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I have a John Deere LX188, and a couple of weeks ago it overheated when I was mowing. Sure enough, the screen had a ton of dust and dirt and was blocking the air flow. I thought that was it, but when I went to mow last week it overheated 15 minutes in. I had to let it cool off for about an hour then ran it again for 15 minutes before it overheated again.

So, the tractor will run for 10-15 minutes now before it shuts off from overheating. Give it an hour to cool down then it will run again for 10-15 minutes before shut down. Coolant level appears to be ok as reservoir is still above the low mark. I checked radiator fins and straightened them out and made sure no blockage.

Any ideas what the issue may be? I've read thermostat and water pump may be the issue, but is there a way to rule one out? How difficult is it to replace these on my own (I'm a novice but take directions well)? Any other ideas or tips are greatly appreciated. Thanks!
 

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That's a good starting place. Radiator, Thermostat, Coolant pump and issues related to that. Then it gets into leaks that mess with air/fuel mix. Like intake manifold, and gaskets with that. Then we get into oil flow/lubrication that means, pump sump/pickup, oil pump, oil passage ways (cam problems). Then it leads to bearings, rods, crank.
 

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If you are totally sure that the correct amount of airflow is going through the cooling system. Next step would be to look inside. Like condition of coolant, correct concentration of mix (coolant to water), and any internal blockage. The blockage could be from corrosion or a stuck thermostat.
 

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Is the light coming on? You say it's shutting down? Are you shutting it off or is it shutting off on it's own? There is nothing in the system to shut the engine off when over heating. If it is shutting off on it's own, your problem lies elsewhere.

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Is the light coming on? You say it's shutting down? Are you shutting it off or is it shutting off on it's own? There is nothing in the system to shut the engine off when over heating. If it is shutting off on it's own, your problem lies elsewhere.

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Thanks for all the replies so far. Yes, it shuts down on its own and at that time the light comes on. I thought there was an automatic shut off if the engine overheated, but apparently the light that is coming on is the oil pressure indicator light (the middle one of the three that are on this model).

My apologies, I thought it was an overheating issue since it just randomly shut down in the middle of a mow when the screens were clogged, and now it will run for 10-15 minutes before shutting down. So, given these symptoms and the fact that it is the oil pressure indicator light, does anyone have any further thoughts on what the issue may be? I checked the oil levels and they're fine.
 

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If the engine slows enough for whatever reason, then the oil light may come on due to low RPMs. I would run it and see if it's loosing spark or a fuel issue. The fact that it cools off and restarts could be ignition related but hard to tell without testing for spark. You can get a couple in line spark testers at an auto parts place. Put one on each cylinder and mow til it quits. Then crank and check for spark.

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If the engine slows enough for whatever reason, then the oil light may come on due to low RPMs. I would run it and see if it's loosing spark or a fuel issue. The fact that it cools off and restarts could be ignition related but hard to tell without testing for spark. You can get a couple in line spark testers at an auto parts place. Put one on each cylinder and mow til it quits. Then crank and check for spark.

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So would this explain why it will run fine for 15 minutes, then I have to let it cool down another 30-45 minutes before it will run again? I have noticed I have to let it warm up a full throttle a little longer the past couple of starts.
 

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When you slowly turn the key to start position, the temp. light should glow and go off as the engine starts or you let the switch return to the run position, as best I can remember anyway. If it doesn't, the bulb may be bad or the temp. sending unit isn't working. You want to know if that works correctly in case it does get too hot sometime.
With the switch turned to on, before cranking, you should see the oil (red) and battery (yellow?) lights come on.

As far as stopping after running a while, don't forget to make sure the vent hole in the gas cap is open. You should be able to blow thru it from the outside. Just thought I should mention that before we go too far. Hope it is that simple. :unknown:

tommyhawk
 

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So would this explain why it will run fine for 15 minutes, then I have to let it cool down another 30-45 minutes before it will run again? I have noticed I have to let it warm up a full throttle a little longer the past couple of starts.
That's what he is saying. It's possible that the magnetos cut out after getting hot and stop firing the spark plugs. When they cool down you are back in business. (Until they get hot again)

Is the engine also not running correctly after a cold start? Seeing you have to let it warm up a little at full throttle.
If the engine doesn't run correctly when cold and stalls when hot you could have a fuel problem.
I'd first check it for spark as suggested. If it still has spark when hot it has another problem.
 

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I don't know why, but a reply that I posted to this thread over 4 hours ago has not yet appeared online. This shutting down after running for approximately 15 minutes issue is a common problem with the LX 188. Check the electrical connectors that plug into the ignition CDI box, they sometimes develop resistance where they plug together.

Also check hat the carburetor has gas in it by unscrewing the fuel bowl drain screw to see if at least an ounce or two of gas drains out. If nothing or hardly nothing drains out, then check for a fuel restriction. Check fuel pressure, should be around 4 lbs.. With the drain screw open, try blowing air into the fuel inlet of the carburetor to see if you can hear air or fuel coming out of the bowl drain.

Also, sometimes the magnetic fuel shut-off vales at the bottom of the fuel bowl will become defective, especially after being run for a while. Check for power to the valve when the engine stalls, you should hear it click when the key is turned on.
 

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Discussion Starter #12
I checked the fuel filter and was able to blow air through it. I also checked for spark with the in line tester and they're both sparking. Air filter has been cleaned too. I'm still having the same issue of it cutting off after about 15 minutes. I don't think it's an overheating issue anymore since apparently this model doesn't have an auto shut off (per a previous poster). Anymore ideas?
 

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Did you confirm there is spark after it shuts down - if so I am leaning toward the carb needing to be cleaned. Aren't the LX188, 178's prone to a little dirt or sludge clogging them? Maybe try a little seafoam in the tank to see if it improves before a rebuild of the carb.

If it has the shut off solenoid on the carb then that is a good candidate for replacement as mentioned earlier. I worked on the Church's Lawn Boy that did what you describe but it just took a little longer, 45min to an hour before the shut off depending on the air temp.
 

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I checked the fuel filter and was able to blow air through it. I also checked for spark with the in line tester and they're both sparking. Air filter has been cleaned too. I'm still having the same issue of it cutting off after about 15 minutes. I don't think it's an overheating issue anymore since apparently this model doesn't have an auto shut off (per a previous poster). Anymore ideas?
Confirm you did these checks when experiencing the problem. For example, ignition problems can arise only on hot engines. And you checked the gas cap's vent? That's the "classic" problem after awhile ... if plugged, a vacuum forms in the tank and fuel delivery stops.
 

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Did you confirm there is spark after it shuts down - if so I am leaning toward the carb needing to be cleaned. Aren't the LX188, 178's prone to a little dirt or sludge clogging them? Maybe try a little seafoam in the tank to see if it improves before a rebuild of the carb.
I have my dad's old LX188 and this same problem happened for the first year and a half I had it...but my yard was small so I put up with it. Then I tried all the steps listed above, went on every advice site-hired a guy who said he was a mechanic to take a look at it and talked to my neighbor's dad who has the same tractor and asked his opinion.

Bottom-line, change the carburetor. As soon as I bought the carb, replaced, it drives like a champ and sounds like it did in 1996.

Except, it continues to overheat if I drive it in warm weather or for longer periods of time and I've noticed it getting progressively worse. I still have the reservoir full of bright green coolant that's been there for three years, and I don't know if it's ever needed to be refilled...I'm starting to worry there's no coolant getting to the engine. Where should I start?

Thanks!
 

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Check thermostat, Is there a temp gauge? Then run and feel hoses for any heat, that will tell if you got flow. Otherwise look to see if coolant pump is working.
 

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Is the light coming on? You say it's shutting down? Are you shutting it off or is it shutting off on it's own? There is nothing in the system to shut the engine off when over heating. If it is shutting off on it's own, your problem lies elsewhere.

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That's correct. what is happening is the fuel is vapor locking before it reaches the carburetor now they said to bypass the mechanical fuel pump because that's where the problem is happening. So I ordered a inline electric uel pump off of Amazon the cost $11. 2psi to 4 psi. For me this did the trick. However this does not work for all lx188. because it gets so hot under that hood and with today's gasoline the ethanol is boiling off and around a hundred and ten degrees so what has to happen is you have to install a return regulated system on this tractor just like on a diesel truck. you can buy these for about $60 online and install it on your John Deere you will never have another problem I promise you I racked my brain trying to figure out why my 188 kept dying I tried everything under the sun as far as putting my gasoline in the refrigerator! that did work by the way! That is until my girlfriend seen it and really how practical is that that. just proves the point.
 
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