Hello, I found the crankcase seal on my LT2180, 18 HP Vanguard engine is leaking pretty badly. Pretty sure I can fix that but I'd like to find the underlying problem first. So far I've only checked compression, 135 lbs each side cold, but I did not have both plugs out at that time, so I'll probably re-check. I did another test running the engine with the dipstick out, I can feel a lot of pressure coming out of the dipstick tube. Should I just assume the head gaskets are bad and replace them? I can't think of any other thing, I had the breather assembly off and it seems to be pretty functional and clean. I need help, my grass is getting out of control.
crankcase seal
- Thread starter Todp
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That 135 cold is not so bad IMO, suggesting 150 hot. Normal crankcase pressure will splatter your face if you get close to the dipstick tube. We once discussed replacing a seal in place, but I don't remember what the pros said. Possible with care using a small slide hammer with a little (modified?) finger to hook the seal. But danger of damage to alloy seal seat.
Just to update: I checked the compression again warm (not hot) with both plugs out. I got 150 on one side and 125 on the other after seconds of cranking, still not bad. I went ahead and pulled the pto clutch and found that the seal was not just leaking, it was completely out of the crankcase cover. Just laying on the crank behind the clutch. This had not been serviced since I've owned it, so I find that kind of odd.I bought a new seal so I'm going to go ahead and replace that, but I'm still at odds as to what may be causing such severe excess crankcase pressure. Any help you can provide is appreciated. Thanks.
cpurvis
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By what frame of reference are you judging your crankcase pressure to be excessive?
Single cylinder engines have very large changes in crankcase volume which creates pressure. I'd replace the seal and see what it does.
Single cylinder engines have very large changes in crankcase volume which creates pressure. I'd replace the seal and see what it does.
"By what frame of reference are you judging your crankcase pressure to be excessive?"
Well, before I noticed the loose seal it was blowing oil into the carb, not to bad but noticeable, especially with the air cleaner off. I inspected the crankcase breather, was nice and clean and seemed functional. I read on another forum about a simple test to judge crankcase pressure: Take off the oil filler cap and leave it loose on top of the filler hole. Normal pressure will allow it to sit there (until it vibrates off). Excessive pressure will knock it right off. I tried that and it definitely knocked it off. I really just want to cover all bases while I have it apart so I don't have to go through several assembly / dis-assembly processes. Not that I mind taking stuff apart, but it gets a little irritating after a while. Also, the concept of fixing problems by attrition can get pretty expensive. By the way, this is a v-twin engine.
Well, before I noticed the loose seal it was blowing oil into the carb, not to bad but noticeable, especially with the air cleaner off. I inspected the crankcase breather, was nice and clean and seemed functional. I read on another forum about a simple test to judge crankcase pressure: Take off the oil filler cap and leave it loose on top of the filler hole. Normal pressure will allow it to sit there (until it vibrates off). Excessive pressure will knock it right off. I tried that and it definitely knocked it off. I really just want to cover all bases while I have it apart so I don't have to go through several assembly / dis-assembly processes. Not that I mind taking stuff apart, but it gets a little irritating after a while. Also, the concept of fixing problems by attrition can get pretty expensive. By the way, this is a v-twin engine.
If this unit came into the shop with the problems you describe, I would be checking for a head gasket that is blown or starting to blow. Being a twin I would first try to figure out the problem cylinder. A leak down tester is my friend here. If you don't have one try these tests. 1. Look at both plugs, is one running darker than the other? 2. Start the engine and with an insulated pair of pliers, pull off one plug wire at a time and notice engine RPM's change. A darker plug and/or a difference in RPM's (drop) would give you a starting point. This is not exact, but if you were going to try to just change one, I would start with the dark plug or RPM's drop. If it were me I would suggest to the owner to replace both, as I would have more than half the parts removed when doing only one. Would also give both of us peace of mind.
bertsmobile1
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The problem with the web is for every good piece of information there is 25,000 pieces of garbage.
That is why there are forums like this there to filter to poo out of the pile.
The volume of gas moved under the piston is the same as the volume above the piston.
Gas will take the easiest path out of the engine so will happily sent a dip stick into orbit.
From memory the valve in the breather is set to around 7 psi, but no one ever pressure tests it , you just blow then suck ( yummy ) to see if it is working.
Only 3 ways for the cases to pressurise.
Hole in the piston / head / loose valve guide
Broken / worn rings or bore > carbon build up on plug
Blown head gasket > smoke comes out of the dip stick tube engine off, lots of oil in the carb.
90% of the time it will be a gasket
9.99 % of the time it will be rings/ bore
0.01 % something else.
I hadn't thought about looking on line for a shop manual, I did find the owners manual online though. The engine numbers are 350447 / 1111-E1. The mower itself is model # 13A-254G710, Serial # 1L053G1005S. I did find the shop manual on the briggs site, but it was $23.00, not a free pdf.Thanks for all your help.