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Discussion Starter #1
Hi all,


I acquired a used tractor from a friend (Briggs motor: 445677). It was running well for a few months and then started blowing black smoke. After reading various threads about Intek engines blowing head gaskets, I decided to replace the head gasket. When I took the heads off however, I did not notice signs of deterioration in the head gasket. Nevertheless, I replaced the head gasket as I had to scrape off bits anyway. I cleaned up a decent amount of carbon buildup from the top of the piston and I used fine drywall screen and seafoam to "sand" the bits of old gasket from all surfaces. Unfortunately, during the process of reinstallation, I over-torqued the head bolts (wrong setting on torque wrench). I, ultimately, torqued them to the correct torque (but I was sure I had at least compressed the gasket or worse, warped the heads). Anyway, I put everything back together and the engine still smoked. It also appear to have oil visibly leaking onto or from where the exhaust pipe connected to the head.


So, I suspected a warped head (either from my over-torquing or from previous overheating - the engine was quite dirty when I got it). I ordered two new head kits (came complete with head, intake and exhaust gaskets). This time when I replaced the heads, I filed down the exhaust pipe connection as it had quite a bit of old gasket material stuck to it. I also made sure all metal contact surfaces were cleaned again and I set the valve gap to .004. With new heads and new gaskets, I was SURE the smoking problem would be solved! Well...still smoking from, again, what appears to be around the exhaust port. This time, I don't see any visible moisture/oil from that area. I should add, that when I run the machine, I don't have the air filter hooked up (if that matters).

I should add, the engine now has an occasional stumble and it will backfire when moving from full throttle to idle. And, the engine smokes more at idle.


I've been reading threads about the issue, but thought I'd post to see if anyone has suggestions about any TESTS I can do to narrow down the problem. I've read the following:


1. take the exhaust pipe off and run the engine to see if oil drips out
2. take the valve cover off and shine a light into the chamber to see if oil is leaking into the chamber


Ideas of the possible problems:
1. is the engine block surface warped from over torquing the head bolts? (except the same symptoms are occurring before and after the head replacement).
2. bad piston rings?
3. ?

Thanks in advance for any help.
 

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black smoke means your running rich,blue,grey smoke is burning oil. I would check my fuel system,like needle valve and seat,and make sure your oil ain't been diluted
 

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Discussion Starter #3
Update:

Thanks so much for the info!

So, I took a MUCH closer look when I ran the engine this time. The smoke was coming out of the exhaust and it was definitely blue (burning oil) not black. I didn’t notice any active leaks of oil on the outside of the engine. It was actually running pretty well, but at idle, it wasn’t maintaining a constant rpm, yet didn’t stall.

So, I did the following tests:

1. Compression test. Cylinder #1 = 120 psi, Cylinder #2 = 70psi. Added a bit of oil to cylinder #1, retested and it maintained the 120psi.
2. Took off the breather cover and ran the engine = didn’t notice oil coming out.
3. Oil level is between the two hash marks.

Question/Feedback:

With the 50psi difference in compression between cylinders, I’m assuming there is an issue with Cylinder #2. And, with a brand new head (including valves), I’m assuming it’s not the valves.

1. Am I correct, at this point to assume the piston rings are shot?
2. I haven’t done the oil compression test with Cylinder #2 yet, but do you think it’s even necessary?
3. Is there harm in running the engine with low compression in one cylinder (potential ring failure)? I just want to get through some of the spring cleanup tasks on my yard before I do further work to the motor!!
4. Are there other tests I should perform at this point?
5. Is it worth taking the block apart to fix the piston? (I’m already out the money for the new heads…lesson learned!).

Thanks so much for your help with this!
 

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Overhaul the engine. 70psi = NG and you'll just keep frustrating yourself with fouled plugs and poor performance.

Oil in the cylinder bumping the numbers says it's not the valves.

Might just be a broken ring or somesuch but you're gonna have to open it up and see.
 

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Make sure you have the #2 cylinder valve clearances set properly. If you set them with the cam in the wrong position, you may have poor compression.
You did not report the compression on #2 after adding some oil to seal the piston rings temporarily. Have you done that, and if so, what are the results?
tom
 

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Discussion Starter #6
Another Update:

"Make sure you have the #2 cylinder valve clearances set properly. If you set them with the cam in the wrong position, you may have poor compression."

Tomw0, I owe you!! I think you nailed it!

So, it appears not all YouTube videos are created equal. I had watched a video showing how to set the valve lash by opening one valve all the way (one at a time) and setting the gap on the other valve when closed (.004 in).

In reading a few articles (one from Briggs) and watching a few other videos, I followed the procedure that calls for adjusting both valve gaps at the same time when the cylinder is ¼ past TDC.

In addition to adjusting the valves in what appears to be the correct way, I also drained the oil and refilled it with SAE 30 and added a Lucasoil additive (according to the directions).

When I rechecked the compression, both cylinders were around 170psi! When I started and ran the engine, there was no sputtering at full throttle or idle and now backfiring. There was still some blue smoke, but I saw visible oil on the outside dripping on the exhaust. I decided to be patient and keep it running while wiping some of the oil away. I suspected it was residual oil from after the oil change and from taking the valve covers off. After a while, I did not see any smoking and there was no blue smoke coming from the muffler.

So, I dethatched the entire backyard and rechecked the engine afterward. I’m happy to report, for now, there is no blue smoke and the engine seemed to be really running great. When I shut off the motor, there was no backfiring.
I think I will still check the carburetor, just to be sure it’s operating correctly. I just wanted to repost because it appears to be a simple valve adjustment when, before today, it appeared to be worn piston rings!

Thanks again and I’ll repost if there are any changes in the wrong direction. These forums have saved me so many times and have only added to my ability to learn as I go. I just really appreciate everyone taking some time to offer suggestions.
 

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Good deal, and thanks for the update. 🍻

At a loss why oil bumped the numbers, but in this case glad to have been wrong.*

*Not the first time. :ROFLMAO:
 

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If everyone would stay off or youtube for repair vids we would all be better off!!
Almost all of them do things either the hard way or the wrong way!
BTW you are not going to warp a lawn mower head by over tightening the bolts.
You will strip one out or snap on off but other than that...they are fine!
No overcompressing gasket either on heads.
These things are little low performance turds and very forgiving.

++
 
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