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Hello everyone here, I'm new here

I own 2 Tecumseh BVS153 engines (Gutbrod lawnmowers), one which is totally normal, one with ignition key and "pulling help". They are probally very very very old, and, still they're running great. The are no problems, unless the problem with blue smoke. Both of them has the same problem, but the "normal" one has more smoke, and after 1 or 2 mowings, the spark plug gets oiled too much and can't run properly, the other one smokes less, and the spark plug doesn't get dirty at all. Both of them loose oil after mowing, so it is frustrating when you know you can always run out of oil, and destroy the engine, so you have always to check oil capacity (usually gets almost empty after 2 hours of mowing). So, if the lawnmoswers get into bigger grass, they smoke a lot more, and if you push the gas to the choke, it also smokes very heavy. There are no perfomance problems, just loosing oil is annoying. I also have a normal sized B&S engine, which works completely normal (no such problems). The two Tecumsehs have a small pipe next to the muffler which usually puffs somekind of white smoke, anytime, and also it is very oil. Is all of this normal? Or because they're simply old (older system) or just their age destroys them..? Is there a fix for it?

- Oil is filled up normal, not over max, not under minimum.
- It is stored normally, not staying with spark plug showing to the floor
- Air filter (sponge) is totally clean, no oil traces
- Carburetor is 100% is clean from oil
- While cleaning, it is leaned on the side as it shows on the sign
- They're 100% clean, and also maintained after every mowing

Thanks everyone in advance, and I hope I found my right LawnMower forum

http://www.briggsandstratton.com/eu/en/support/faqs/engine-problem-solving-tips

click on troubleshooting-repair & type in smoking

this applies to all engines, not just B&S.

mechanic mark said:

http://www.briggsandstratton.com/eu/en/support/faqs/engine-problem-solving-tips

click on troubleshooting-repair & type in smoking

this applies to all engines, not just B&S.

Click to expand...

Thanks, I'll try these tips!

Blue smoke indicates it is burning oil. The piston rings could be worn out or the valve guides bad or both. since the engines are old, this is normal.
you should be adding 30 weight oil to the engine. if you are using a 10w??? then it is too thin of oil.
from an environmental point of view, do not use anymore until either fixed or replaced.
another point of view, keep the oil full and put in a spark plug that has a slightly higher heat range. this will keep the plug from fouling as quickly.

Mike_Goad said:

Blue smoke indicates it is burning oil. The piston rings could be worn out or the valve guides bad or both. since the engines are old, this is normal.
you should be adding 30 weight oil to the engine. if you are using a 10w??? then it is too thin of oil.
from an environmental point of view, do not use anymore until either fixed or replaced.
another point of view, keep the oil full and put in a spark plug that has a slightly higher heat range. this will keep the plug from fouling as quickly.

Click to expand...

This is the answer I wanted
Few questions:
1. Is it hard to change the piston ring, and do you need to replace a original one, or custom with the needed size?
2. I'm using 15w oil, should I switch to 30w?

I wish I couldn't use them, but they're my main mowers. The oil stays on it's max limit, so a spark plug I use is a Bosch's, it looks good, and it always gets dirty of oil, and on the other mower with the same issue all I can see is some hard burned parts, but no oil at all. Thanks for your info! I'll try to replace the piston rings in both mowers, while it's winter, now I'm mowing a lot of yards...

Not brain Surgery , but not for the faint of heart either . Compression reading would go a long way towards confirming rings vs valves . If the cylinder has excessive taper and wear than a rebore will be most likely required since a parallel honing will not suffice . Depending on how much wear is found , you may be able to go 10 thousands over bore ring set . You would need a socket set and torque wrench and ring compressors . Do you currently have a Service Manual ? Also as Mike indicated , a straight 30 or 40 weight oil may help short term within less oil consumption , multi weight oil in old Tec,s is foolish. The Bosch plug use is the Best for Tecumsehs .

Tyy said:

Not brain Surgery , but not for the faint of heart either . Compression reading would go a long way towards confirming rings vs valves . If the cylinder has excessive taper and wear than a rebore will be most likely required since a parallel honing will not suffice . Depending on how much wear is found , you may be able to go 10 thousands over bore ring set . You would need a socket set and torque wrench and ring compressors . Do you currently have a Service Manual ? Also as Mike indicated , a straight 30 or 40 weight oil may help short term within less oil consumption , multi weight oil in old Tec,s is foolish. The Bosch plug use is the Best for Tecumsehs .

Click to expand...

Most likely I will change the piston rings, and see will it fix it, if not, I'll look for further info. I should really replace them, the engines are probally older than 13 years, and probally never been changed yet. I have already a socket set and a torque wrench, but not quite sure for the ring compressors. A service manual? I'm probally the fifth or later owner of these lawnmowers :/ so there's no manual. I'm currently using 15w oil, I should change to 30-40w oil. Thank you for your info