I *think* some other JD models used the FD series engines (like the early UTV & commercial front mower deck models... might could use those radiators too but not sure.)

Top end on these things are always "gunky". I think they came with stock 160 degree thermostat... which doesn't help with the rich as a fat pig jetting. So yeah... they are messy up top... sounds normal your description.

John Deere did eventually offer a 180 degree thermostat... I actually think there was a bulletin on it. I think they still sell it.

 

[jsean]

Driver's side, as in a car (sorry that wasnt clear)... if you are looking toward the front of the mower... you would kneel down by the left, front wheel... find that metal plate where throttle/choke attach... and push on all the linkage toward the right side of the machine.

You said you changed the carb... did you get the governor adjusted/ put back correctly?

As for the coolant leak... probably radiator needs some work if it's not a head gasket (which sounds like some of your symptoms could resemble that but not the black smoke... and if your oil isn't milky then... should be fine on that front.)

If it's the radiator... find a good radiator shop and have it fixed. People who cannibalize parts from non functional machines have the parts (like a radiator)... but you'll overpay big time.

I highly doubt Kawasaki still sells this radiator. And if they did it would be big money anyway.

IF you don't have a radiator shop nearby AND there's not a reasonable one listed on ebay/ craigslist/ marketplace... I would just look for a complete engine from a used LX 178/ 188... and I *think* some other JD models used the FD series engines (like the early UTV & commercial front mower deck models... might could use those radiators too but not sure.)

Top end on these things are always "gunky". I think they came with stock 160 degree thermostat... which doesn't help with the rich as a fat pig jetting. So yeah... they are messy up top... sounds normal your description.

John Deere did eventually offer a 180 degree thermostat... I actually think there was a bulletin on it. I think they still sell it.

Oh gotcha! Thank you for the clarification. This morning I went back and verified that the linkages were moving freely and gently nudged the linkages to the left/drivers side.

Prior to putting the plastic intake elbow on post carb replacement - I did verify that the throttle and choke flaps opened/closed (it was a little hard to verify on the throttle flap with it being hidden in the back). I adjusted the throttle, choke and governor per the FSM. Haven’t touched those since.

Interestingly enough, there was a small pool of coolant below the radiator (about 7am this morning and I last did my run post plugs swap yesterday at 5:30pm). Something didn’t seem right for the radiator to be leaking after all these hours. I popped the radiator cap off with the engine stone cold and off - sure enough, a healthy amount of antifreeze dumped out.

The antifreeze level is just above “H” in the reservoir and almost up to the top of the radiator neck. Prior to this issue, the reservoir level was about steady at maybe 1/2” below “H” since last fall when it got its annual antifreeze spill and fill and the radiator level was right at the overflow hole/hose level.

So did I just blow my head gasket given the coolant levels, radiator being pressurized and still overfull after dumping some coolant along with the general reluctance to start yesterday?

I tried to spin the cooling fan below the radiator by hand and it’s there SOLID! Can someone with a LX178/188 verify if that’s the case with your machine too?

 

[genynnc]

Ok.

I don't know. It's hard to say without being there in person.

Pushing coolant out adds to head gasket symptoms.

Fan I dont believe should spin by hand. I *think* it is driven by a gear in the crankcase (mounted to shaft in water pump) so unless the crank is turning... I dont think it should.

 

[Lawnman23]

Looking at parts diagrams online for this engine, it looks like the fan spins directly off the top of the crankshaft. So it should be solid when engine is off.

 

[jsean]

Thank you both! You guys are correct about the cooling fan.
I swapped ignition coils around just to verify, didn’t make any difference I could tell. Also, when I ran it the first time this morning with no radiator cap on, the coolant just sat around at the top. Shut it off and restarted it - this time there were several bubbles in the radiator neck and then the coolant level in the radiator fell about a solid 1.5-2” within the first maybe 2-3 seconds. After the antifreeze level fell, I couldn’t see any more bubbles - but I didn’t check closely.

Just pre cold start, after it had already dumped the coolant out when I first opened the radiator.

This is post the 2nd run after the coolant level dropped. It’s currently flush with the radiator (the top horizontal part of the radiator = level of coolant) now. Sorry for the poor picture - I took a picture with flash because there were quite a few small floaties at the top of the coolant.

Here’s a video of it running - I can’t quite tell if the smoke is grey/black or blue. I did replicate a few small puffs of white smoke during startup this morning similar to last evening.
JD LX178 Idling

 

[genynnc]

I don't know about the coolant deal.
I dont know "how fast" the thermostat takes to open or how long you ran it initially from the 1st start of the day.

Seems like you have 2 issues that are seperate- carb issue & some sort of coolant level issue.

Without more diagnosis or symptoms... who knows. You need to do a compression check. A slightly failed headgasket can contribute to both issues you are having but lots of variables are existing.

The video... I can't really see a lot of smoke... and the sound of the engine is hard to tell from the video exactly how its running.

Sorry couldnt help further.

 

[The_Eric]

Seems like you have 2 issues that are seperate- carb issue & some sort of coolant level issue.

I'd agree with 2 possible separate issues, but I doubt that it's a carb problem - evidenced by the fact that a second carb did nothing, the problem apparently exists on one cylinder and in the video he linked, there is a ton of reversion. This stinks to me of a mechanical issue, probably a cam/pushrod/valve issue of some sort.

OP - pop the rocker cover on that side and give things a gander.. if nothing jumps out at you (or falls out for that matter) then check valve clearance.

 

[jsean]

I don't know about the coolant deal.
I dont know "how fast" the thermostat takes to open or how long you ran it initially from the 1st start of the day.

Seems like you have 2 issues that are seperate- carb issue & some sort of coolant level issue.

Without more diagnosis or symptoms... who knows. You need to do a compression check. A slightly failed headgasket can contribute to both issues you are having but lots of variables are existing.

The video... I can't really see a lot of smoke... and the sound of the engine is hard to tell from the video exactly how its running.

Sorry couldnt help further.

No worries! Thanks for the constant ideas on what I can check. I’d hate to give up on her just yet.

 

[Chris142]

too much fuel or too little air

 

[jsean]

I'd agree with 2 possible separate issues, but I doubt that it's a carb problem - evidenced by the fact that a second carb did nothing, the problem apparently exists on one cylinder and in the video he linked, there is a ton of reversion. This stinks to me of a mechanical issue, probably a cam/pushrod/valve issue of some sort.

OP - pop the rocker cover on that side and give things a gander.. if nothing jumps out at you (or falls out for that matter) then check valve clearance.

I think you might be on to something. So I verified that the left side cylinder doesn’t get any spark - irrespective of the coil. No matter what coil I got On the left side, unplugging it does nothing. Unplugging the coil on the right side results in the mower shutting off. What’s causing the cylinder on 1 side to not run no matter the coil or spark plug in there?

Also, with the radiator cap off, during startup it shoots coolant out about 6” before settling down. Does that indicate anything?

I’ll open up the valve cover on the left side to verify later today and post back here

 

[The_Eric]

I think you might be on to something. So I verified that the left side cylinder doesn’t get any spark - irrespective of the coil. No matter what coil I got On the left side, unplugging it does nothing. Unplugging the coil on the right side results in the mower shutting off. What’s causing the cylinder on 1 side to not run no matter the coil or spark plug in there?

Also, with the radiator cap off, during startup it shoots coolant out about 6” before settling down. Does that indicate anything?

I’ll open up the valve cover on the left side to verify later today and post back here

You say that there is no spark, but did you actually check it? Like ground a spark plug against the engine and turn it over? The way you're talking makes me think that there is a bit of a communication barrier or breakdown. Swapping coils with the same running concerns would generally indicate that it not a spark problem. If you're not actually getting spark, then there is no sense in pulling the rocker cover or tearing anything else apart.

 

[jsean]

You say that there is no spark, but did you actually check it? Like ground a spark plug against the engine and turn it over? The way you're talking makes me think that there is a bit of a communication barrier or breakdown. Swapping coils with the same running concerns would generally indicate that it not a spark problem. If you're not actually getting spark, then there is no sense in pulling the rocker cover or tearing anything else apart.

Sorry if my wording was unclear.
1. When I unplug the coil on the left side, there is no change to the way the engine is running.
2. When I unplug the coil on the right side, the engine sputters and dies.
Both steps above are same irrespective of coils being swapped or changing out a new coil on the left cylinder.

When I take the spark plug out on the left side and ground it against the engine, I’m able to verify spark.

If I unplug the right coil, and crank using just the left cylinder plugged in, it will not start. If I unplug the left cylinder and crank only using the right cylinder, it’ll start up. This is completely independent of which of the 3 working coils I have when they are installed on the left cylinder.

Not sure if that helps diagnosing what’s happening or not?

 

[The_Eric]

Sorry if my wording was unclear.
1. When I unplug the coil on the left side, there is no change to the way the engine is running.
2. When I unplug the coil on the right side, the engine sputters and dies.
Both steps above are same irrespective of coils being swapped or changing out a new coil on the left cylinder.

When I take the spark plug out on the left side and ground it against the engine, I’m able to verify spark.

If I unplug the right coil, and crank using just the left cylinder plugged in, it will not start. If I unplug the left cylinder and crank only using the right cylinder, it’ll start up. This is completely independent of which of the 3 working coils I have when they are installed on the left cylinder.

Not sure if that helps diagnosing what’s happening or not?

Gotcha. Well it sure sounds and looks like a mechanical issue to me then. Keep us posted please!

 

[Bighorn2500]

I’d say the CDI igniter box went bad. I replaced mine two summers ago.

I had a similar issue on my ‘96 LX188, I sourced a New old stock one on eBay because they aren’t cheap. I went OE because the amazon knockoff looked cheap.

 

[SHOZ]

I just had my needle valve stick open and this carb I have has an overflow vent dumping fuel. But was running rich. Same mower also had the fuel pump injecting air into the pre pump gas line. Change pump then needle stuck.

 

[jsean]

I took the left side valve cover off to discover this. Seems like the valve dropped, I’m guessing this motor is done?

 

[jsean]

I’d say the CDI igniter box went bad. I replaced mine two summers ago.

I had a similar issue on my ‘96 LX188, I sourced a New old stock one on eBay because they aren’t cheap. I went OE because the amazon knockoff looked cheap.

That was my thinking too - from what I saw on the mower forums though, a bad igniter shows up as spark on 1 side and no spark on the other. In my case, I have consistently strong spark on both sides.

 

[SHOZ]

You can get a used head off ebay and new head gasket for the cheap.

 

[jsean]

Hadn’t considered that as an option. Is the dropped valve due to a blown head gasket? Or could there other problems that are hidden?

 

[SHOZ]

My F510 had exhaust valve issues and that's what I did. It was a cheap and relatively easy fix. Years of neglect as far as blowing out debris from the cooling fins. Cost about $80 total.