Engine hydraulic & backfiring probs

[Vince P]

I have a Steele brand, typical inexpensive 3500 watt generator with 4-stroke engine. I think of it as "no name brand", but Google turns up a number of hits, yet no website of their own. It says 196cc engine. Looks like a lot of similar engines in the 6 hp. range. Nearly identical to the "Predator" engines from Harbor Freight.

During a recent power outage, I was running it when it stopped after several hours. I believe it had been stopped for a while before I became aware. I checked oil, and it was low. I topped up the oil and re-started it. After a few minutes, it started to backfire, bogged-down, and stopped. Pulling the recoil starter, it was difficult to pull at some points in the rotation of the engine. Easy, then difficult, then easy again. It felt like what I might expect if it was experiencing a hydraulic locking to some degree. I could get it to fully turn over, but It was too difficult to pull to start. I tried several times. I decided that it was seized and that I should recycle it. Days later, before doing so, I took out the spark plug, as I just couldn't make sense of the symptoms as being truly seized. It turns over fine.

I put the plug back in after some hours, and I still have trouble turning it over. What to do?

And what might cause the backfiring and bogging?

Thanks for any thoughts.

 

[Dutchy491]

Check the valve lash and remove the spark arrestor if it has one….
Change the spark plug to the appropriate NGK brand too.

 

[fantastic]

Did it suck in any moisture or was it raining? If so you need to blow out the cylinder after taking out the spark plug.

 

[vwmaniaman]

Was the gas new? Pull the rope several times with the plug removed. Then drain the gas. Put a cup of SeaFoam in the tank and pull it over a couple times. Re-install the spark plug and add gas to half fill the tank. All my stuff that sits around gets that way if fuel is left in the tank while in storage. I always run them dry when I know they won't be used for a while. Generators are in that category.

 

[The_Eric]

Like mentioned, check the valve lash. The exhaust valve could be too loose or you could have had some problems with a pushrod bending or falling out of the rocker or damage to the rocker/pedestal. This would explain the popping and being very hard to pull over.

 

[FowVay]

These engines have a compression release built onto the camshaft and that could have failed when run low on oil. Honda recalled their engines due to failing compression release arms. If that's the problem then you can try to source a new camshaft for it. I bet a cam out of a Honda would work also.

As mentioned above, remove the valve cover and check the valve clearance and check the pushrods for movement. Observe the valve movement while pulling it over and see if you get that little initial burp of the exhaust valve opening when you pull it through.

I did a quick search and found a manual for the generator. There is a parts list and parts available but you'd have to write to the company to source the parts I suspect. Here's the camshaft parts list:

 

[ironman_gq]

Very common for the spark arrestor to get clogged on these generators, especially if it's using some oil. Also replace the spark plug with an NGK, these usually ship with a torch or fake bosch plug and they are not the greatest. Switch to a good HDEO like rotella T6 or similar, these engines do run hot under heavy load which increases oil usage.

 

[Vince P]

Thank you all for your ideas. I will respond before too long.

-Vince

 

[Vince P]

I checked into the valve clearances and took a look inside the combustion chamber. No fluid of any kind there.

• The machine was not operating in the rain.
• It had fresh fuel. I had drained the tank, added fresh gas, started it, closed the fuel cock and run the fuel out, then drained the tank, 6 months ago.
• There's nothing in the combustion chamber. It's dry (checked with a swab, then a scope).
• It doesn't have a spark arrestor on the exhaust. Never did.
• I come to find that this thing is made by a Chinese company with a North American subsidiary, JD North America. https://www.jdna.com/ They have some parts available, apparently.
• Looks like problems with the valve train; especially with the exhaust.
• Very bad that I didn't keep an eye on oil. I'm used to a mower that gets used for 35 minutes every week for a month, then about every other week for a couple more. Hardly the same as an engine that's used 24 hours a day for 3 or 4 days. Duh!

FowVay- thanks for that info. I've now downloaded that manual.

When I looked at the rockers, they both had a lot of side-to-side play. Seemed wrong. Then I see that the "push rod guide plate", a plate under the rockers with holes through which the push rods extend, is in bad shape, especially on the exhaust side, where it's actually worn through to the point that it doesn't do it's job at all to guide the push rod. I removed the rocker on the exhaust side.

Ugly!
The plastic surrounding the hole on the intake side was melted and distorted, but it wasn't totally destroyed like on the exhaust side.
I didn't try to measure the valve lash. It seemed bad enough the way the rockers could move around that I felt like all bets are off.
I'll get a replacement for that plate and re-set the valve clearances and see what that produces. I'm not inclined to take it apart to examine the camshaft and its compression release mechanism until I do the above. But then again, I don't really know what caused that damage, and if it's simply from lack of oil, what else might be damaged?

So, does this sound like a reasonable plan?
I have sent a message to the company asking about valve clearance specs, but if I don't hear from them, can any of you recommend clearances for a 196cc Honda clone engine?

Thanks, Vince

 

[The_Eric]

For valve clearance, somewhere around .005" for the intake and .006" - .008" for the exhaust should be okay.

Side to side movement is somewhat normal, but excessive clearances, (like .012" or .015" and greater) will definitely cause the compression release to not work and make it a real pain to start.

 

[BC1]

Set both valves at .006 and try to start it. I would not spend any money until you know it is not blown up. That plate does not matter for now nor does the exact spec on the valves.

 

[Vince P]

I'll try that. Thanks.

 

[meep]

3 solid raps with a hammer on the engine plate where the cam sits regularly freed up a sticky compression release on my predator engine. Much easier than taking it apart every time to start it.

 

[Vince P]

I re-set the valves to ~.006 despite the floppy rocker arms. Pulling the starter cord, all seems normal. So I think the compression release mechanism is still operating. I was hopeful that it could start. I still am. But before it fired-up, the rocker arm slipped out of position, off the valve stem, and it wasn't really possible to give it a good pull again. I took the valve cover off and re-centerd it, but same thing again. I'm awaiting a new plate that should keep things in line enough to work, hopefully. I have fuel and spark (I mean.... I assume. I did before it all stopped). So it ought to work.

I appreciate your help!