Briggs Intek 20HP Using Oil

[reynoldston]

Sorry I misunderstood. For some reason I thought you guys were thinking that there was a seal where the seat is. What is the model and type of this engine? I can find out if it has valve seals

Mr.Shamrock has a B&S Intek that is using oil but not leaking or smoking, but want to know where the oil is going. I guess we are getting away from the original question. He was going do do some test but never got back to us yet.

 

[Mr. Shamrock]

I spent a little time on the mower today and put new oil, filter, and plugs in it. I checked the compression again and it is left:115 and right:125. I pulled the valve covers and there was a little oil in there but I don't think any more than normal. One thing out of the ordinary is the oil that I drained and what was left in the head, which is not very old at all, was real black. If I wasn't the one changing the oil I would swear it hadn't been changed in a very long time. I actually took a grinder and opened the old oil filter up and besides being really dark there wasn't anything that caught my attention. There has to be a serious carbon build up in the motor somewhere. I probably have one more cut this season and then I think I am going to pull the heads to see what the deal is. There is no reason why oil that might have 12 hours of run time should be so dark. Every other mower I have had the oil looked almost new when I changed it each time. This really has me stumped!!!!!
Oh I also let it run for a little while with the air filter removed to see if there was any sign whatsoever of oil burning there - none and the filter and filter housing are both bone dry.

One thing I thought of today after racking my brain for anything abnormal since I bought this mower new is - When I bought it I had the ninja mulching kit put on it which consists of mulching blades and a block off plate for the side chute. When I was ready to put new blades on I bought a set of gator blades for it. The gator blades when combined with the block off plate made for a VERY dusty ride. I used it for about 4 or 5 cuts like that before I had enough and contacted the manufacturer of gator blades. They told me I should not use them with the block off plate so I immediately put the side chute back on. I have since went back to the snapper blades and the block off plate, but I wonder if the extreme amount of dust being sucked in could do something. I blew out the fliter and prefilter after each cut and they were nasty, but I am sure some probably got by. Again this was only a few cuts, but that is the only thing I can think of that stands out as out of the ordinary since I bought the mower.

 

[Mr. Shamrock]

I know I said I was going to do a leak down test and I still am. I had people coming over today for the football games so I didn't have a lot of time. I will post back with my results.

 

[reynoldston]

Keep us updated on this leak down test and don't forget the vacuum test.

 

[Mr. Shamrock]

I did a leak down check and what I think is a vacuum check. I have never performed a vacuum check on a cylinder in all my 17 years or wrenching. Anyway, on both cylinders air was heard to be escaping from the exhaust and through the oil fill tube. I loosened both rockers completely to make sure both valve were completely closed. I don't have a gauge to see what percentage of loss I was getting, but with just the ear test they both sounded the same. Now the vacuum test I just hooked my Mightyvac handheld tester to the same adapter I used to put the compressed air in the cylinder. I could not get either cylinder to hold a vacuum and the only difference was if I pumped the tester on the cylinder with the higher compression I could get 5 inches Hg and then as soon as I quit pumping it dropped to zero. On the lower compression cylinder the needle would just barely move when I was pumping it. Not even enough to get it to 1 inch Hg. Any idea's?

 

[jmurray01]

At least you are one step closer to getting an answer!

 

[reynoldston]

So you are getting blow by pass the rings which to me you will get some of. So I just don't see what it is telling you? You have to measure this some how to know what it is telling you. Getting blow-by pass the exhaust valves I would say isn't right. I would check them for carbon buildup or it may be time for grinding the valves and valve seats which at that time check the valve guides. You did say you loosen the valve adjusters so you don't have a tight valve. Now I guess I still don't understand what you are doing with the vacuum test. I just never heard of the test you are doing? I thought the vacuum test had something to do with measuring the vacuum in the crankcase with the engine running??? My thought on the vacuum crankcase test you would want negative pressure at the fill tube and if positive you would have bad piston rings? Maybe you could explain to me what your vacuum test is going tell you as far as oil consumption gos? I am always willing to learn.

 

[Mad Mackie]

With leak down testing generally the following:
A leaking exhaust valve will leak air into the exhaust system.
A leaking intake valve will leak air into the intake manifold/carb/throttle body, etc.
Piston rings will always leak air by, how much is too much is the question, but this leak goes into the crankcase and noticed at the dip stick tube and or crankcase vent.

 

[Mr. Shamrock]

Your right I did the test wrong - brain fart. Like I said I have never had to do a crankcase vacuum test, but apparantly it should be performed with the engine running. I am done testing it - I guess I need to pull the heads after I do my last cut and see what it looks like. I wish I had a boroscope so I could just take a peek inside the spark plug hole. I still can't comprehend how a little carbon build-up on the exhaust valve would cause this scenario?!?!?!?!

What do you guy think of this - connect my compression tester hose (without the gauge) to each cylinder. Use a product like Seafoam and spray it down the hose until it comes out - keeping the hose pointed up and making sure it is higher than the spark plug hole. So this should fill the inside of the cumbustion chamber with the Seafoam. Let it sit for a few hours or even over night and then do the other cylinder. Then just remove the hose and turn the motor over to push out all the liquid. This should loosen up the carbon. This is basically what I did to the intake side only simply filling up the intake port which enabled the valve to be completely covered in the cleaning liquid and there is no leakage at all there.

 

[Mad Mackie]

I wouldn't leave any liquid of any kind in an engine overnight and particularly any volume of it.
You need to get and read the parts manual and service manual for your engine so you know how compression release systems work and how they affect compression testing and leakdown testing results. Unless your engine has more than 500 hours of operation on it I doubt that it has much carbon buildup anywhere in it.
If this B&S Intek twin that has the air filter cover with 4 screws holding it down and is more than 3-4 years old then there may be a problem with the air filtering system. Some V twin models suffered from dust particulate injestion as the air filtering systems had air leaks down stream from the air filter. This dust injestion causes premature piston ring and cylinder wall ware which increases crankcase pressures beyond what the engine is designed to deal with and in time engine failure.