Groundsmaster 52 runs 10 minutes, then dies

[Deano]

I'm on the edge of my seat!!

 

[jaxs]

What was the solution, Volvoman?

I'm on the edge of my seat!!

A watched pot never boils.

 

[MossRoad]

A watched pot never boils.

8 minutes of your life you’ll never get back…

 

[Volvoman]

Sorry for not getting back sooner. By now, I had hoped to have this thing all figured out! Unexpected delays have prevented me from finishing this mystery off. First, the OEM carb kit purchased from an online seller never arrived. No response to my email requests for a status report. Nothing! Very odd, as the seller had positive feedback relative to speed of shipping his stuff. Very strange, like something happened to him that he wasn’t able to reply to my status requests. So, that wasted an extra week plus. So, I purchased a second OEM Briggs carb kit via ebay. It arrived after another week, but was incomplete due to being an “open box” sale. No mention that “open box” actually meant missing parts. The listing photo showed a complete kit, but that’s not what I got. Another week wasted. So, went back for a third try and purchased another OEM Briggs kit via ebay again. It’s not here yet, but I am hoping to have enough parts between the two kits to make a full set. All said, these snafus have eaten up more than two weeks where I had hoped to have had the GM 52 back running again! The next kit is supposed to be here by end of this week, in which case I will have the weekend to disassemble and reassemble the carb. Will report back here once that happens. I’m on the edge of my seat, too!

 

[Volvoman]

What was the solution, Volvoman?

Thanks for asking hanie. See my above reply for the latest update. Time hasn’t been on my side the past couple of weeks, especially when reliant on others to follow though as expected. Not to mention, my lawn grass is getting doggone long, too!

 

[jaxs]

I hope watching over your shoulder and whispering doesn't bother you.

 

[Volvoman]

Not a problem at all. I appreciate the support here and will post findings as soon as possible. In the meantime, some other projects here are getting my long overdue attention.

 

[Tntcwg3]

I ran into a similar issue once, engine would run several minutes then suddenly run out of fuel, it turned out that the vented fuel cap was bad, causing the tank's fuel flow to stall as it drew down into a vacuum. Customer had removed the plastic cap and partially melted it by setting it inverted on an exhaust shield.

 

[ljgordon]

I ran into a similar problem. Did all you did. Had the carb off 5 times. Finally determined the old fuel line was delaminating inside, thus stopping up jets.

 

[Volvoman]

Here’s the latest: The latest carb kit arrived yesterday, so today was the day to put it in. As mentioned earlier, I had pulled the carb off already and cleaned it up as best I could, but still no change in the engine stalling out after a few minutes. Today, when pulling the carb off, I took extra care to check everything that could be disassembled for any plugging. None could be found except the high speed jet had some debris stuck at the end of the long removable tube. As I was replacing it with a new one, any potential issue with that should be eliminated. Otherwise, all replaceable components were replaced, the carb reassembled, the pulse line double checked for vacuum and everything put back together properly.

After reassembly, the adjustable valves were pre-set to start the engine. It started up after a minute of cranking. I then adjusted the slow and high speed valves. I noticed that when I flicked the throttle, some bluish smoke came from the exhaust, but this mostly disappeared once the high speed jet/valve was adjusted to it’s best setting. But, one strange thing…..every few seconds, a single misfire would occur while the engine was running at normal high operating rpm. Same at low rpm. This was abnormal for this engine, as it typically ran smoothly with no misfires of any kind.

Thus far, the tractor was sitting outside the garage while I was adjusting theh carb while the engine was running at high rpm to adjust the high speed valve/jet, which the manual refers to as the “needle valve”. Since forever, I have used the term “needle valve” to refer to the float operated valve with the neoprene tip. Apparently, I have been using the incorrect term forever, but I will continue referring to it as the high speed valve/jet here to avoid any further confusion to what I am describing.

So….after letting it run for a few minutes, I was about to head back inside the garage to get a shorter screwdriver for making final carb adjustments. Suddenly, the engine stopped. Huh? Hopped back on the tractor and cranked the engine over for another minute, but absolutely dead and wouldn’t fire at all.

Ok, now time to use the newly acquired spark tester, an Oregon model that is shown in the photo. Not having used this type before, I wasn’t certain how to hook it up, but I hooked the clip onto the spark plug and inserted the bare road into the spark plug wire. Not sure what that third rod is for, but it sticks into the spark chamber of the tester with it’s point less than one millimeter from the bare rod. Anybody have one of these and know what that third rod is for? Anyway, I cranked the engine and not one sign of spark in the tester viewing window. Okay, let’s wait a half hour, then see if any spark. After a half hour, I cranked the engine over again, and saw a super faint spark shoot across the window. Continued cranking for another thirty seconds but only saw one or two of the same barely visible sparks shoot across the viewing window. Otherwise, nothing.

So, this mystery has evolved yet again, kind of. Why I had been able to restart the engine the last time it ran, but only by choking, is strange, since now it won’t start at all. Now, I am back to thinking about the coil, as this was one of the initial suspects that I chose to not pursue (this would classify as ”denial” since I really didn’t want to think about having to pull the engine from the tractor to replace the magnetron behind the flywheel. I’ve had this engine out twice before when the welch plugs fell out and caused the engine to suck in dirt and ruining the cylinder wall, and didn’t want to think about going thru that again. But, since I have already replaced the condenser with no improvement from doing it, the coil remains the final suspect. Unless a scuffed or broken wire has shorted the ignition out. I can’t see any externally, so likely will be removing the engine for the third time. If so, it won’t be going back in until it’s been to the rebuild shop to have a leakdown and compression test, then most likely an overhaul that may include a rebore. Not looking forward to the next chapter…

 

[MossRoad]

Yikes!

 

[jaxs]

That secound rod looks to be for a different plug boot. Lay the tester on an insulator or suspend it away from any ground source. That white wire looks close enough for spark to jump to instead of going where its supposed to.

 

[Volvoman]

Have the appointment to bring the GM 52 in to a nearby small engine shop tomorrow, where they will check the coil as well as any other suspect components. If a major OH is needed, they could do that, but of course weren’t high on making the recommendation due to cost. (I totally understand, but asked if he could recommend an equivalent style of mower that will handle steep side inclines well, like the Groundsmasters will do, considering they have individual left and right brakes. Zero Turns don’t work on steep sidehills, so they are not a consideration for my application.) In the meantime, I did a compression test using my own tester. A consistent 108 PSI reading on repeated tests. On an old L head engine like this, from what I have read this seems within the acceptable range. Your thoughts? I don’t have the equipment to do a leak down test, but the small engine shop does, so that may be more helpful in determining why I am seeing some blue exhaust smoke. Via our phone conversation, he didn’t rule out anything as being responsible for it, especially when it has not been an observable symptom prior to this most recent series of events. As for oil consumption, I find my self adding about 12 pint of oil every 40-50 hours, which I don’t consider alarming. Again, any thoughts?

 

[MossRoad]

…I find my self adding about 12 pint of oil every 40-50 hours,…

I hope you meant 1 to 2 pints, because 12 pint is 3 quarts.

 

[stevem5215]

I have two slope mowers I say. A Steiner 420 which has a 48" mower deck and a Simplicity Citation XL with a 61" deck. Both cut my slopes without issue. I use the Steiner up and down with ease and the Simplicity does a good job sideways. I'm smart enough to never cut anything after or during a rainstorm of course. But the Simplicity actually works very well sideways due to it's weight and wide tires.

As for it stalling out. Did you do the compression test with the engine hot ? That can make a difference. Also, you are on track for the ignition system check outs but again if they can't test it while hot then you'll still not be sure what's going on with it.

 

[Volvoman]

MossRoad, thanks for reminding me to proofread! Must have hit the “1” and ”2” at the same time maybe? It should have been only “1” pint, not 12 pints. LOL!

Stevem5215, no I did the compression tests while it was cold, the same time as I did another spark test. The spark test showed weak spark while cold. If I can get it started today, will run it until hot, then run both tests again. Last time I did the spark test while hot and saw no spark at all in the tester window. Will do the repeat test while hot to see if the same result of no spark is obtained.

Will post the results this evening…

 

[laurencen]

does this have a separate coil? if it does move it away from the engine and try it, seen some years ago where a vehicle coil went bad when it got hot, I moved if from the top of the motor and it ran fine until replaced

 

[LittleBittyBigJohn]

I had a coil go out on my V twin Kohler. Symptom was good power then less power then 1 cylinder would completely stop firing. Typically but not always it would be ok until it wasn't. Then at some point a cylinder would just drop out. It sounds different than you would expect. Almost sounds like it's running normal but hardly any power at all. By the time I figured out the problem it would hardly ever run on both cylinders.

Edit-
I just re-read your initial post. I think coil is worth checking. Mine would sometimes fire right back off once I killed it. Other times it would take forever. I was never smart enough to correlate it with engine heat. Could have been heat related. I don't know how to check a coil. There just happened to be info online about mine having bad designed coils and described the symptoms. I bought new ones and changed them on the hope it would correct the issue, after having replaced plugs and carb already. Totally fixed it and it had more power than before, even when it had been running good.

 

[Volvoman]

Here’s the latest update. This afternoon, I tried starting the engine dead cold. It started, but not after I had flooded it. With the new carb kit and the new fuel pump having far more pumping ability than the original pump, I will need to learn how to start it again, like a new-to-me outfit again. Not sure if I will leave this new fuel pump in there, as the old one was probably fine, not to mention it had a lower pump output which seemed a good match to the carburetor.

Anyway, after the flooding episode, it started. First, I ran it in the garage at low, then high idle for about five minutes. At both rpm ranges, the engine mostly ran smoothly, but with single spark misses every 2 to 3 seconds. Something not right to cause that, but wasn’t sure what it may be. But, as I will describe next, it is probably related to what happened next, when I pulled out of the garage, engaged the mower deck, and began to mow grass. After mowing about 40 feet, the engine stopped dead. I cranked it over for about two seconds and it re-started.

At this point, the deck is disengaged, so all that I am trying to do is drive it back into the garage. So, after the restart, I was able to touch the foot hydro pedal and move it about five feet. Then, the engine stopped dead again. Restarted it once more, and moved it another five feet before the engine stopped again. But, now, it won’t restart at all.

So….to get it back into the garage, I cranked the starter and engaged the hydro pedal to move it ever so slowly until it was back into the garage in a dark space. No way will one person push this thing one inch while the hydro is still holding pressure, and the bypass valve is located in a nearly inaccessible location beneath the pan which supports the seat, only accessible by removing the pan which covers the entire differential, axles, and hydrostatic pump. Cranking the starter and inching it is by far the simplest way to get it back into the. garage, even though I prefer to not resort to that method.

Once in the gargage, I opened up the engine hood/bonnet to do two things: First, check for spark. Using the newly acquired Oregon spark tester, I was able to see zero spark in the dark garage. Not one arc. Nada. Obviously, the engine had been running before, so the coil was generating spark for that to take place. But, once hot, the coil stopped putting out spark. Second thing I did was to check compression while hot. I mentioned up thread that the cold compression was 108 psi. Taking a new test while hot, the compression was a consistent 105 psi, so only a slight reduction. I believe that is in the acceptable range for this engine, but perhaps someone here knows otherwise. Again, its the old L head, cast iron engine, model 326437.

At this point, I am quite certain the problem all along has been what I didn’t want. That being the ignition coil is needing replacement. As mentioned up thread, the coil on these engines is located inside the flywheel, necessitating the engine be pulled entirely from the tractor to access the flywheel shroud, then the flywheel, and the cold sitting smugly beneath it.

I have done this coil replacement job myself in the distant past on the original engine. Were the engine a lightweight, I would probably sacrifice a day or two to do the job myself again. But, I’m not getting any younger, and this engine is a monster, totally cast iron brute of an engine, requiring an engine crane/cherry picker to lift it out. But, that’s only after having to remove several other major components on the tractor/traction unit before lifting the engine out.

Feeling benevolent, it may be time to share the joy of pulling one of these with the small engine mechanic who was eager to take the job on. Besides, he’s all of 40 years younger than I am, so he likely needs another horror story to share with his buddies anyway. I’m headed his way tomorrow morning to leave it with him. Over the phone, he was confident he could whip the coil out and have a new one back in and the tractor running fine by the next day. Um, that could be optimism talking, but then again, maybe he’s right on. We’ll know more in a few days. I don’t plan to pick up the tractor for at least a week, to make certain he’s had plenty of chances to work it hard to be sure that replacing the coil is the solution. Keeping my fingers crossed!

 

[Volvoman]

What was the solution, Volvoman?

After nearly 3 months in the shop, the GM 52 is out and runs like new again. It the coil after all. It took the small engine mechanic quite a bit of time, as he was unfamiliar with old Briggs L head engines and had to learn while delving into this one. When I brought the GM 52 to him, I also brought along a new coil, telling him that is what I suspected what causing the problem.

Being conscientious, the young mechanic wanted to try other possibilities before having to pull the engine to access the coil. Pulling the engine was also a first for him, as he had never seen a GM 52, much less worked on one. To make a long story short, before he finally settled on it being likely the coil, he had pulled the engine twice and performed other remedies, nothing of which worked. The third time out, he replaced the coil, but after putting everything back together, he had no spark at all. Totally dead. Soooooo, out the engine came again and this time he took more time, a whole lot more time, to check for faulty grounds, etc. Upshot of his slowing down was that once reassembled, it started and ran perfectly. Not wanting to push his luck again, as he had me pick it up after the first foray into it, so I could try it again only to have the same problem, that of dying after only a short time. This time around, he kept it for an additional 3 weeks, starting it and mowing for a half hour at a time for several different trials. Finally being satisfied, he declared it fixed and I picked it up this morning. I must say, it does run better, being smoother and more responsive than it has been in a very long time. One other improvement….the smoking issue that I mentioned in one of the earlier posts, the blue smoke, well, it has also disappeared entirely. As said, the engine now starts easily, runs smoothly, and accelerates instantly. How a coil affects all of this is more than I expected as well. All said, I will be giving it a thorough workout this weekend, mulching 2 acres of oak leaves before parking it for the winter.

Lessons from this experience: 1. Don’t expect the current crop of younger mechanics to necessarily have the broad experience with these old engines to be able to diagnose and repair them the first time around. 2. Be patient and give them the time they need to get it figured out right. 3. Don’t forget to congratulate them heartily for being victorious at a project many would not attempt. 4. Be thankful that I now have an old Groundsmaster ready for service again. Maybe not 39 more years from when I first got it, as I don’t expect to be around for that to happen. But, maybe as long as I care to use it.
5. Also, be thankful there are some young mechanics around who will willingly take on the challenge of working on one!

The other lesson of course is that the engine coils on these old Briggs flathead engines do fail, and when they do, it may take awhile to figure it out. At least, these are the lessons I have learned about them.