2000 Workhorse ST350- blown engine replacement

Elcoyote · 01-11-2018, 04:54 PM

Thanks y'all for the replies and help so far.

Today I replaced the exhaust gasket, rear leaf spring bushings, and drive belt. Decided to take it for a shakedown run, up our road to the cul de sac and back... about a 300 yard run total. Coming back down the hill, I started getting a knock every time the piston would go up to TDC.
Pulled it into the garage, and pulled the spark plugs, and turned it over. No knock. Reinstalled left cylinder plug only and turned it over. Knock every revolution. Removed left plug, installed right plug, no knock. Put the left plug in, backed it out 5 full turns thinking the piston might be hitting the plug (without any evidence on the piston head or plug indicating this), and when turning it over, I still had the knock. There was a small bit of dirty oil or gas on the plug, but couldn't discern which. Pulled the dipstick and smelled the oil. Aside from smelling a bit "off", perhaps even a bit burned or old, and despite being fresh oil, I couldn't smell any gasoline in the oil.
So the knock only appears when there is a spark plug in the engine, which to me means that the knock has something to do with compression in the cylinder, and likely is due to a failed piston ring. Am I on the right track here?

Rooster59 · 01-11-2018, 04:57 PM

Just guessing that the compression creates enough pressure to make the rod knock in that cylinder when without compression it is free to float enough not to make noise. I think the previous advice to pull it apart before you go further is now your action plan. Before any damage goes beyond the budget.

Elcoyote · 01-11-2018, 04:58 PM

Copy that. Disassembly will commence soon.

Spicyunicorn · 01-11-2018, 05:25 PM

X2 on what rooster said.... One very important thing on these that I've seen people over look is when reassembling Is the oil pump must be primed! I've heard of people packing them with grease but I've had better luck with putting a vacuum over the oil passage that feeds the oil passage in the valve cover and turning motor over it will help pull out into the pump

Rooster59 · 01-11-2018, 09:24 PM

If memory serves there is a Robin engine service and parts manual available on PDF in a sticky thread. I downloaded it months ago. If you don't see it PM me. I can email it to you tomorrow from my laptop.

Seems like it said something about pouring oil down an oil passage above the pump from the cam journal. That is when I decided if I was going to rebuild one I would let someone else do it. Not that it is tough, just never rebuilt an engine like that.

BrewCityMusic has good recommendations for rebuilders. There is a reputable one in St Louis too. I've been to their place. Looks like they do good work too.

Cartmaster · 01-12-2018, 01:14 AM

With the rebuild manual, it is such an easy job to do, i recommend having a shot at it. The manual gives you everything you need to know. If you cannot find it i too have online storage and can direct you to a download from there.

As already stated, it is most likely to be the rod end causing the knock. A broken ring would be a light tinkling noise.

Time to get those wrenches out LOL. You will not regret it.

Elcoyote · 01-13-2018, 01:09 PM

Thanks y'all. I do not have a manual for this engine, and didn't see one in a sticky. I would love to get one before I start breaking it apart. I will send a PM to both of you...

clarkj2416 · 01-13-2018, 01:35 PM

Here is a link for the manual's.
http://www.buggiesgonewild.com/ezgo-...iagram-id.html

clarkj2416 · 01-13-2018, 01:55 PM

I have a lot of experience with these engines. I have rebuilt and sold many over the last 6 years. The intake valves are notorious for wearing down and sucking up into the head. I definitely recommend replacing them. Be sure to measure the cylinder bores. (preferably with a bore gauge) Even if there is still cross hatching visible. The most wear will be where the piston rings are at when the piston is at TDC. They almost always need to be bored. Parts are readily available but I recommend shopping around. I've seen some sites with ridiculous prices. If you have any questions during the rebuild process I can help.

Golf cart guy · 01-14-2018, 08:08 AM

With little to no OEM engine parts available, don't expect the motor to last long once its rebuilt if its used often. The aftermarket motor parts are junk. Even rebuilders like motors and more will tell you this. Even gasket sets are junk.
If you just want to get it running and sell it, rebuilders will get you back a running motor.

01-11-2018, 04:54 PM	#21
Elcoyote Not Yet Wild Join Date: Oct 2015 Location: Seguin, Tejas Posts: 56	Re: 2000 Workhorse ST350- blown engine replacement Thanks y'all for the replies and help so far. Today I replaced the exhaust gasket, rear leaf spring bushings, and drive belt. Decided to take it for a shakedown run, up our road to the cul de sac and back... about a 300 yard run total. Coming back down the hill, I started getting a knock every time the piston would go up to TDC. Pulled it into the garage, and pulled the spark plugs, and turned it over. No knock. Reinstalled left cylinder plug only and turned it over. Knock every revolution. Removed left plug, installed right plug, no knock. Put the left plug in, backed it out 5 full turns thinking the piston might be hitting the plug (without any evidence on the piston head or plug indicating this), and when turning it over, I still had the knock. There was a small bit of dirty oil or gas on the plug, but couldn't discern which. Pulled the dipstick and smelled the oil. Aside from smelling a bit "off", perhaps even a bit burned or old, and despite being fresh oil, I couldn't smell any gasoline in the oil. So the knock only appears when there is a spark plug in the engine, which to me means that the knock has something to do with compression in the cylinder, and likely is due to a failed piston ring. Am I on the right track here?

01-11-2018, 04:57 PM	#22
Rooster59 Gone Wild Join Date: Jul 2017 Location: East Central Missouri Posts: 1,955	Re: 2000 Workhorse ST350- blown engine replacement Just guessing that the compression creates enough pressure to make the rod knock in that cylinder when without compression it is free to float enough not to make noise. I think the previous advice to pull it apart before you go further is now your action plan. Before any damage goes beyond the budget.

01-11-2018, 04:58 PM	#23
Elcoyote Not Yet Wild Join Date: Oct 2015 Location: Seguin, Tejas Posts: 56	Re: 2000 Workhorse ST350- blown engine replacement Copy that. Disassembly will commence soon.

01-11-2018, 05:25 PM	#24
Spicyunicorn Gone Wild Join Date: Jun 2015 Location: NW Iowa Posts: 1,669	Re: 2000 Workhorse ST350- blown engine replacement X2 on what rooster said.... One very important thing on these that I've seen people over look is when reassembling Is the oil pump must be primed! I've heard of people packing them with grease but I've had better luck with putting a vacuum over the oil passage that feeds the oil passage in the valve cover and turning motor over it will help pull out into the pump

01-11-2018, 09:24 PM	#25
Rooster59 Gone Wild Join Date: Jul 2017 Location: East Central Missouri Posts: 1,955	Re: 2000 Workhorse ST350- blown engine replacement If memory serves there is a Robin engine service and parts manual available on PDF in a sticky thread. I downloaded it months ago. If you don't see it PM me. I can email it to you tomorrow from my laptop. Seems like it said something about pouring oil down an oil passage above the pump from the cam journal. That is when I decided if I was going to rebuild one I would let someone else do it. Not that it is tough, just never rebuilt an engine like that. BrewCityMusic has good recommendations for rebuilders. There is a reputable one in St Louis too. I've been to their place. Looks like they do good work too.

Today
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01-12-2018, 01:14 AM	#26
Cartmaster British born Nincompoop Join Date: Feb 2007 Location: United Kingdom Posts: 2,461	Re: 2000 Workhorse ST350- blown engine replacement With the rebuild manual, it is such an easy job to do, i recommend having a shot at it. The manual gives you everything you need to know. If you cannot find it i too have online storage and can direct you to a download from there. As already stated, it is most likely to be the rod end causing the knock. A broken ring would be a light tinkling noise. Time to get those wrenches out LOL. You will not regret it.

01-13-2018, 01:09 PM	#27
Elcoyote Not Yet Wild Join Date: Oct 2015 Location: Seguin, Tejas Posts: 56	Re: 2000 Workhorse ST350- blown engine replacement Thanks y'all. I do not have a manual for this engine, and didn't see one in a sticky. I would love to get one before I start breaking it apart. I will send a PM to both of you...

01-13-2018, 01:35 PM	#28
clarkj2416 Not Yet Wild Join Date: Aug 2011 Posts: 14	Re: 2000 Workhorse ST350- blown engine replacement Here is a link for the manual's. http://www.buggiesgonewild.com/ezgo-...iagram-id.html
clarkj2416 Not Yet Wild Join Date: Aug 2011 Posts: 14

01-13-2018, 01:55 PM	#29
clarkj2416 Not Yet Wild Join Date: Aug 2011 Posts: 14	Re: 2000 Workhorse ST350- blown engine replacement I have a lot of experience with these engines. I have rebuilt and sold many over the last 6 years. The intake valves are notorious for wearing down and sucking up into the head. I definitely recommend replacing them. Be sure to measure the cylinder bores. (preferably with a bore gauge) Even if there is still cross hatching visible. The most wear will be where the piston rings are at when the piston is at TDC. They almost always need to be bored. Parts are readily available but I recommend shopping around. I've seen some sites with ridiculous prices. If you have any questions during the rebuild process I can help.
clarkj2416 Not Yet Wild Join Date: Aug 2011 Posts: 14

01-14-2018, 08:08 AM	#30
Golf cart guy Gone Wild Join Date: May 2015 Location: Central Florida Posts: 2,114	Re: 2000 Workhorse ST350- blown engine replacement With little to no OEM engine parts available, don't expect the motor to last long once its rebuilt if its used often. The aftermarket motor parts are junk. Even rebuilders like motors and more will tell you this. Even gasket sets are junk. If you just want to get it running and sell it, rebuilders will get you back a running motor.

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