Briggs and Stratton engine

[vmaximus]

My B&S 5hp engine fitted to a rotovator seized yesterday it would not budge with the pull chord so i removed the spark plug and put copious quantities of oil through the spark plug hole and managed to move the piston by turning the crank a small bit at a time with the belt pulley retaining bolt until it became free and would turn quite easily. Now i have to say at this point that the sump had run dry of oil that caused the seizure. After re-filling the crank case with oil i turned the engine over for about 3-4 minutes without spark plug fitted then managed to start the engine and it ran fine although it smoked enough to give an Eco warrior an heart attack while it burned the oil from the cylinder and valves. Now my question is although it has run for about 1.5 hrs it still smokes to some extent even when hot, compression has been checked and 3-5 pulls gives between 70-80 (ish) psi and if i put a bit of oil into the cylinder it get to just below 100psi so compression is good, it looks like the engine was stopped before a complete seizure occurred so why does it still smoke, it smokes more if the engine nearly stalls then picks up although it doesn't seem to affect the engine speed, how long would it need to run before it has burned the unwanted oil from around the valves also the plug gets a heavy carbon or unburnt oil deposit on it. If the compression is good could it be that the oil ring is worn or damaged and letting oil from the sump up into the engine and perhaps it may need new governor springs. I have another piston from another engine that i could fit without too much difficulty but i don't want to go that route if its only a matter of waiting longer for all the oil to burn off,, any thoughts would be greatly appreciated. Pud.

 

[Pete.]

If it seized up when running through lack of oil then I'm afraid the damage is done. It may well run but without a rebuild it's on borrowed time.

 

[angellonewolf]

dont know if this helps but i was given a briggs engine that was run out of oil it ran ok for a few weeks but it then let go and a large hole was in the side of the engine

as above prob on its way out

 

[gaz1]

b and s isnt enough which type of engine is it

 

[Fastdruid]

At a guess it's smeared the pistons over the rings and they're sticking hence why it's burning oil.

 

[Migmac]

I’d strip it and rebuild it.

 

[vmaximus]

@Gaz 1 its a 5hp 135202 engine, @Fastdruid, but why would it have good compression if the rings are sticking, not arguing just inquiring. Pud.

 

[vmaximus]

Migmac. its been in bits that many times it could do it itself

 

[minimutly]

Alloy bore. Now has a nice long gouge down the inside of it. Well done.
I bought a Hayter mower like thi, engine in bits. I rebuilt it, without rebore, it cut my grass for years, accompanied by a cloud of blue smoke.

 

[8ob]

My money would go on a Loncin or similar replacement, sounds like the B&S has lost its newness.

Bob

 

[brightspark]

My money would go on a Loncin or similar replacement, sounds like the B&S has lost its newness.

Bob

yep briggs and scrap em

 

[vmaximus]

Now then chaps, it's not that I have to rely on this rotavator. I have a new Honda (7 weeks old) that makes this m/c look daft it's just that I would like it running as a spare one. I know that the engine is quite old and B&S are not built the same as Honda but it's a bit too good to get rid of but I'm not spending a lot of dosh on it. The one good point is that B&S are easy to work on.

 

[vmaximus]

@ not done it yet. What should a good compression be on this type of engine, information about cylinder pressures are abit sparse, ive read between 60 and 110 psi so 80psi is not so low. When I first rebuilt the engine compression was so high it used rip the pull handle out of your hands and felt like it had almost broke your fingers, that was too high. I think B&S don't publish the compression results. Pud.

 

[gt6s]

yep briggs and scrap em

Also known as PIECE OF SH1T

 

[Fastdruid]

@Fastdruid, but why would it have good compression if the rings are sticking, not arguing just inquiring. Pud.

If compression increases after putting a little bit of oil down the bore then the issue is rings. I wouldn't normally think 80psi is good tbh but then again I don't know what it should be, in comparison my my bikes *lower* limit of serviceability is about ~156psi (and should be 213psi)!

 

[m_c]

You'll probably find the piston itself has picked up on the bore, which is what would have caused it seize. In the process of that happening, some of the melted piston has likely ended up jamming the rings.

You really need to take the cylinder head of and have a look. If the bore looks ok with no major grooves, then you'll likely get away with just a new piston and rings. If the bore's damaged, it's just not cost effective to repair., as by the time you factor in a rebore, piston, and gaskets, you can get a new engine.

 

[pedrobedro]

as by the time you factor in a rebore, piston, and gaskets, you can get a new engine.

Plenty of Chinese ones on eBay at under £100 or Loncins a bit dearer.

 

[vmaximus]

No intention af replacing the engine, it's either a cheap repair or nothing.

 

[angellonewolf]

No intention af replacing the engine, it's either a cheap repair or nothing.

most prob buy the time you buy piston rings and all the gaskets you coukd buy another 2nd hand rotovator

same problem i have with mower its not worth spending on parts when you can buy a mower with a broken deak and nick the engine on it for 20/30 and if lucky even a free one now and again

 

[vmaximus]

Thanks for the replies, as I've said before I have a new Honda rotavator so a costly repair or new motor

is out of the question. I can get piston rings quite cheaply and that is about as much as I'm going to spend but the question remains what should the compression be after rings and piston rebuild. I am not going to buy a new motor or throw good money at a second hand one, been there and done that and landed up forever spending on them so a cheap repair for a spare is all I want to do. Thanks once again for all replies. Pud.