Onan P220 surging/hunting at operate

[WheelHorse520H 708]

Okay, so I am delayed for a while because the paint on the muffler and heat shield flakes off because the directions on the paint can were unclear. So repainting needs to start hopefully this coming week. On another note I have a few spots on the cylinder heads that need to be cleaned again but over all they look pretty good. I true-ed the gasket surface on the heads like you said @lynnmor with 400 grit sandpaper and a smooth surface. Let me know if I need to do more because there is some dark spots on the gasket surface anyway. Pictures below.

Thanks for the help,

Andrew

[lynnmor 7,308]

What did you use for paint?  I never heated the parts before installation, just left the engine season it.

 

The heads should be lapped till the dark spots are nearly gone.

[WheelHorse520H 708]

2 minutes ago, lynnmor said:

 

What did you use for paint?  I never heated the parts before installation, just left the engine season it.

 

 

I used VHT Flameproof exhaust paint, I heard it looked really nice when it was done, but I learned

it smudges easily if it’s not baked. The directions say you can bake it or run the engine to cure it, I baked it because I didn’t want to smudge the paint during the installation process.

6 minutes ago, lynnmor said:

 

The heads should be lapped till the dark spots are nearly gone.

Okay I thought so but figured I would double check before I went too far. Thanks,

Andrew

[Horse Newbie 7,075]

2 hours ago, lynnmor said:

never heated the parts before installation, just left the engine season it.

When I painted my heat shields and muffler on my 1994 520H, I primed with high heat primer( Rustoleum), painted with high heat(Rustoleum) paint, and installed, paint seems to be doing fine- only 10 hrs run time since painted though...

[Jeff-C175 7,202]

4 minutes ago, Horse Newbie said:

I primed with high heat primer

 

I was going to recommend a primer too!  Thanks for bringing that up.

 

And rough up the metal to give it some 'tooth'.

 

ESPECIALLY on smooth metal parts like the heat shields above the exhaust on a tractor... which don't get THAT hot and may not 'cure' the paint as needed... unless you want to do it all over again when it flakes off!

Edited July 24, 2021 by Jeff-C175

[tom2p 2,394]

my 312-8 muffler has some bare spots - been like that for years 

 

I hit it with WD-40 now and then

 

[WheelHorse520H 708]

9 hours ago, Jeff-C175 said:

 

I was going to recommend a primer too!  Thanks for bringing that up.

 

And rough up the metal to give it some 'tooth'.

 

ESPECIALLY on smooth metal parts like the heat shields above the exhaust on a tractor... which don't get THAT hot and may not 'cure' the paint as needed... unless you want to do it all over again when it flakes off!

I went to O’Reilly’s and got primer and paint rated for 1300-2000 degrees F. If you look in the pictures in post #101 closely (you might have to zoom in) you can see the primer didn’t flake off just the actual color. The shields not getting hot was part of the reason I cured it before I put them on, that and I didn’t want to smudge it when I put it in. It smudges wicked easily before it’s cured.

[WheelHorse520H 708]

So, I now have to glass bead the heads. I guess the cloth I had them sitting on had some oven cleaner on it or the heads did or something. Even though I was wicked careful to rinse them off a couple of times. What would the oven cleaner do other than cause the heads to be discolored?

Thanks,

Andrew

P.S. I have them soaking in some SeaFoam Deep Creep to try to remove some of the stuff built up. Pictures below ⬇️.

Edited July 26, 2021 by WheelHorse520H

[Jeff-C175 7,202]

1 hour ago, WheelHorse520H said:

What would the oven cleaner do other than cause the heads to be discolored?

 

Leave it on too long and it 'etches' the aluminum... but if this is what it looks like, I'm not sure what could cause that.  

 

 

Is that actually 'bubbled' up?   Can you post a higher resolution photo of that?

 

[WheelHorse520H 708]

4 minutes ago, Jeff-C175 said:

 

Leave it on too long and it 'etches' the aluminum... but if this is what it looks like, I'm not sure what could cause that.  

 

 

Is that actually 'bubbled' up?   Can you post a higher resolution photo of that?

 

Yeah, I can but I don’t think it’s the aluminum that bubbled I think it was just stuff in the cloth like dust that the chemicals clumped together. I took a bunch…

 The liquid is the SeaFoam by the way.

Edited July 26, 2021 by WheelHorse520H

[Jeff-C175 7,202]

18 minutes ago, WheelHorse520H said:

stuff in the cloth like dust that the chemicals clumped together

 

Is it 'hard'?  Does it wipe off or is it bonded to the aluminum?

 

You need to be careful with stuff like rags and oven cleaner.  If clumped up and enclosed it's possible for an exothermic reaction to occur and cause them to spontaneously combust.  ESPECIALLY if there is any OIL on them also.

 

Once when I was younger and more foolish than I am now, I was applying Linseed Oil finish to a piece of furniture.  I threw the rags into a cardboard box.  About 15 minutes later I happened to notice SMOKE coming from the box which I threw out the door.  The moment it hit the ground it burst into flames!  Close call...

 

 

Edited July 26, 2021 by Jeff-C175

[WheelHorse520H 708]

18 minutes ago, Jeff-C175 said:

 

Is it 'hard'?  Does it wipe off or is it bonded to the aluminum?

 

You need to be careful with stuff like rags and oven cleaner.  If clumped up and enclosed it's possible for an exothermic reaction to occur and cause them to spontaneously combust.  ESPECIALLY if there is any OIL on them also.

 

Once when I was younger and more foolish than I am now, I was applying Linseed Oil finish to a piece of furniture.  I threw the rags into a cardboard box.  About 15 minutes later I happened to notice SMOKE coming from the box which I threw out the door.  The moment it hit the ground it burst into flames!  Close call...

 

 

Good to know, I think I am going to throw the rag out anyway, it is on borrowed time. I got it and it was yellow, not it is black and green and red from all the chemicals I mop up with it.

 

The crud on the cylinder heads does scrub off, but it doesn’t just come off by wiping a finger across it.

[Jeff-C175 7,202]

9 minutes ago, WheelHorse520H said:

throw the rag out

 

This caution applies to ANY oily rags.  Even vegetable oil believe it or not.  Many a restaurant fire is cause by oily rags spontaneously combusting.

 

It's also the reason that well equipped garages have sealed metal cans for rag disposal.  The ones that aren't well equipped often burn down! 

 

So why do you need to glass mead them?  Hopefully the metal is not too pitted on the gasket mating surfaces.

Edited July 26, 2021 by Jeff-C175

[WheelHorse520H 708]

6 minutes ago, Jeff-C175 said:

 

So why do you need to glass mead them?  Hopefully the metal is not too pitted on the gasket mating surfaces.

There is some carbon built up that I cannot scrub off and the three different chemicals I tried (engine degreaser, oven cleaner, and the SeaFoam) did not work. Unless I am mistaken I believe on the first page of this thread @lynnmor recommended glass beading the heads. However I also have to do it for the exhaust to prep that for repainting. Although I need to look at that more and determine what actually needs to be done.

[lynnmor 7,308]

Just reapply the oven cleaner brush off the junk and wash with very hot water.  Glass bead doesn't do well to remove soft material.

[WheelHorse520H 708]

Just now, lynnmor said:

Just reapply the oven cleaner brush off the junk and wash with very hot water.  Glass bead doesn't do well to remove soft material.

Okey dokey. I’m glad you said that, it’s too hot today to have a hood and long sleeves on for blasting.

[lynnmor 7,308]

Just now, WheelHorse520H said:

Okey dokey. I’m glad you said that, it’s too hot today to have a hood and long sleeves on for blasting.

 

Glass bead is too expensive to use outside of a cabinet, I only use cheap sand when blasting outdoors.

[WheelHorse520H 708]

1 minute ago, lynnmor said:

 

Glass bead is too expensive to use outside of a cabinet, I only use cheap sand when blasting outdoors.

How much is the cheap sand? The glass I use is a little over $1 per pound.

[lynnmor 7,308]

1 minute ago, WheelHorse520H said:

How much is the cheap sand? The glass I use is a little over $1 per pound.

 

Check with Home Depot for price, but sand may be too harsh for cylinder heads.

[WheelHorse520H 708]

9 minutes ago, lynnmor said:

 

Check with Home Depot for price, but sand may be too harsh for cylinder heads.

That’s okay, the heads look better after I just did that little procedure you described. The heads are a little darker but the carbon is only is a few spots the diameter of a paper clip or so. Nothing to worry about I think.

[Jeff-C175 7,202]

1 hour ago, WheelHorse520H said:

Nothing to worry about I think.

 

That gray color is what I expect from the oven cleaner.  SOME of the 'degreaser' detergents will also turn aluminum gray too.  Make sure to read the labels if you use any of those.

 

Also, keep in mind that once you have the engine back together again and running for a few hours, that carbon that you worked so hard to remove will begin to accumulate again so it's really not 100% necessary to get every single little specktoid of carbon off of them.  I generally just get the loose stuff and do a little bit of scraping/chiseling (carefully) of the harder deposits.

 

And YES... be VERY careful with blasting Aluminum!  Look into SODA BLASTING !

 

https://sodablastingguy.wordpress.com/2013/10/04/cleaning-aluminum-cylinder-heads-with-soda-blasting/comment-page-1/

 

Edited July 26, 2021 by Jeff-C175

[WheelHorse520H 708]

18 minutes ago, Jeff-C175 said:

 

Also, keep in mind that once you have the engine back together again and running for a few hours, that carbon that you worked so hard to remove will begin to accumulate again so it's really not 100% necessary to get every single little specktoid of carbon off of them.  I generally just get the loose stuff and do a little bit of scraping/chiseling (carefully) of the harder deposits.

That’s why after the three cleaners and the scrubbing I said it was good enough.

[tom2p 2,394]

lookin good 

 

if you are auditioning for the job to do my 416 - you are well on your way 

 

I will pay close attention to the valve adjustment part of the audition 

lol

[WheelHorse520H 708]

1 minute ago, tom2p said:

lookin good 

 

if you are auditioning for the job to do my 416 - you are well on your way 

 

I will pay close attention to the valve adjustment part of the audition 

lol

No way! I do not want to go through this again anytime soon. Especially the part with all the paint flaking off!

[tom2p 2,394]

2 hours ago, WheelHorse520H said:

No way! I do not want to go through this again anytime soon. Especially the part with all the paint flaking off!

no worries - muffler is fine ... paint on the muffler is not too bad ...