New engine vs. rebuild

[Mr. Shamrock]

Many of you probably have seen my other thread about my B&S Intek 20HP V-Twin using a lot of oil. What are your opinions on complete new engine, short block, or rebuilding this one? OR go trade the whole mower in on a new one and call it a day?!?!!?

 

[Rivets]

You don't give us a lot of info. Is $$$$ a problem? What is it on? How old is the engine? Do you know what is causing the oil consumption? Before I can say which way to go, I would need more info. I have told customers to do all three depending on the answer to the above questions. We have a dealer in our area sending us a lot of business because he always says new engine. 90% of the time he is wrong. I like that. I love to do rebuilds, but only do them when that is best for customer. New engines are easy but don't bring back a lot of business. Most of the time a new engine is not worth the price of the equipment.

 

[Mr. Shamrock]

Sorry for the lack of information. The mower is a 2007 Snapper 250Z Zero Turn that is in excellent shape. I bought it new and have taken very good care of it. I see used units in similar shape going for $1500-$2000 so it still has decent value. I am fairly certain the oil consumption is rings and/or cylinder wear. These B&S Intek V-Twins apparantly have am issue with dust inhalation causing this (from what I have read). I was hoping for the best and pulled the heads recently and there was a lot of carbon build-up on the valves and on top of the pistons. I cleaned everything up and replaced all the gaskets and it did not help. The cylinder walls were real smooth and there was almost no sign of cross hatching. The mower runs perfect and does not smoke, which is baffling to me, but will consume about 1/2 a quart of oil every couple hours. I am definitely up for any and all suggestions. I normally don't like the "mechanic in a bottle" stuff but even sent the people at Lucas an e-mail last night to see if they thought a mix of their oil stabilizer would help any. From what I have read a 20% mix of it has helped others in this situation. I know ultimately there is no substitution for mechanical repair, but I am just hoping to slow the oil use down a bit and make it through another season or more. Thanks for the response!

 

[reynoldston]

If you just want to get through another season why not try a heaver weight oil.

 

[Mr. Shamrock]

If you just want to get through another season why not try a heaver weight oil.

I thought of that - maybe a straight 40 weight. I think I am going to pick up a bottle of Lucas oil stabilizer and us it to top off the level next time up to 10-12 ounces or so. They say that a 20% mix is what is recommended. If that doesn't work the next oil change will be with some 40 weight unless I find out it is highly not recommended.

 

[Rivets]

Thanks for the added info. Got a few more questions. When you pulled heads was the carbon build up wet or dry? If it was dry I don't think it is real serious. Do you have a compression tester? If you can get one please take a compression test. This will give us a lot of valuable info on how to proceed. I also am not a fan of "Mechanic in a bottle", but it might be worth a try. Remember, air cooled engines do run a lot hotter than liquid cooled one. Have you checked the breather? This could be the cause if the compression test comes out good. If it gets heavy use for more than three hours of continuous use, this type of consumption could be in the normal range. If you pull the valve cover, do the valve stems look discolored or have a build up on the? Finally, is there any evidence of oil where the greater tube enters the air cleaner? I know these are a lot of questions, but I need to picture in my mind to give you any help.

 

[Mr. Shamrock]

The carbon was dry and was real thick on top of the piston...

The breather was the first thing I checked at the end of last season and even though it and the reed valve looked OK I went ahead and replaced it just to be sure. It made no difference. The little sponge/Brilo pad looking thing in there was real dirty, but like already said replacing it did absolutely nothing. I also ran a compression test at the end of last season and the numbers were acceptable as far as the variance between the 2. From what understand on these engines the compression release makes it hard for the manufacturer to give an exact spec and they want to see numbers that are close not necessarily a certain PSI. One was higher than other, but was close enough to fall in the OK category. I have not rechecked since pulling the heads though. There never has been any evidence of oil in the breather tube. It is dry as a bone in there. Thanks again for all your help!

 

[Rivets]

Thanks. Looking at the pictures and read your answer two things look odd. Normally oil conmsumtion in the cylinder would have both valves black. Don't see this. Secondly from your written answers I don't think you are burning an above average amount of oil in the cylinders. Does look like the engine is running a little hot and on the rich side, which would add to consumption. I would agree with reynoldston worth a try with heavier oil, just will be harder to start below 50 degrees.

 

[Mr. Shamrock]

OK thanks. I will try the heavier oil. I never cut my grass when it is cold anyway so the cold start thing isn't an issue. Here in Greenville, it usually goes from too cold for grass to grow to hot as hell in a matter of weeks. This mower has a cover that goes over the engine which I have though about removing a few times - would this make a difference?

 

[Rivets]

Yes, keeping it clean would help. Just thought of something, is this engine running faster than 3200 rpms? It was designed to top end at 3200. Running to fast and your hot weather will definitely add to oil consumption. It may be just working to hard.