DavidL 2 #1 Posted May 21, 2020 Can anyone help - just rebuilt the engine on by K181 8HP tractor (1976). It was running well then all of a sudden there was a large amount of smoke from the wiring under the tank and the wires looked burned. One of them came from the starter solenoid. I can't find a good wiring diagram, and am not sure what the heat sink is near the ignition switch. It is possible one of the connection to that heat sink got disconnected. What is that heat sink? And any suggestions about what the problem might be and how to fix it. Thanks very much, David Share this post Link to post Share on other sites
ZXT 2,401 #2 Posted May 21, 2020 (edited) 13 minutes ago, DavidL said: Can anyone help - just rebuilt the engine on by K181 8HP tractor (1976). It was running well then all of a sudden there was a large amount of smoke from the wiring under the tank and the wires looked burned. One of them came from the starter solenoid. I can't find a good wiring diagram, and am not sure what the heat sink is near the ignition switch. It is possible one of the connection to that heat sink got disconnected. What is that heat sink? And any suggestions about what the problem might be and how to fix it. Thanks very much, David The "heat sink" you're talking about is the voltage regulator. I'd get in there and look for wires that have chaffed and become bare before anything else. I've not seen a voltage regulator "let the smoke out", but I suppose it's possible. The ammeter is another good possibility. Inspect it. Also, welcome to the forum! Edited May 21, 2020 by ZXT 1 Share this post Link to post Share on other sites
lynnmor 7,726 #3 Posted May 21, 2020 Pull off a battery cable NOW! Then trace wiring till you find the short. 1 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,393 #4 Posted May 21, 2020 Welcome to the forum. Just a guess on the model you have Garry Share this post Link to post Share on other sites
WHX?? 51,421 #5 Posted May 21, 2020 Sounds like the guys have got you covered.. Share this post Link to post Share on other sites
DavidL 2 #8 Posted May 21, 2020 2 hours ago, ZXT said: The "heat sink" you're talking about is the voltage regulator. I'd get in there and look for wires that have chaffed and become bare before anything else. I've not seen a voltage regulator "let the smoke out", but I suppose it's possible. The ammeter is another good possibility. Inspect it. Also, welcome to the forum! Thanks very much. I'll take a look 1 Share this post Link to post Share on other sites
DavidL 2 #9 Posted May 21, 2020 1 hour ago, gwest_ca said: Welcome to the forum. Just a guess on the model you have Garry Thanks very much. it's a four speed but I assume the wiring is the same. 1 Share this post Link to post Share on other sites
DavidL 2 #10 Posted May 26, 2020 On 5/21/2020 at 9:30 AM, gwest_ca said: Welcome to the forum. Just a guess on the model you have Garry Garry - thanks again. Is there any way to test the regulator without having the engine running? Share this post Link to post Share on other sites
pfrederi 18,566 #11 Posted May 26, 2020 I do not think there is any bench test for regulators. Must be hooked up and engine running. 1 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,393 #12 Posted May 26, 2020 The aluminum body of the regulator requires a good ground. As many of our tractors get older the chassis ground deteriorates so we add a ground wire to one of the mounting bolts and go back to the ground cable of the battery. One other thing you can try. These regulators must see battery voltage before they can regulate the charge current. On the flip side if they do not see battery voltage there is no way for the charge current to get to the battery. Turn the key to the RUN position without the engine running. Measure the battery voltage across the battery posts. Now move the + test lead to the DC terminal on the regulator. Should have the same voltage reading. If not the connections are compromised somewhere. Garry Share this post Link to post Share on other sites
DavidL 2 #13 Posted May 27, 2020 17 hours ago, gwest_ca said: The aluminum body of the regulator requires a good ground. As many of our tractors get older the chassis ground deteriorates so we add a ground wire to one of the mounting bolts and go back to the ground cable of the battery. One other thing you can try. These regulators must see battery voltage before they can regulate the charge current. On the flip side if they do not see battery voltage there is no way for the charge current to get to the battery. Turn the key to the RUN position without the engine running. Measure the battery voltage across the battery posts. Now move the + test lead to the DC terminal on the regulator. Should have the same voltage reading. If not the connections are compromised somewhere. Garry Thanks Gary - I am not sure if the regulator is any good. It looks a bit burned. I thought I saw a link to a replacement, but I can't find it back. Do you know what replacement will work? Thanks again. David Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,393 #14 Posted May 28, 2020 Any chance your tractor is a 1975 model? No 4-speeds in 1976 except for in Europe. The original regulator is # 101450 and rated to handle 15 amps. Here is a replacement supplied by Stens https://www.bantasaw.com/catalog/viewproduct.asp?i=&p=6309 Garry Share this post Link to post Share on other sites
DavidL 2 #15 Posted June 1, 2020 Thanks all. I rewired it and it was running well. The regulator seems OK. Then it stalled a few times. Not sure what the problem is now. Share this post Link to post Share on other sites
