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crankcase seal

#1

T

Todp

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.


#2

M

motoman

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.


#3

T

Todp

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.


#4

cpurvis

cpurvis

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.


#5

T

Todp

"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.


#6

R

Rivets

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.


#7

B

bertsmobile1

Todp said:
"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.
Click to expand...

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.


#8

T

Todp

bertsmobile1 said:
The problem with the web is for every good piece of information there is 25,000 pieces of garbage.
That's how I ended up here, better information. Some of the other forums I've been to provide NO follow up to questions posted. Very frustrating. So, a few more questions ( I suppose I should buy a manual) what are the torque values for:1) the pto clutch and 2) the heads? I'm going to replace both head gaskets, seems to be the way to go. Like Rivets said, it's halfway apart now. Don't want to do all this twice. Thanks for everyone's comments.
Click to expand...


#9

R

Rivets

Don't have tot purchase a manual. They are available online in PDF form, if you do a little searching. Post model, type and code numbers for your engine and we will help you find one if need be.


#10

T

Todp

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.


#11

R

Rivets

Try this website. http://www.mytractorforum.com/280-s...ies/242387-briggs-statton-repair-manuals.html

Or this site. http://www.nflramsofficial.com/service_manual_vanguard_v_272144_download.pdf

You're looking for a Vanguard twin manual #272144.

If your can't get them to open, do a google search "vanguard v-twin service manual 272144 pdf"


#12

B

bertsmobile1

The other problem with the web is everyone seems to think that everything they want should be available on line for free.

I am yet to see any Vanguard manuals on line for free.
Most of the older B & S manuals are there as there is no longer any commercial potential in trying to sell them.
On Evilbay you will see a lot of 12 y/o selling downloads of Briggs manuals, usually on CD and usually ripped off a free download site.
In particular this one http://www.mymowerparts.com/about_us.php
Occasionally a cranky tech will download stuff off the Briggs Power Portal ( dealer only) web site and flog them on a CD .
OTOH $ 23 is not exactly expensive.
I paid over $ 200 each for several of the manuals I have here and since buying the business have spent better than $ 5000 on manuals, many of which will most likely only ever be used once.
OTOH when I retire, the library that goes with the business will be extensive and all on paper.

We will happily walk people through individual problems, that is why we are here to learn and then share what we have learned with others.
$ 23 is about 1/2 hour labour charge so the book will pay for itself the first time you use it.

The other thing I have noticed is when selling a used mower, people bid hardest on any mower than comes with a service manual and even more if it has an IPL as well.


#13

T

Todp

Thanks for all the help, one final question: do I need any sealant? I've read that if it's not recommended don't use it, and I only want to do this once. What type for the seal and/or head gaskets?


#14

I

ILENGINE

No sealant. Head gasket surfaces need to be clean and dry. I put some oil on the seal part that goes around the crank just to prevent dry start. Some people put a little RTV around the outer edge of the gasket, but not normally needed unless the surfaces are scratched and leak around the seal.


#15

T

Todp

cylinder.jpg

As you might see, there is a lot of crud where the head gasket was leaking. I'm thinking the head and cylinder might be toast, there was a good amount of etching on both surfaces where it leaked. I put it back together with the new gasket so we'll see how it goes. Unfortunately I broke a rocker arm bolt when re-assembling ( for got to re-adjust my torque wrench after torquing the head:ashamed:) so I'm still a day away from starting it at least.:frown:


#16

B

bertsmobile1

lap the head on a sheet of glass with some wet & dry on top of it. 600 or finer.
Do it with a tap running water over it and move the head in a figure of 8 motion.
For the barrel use a large flat wet stone to flatten the face lubed with WD 40 or similar.

All that crud in the barrel has fallen in when you took the head off

Make sure you clean it all out before you put the head back on.


#17

T

Todp

All that crud in the barrel has fallen in when you took the head off
Click to expand...
Not exactly, if you look close enough you can see that the crud isn't IN the barrel, it fringes the barrel from about 6 o'clock to about 8 o'clock. And a lot of crud fell into the barrel, but I blew that out.


#18

B

bertsmobile1

If you are talking about a ring of hard black carbon build up then you leave that there unless you have a ridge reamer to clean it out properly.


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