Briggs Intek 24hp - Still Smoking after Two New Heads

Messages
3
Location
Southbury, CT USA
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.
 
Messages
2,181
Location
missouri
Do you know the difference between black and Blue( light gray) smoke. If you have a good running mower, you can put oil in the muffler (about a tea spoon) and see what oil smoke looks like. If you have oil smoke, then you probably have worn rings. Black smoke like you see from the "tuned" diesels is fuel. You needed the carb fixed. 10% of what you have spent so far. This is a good time to look at northern tool or some of the surplus engine sites and do a repower. Rod
 
Messages
144
Location
MO USA
I would check the crankcase breather system and make sure that is venting properly. If it is clogged or not flowing correctly, it could be causing some of the engine symptoms you are seeing.
 
Messages
6,549
Location
Connecticut
+1 to all of the above -If blue oil smoke, then it is likely a breather issue with the crankcase, or worn piston rings -If black smoke, it is likely a carburetor issue (stuck float, running rich, etc) which would also contribute to backfiring.
 

Chris_W

Thread starter
Messages
3
Location
Southbury, CT USA
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. As mentioned, 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!
 
Messages
5,615
Location
Ohio
I often found when the breather gets plugged, oil works its way up to the air filter, soaking it. If yours is dry, I would look at carb issues. Float sticking or damage is what comes to mind. I often find the shaft pin for the float hinge gets pitted and causes the float to hang up.
 
Last edited:
Messages
6,549
Location
Connecticut
Originally Posted by Chris_W
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. As mentioned, 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!
How did the cylinder bores look when you had the cylinder heads off? Was there a lot of scoring? At 70 PSI, I'm thinking the damage has been done at this point if it is the rings. As far as taking it apart that is up to you, the parts certainly aren't that expensive compared to finding a good used engine.
 

Chris_W

Thread starter
Messages
3
Location
Southbury, CT USA
Another Update: Thanks for the tips and the cylinder bore looked fine when I had the head off. That clue, thank you, and another's advice led me to the valve adjustment I had done previously. 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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