formariz 11,865 #1 Posted February 12, 2015 (edited) Of all my tractors only the 653 has a Techy . All others are Kohlers. All Kohlers from k90s to k301 when starting wether you have the throtle all the way open,closed or in between they crank full speed. Not the Techy. Starter almost wont crank it if throtle is anywhere open. Close the throtle ,open choke, and it cranks. Not full speed the way it should, but it cranks sufficiently so that engine starts. Engine will start at idle and then i can increase throtle. This is the rule when cold. When hot I can open throtle a little less than half and it will crank and start immediatly. It will crank a lot faster with no throtle at all. Can anyone explain to me why it does this? it has always been like this. This is an engine with probably much less than 100 hours on it never touched,literally. Edited February 12, 2015 by formariz Share this post Link to post Share on other sites
bmsgaffer 2,043 #2 Posted February 12, 2015 See my post on your other topic in electrical... Share this post Link to post Share on other sites
formariz 11,865 #3 Posted February 12, 2015 (edited) quoting other post; I think both of your posts connect here. 12.35 is not a fully charged battery. Should be about 12.7 or so. 12.35V is somewhere around 50-60% SOC (state-of-charge) at rest. Might have something to do with your hard starting problem. Either a poorly functioning charging system or weak battery. It will act exactly the same with a new fully charged battery even with a jumper connected to at the same time. Starter cranks pretty normally with throtle closed. Its when throtle is open that it will barely crank. Edited February 12, 2015 by formariz Share this post Link to post Share on other sites
bmsgaffer 2,043 #4 Posted February 12, 2015 Bummer, I thought I had something. I dont have a Tecky so I will stick to what I know and let someone else chime in here Share this post Link to post Share on other sites
squonk 38,988 #5 Posted February 12, 2015 I would do a voltage drop test on the cables. They may look ok on the outside but could be corroded / broken strands under the insulation. And a battery at . 12.3 volts is only about 40 % charged. Share this post Link to post Share on other sites
formariz 11,865 #6 Posted February 13, 2015 (edited) I would do a voltage drop test on the cables. They may look ok on the outside but could be corroded / broken strands under the insulation. And a battery at . 12.3 volts is only about 40 % charged. I'll do that next but this thing is nearly mint., believe me there is nothing corroded in it.But why wouldn't any of these symptons happen if the throtle is closed? Kind of makes me think that it is carburater/engine related. What would the open throtle do to an engine to make it harder to crank? Edited February 13, 2015 by formariz Share this post Link to post Share on other sites
Terry M-(Moderator) 2,126 #7 Posted February 13, 2015 Just a shot in the dark here...but any chance that when you push in the throttle, the cable might move just enough to contact and possibly hit something to cause a partial ground??? sometimes that stuff is rather close together......been there and had it happen. Share this post Link to post Share on other sites
Save Old Iron 1,563 #8 Posted February 13, 2015 (edited) throttle / crank relationship is engine grounding thru the throttle cable? is the cable getting hot during cranking? run a battery jumper cable from the engine to battery - and try the experiment again. Edited February 13, 2015 by Save Old Iron Share this post Link to post Share on other sites
formariz 11,865 #9 Posted February 13, 2015 Just a shot in the dark here...but any chance that when you push in the throttle, the cable might move just enough to contact and possibly hit something to cause a partial ground??? sometimes that stuff is rather close together......been there and had it happen. throttle / crank relationship is engine grounding thru the throttle cable? is the cable getting hot during cranking? run a battery jumper cable from the engine to battery - and try the experiment again. Now there is something I never thought about! I will be checking that tomorrow! Share this post Link to post Share on other sites
formariz 11,865 #10 Posted February 13, 2015 throttle / crank relationship is engine grounding thru the throttle cable? is the cable getting hot during cranking? run a battery jumper cable from the engine to battery - and try the experiment again. Run a cable directly from battery to starter? Share this post Link to post Share on other sites
TT-(Moderator) 1,128 #11 Posted February 13, 2015 If it's not a mechanical issue (starter brush plate warpage, ignition timing, or compression release), here's my theory - and I've witnessed this scenario on engines other than Tecumseh too...... When the throttle plate is closed, air flow entering the cylinder is restricted. Air in the cylinder can still flow freely out of the unrestricted exhaust. When the piston descends on the intake stroke, it creates a vacuum - or at least doesn't fill as full with air. As the piston travels upward on the compression stroke, the normal volume of air is not in the cylinder, effectively decreasing compression. If air is allowed to flow freely through the intake, (throttle plate open) the cylinder fills to its normal volume on the intake stroke. More air (volume) in the cylinder when the piston is coming up means more compression. 2 Share this post Link to post Share on other sites
formariz 11,865 #12 Posted February 13, 2015 (edited) If it's not a mechanical issue (starter brush plate warpage, ignition timing, or compression release), here's my theory - and I've witnessed this scenario on engines other than Tecumseh too...... When the throttle plate is closed, air flow entering the cylinder is restricted. Air in the cylinder can still flow freely out of the unrestricted exhaust. When the piston descends on the intake stroke, it creates a vacuum - or at least doesn't fill as full with air. As the piston travels upward on the compression stroke, the normal volume of air is not in the cylinder, effectively decreasing compression. If air is allowed to flow freely through the intake, (throttle plate open) the cylinder fills to its normal volume on the intake stroke. More air (volume) in the cylinder when the piston is coming up means more compression. So, when throttle is wide open, there would be higher compression in engine as opposed to throttle being closed restricting air intake therefor lower compression? How normal if normal at all is that? Increasing compression so much that starter will barely turn it? Edited February 13, 2015 by formariz Share this post Link to post Share on other sites
TT-(Moderator) 1,128 #13 Posted February 13, 2015 As I stated, it's just a theory ~ and perhaps you'll find information gained from actual tests, etc. I can't come up with any other explanation. Share this post Link to post Share on other sites
formariz 11,865 #14 Posted February 13, 2015 Quoting: If it's not a mechanical issue (starter brush plate warpage, ignition timing, or compression release), here's my theory - and I've witnessed this scenario on engines other than Tecumseh too...... Starter works fine with throttle closed so it does not seem to have anything wrong. Ignition timing--- tractor starts fine with this condition . It just has to start with no throttle. Once hot it will start with throttle or without it. When hot starter spins engine with throttle open. Wouldn't incorrect timing create a starting issue? Compression release---- how would throttle position affect that? Engine just having too high compression due to restricted air intake as discussed in previous post Share this post Link to post Share on other sites
TT-(Moderator) 1,128 #15 Posted February 13, 2015 What I am saying is that if all potential mechanical issues are ruled out, (which I can't see why they wouldn't be on this particular low-hour engine) the only explanation I can come up has to do with the actual compression of the amount of air entering the cylinder. The throttle plate position shouldn't affect any of the mechanical components. Share this post Link to post Share on other sites
formariz 11,865 #16 Posted February 13, 2015 What I am saying is that if all potential mechanical issues are ruled out, (which I can't see why they wouldn't be on this particular low-hour engine) the only explanation I can come up has to do with the actual compression of the amount of air entering the cylinder. The throttle plate position shouldn't affect any of the mechanical components. I am leaning towards your theory as to why this is happening. I will do a couple more electrical tests to eliminate the possibilities suggested earlier. It just drives me nuts when I can't understand something. Tractor works fine , again it just has this quirky thing about it. Since it is really probably the only one out there of this model in this condition, looking like it just came from the dealer and totally original, I work really hard at not changing anything on it. Had to change the fuel line sometime back and just doing that was killing me, so old fuel line is saved. Issues I know. Share this post Link to post Share on other sites
Save Old Iron 1,563 #17 Posted February 13, 2015 Run a cable directly from battery to starter? engine block (ground) directly to battery negative terminal. the battery jumper cable becomes a better ground than the (possible) ground thru the throttle cable. Share this post Link to post Share on other sites
Save Old Iron 1,563 #18 Posted February 13, 2015 and it never hurts to do a poor man's load test on the battery measure the battery voltage while cranking. Share this post Link to post Share on other sites
Save Old Iron 1,563 #19 Posted February 13, 2015 Run a cable directly from battery to starter? and yes , no harm in trying the same experiment using a battery jumper from battery positive to starter positive. eliminates wiring and starter solenoid issues. Share this post Link to post Share on other sites
Callen 64 #20 Posted February 13, 2015 I would check your intake valve lash. If it is excessive it would bypass the comp release.When the engine shuts off, the block cools and shrinks faster than the valve, closing the lash. Or the release mechanism is sticking when it is cold. TT's theory is right on about the throttle position. 1 Share this post Link to post Share on other sites
squonk 38,988 #21 Posted February 13, 2015 If it's not a mechanical issue (starter brush plate warpage, ignition timing, or compression release), here's my theory - and I've witnessed this scenario on engines other than Tecumseh too...... When the throttle plate is closed, air flow entering the cylinder is restricted. Air in the cylinder can still flow freely out of the unrestricted exhaust. When the piston descends on the intake stroke, it creates a vacuum - or at least doesn't fill as full with air. As the piston travels upward on the compression stroke, the normal volume of air is not in the cylinder, effectively decreasing compression. If air is allowed to flow freely through the intake, (throttle plate open) the cylinder fills to its normal volume on the intake stroke. More air (volume) in the cylinder when the piston is coming up means more compression. That's why they say do a compression test at wide open throttle. 3 Share this post Link to post Share on other sites
pfrederi 17,169 #22 Posted February 13, 2015 I do not think Techys from that era had compression release. The H and HH60s of that vintage did not. By the 1980 it showed up on some. i have an HH70 on my L107 that has ACR. We got it to make it easier for my father to start it as the L107 came with an H60 that did not have Acr. Share this post Link to post Share on other sites
rustyoldjunk 127 #23 Posted February 13, 2015 (edited) I have witnessed the same thing with a few cast iron Teckys that I have owned. I have a great running HH120 now that is a joy to run. It will run all day smoothly without missing a beat and starts with a couple of revolutions...But the throttle must be closed to get it turning over even with a 300 amp booster box on it. I have noticed that with a little gas dribbled in the carb it gets way easier to turn over. The other Teckys that I have owned that done this also ran great and started quickly within a couple of revolutions. Edited February 13, 2015 by rustyoldjunk Share this post Link to post Share on other sites
Rob R 951 #24 Posted February 15, 2015 I have seen this quite a bit on the gen/start HH120's and it is basically too much compression so..... either the compression release cam is not operating or is worn out, the engine has carboned-up and the compression is raised, or the exhaust valve clearance is too tight. The reason fooling with the gas intake helps is that as the engine fires it helps with the rotation of the engine.... of course this condition really get bad in cold weather when everything is tight and battery output voltage drops.... hope this helps Share this post Link to post Share on other sites
TT-(Moderator) 1,128 #25 Posted February 15, 2015 I do not think Techys from that era had compression release. The H and HH60s of that vintage did not. Absolutely correct Paul. I was only listing various mechanical components found on small engines that could cause this issue. My boss has a newer pull-behind finish mower with a Briggs OHV single and (eventually) it pulled over so hard that he ended up breaking the starter cord. The cause ended up being the exhaust rocker arm stud loosening & slightly backing out of the head. That created excessive valve clearance, which entirely cancelled the ACR function. It's amazing how much difference ACR made in that application. Cas ~ I know your 653 is a well-kept, low-hour machine. It might not have been used much, but I'm wondering how many times someone has attempted to start it over the years. A couple of long cranking attempts could have overheated the starter enough to cause issues with the brushes & mounting plate. Even though it still works, it could be weak. I know you don't want to disturb the paint, etc., but it might be worth trying a different (new - or known to be good) starter for comparison. Share this post Link to post Share on other sites
