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Briggs 35 hp vanguard

Posted by implanecrazy (My Page) on
Fri, Nov 13, 09 at 10:02

HI, I am new on here.

I have a new B&S 35hp vanguard engine that I bought new back in March to fit to a hovercraft I was building.

I have had 2 problems with this engine, the first one was a valve pushrod adjuster came undone on the left cylinder inlet valve after less than an hours running. Luckily nothing got damaged on that side.

The above happened while I was trying to sort out the other problem with the engine.

The engine only runs on the right hand cylinder now & again.

I have replaced both coils & also rewired the coils to a double pole kill switch, so I could eliminate the coil diodes, as I know of several people that has had trouble with them. Initially the diodes were left in the circuit until I replaced the coils.

Problem still persisted.

Next I have checked valve clearances.

I have replaced spark plugs

I have stripped the carb down 3 times & blown out all the jets with compressed air.

This engine has only had approx 3 hours running & all of that has been spent trying to get it running properly. I am beginning to think these B&S vangaurd engines are a pile of *rap & I should of bought a Kholer or Kawasaki.

I am reluctant to send the engine back under warranty as I would have to remove it from the hovercraft, then transport the engine 300 miles one way (600 round trip). Then have to go & collect the engine another 600 miles + all the time & wear & tear on my car, then have to spend several hours replacing the engine & setting up all the pulleys etc again.

I have put a video on YouTube of the bag of nails running. The problem is always on the right hand cylinder, I even swapped the jets in the carb from right to left & problem stayed on the right. I have done a compression test & both cylinders were 125 lbs sq inch at cranking speed. ( I earthed the plugs to the engine lifting eyes so not to mess up the coils)

The fuel is clean & fresh, I put the fuel tank above the pump to eliminate it being a pump problem.

When the engine does get to 3000 RPM it sounds fine, but it rarely gets past 2400 as it is only firing on the left side.

I am beginning to think that I either have a valve problem or even valve timing is out slightly on the right side.

I am reluctant to remove the head to find out, but to take this engine back to Briggs is going to cost me several hundred pounds so probably cheaper to do it my self.

I have spent nearly 30 years working on cars in the motor trade, so fully capable of carrying ou the above.

here is a link to the engine running. The video has not been cut.
http://www.youtube.com/user/implanecrazy#p/a/u/0/OXWPK3Cwlg0

Any suggestions as to what could be the problem with this engine much appreciated.

Many thanks


Follow-Up Postings:

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RE: Briggs 35 hp vanguard

Engine numbers for the above are:
Model: 613477,
Type: 0133-E1,
Code: 08072312


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RE: Briggs 35 hp vanguard

***"valve pushrod adjuster came undone"***
What do you mean "undone"? Did you find the adjuster screw and jam nut loose? and was the pushrod separated from the rocker arm? OR.........was the adjuster screw and jam nut tight, but you found the pushrod separated from the rocker arm?
OR (finally) did you find the adjuster screw and jam nut loose, but the rocker arm still in place? Here's why I ask so many questions.
If you found the adjuster screw and jam nut loose (whether the pushrod was separated from rocker arm or not), there is the possibility that some time in the initial running of the engine, the pushrod got caught on the edge of its socket in the rocker arm. If that occurred, the valve would not be able to seat, and the open valve could have been struck by the piston. If that happened the valve may have bent slightly enough that it now tries to "stick" in the valve guide at times, causing that cylinder to just barely run at all.
If you found the pushrod separated from the rocker arm but the adjuster screw and jam nut were still secure, that would indicate that the valve was already sticking or had been stuck, and the pushrod got loose during the "slack time" before the piston came up and smacked the valve down. I hear a "chirping" that has a metallic ring to it when the RPM drops into the 1,000 to 2,000 range. Can you confirm whether this sound is coming from the engine or not? And last, the digital tach! Where does the tachometer pick up its signal? If it uses an induction coil type of signal generator that merely wraps around a spark plug cable, it would not be suspect. If, however, the signal to the tach is obtained by "piggybacking" onto one of the coil kill wires........the tach itself might be capable of killing the spark intermittently. Have you ACTUALLY confirmed that the cylinder has spark (or no spark) during the times that cylinder goes AWOL? Nice vid and HC by the way.


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RE: Briggs 35 hp vanguard

IMO that engine costs too much to not take it back for warranty problem. Your tinkering with it may have voided the warranty? Now where will you be? out of air!?!


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RE: Briggs 35 hp vanguard

The adjuster & lock nut came undone & actually fell off of the rocker arm. This was on the left hand cylinder, which runs fine. I am having problems with the right hand cylinder.

The tiny tach wraps around the lefthand plug wire.

A rep from briggs phoned me today & put me in touch with a hovercraft manufacturer that uses this engine. He has suggested turning the carb around on the inlet manifold & see if the problem moves to the left cylinder. I shall try that tomorrow, at least it will rule the carb out or prove it is the carb.


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RE: Briggs 35 hp vanguard

***"This was on the left hand cylinder, which runs fine."***
OOPS! Sorry about the overlook. The tach was about what I expected, but you never know. Good to hear that Briggs is at least talking to you on this. Please update with new info as you get it.


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RE: Briggs 35 hp vanguard

I have found out what the problem was with my engine.

It was my fault.

Before I fitted the engine into the hovercraft, I needed to alter a few things to make the engine more reliable in a salt water environment. One of the alterations was to remove the ignition coils & give them several coats of clear PCB lacquer.

When I refitted the coils I fitted the right hand one on the wrong way around. It does say on the coils cylinderside & this side out, but when fitted that way on the right side the HT lead faces towards the lefhand side, so I thought the coils were probably used on single cylinder engines & didnt apply to this engine.

How thick am I!!!!

So anyone experiencing similar problem with ther briggs engine, Check that your coils are on the right way, even if they look right check what it says on the coil.


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RE: Briggs 35 hp vanguard

Glad you were able to find and fix the issue. You have a good head on your shoulders (despite this accidental oversight). I'da probably never thunk of that being an issue. Anyway, great save, and I'm glad I ain't eating crow all by myself at Thanksgiving this year.
Happy Thanksgiving all.

Here is a link that might be useful: Crow is best if shared


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