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Subaru/Robin EX30 main bearings


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02-07-09, 12:24 PM   #1  
Subaru/Robin EX30 main bearings

From a Powermate 5000 generator I found used, drained the old oil, replaced, ran again, drained, refilled and was running it for about 15 min and heard the notorious occasional....sound

Even though I bought it at a very low price, a little labor is fine, I have torn down and rebuilt a couple GM v8's so this should not be a big prob I hope.

Drained a little oil from the pan and noticed a few very tiny metal particles indicating possible bearing failure. I haven't torn it down yet but if anyone has been inside these engines a few pointers would be welcome.

I assume remove the generator and the rear cover and hopefully the crankcase whould be accessible.

I would like to just throw a set of bearings in and be done if the crank is fine, i'm guessing it is but won't know until I can mic it.

Hopefully it's an easy process, don't want to pull the head if possible, again all help appreciated.

 
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02-07-09, 01:39 PM   #2  
Quality engine. I have never done anything other than minor maintenance on one. Good thing is Subaru has all manuals available for free on their website.

Subaru Robin - Manuals

 
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02-07-09, 07:49 PM   #3  
Should have stated it's the rod bearings, I believe the crank rides in different bearings for support but I believe the rod bearings are suspect.

I'm actually surprised the bearings are going, unless the previous owner just seriously neglected it. The oil was very dirty when I first drained it, dark brown.

 
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02-07-09, 09:27 PM   #4  
I haven't had to go into a robin/subaru yet, but most small engines don't have rod bearings. The bearing surface is part of the rod itself, and you have to replace the rod. Open it up and see. Take measurements or use plastiguage to check clearances and get an idea where the knock is coming from. I think this engine will have ball bearings for the crankshaft. The rarely go bad.


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02-08-09, 06:42 AM   #5  
Just curious, what's the RPM limit on these engines?

I know they run in the mid 3K range but how close is that from max?

Looking at the engine diagram you are correct, no bearing halves, just a rod.

Are the piston pins press fit?

 
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02-08-09, 07:28 AM   #6  
Subaru robin EX30

I am having same problem with my ex 30 on my little 5000w generator as well. I bought the generator from home depo used after hurricane gustav and it looked in pristeen condition, oil looked good still had tags on it. got it home started it and smoked like hell when first started. so i ran it a bit, changed the oil and to my suprise fine metal powder in the oil as well as a few bits of metal. well to make a long story short I ran it a few more times and changed the oil each time and more and more metal and a bit of a faint ocasional knock. Tried to bring back to HD but they wouldnt exchange or refund it. so now I have a 400 dollard busted generator which will take 2 or 3 hundred bucks to fix and a new one is like 549.99. Im gussing whoever had it never change the oil after breakin there is definately something wrong with the valve seals as it quits smoking shortly after it starts. im wondering it the timing chain tentioner is loose in there and the chain is slapping and cutting something also this is what the knock sounds like to me. I went all over the block with large screwdriver like a stethoscope and didnt really hear anything sound like it coming from flywheel area but I took cover off and nothing is obstructed. weird! oh well hope this helps.

 
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02-08-09, 07:50 AM   #7  
Make sure the oil isn't overfilled.

These engines are checked with the dipstick screwed all the way in, should be below the threads for a visual.

Seems like a new rod is about $70, $125 for all the parts if needed...piston,pin,clips,rod, etc, hopefully it won't get to that.

My oil was crazy dark, could have been an issue..possibly stored for long periods without draining causing the acidic oil to eat bearing material.

If the crank checks out, that will be great...looks like a pretty easy fix. Don't trash the generator yet Miller, open up the rear case and see where the knock is coming from, i'm guessing the rod but hard to tell.

If I have to pull the head, are the chains going to be in my way, how can I index them?

I'm going to tear it down tonight and take a peek.

Beer 4U2

 
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02-08-09, 05:27 PM   #8  
I don't know. I'm sure there will be marks to time it. If it is not obvious, post back and I can tell you how to time it without marks. The wrist pin is probably not press fit, just pushed in place.


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02-08-09, 06:24 PM   #9  
I have it down to the rotor and of course the tapered fit of the crank will make this a bugger to remove. Coleman has a removal tool which is just a similiar threaded bolt that holds the rotor on but longer.

When I removed the plastic cover of the generator, there was a piece of blue stone in there, about the size of a small spark plug with the ceramic busted off....very easily could have made the knocking sound I heard but would it explain the metal particles????

When I say metal particles, I mean sand size but only a couple..generally there shouldn't be any but with no filter now i'm 2nd guessing the whole operation

I might just put the motor back on the frame and fire it up with just the rotor to see if it knocks.

Either way, how do I get the stator off

Edited for content

 
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02-10-09, 07:05 PM   #10  
Time for some

I had it down to the motor and rotor and was ready to whack the rotor with a deadblow to remove from the shaft to ready myself for tearing into the motor.

I spoke with a Subaru tech and he said to check the valve clearance. Intake was good, exhaust was .004 more than spec. Whether or not that would make a knock....just might a little but I found a piece of bluestone in the brush cover and was likely rattling around.

Adjusted valve, removed stone, ran twice as long as previous and was as smooth as it could be. Beer 4U2

I'm very impressed with this motor, runs very smooth and quiet.

Miller:

Check the valve clearance, make sure you are using 10W-30 oil. I have 5-30 in it now but will likely change it out once I get another 30 min on the engine just to get everything cleaned out.

Pull the black cover off the end and make sure there is no debris in there, that thick plastic will sound like a knock.

Make sure the engine mounts are tight, transport handle isn't loose, take a piece of thick foam and place it under the gas tank to keep the metal heat guard form rattling.

Mine rattled all around and now it's very smooth and quiet.

Let is know if it works.

 
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02-10-09, 08:00 PM   #11  
Awesome! It doesn't surprise me... Robins are excellent engines. I wonder why I don't see more of them.


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04-18-09, 04:03 PM   #12  
I'm actually in the same boat with mine right now, it was knocking quite a bit, & the oil looked like it had glitter in it. I did'nt find any debris in the generator housing.

Does anyone know how to remove the rotor from the crank?

Thanks!

 
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04-18-09, 08:39 PM   #13  
A solid side blow with a block of wood on the rotor in a spot where it won't damage anything and hard enough to jar it loose, but not so hard that it bends the crank. This is assuming you have it disassembled and the rotor bolt out.


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04-23-09, 08:29 AM   #14  
Robin EX30 update

I recently tore engine down did not find any evidence of something coming apart. only thing i noticed was the governor plastic gear was a little wobbly the only wear i found was on cam lobes but looked normal to me. bearings were nice and smooth, no slack in connecting rod or scoring of piston or cylinder it looked beautiful. cylinder still had cross hatch marks from honing. connecting rod bearing had no slack and no wearing. and this is from an engine that has glitter like powdery metal in the oil. I reassembled engine and it runs fine. what's even weirder is that knock seems to be gone but it make plenty of rattling noise from flywheel cover. I went so far as to buy a brand new generator with this same engine. and guess what? smokes like hell when you start it and has that same weird knock. all in all I am going to say this is probably normal for this engine. I also has suspected the timing advance circuit as the source of the knock as slight pre ignition. Yep Thats right pre ignition. I will try some 89 octane gas to see if this is what going on. I tried adjusting the valves as was suggested and it wasn't that. I do suggest changing the oil often during the break in of this engine. the manual even says change after 20 hrs to remove metal flakes and contaminates after break in. It also mentions using higher octane fuel if it knocks. I have previously called around my area for info on this little engine and one guy I spoke with said he wouldn't touch it with a 10 ft pole. HA! i thought. I asked him why and he said he just didn't like the robin engines and parts were an issue. In summary I have completely tore this engine down and could not find any thing as a major defect. I reassembled it and it runs fine just a noisy rattly little engine. I think it will hold up well as I cannot find any thing bad on these engines. other than the governor gear and compression release mech. its a pretty solid little engine. it has a timing chain which is easy to time and install. subaru robin web site has video for free on how to time the engines and remove the head and reinstall. I reused my head gasket and it seems to be fine but it recommends using a new one each time. I used permatex red for crankcase gasket. and the other gaskets were fine. I think they lean these little engines out a bit which may be contributing to the knock.
i have to choke every dam one i've seen to get it to start, seems like every small engine i come across these day thats new you have to choke em to get them to start. even on a hot day after it been running for a while. Oh well any way. I think the metal in the oil will go away after some use I think that this is normal break in on the robin. I would change the oil more often than 20 hrs for break-in though due to it having no oil filter. Keep the valves adjusted periodically according to maintenance schedule. you can go to subaru robin web site and download manual, parts list, service manual with tolerances and specs, how-to procedures for free. as well as some tutorial videos posted on their site. I hope this helps and good luck

 
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06-07-09, 01:22 PM   #15  
I started a new thread on this since I have tore it down.

Mr. Miller...I had no slack in my connecting rod either except for the .010 side-to-side play but you aren't going to hear/feel a 2 thousandths gap. I used Plastigage and it revealed a .0025 excesssive clearance.

There is carbon on top of the piston but there are metal flakes in the oil as well.

 
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06-08-09, 03:16 PM   #16  
Robin ex30

I didn't mic anything but engine looked fine to me, did you look at timing chain when you took it off, I didn't because i watched video first then tore engine down. I wish I would have noticed the chain to see it maybe it was a tooth off the lower sprocket on the crank witch might cause it to ping and knock a little but thats just my best guess. It sure doesn't knock anymore, I stood there and watched it run a bit not long ago and tried to think why it would knock before and not now? timing chain was all I could think of. everything was tight and you can't adjust the spark timing it s got an advance high rpm trigger coil in its cdi magneto. I haven't checked for metal in the oil since last rebuild but its not knocking. so heck man I really wish I could tell you something solid about it. I really wish i took notice of the chain orientation on the crank when i tore it down. If you find out holler back at me I'm curious to know too. If you need me to check something on mine for you let me know. just fyi My new engine does that knocking crap too straight out of a sealed box. maybe I will tear it down and look at chain on that one. I will let you know what I find when I do it.

 
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06-08-09, 06:05 PM   #17  
These engines are literally a joy to tear down compared to most others. The chain is a super easy setup....look at the top gear, there are two hash marks that sit even with the top of the head with a notch at the 12 O'clock position, at TDC there will be a small punck mark on the crank at the very bottom. The chain has two shiny links that ease reassembly, one goes at the top and one at the bottom.

As far as a knock goes...dunno, check to make sure everything is tight, I noticed the heat shield above the engine and under the fuel tank will shake like crazy...a piece of foam cured that.

I spoke to a guy who works on these engines frequently...and this is coming from his mouth so take it for what it's worth.

He said use straight 30W and fill it to "spill to spill", meaning, with the engine level, fill it until it pours back out and where it stops pouring out, replace the cap/dipstick, when the excess pours out from the dipstick, wipe it down.

Not sure why, book calls for 1L but for the scoop to splash it needs the extra height. I will try it when I re-assemble it.

The mic won't help you determine the rod clearance unless you have them both out. Get some green or yellow Plastigage ( I used green) and remove the rod cap, insert the piece of gauge, and torque the cap back down. This is where I received my .051 reading where spec is .049 max.

 
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