[nicksorg]

Hey guys. I did a rebuild of the K341 in my 79 300 last April. I had the machine shop bore the cylinder, balance the crank, and do a valve job. I installed the piston, rings, and everything else. The motor runs good, but still smokes on startup. I'm wondering how long it takes for rings to seat? I didn't use it much this summer and I estimate about 6 hours on the engine.
Thanks
Nick

 

[gonetofarm]

Sounds like the rings might not be seated yet. I have never had one smoke though on startup after a rebuild. Did you get the ring gaps staggered properly?

 

[nicksorg]

I know the ring gaps were staggered, because I had to tear it down a second time and made sure it was correct.

 

[al_m]

What colour is the smoke?If it is blue the engine is burning oil.black smoke would indicate a rich fuel condition,and normal with a full choke start up

 

[msgwelter]

Are you using 30W non-detergent oil?

 

[dr_evil]

NICK - Have you even changed the break-in oil once yet?

It takes heat and LOAD to properly break in a rebuilt Kohler. The rings have a light chrome plate on the wear surface that takes time and lots of pressure to break in properly. After the first start and carb adjustment you should run the engine at variable RPM for a half hour and re-torque the head gasket to spec. in the order the manual shows. Each bolt/nut will need some tightening. Then run the engine at full RPM at 1/4 load for an hour and increasing load after each hour to 1/2, then 3/4, then full load. During those hours you run at the suggested load for 5-10 minutes then reduce load but maintain a fast RPM. Really low or no-load operation is not recommended except for cool down before shutting the engine off. On a new tight rebuilt engine I recommend 3 to 5 minutes before shut down.

A puff of blue oil smoke on start up is not uncommon, but should clear up after a few seconds. Ring gap staggering is somewhat important but rings rotate around the piston in operation so as long as the gaps don't all align they shouldn't bother or cause smoking. There is an end gap adjustment that is critical, when up to normal operating temp if the gap is too small the ring ends could touch and that causes HUGE problems.

I rebuilt a K321 and installed it in my tractor about 4 yrs ago and it now has 150 hrs on it. I had to use it on some light spraying pulling my 55 gallon sprayer when it only had about 10-15 hrs on it and I think that light loading extended my break in period by 40-50 hours. It had about 100 hours on it before it seemed to be broke in.

If everything is correct, I wouldn't worry about a little smoke on start-up until after 50-60 hours.

 

[nicksorg]

Thanks guys. The smoke is not black so its definitely burning oil. Unfortunately, I can't remember what oil I used after rebuild. I am planning to change the oil this week. Should I stick with the 30w non-detergent considering the cold temperatures in the Northeast?

Dennis, I have a 49 blower, so I'll consider how I approach the snow as far as load.

 

[dr_evil]

NICK - I'd consider using a synthetic oil if your tractor is stored in an unheated garage/shop. I really don't like running non-detergent oil in ANY engine but I did in my K321 for 2-3 operating hours. Then I used 15W-40 Rotella for 10-15 hrs then switched to Rotella SB 5W-40. I broke my engine in during the spring & early summer so had warmer temps to contend with. I don't think switching an engine to synthetic after 5-10 hrs is a bad thing, might extend the break-in time a bit but my Wife drove a '99 Lumina with a 3.1L V-6 for 80,000 trouble-free miles that had synthetic oil in it from the factory.

I think the snow blower would be great for breaking in your engine. Since you've got a few hours of run time on it, once the engine is warm you can really get a load on the engine and build heat, then with the cold air you can cool it down fast. Much quicker & easier break-in than mowing IMHO. Once the engine is warm I'd vary load from half to full load for a couple minutes at a time. After a couple more hours of running you should be able to extend the time you load the engine up to 100%. By spring I suspect your smoking issue will be gone.

 

[msgwelter]

Nick, back in the OLD DAYS, a friend of mine did a complete rebuild on a bored out Ford 352. He used chrome rings and the best detergent oil he could find. The engine was a smoker. I asked a mechanic that I knew well about the problem. He said to drain the oil, put in some cheap non-detergent 30w oil for break-in. The smoking stopped and the engine rings sealed up in short order. I use 30w non-detergent on every engine I rebuild and have never had a problem.

 

[arp123]

I agree with Mark. Using a Non-detergent oil is key for breaking in an engine. I have read this several places and asked a gentleman that taught a small engines class. He said it's the best way to break in a rebuilt engine.

Andy

 

[nicksorg]

Thanks for the suggestions. I changed the oil last night using 30W non-detergent. I'll run it for 5 hours and then figure out what to do next.
Nick

 

[iruossim]

Nick, I know you said they did a valve job, but can you tell me if the machine shop changed out the valve guides? You could be blowing oil into the engine through this route.