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TC10284

520H - Engine Freeze(?) Plug Loose under exhaust

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TC10284
Posted (edited)

Been working on a 73501 520H. I took off the exhaust and carb/intake earlier this evening to adjust the valves. When I was removing the exhaust, I found the following: https://photos.app.goo.gl/X8Xkuo1ShqTnMRge9

I'm not sure what this is called other than a freeze plug(?), but it was loose and there is a minor oil leak from it. BTW, I have cleaned off all the crud around and on top of it. 

How can this be fixed? 

 

Another issue is that it burns some oil when throttling up. It's definitely oil, because I can see/smell it. Not sure if adjusting the valves will help any on this, however, I did find oil on one of the rear intake bolts. As well as both intake valves were pretty badly out of adjustment (basically no gap with the gap finder). Haven't changed the oil or filter yet, but will once I work out the larger issues. 

 

Edited by TC10284

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GMan

TC,

How many hours are on the engine? I have had the same thing happen with regard to the plug which is like a freeze plug but seals the end of the camshaft. I have taken the plug clear out, turned it over and used a ballpeen hammer to put the bell shape back into the plug. Then thouroughly clean the end of the camshaft and apply some oil resistant gasket sealant sparingly around the groove where the plug sits, re-insert the plug and lightly tap the end of the plug with the flat end of the ballpeen hammer to "reset" the plug, then let it set overnight to give the sealant a chance to set up before again running the engine. Much the same as installing a freezeplug into  any engine block. Before reinstalling the cam end plug try to determine if the cam has excessive end to end play which could be the reason the plug came out in the first place as that would indicate worn cam bearings especially if the engine had one of the narrower width ones installed. Regarding the valves it is a possibility the valve seals need to be replaced. You could install new ones while you are working on this situation but it would require pulling the heads to do so. But that would be a very good time to de-carbon them................Hope this helps.............Gary

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TC10284

Gary,

 

It has a little over 1100hr on it the timer. 

I'll try your suggestion with the ballpeen hammer and see how that goes. 

 

Thanks!

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lynnmor

You can get a new plug from here: welch plug

 

The intake valve seals surely need replaced by now, but I think you have much bigger problems.  Did you check the compression? 

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TC10284
13 hours ago, lynnmor said:

You can get a new plug from here: welch plug

 

The intake valve seals surely need replaced by now, but I think you have much bigger problems.  Did you check the compression? 

 

I'll get a new plug if I can't get the existing one to hold/seal. 

 

Pretty sure I did check compression when I was working on getting it running in the beginning. If I recall, it was either 105 or 115 psi for both cyl. I'll check it again tomorrow or soon. 

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TC10284

 

On 5/15/2019 at 9:11 AM, lynnmor said:

You can get a new plug from here: welch plug

 

The intake valve seals surely need replaced by now, but I think you have much bigger problems.  Did you check the compression? 

 

I forgot to do the compression check earlier. I'll try it tomorrow if I have time. 

I was able to use a ball peen hammer to expand the existing welch plug and gently beat it back into place. Then seal with red gasket maker. 

 

How difficult is it to replace the intake valve seals? I'm guessing removing the heads.

 

The valves were pretty bad out of adjustment - both sets. That's fixed but of course didn't help the smoking. 

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lynnmor

When you adjusted the valves, you should have pulled the heads and replaced the intake valve seals, you also would have been able to inspect cylinder walls and valve seats.  The worst part of pulling the valves is getting a proper valve spring compressor to remove the keepers.  Stuff the oil drain holes to prevent the keepers from falling into them.

 

I doubt that the valve seals are the majority of your oil consumption problem, and a major overhaul may be the real answer.  Since the valves all needed considerable adjustment, something else is going on, usually little adjustment is needed. Are you sure that you had the lifters on the base circle of the cam when you did the adjustment?   A compression test might tell you if serious problems exist.

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TC10284

Compression check shows 100psi on front cyl and 93 psi on rear cyl.

Still smokes when I rev it up incrementally, but it's not terrible. 

 

 

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lynnmor

The compression isn't too bad.  All of my Onans will produce a bit of smoke on a cold start, once warmed there is almost none. 

 

There is a breather above where you found the loose plug, remove and clean that.  I have never found any problem with those but it is worth a try.  The procedure is on page 6-2 in the manual.  service manual

 

If oil consumption remains high, it may be worn oil rings, bad intake valve seals or worn valve guides.

 

 

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TC10284
19 minutes ago, lynnmor said:

The compression isn't too bad.  All of my Onans will produce a bit of smoke on a cold start, once warmed there is almost none. 

 

There is a breather above where you found the loose plug, remove and clean that.  I have never found any problem with those but it is worth a try.  The procedure is on page 6-2 in the manual.  service manual

 

If oil consumption remains high, it may be worn oil rings, bad intake valve seals or worn valve guides.

 

 

 

Good call! I'll try that next, but yeah, I'm pretty much expecting it to be something within the engine itself like you mentioned in your last line. 

I drove it around some for about 15min doing various throttle positions and it would either smoke on throttle up, or when I bounced from a bigger bump. 

 

But I've done as much as I can, AFAIK, to it, without pulling the heads or engine off. And it'll likely only be used two or three times a season since I have so many other WH tractors to use, so I'm going to call it "good enough" unless it gets severe. 

 

Thanks for your help lynnmor! I really do appreciate you pretty much always replying to my numerous posts!

 

Right now I'm looking at trying to adjust the neutral position in the motion lever. Pressing the brake all the way down results in it pulling the motion lever forward and tractor wanting to go forward. Typically I don't use the brake, but the neutral position is really sensitive on this guy. Been doing some Googling on that issue, and am gonna try a few things I found. 

Edited by TC10284

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lynnmor
2 hours ago, TC10284 said:

Right now I'm looking at trying to adjust the neutral position in the motion lever. Pressing the brake all the way down results in it pulling the motion lever forward and tractor wanting to go forward. Typically I don't use the brake, but the neutral position is really sensitive on this guy. Been doing some Googling on that issue, and am gonna try a few things I found. 

The part that rides in the crooked slot may have serious wear.

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TC10284
3 hours ago, lynnmor said:

The part that rides in the crooked slot may have serious wear.

I think I got it resolved after a lot of playing around with it. Still seems sensitive, but it's definitely better. Found crud build-up under the metal washer as well. 

 

 

Last up is getting a replacement 83-2820 spring for the parking brake and seeing if I can find where it's supposed to connect to. I found a couple on eBay, unless there is a generic somewhere yall know of.  

 

Thanks!

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