520h with water

[wrightorchid 261]

[wrightorchid 261]

I noticed that there is only 1 screw holding on the fuel pump.  My 312 has 2 screws and a gasket.  Maybe this is it?  Is it possible to just get a gasket if this is it?

Edited June 25, 2020 by wrightorchid

[lynnmor 7,817]

Get the gasket for around the oil filter to prevent loosing cooling air.

 

The fuel pump has a pulse line on the back side, if it leaks a small amount of oil can come out.  Use 1/4" fuel line to replace.

 

The oil filter is on a mount that has a gasket to the block, that can leak.

 

The one screw holding the fuel pump is not causing a problem, but you should replace the missing sheet metal screw.

 

Start soaking any and all fasteners on the engine with penetrating oil.  Do this several times a day for as many days you have.

 

The intake and exhaust bolts strip easily, take care removing and installing.  Onans need indoor storage.

 

Use only genuine Onan gaskets for the above.

 

Glass bead and paint the muffler with Rustoleum High Temperature paint, these things cost too much to not protect them.

[wrightorchid 261]

I'll have to determne the source of the oil leak.  Thanls for your help.  The current muffler has the rear end rusted out.    I am in Florida with high humidity.  I wish iI had dry, low humidity storage.  I will try to get it out of the rain and under cover.  The links to the correct parts has been really helpful.

[EricF 589]

On 6/25/2020 at 6:07 PM, lynnmor said:

Get the gasket for around the oil filter to prevent loosing cooling air.

 

Can't stress that enough. The oil filter gasket isn't there just to make everything look pretty -- It makes a significant difference in keeping the air blowing through the engine's cooling fins on the back cylinder. Without it, a whole lot of air gets blown past the oil filter and never makes it across the engine. With the Florida heat, you don't want to starve your engine of vital cooling air.

[wrightorchid 261]

Thank you!  I certainly don't want the valve seat to go south!  It only has 590 hours on it, but I don't know the history on it.  It is very hot here and air quality is bad with the saharan dust, so not much getting done on it this week.  I have lots to do on it.  My 312 needs a rebuild, as best as I can tell, so this got pushed into service.  The horses ate not very common down here.

[wrightorchid 261]

The oil leak is definitely from behind the fuel pump.  The line has a crack in it where it connects, and I saw it pulsing the oil when mowing.  I have removed the bolts I can see holding the shroud on, but there is something on the upper right that is still holding it on.  I have looked at the manuals, but don't see where another bolt remains, or is hung up.  Any ideas on this?  I do see a bolt on the ignition coil. but can't get a socket on it.

Edited July 9, 2020 by wrightorchid

[lynnmor 7,817]

You need to pull the coil, the bolts holding are in there.

 

When you get it off, clean the fins well, even between the engine and frame.

[wrightorchid 261]

Thanks.  So much for a simple fix.

[wrightorchid 261]

I am unable to get a socket nor nut driver on the bolt heads holding it in.  I'll try removing the wires going to it, and hope nothing breaks.  The positive post is a bit rusty.  I'm not sure how a mechanic in the day could replace the line with only 0.3 hours of labor.

Edited July 9, 2020 by wrightorchid

[wrightorchid 261]

Shroud finally off after removing the wires from the coil, and loosening the rear tin.  Not much dirt in the cooling fins,but blown out for good measure.  The fuel pump line has a date of 2006, It is stuck to the connection on the block.  Any safe suggestions for removal?

[lynnmor 7,817]

I guess the clamp is off, or is it stuck as well?  With the clamp off, slit the hose with a utility knife, just try to not cut too deep and mess up the nipple.  Use a twisting motion to break it free.  Did a previous owner use some kind of adhesive?

 

When installing a new hose, let it long till you are ready to install the fuel pump.  If the hose is too long it may buckle, you want just enough length to get it on the pump.

[wrightorchid 261]

Yes, the clamp is off, but still stuck.  I tried twisting, but no avail.  Will try cutting it.  I was concerned about damaging the nipple.  This has been far more complicated than I thought it would be.  If they had separated the coil bracket, it would have been much easier.  

 

[lynnmor 7,817]

4 hours ago, wrightorchid said:

 If they had separated the coil bracket, it would have been much easier.  

 

I've said that many times.  Since the fins should be checked periodically I should come up with a fix for that.

 

If you cut the hose about 1/2 " beyond the nipple, you can start slitting and see what you are doing as you advance.

[wrightorchid 261]

Putting it all back together.

 

[wrightorchid 261]

I got the tins on, will connect the coil and fire it up tomorrow.

The coil has a crack in the plastic hump (?) between the posts.  Is there a good filler glue for this?  The coil does work, and these seem to be fairly expensive to replace.

 

I'm sure these went back together much easier when they were new, and did not have parts our of alignment, and cross threaded, rusted bolts.  People have to be careful with aluminum blocks!  

Looking at the exhaust manifold bolts, they are really rusted, and don't look too promising, as far as future removal goes. The bolt heads are not very complete, and will be hard to get a wrench on without breaking or rounding over.  I did put some penetrating oil on them.  I may have to try welding the end of the muffler, or getting creative.  I wonder if this would damage the electronics if done on the motor?

Thank you again for your assistance with this.

[lynnmor 7,817]

Don’t know if it matters on the coil. 
In order to adjust valves the manifolds should come off.  Use a six point socket to help prevent rounding, if it is still too loose try a metric socket.  If you can break the bolts loose, stop and soak with more penetrating oil for a day.  If you feel increased resistance, turn the opposite direction a bit.

I run a plug tap in the manifold mounting holes to increase depth and clean the threads, then I use the next size longer bolts to prevent stripping.  Check to be sure the bolts will not bottom out.
Watch for mufflers on auction sites and just bite the bullet and pay up, good ones are getting scarce.

You could disconnect the module and stator wires if you weld.

[wrightorchid 261]

I do already have a muffler in OK condition that I bought a couple years ago, when the prices were lower. My 312 needs a new motor/rebuild and I can't afford the down time if there are complications.  Will try to do in the fall, when the grass is not growing 6 inches a week.   The extra horsepower is really great, and it cuts well even in the the tall, thick stuff.  Thanks for your help.

 

[wrightorchid 261]

Latest update!  It died and won't restart.  It does turn over, but nothing happens. I am guessing carb as the fuel pump is working.  There was more gunk in the fuel filter.  This is the 3rd one so far.  I did try to clean the tank, but must still be some gunk.

 

How do you cean this carb?  I know this sounds basic, but I have never done this.  Is a kit needed?  Can this be done without removing and replacing gaskets??  I did not find details on this when  searching. 

Is there a better type of filter to use?

The governer tab on the side of the carb is broken off. I am trying to keep it under 3500 rpm when running. Any ideas on a fix?

 

The voltage meter when running is way past 16 when running and is about 13 when off.

 

 

 

Edited July 19, 2020 by wrightorchid

[lynnmor 7,817]

Before tearing into the carburetor, pour about a teaspoon of gas in and quickly try to start.  If it fires, then you know the problem is fuel related.

Some have luck with pulling the top off the carburetor, just a few screws and linkage.  Be very careful that things don’t fall down in.  I prefer to pull the manifold and do it right.  The carburetor may need a gasket if you pull the top, but often the old one can be reused.  If you pull the manifold, you will need new gaskets, use only genuine Onan gaskets for that.  Cheap rebuild kits are available on eBay but toss the manifold to block gaskets.

Use a clear fuel filter with pleated paper, preferably a name brand.

 

Try cleaning the surfaces where the voltage regulator mounts if that doesn’t work, new regulators can be had on eBay for $10.

Edited July 20, 2020 by lynnmor

[wrightorchid 261]

Yesterday after it sat for a couple hours, I tried again, and it fired right up. It was at the bottom of the hill, away from the shop, and I know I can't push it.   Today it started fine, and I mowed the back yard.  Shut down, and added more gas, to do the front.  It tried to turn over, but was weak and got weaker, like a dead battery.  I put the battery on the charger, I am not sure if it is charging properly, since It is pretty new.  Will try again tomorrow.  

[lynnmor 7,817]

AutoZone and Advance Autoparts will test a battery for free.  Just charge it for hours before taking it in.

[wrightorchid 261]

It's sat a while, and the grass is getting very tall.   I had charged the battery up, and it fired fine, then promptly died.  I am unable to get it to start.  It turns over fine.  Tried a few shots of starter fluid, and it would try to start, so I think I am getting spark..  I'm sure it is getting fuel.  Not sure what to do at this point.  still getting some crud in the fuel filter, so I'll change that again.

[lynnmor 7,817]

How do you know that the carburetor is getting fuel?  You can pull the gas line to the carburetor and direct into a container while cranking.  If that tests OK, pull the carburetor and clean it properly. 

[wrightorchid 261]

I connected an inline spark plug tester, and it does not light up while turning over, so maybe an electrical issue also.  I have gaskets and carb kit on order and should receive in a few days.