Well, I found out why I'm down on power (WorkHorse GT-1800)

[kadetklapp 1]

Finally found the time to load my Horse up and haul it to my buddy's house to tear down the motor. We didnt' have to look far. I suspected ithad a dead cylinder as I couldn't get any power out of it and it had gradually gotten worse. I suspected the rear cylinder to be the problem (IDK why, I just did) but we checked it last night and it had good compression. So, we pulled the front plug and found -ZERO- compression. We pulled the head off (bolts were hardly tight) and found this-

When I bought it, I had been told by the previous owner that two years prior he had the valves redone. ya, poorly! Looks like we will be doing at least a partial rebuild. Hopefully it didnt' screw anything else up. That would explain the horrendous lack of power on inclines and it nearly stalling when you activate the PTO. I'm impressed it started and ran at all. The head bolts obviously hadn't been retorqued as we were able to run them out by hand after only a couple of turns with the wrench. What I'm wondering is if this could contribute to the valve seat failure or if there was another problem maybe...

[kadetklapp 1]

My mechanic friend consulted a local machinest. Turns out the engine will have to be completely rebuilt. Not something I can do right now. I guess I'll have to get rid of the tractor. Quite disappointed.

[AMC RULES 37,117]

You know, that's a pretty desirable model if you decide to part it out. :confusion-shrug:

[C-85 674]

Here's what I recommend, as I've seen this before. This doesn't happen that offten, but I have seen a very few engines with this condition.

I'm not sure what determined the full re-build from this situation, we don't have all the info on this

In any event here's what I'd do -

First,I don't think I'd throw in the towel this fast!

Now that you've got it torn down this far I'd take the valve out.

I'd look at the valve and the seat that popped out. Check to see if the valve stem got bent from this and check it's seat for errosion or burning. Then check the seat that's loose to see if it's damaged. Most of the time I've found that these seats can be re-installed back in the block by putting them back in and then prick punching around the outside rim of the seat on the block to keep it from coming back out again. It doesn't take that much to hold them in. After you get that done I would either re-cut the seat if it needs it, but it may be okay or re-lap the seats with valve grinding compound if that is needed. Then check the valve clearance to see if it's in spec. You might get real lucky and just be able to just put it back together and run it.

Or you may be able to just buy a new valve and or seat and fix it that way, but it should be an fairly easy fix.

This may not be as bad as it seems and right now you don't have much to loose by checking these simple things!

Please let us know how you make out!

C-85

[kadetklapp 1]

Hey C-85, just got off the phone with my mad mechanic and he's trying to prick pinch it back in. Guess great minds think alike. The other option is to weld it in. I'm not sure if he's taken the side cover off and looked at the valve stem and spring. The theory is that it's so worn that after he prick pinches it in it will just pop right back out again. It's worth a try and doesn't cost anything so he's going to do it, we will see what happens. As for welding it, thats some pretty minute work so he's not sure how well that will go over.

[kadetklapp 1]

It's back in and running. He says running bad, but it has good compression in that cylinder now. So not sure if there is another issue related to old fuel or worn plug or something but that's where we sit. My guess is it will spit the seat out in short order, but we'll see.

[C-85 674]

Thanks for letting us know and I think this is great news!

Like I said before that seat doesn't need much to keep it in place, there no real presure on it that would push it out.

Good luck with the additional running problem!

C-85

[kadetklapp 1]

It's running just as bad as before. It does have compression in the front cylinder though. I don't know what in the world is up with it. Maybe the valve needs adjusted....

[woodchuckfarmer 333]

I took my 20hp onan to an engine shop to have new intake valve seats installed in it. He had no problem with just doing the seats. Cost was $130, i didnt think that was a bad price. I think id get a second opion.....good luck.....Wayne

[kadetklapp 1]

Ok, i need an exhaust valve. The one in it is shot. Will not seal. Turns out none of the regular parts sources have one. Any ideas?

[Sparky-(Admin) 21,254]

Are they NLA (no longer available)? Or just hard to find?

Mike..........

[kadetklapp 1]

According to most sites they are no longer available.

[kadetklapp 1]

I cant' even look up the exhaust valve part number on B&S website.

[Indy w h 5]

What HP is this engine ??

[WH854 44]

I cant' even look up the exhaust valve part number on B&S website.

Try This

http://bsintek.basco.com/BriggsDocumentDisplay/Z6mquEVJ1DajI.pdf

[kadetklapp 1]

I cant' even look up the exhaust valve part number on B&S website.

Try This

http://bsintek.basco...mquEVJ1DajI.pdf

Will do, thanks.

It's an 18 hP motor.

[kadetklapp 1]

If it's PN 390420 (old) or PN 691794 (new) then it's "No Longer Available".

I can get new intake valves all day. It's seemingly impossible to find a new exhaust valve. Not good news!

Per Parts Tree-

33 Diagram: 422437-0663-01 Cylinder,Cylinder Heads,Sump BRP Briggs and Stratton 691794 (replaces 390420)

Valve/Retainer Kit Not available

[WH854 44]

If it's PN 390420 (old) or PN 691794 (new) then it's "No Longer Available".

I can get new intake valves all day. It's seemingly impossible to find a new exhaust valve. Not good news!

Per Parts Tree-

33 Diagram: 422437-0663-01 Cylinder,Cylinder Heads,Sump BRP Briggs and Stratton 691794 (replaces 390420)

Valve/Retainer Kit Not available

You can get aftermarket here

http://www.rcpw.com/search/?quest=390420&search.x=0&search.y=0

Chas

[kadetklapp 1]

If it's PN 390420 (old) or PN 691794 (new) then it's "No Longer Available".

I can get new intake valves all day. It's seemingly impossible to find a new exhaust valve. Not good news!

Per Parts Tree-

33 Diagram: 422437-0663-01 Cylinder,Cylinder Heads,Sump BRP Briggs and Stratton 691794 (replaces 390420)

Valve/Retainer Kit Not available

You can get aftermarket here

http://www.rcpw.com/....x=0&search.y=0

Chas

You are the man!

[baerpath 517]

If you don't make out and are close I have complete briggs 18. 16 and a 12.5 twins for sale.

Duane

[JackC 617]

If you can't find a valve, a machine shop could probably make one if you could provide them with a similar or bigger valve that they could cut down to match.

There are still some bone yards around where you might be able to find a twin cylinder Briggs with what you need.