Craftsman LT1000 with a Briggs & Stratton 31G777-0167E1 engine

[Legal v8]

This engine has recently started having a problem with blowing oil out of the dipstick tube if removed during operation. It didn’t do this last season. I verified the crankcase breather is open and not clogged, checked the head gasket (it was GOOD before removal), and checked the cylinder bore for any damage. The bore looks perfect, though I haven’t removed the piston to look at the rings. The compression is very good and the engine does not smoke at all. I havent seen oil coming out of the fuel pump, but there is a little oil residue in the intake tube between the carburetor and cylinder head. pushrods are perfect, and the valves appear to be sealing well. I’m considering ordering a few gaskets, a set of piston rings, and just re-ringing it and hoping the problem clears up. Any ideas or help?

 

[Rivets]

From your description I suspect a blown head gasket. If you didn’t replace it when you inspected it, you should have, as they are not reusable. Proper torquing sequence and value are a requirement.

 

[Legal v8]

From your description I suspect a blown head gasket. If you didn’t replace it when you inspected it, you should have, as they are not reusable. Proper torquing sequence and value are a requirement.

The head is still off of it. as I said in the OP; The gasket that I removed had NOT failed. It did come apart when I pulled the head, and as such, will be replaced with a new one.
I have read numerous threads about oil blowing from the dipstick tube. Bad head gasket, plugged crankcase breather, or bad rings. The bad rings comment is usually preceded by mention of the engine blowing smoke when running. My engine doesn’t smoke at all. Given the bore was as nice as it is and there isn’t a lot of carbon built up on the piston or head, and the compression is superb (based on plugging the hole with my finger and having it blow my finger away a good 1/4”), I don’t suspect the rings are stuck or broken. However, I will pull the crankcase apart and pull the piston to inspect It and the rings. just because the rings aren’t stuck and the oil ring is still doing it’s job, the compression rings might not be sealing well enough. The breather is clear and allowing air to flow through it, so I don’t believe that to be the problem.

This has me stumped; I’ve never had a Briggs engine with this problem.

 

[Legal v8]

I don‘t like throwing parts at something in hopes of it working, but I don’t think there is anything else that can be done. I’ll pull it all apart and replace the rings, clean the breather/filter assembly, and reassemble with all new gaskets. A youtuber that does a lot of small engine work says to replace the aluminum intake pushrod with another steel exhaust pushrod because the aluminum ones break; however mine was in pretty good shape. Does anyone have an opinion they’re willing to share on this?

 

[bertsmobile1]

Whenever I need to adjust the valve lash I pull out the pushrods, check them for wear at the guide and reverse them
When an inlet needs repair it gets changed with a steel one .
Oil will throw up the dip stick tube because with the exception of the 3 crankshaft journals the rest of the engine is splash lubricated so there shoud be drops of oil being thrown everywhere some of which will get carried up te dip stick tube
I have seen some of those videos posted by idiot morons with less than no idea what they are blubbering about which is why I rarely advise to go anywhere other than factory & parts stores videos , Taryl , Donny Boy or Steves saloon ( although I have problems with beer drinking & wrenching ).
You can make a lot of money by posting rubbish as the time people spend abusing & critising you is metered so adds to your view time .
The breather should be a ONE WAY devise so it should blow out into the air filter & not suck
The theory is the engine pulls a slight vacuum in the crankcase to prevent leaks .

 

[Legal v8]

Whenever I need to adjust the valve lash I pull out the pushrods, check them for wear at the guide and reverse them
When an inlet needs repair it gets changed with a steel one .
Oil will throw up the dip stick tube because with the exception of the 3 crankshaft journals the rest of the engine is splash lubricated so there shoud be drops of oil being thrown everywhere some of which will get carried up te dip stick tube
I have seen some of those videos posted by idiot morons with less than no idea what they are blubbering about which is why I rarely advise to go anywhere other than factory & parts stores videos , Taryl , Donny Boy or Steves saloon ( although I have problems with beer drinking & wrenching ).
You can make a lot of money by posting rubbish as the time people spend abusing & critising you is metered so adds to your view time .
The breather should be a ONE WAY devise so it should blow out into the air filter & not suck
The theory is the engine pulls a slight vacuum in the crankcase to prevent leaks .

Yes, I know there should be a slight vacuum in the crankcase. The breather works one way as it should - flow direction is to the carburetor. I have to pull the whole engine apart to swap rings, so I’ll clean everything up inside the breather.
I normally wouldn’t be so nutty about an engine of tractor, but this particular engine and tractor has a lot of sentimental value. I wish it were a V-Twin, but it does the job.

 

[StarTech]

When removing the Mica coated head gasket it must be carefully removed or you might not see the damage area. These engine has a tendency to blow between the cylinder and the push rod galley. Usually on the side opposite of the head and some damage might not be noticed to the untrained eye. Also these heads can warp which is why they should check with a straight edge. They need to perfectly flat.

And torquing heads back down you should use at least a three step torque procedure. I just did a Kawasaki that per their service manual took seven steps. A total of 14 steps as there was two cylinder heads.

And of course it going to blow oil out the dipstick tube with the dipstick removed as you have bypass (disable) the breather's check valve system. Allowing to engine to full amount of air and blow full amount out. Basically you allowing the to breathe freely.

One note on smoking the modern oils don't smoke like the older oils. I have seen these engines with blown head gaskets to be consuming up to a half a quart of oil per gallon of gasoline burn and not smoke. I could oil burning but no smoke.

Here I don't simply tear an engine down before doing non invasive tests like leak down test with the rocker cover off. An leak down will point you in the right direction as to the problem with you suspect rings/cylinder or head gasket problem. But this takes some experience to recognize to differences in the test results.

And just throwing parts at problem definitely can get expensive without a good results; unless, you hit upon the problem.

 

[bertsmobile1]

I see it mostly with the Kawasaki twins
Oil spewing out the muffler but almost no smoke untill the air filter is choked with oil & causes the engine to run way too rich

 

[Legal v8]

Thanks for your input, fellas. The engine in question here is a 17.5hp Intek - it doesn’t smoke nor does the oil level drop. When I removed the head and head gasket, I removed it as carefully as I could being careful of the thin bridge between the bore and lifter/pushrod valley, which came off intact. The mica coating was still adhered on both sides of the gasket and there wasn‘t any evidence it burned through. I will try to post a photo of it for some secondary opinions though.

 

[Rivets]

Just my opinion, but when trying to reuse a head gasket on a Briggs engine you are only asking for trouble. Today’s gaskets are not like the ones produced 20 years ago and I never even think about reusing one.