# Briggs & Stratton 20hp Vangurd v twin head



## SikaStag (Aug 7, 2009)

Hi
I have just purchased an Argo type 8 wheel vehicle that was manufactured in Scotland. 

When I unloaded the vehicle from my trailer and gave it a spin around the field it seemed to be lacking power, when I climbed a small slope with it, it started to belch out white smoke. 

The exhaust pipes are wrapped with a heat proof bandage, there was a lot of smoke coming from one of the bandages, I stripped it off and found that oil was leaking from the exhaust, I was also getting oil coming back through the carb, I checked the oil dip stick to see if it was too high which it was, roughly quarter an inch over full, I drained the engine and re filled to the correct setting, I started the engine after forgetting to replace the dipstick, to my surprise the oil was spluttering out where the dipstick goes, also coming from the flexi joint on the exhausts.

I now know there is excessive back pressure which has probably been caused by the engine being over filled with oil. my problem now is how do I know what is causing the problem, is it a seal that has blown or is it excessive wear on the rings.
I did check the compression in both cylinders which seemed to be ok, I have since read that the compression should be tested when turning the engine in reverse, is this the case?.
I would be very grateful for any help in finding out what's causing my problem.

Cheers


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## Madcat737 (Aug 2, 2009)

The oil pressure in the dip stick spout is normal. When the cap is on ,the crank case pressure is released thru the pvc and ported into the intake to be reburned. That valve could be stuck. Was the unit by any chance sitting on the trailer enigne nose down? If so what happens is oil runs into the exhaust valve stems and drains into the cylinders. The exhaust valve stems do not have seals on the due to heat. Have you tried runnning it for a while and see if it burns off?


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## SABL (Jul 4, 2008)

PVC (Positive Crankcase Ventilation) may very well be the cause. What is troubling is how excessive pressure is making it's way past the intake valve/s. 

You did not mention the manufacturer of the engine or the size, and number of cylinders. The age and hours would also be helpful. 

1/4" doesn't say much on the overfill of the oil......could be relevant on a small engine but I am inclined to believe the engine is of decent size if you are trying to turn 8 wheels. 

Give as much info as you can.....and keep your kilt away from the chain!!


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## SABL (Jul 4, 2008)

OOPS!!

I didn't catch the B&S Vangard....my bad.


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## SikaStag (Aug 7, 2009)

The trailer was a flat bed, nor tilting of engine part from going up a slope, in which case it would belch out white smoke, the oil in the engine was showing on the dip stick as having been newly replaced.
The machine is a Hillcat775, made by Scottrack here in Scotland, it starts first turn of the key with the choke pulled out, purrs away nicely.

What is the PVC?.
What about the oil coming up through the carb?.

No I haven't had it running for a while, Maximum time about 10 minutes, the throttle just seems to be not responding as it should, or should I say the engine is not responding to the throttle as it should.

The clock shows 1100 hours use, can not vouch for accuracy, purchased machine last Friday.

Cheers


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## Madcat737 (Aug 2, 2009)

1100 hours is quit a bit. You could have an oil ring not sealing and still show good compression. I just rebuilt mine and it was showing 160 psi per cylinder and smoking like a train. You can tell the wear of a ring by the end gap of the ring. (.005 is new.)You could also have a blown head gasket. head gasket is a relativly easy task to replace.Pull the plugs and have a look at them. They will tell you alot


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## k2skier (Sep 30, 2008)

If you have a shop close by that could do a leak-down test (this pressurizes the cylinders) it will tell you if you have a crankcase leak, bad rings, valves...

Is the air filter getting oily too? If it is it's either bad rings, crankcase breather (PCV valve) or a leak in the crankcase, (you have already ruled out too much oil).


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## SikaStag (Aug 7, 2009)

The plugs are sooted up, not just a covering of black soot, the soot is hanging from the plug (What should the plugs look like for a blown head gasket).

As I said earlier the Hillcat starts first turn of the key with choke, with not a sign of smoke coming from the exhaust, seems to be once it is running for a period of time that the white smoke starts to belch out of the exhaust and the bonnet air vents, its like the oil is starting to work its way up through the pistons and as it passes through the exhaust it starts to smoke bad.

Where do I locate the PVC valve to check it out.

Air filter is not oily, I noticed the oil coming through the carb when I had the air filter assembly removed.

What should the plugs look like for a blown head gasket.

Thanks guys for all the good info, I reckon it could be the the pvc valve, on the other hand the compression seemed good on both cylinders, I would say the same pressure was felt from each cylinder, a compression test would be helpful to rule out that as a problem, I would have though if the rings had excessive wear the engine would be running smokey all the time.


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## Madcat737 (Aug 2, 2009)

"I would have though if the rings had excessive wear the engine would be running smokey all the time."
Not necessarlily,I have seen engines only smoke under a load and run clear otherwise.Once the engine heat up and everything expands things change. 
Your sooted up plugs,are they wet with oil? 
Here is what will get you oil in the cylinders providing its service to correct level.
Oil rings worn,head gasket and valve seals or plugged pvc valve. That's pretty much it. 
To find the ,valve look for a tube that runs to the intake throat and connects to the engine crank case. The pvc valve is no more that a reed type valve with a screen in it.
If you can feel air pulsing out of it while the engine is running its probably fine.


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## SikaStag (Aug 7, 2009)

I think I have solved the problem.
I was rebuilding the breather assembly when I noticed that the paddle in the carb that closes when the choke is engaged was in fact only open about 1/4", I pushed the lever that the choke cable is connected to and low and behold the lever moved back almost a 1/2", I checked back in the carb and the paddle was horizontal, fully open. I left the machine running for about 20 minutes to burn off any excess oil from being overfilled, took it for a test drive, worked great was going up steep inclines without a problem.

The soot on the plugs was bone dry, obviously the mixture was very rich with fuel and not getting enough air.
The oil being overfilled was a red herring, was nothing to do with the performance of the machine, once it was burnt off there was no other problems from that department.
I would like to thank you guys for taking the time to help me reach a solution to the problem.

Many thanks

Cheers


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