Briggs and Stratton Engine Rebuild Question

[El_Schaf]

As you may know from my other post, My husky lawn tractor quit functioning. After consideration of the cost of a new tractor, and the cost of parts to rebuild a motor on my own, I decided to pull the engine (intek I/C 17.5 horse, one cylinder, vertical shaft) and see if what was wrong was fix-able.

The symptom after the engine quit working is that it wouldnt start (duh), when I tried to start it back up, the starter would just spin the crank, relatively fast, like there wasnt resistance.

Well, I pulled the motor, thinking that something in the bottom end was not connected, and I might need a new rod or crank or something similar. During my teardown, I pulled the head off and noticed that the Intake valve was stuck open. There was so much crud on the valve stem, that it did not want to seat. I could see light all the way around the valve and knew this wasnt good.

I cleaned the valvestem and reinstalled, it now seats and functions smoothly.

While I had the head off, I played with the crank and noticed that the piston moved up and down with ease, and that the bore looked fine- I did not have time to pull the flywheel and get a look at the bottom end last night.

When I reinstalled the head, I made sure that the valves were functioning properly by turning the crank and viewing the action. - All ok

I noticed however, at this point, that I could still turn the crank by hand with the flywheel and PTO even through the compression stroke (was slightly more difficult than before).

Should I be able to turn this by hand? I'm wondering if this means I don't have compression?

Also, is there an adjustment to the valves that i need to do?

 

[Colt45ws]

Is this an OHV or flat head?
It should have some resistance. Do you have a compression gauge to find out what it has?

 

[El_Schaf]

OHV. I have no gauge, may purchase if not too expensive. There is some resistance, im just not sure if it should be ALOT or ...SOME resistance :-(

 

[dwendt44]

The exhaust valve may be crudded up too.
Lapping the valves (a lost art) might improve the compression.

 

[IndyIan]

One hand or two to turn the motor? What's the flywheel diameter? My 300 kingquad atv has a backup pull start but the pully might be 5-6" diameter? Anyways if you forget the compression release its not easy at all to pull over and almost impossible to start that way.
That said it starts with the compression release on, so good compression isn't a requirement for starting.
If you can get your motor going you should run a bunch of cleaning stuff in the gas and good synthetic HDEO to help things from gumming up again.

 

[DieselTech]

I agree, I would pull the head apart and lap the valves. Tool and compound is very inexpensive. This will ensure a good valve seat

 

[El_Schaf]

Hmm, Hand lapping doesn't sound too bad. Excuse to go to the auto parts store, anyone!? Oh, and the flywheel might be 10 inches in diameter, IIRC?

 

[El_Schaf]

Ok All, new problem. I have the beast back together, running and driving. Lapped the valves and the engine starts /runs what seems like fine.

The problem now is SMOKE. LOTS of SMOKE.

Other Sympotom - Tube from Crankcase to the intake (pre Carbeurator) is also spewing this smoke, and generally blows off the intake tube shortly after startup. This tube seems to be letting out some oil spray as well.

While I had the head off, I poured seafaom on to the piston to let it soak and it held the liquid above it in the cylinder, making me think that the oil rings should be good, but the tube from the crank case seems to tell me im getting nasty blow/by or something.

If my rings are ok, could this mean that valve stem seals are leaking?

Any help would be appreciated.

 

[El_Schaf]

More info - I forgot. Head gasket - Was not ok in one spot. I filled this portion (~1cm) with RTV and sealed her up. Maybe this RTV didnt hold?

I'm also confident it isn't overfilled with oil

 

[boraticus]

How much Seafoam did you dump into the cylinder? From what you're describing, you have too much oil in the crankcase despite your claim that you don't. Sounds like the Seafoam may have leaked past the rings and into the crankcase thus increasing the oil volume. I suggest you drain some of the oil and see what happens. A freshly rebuilt engine will smoke a bit at first but should stop withing half an hour or less.

a bad head gasket will cause other problems but not necessarily smoke. RTV is not a substitute for a head gasket. Suggest you change it a.s.a.p.

 

[TedT]

I read that some Intek engines have head gasket issues that cause the symptoms you discribe. Try a new gasket. BTW, silicon sealer is not appropriate for a head gasket.
Ted

 

[cronk]

+1, try an new head gasket.
You should always use a new head gasket if you remove the head.
On an OHV Briggs there is an oil passage to allow oil to flow to the head and lube the valves. If your gasket is bad, you could be sucking oil into the cylinder, which would also leak compression into the crank case.

 

[thomassanders]

This is a very interesting thing to read. Having a good (removed non site sponsor link) would be able to really make things right for your vehicle. Added up with these infos, i know that things will be okay when you do some stuffs.

 

[Jim 5]

Smoke blowing off and coming out of your PCV line indicates to me some major blowby.

I don't suppose you took the rings off the piston, squared them inside the bore and measured the end-gap?

That much blowby could have caused all of the deposits on the intake valve. After all, you'd be pressurizing the crank-case, which is filled with engine oil splash/vapor. This mix of exhaust gas and crankcase-oil vapor gets sent under pressure into the intake and collects on the intake valve (just like the Direct Injection engine problems in moder cars). This caused it to stick open, resulting in your engine losing all compression resulting in a no-run condition.

Seems like if that is the case, your problem started out with bad piston rings, which will start the cycle all over again.

...just a theory.

 

[100td]

Have a read of this thread
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=963775#Post963775
There is no way you will get out of it with some RTV, it is a known problem with these engines.

 

[greenaccord02]

Get a replacement head gasket and also ensure that the gasket surrounding the valve cover is intact. Sealer will work for the valve cover, but you need to get a new head gasket if it has a break in it. Drain and re-fill the crankcase with oil, and nothing else. I don't think you've overfilled it necessarily, but the seafoam in your oil may be boiling/burning off and causing the smoking you see. It would also explain the crankcase ventilation tube blowing out smoke. I doubt you have bad rings, but until you run it awhile after the disassembly they won't seal right again. Once you've got it where it runs somewhat smooth and the crankcase ventilator isn't blowing off anymore, let it run (and smoke) for 15 minutes straight, then kill it for an hour or so. When it fires up again, I don't think you'll see much smoke.