Briggs & Stratton Quantum 55

[NickB 0]

Hi All,

 

I’m hoping someone can advise me regarding sump removal from my B&S Quantum 55 engine.

 

The engine is has a PTO driving the rear roller, but it I think the roll-pin securing the gear to the PTO shaft has sheared - hence the need to remove the sump to access the gear and replace the roll-pin.

 

With the engine inverted on the bench (see attached pic), I removed the 7 bolts securing the sump to the crankcase expecting to be able to lift the sump off, but after lifting it about 10mm fairly easily I’m the feeling some resistance.  Initially, the shaft to which the blade would attach remains in place as I lift the sump, but after 10mm it seems that the sump is catching on something and lifting the shaft too.

 

Any help or advice or would be much appreciated.

 

Cheers,

Nick

[Wristpin 400]

Are we to assume that you are trying to pull the sump over all the crud on the crank ?
Taking it at face value you must clear all that crud off the crank  - scraping and fine sand paper. May even be helpful to pull out the oil seal so as to clean right down to the clean part of the the crank, then plenty of thin oil.

[mattblack 76]

You'll need to remove the woodruff key to get it off completely anyway.

 

Can you get a thin piece of wood in when it's lifted as far as it will go to hold it up while you have a look inside with a light?

[NickB 0]

On 4/13/2024 at 11:53 PM, Wristpin said:

Are we to assume that you are trying to pull the sump over all the crud on the crank ?
Taking it at face value you must clear all that crud off the crank  - scraping and fine sand paper. May even be helpful to pull out the oil seal so as to clean right down to the clean part of the the crank, then plenty of thin oil.

I removed the worst of the crud with a wire brush before attempting to lift the sump, and the shaft is tapered immediately above the oil seal, so what remained didn’t cause an issue.

 

Anyway, I did manage to remove the sump with some gentle tapping with a mallet.

 

On 4/14/2024 at 8:43 AM, mattblack said:

You'll need to remove the woodruff key to get it off completely anyway.

 

Can you get a thin piece of wood in when it's lifted as far as it will go to hold it up while you have a look inside with a light?

It wasn’t necessary to remove the woodruff key, because the shaft is tapered immediately above the oil seal.

 

I’d already had a look through the 10mm gap and I couldn’t see any obvious reason for resistance, but I did eventually manage to remove the sump with some gentle tapping with a mallet.

Edited April 15 by NickB

[Wristpin 400]

Just make sure that you can account for every bit of the failed roll pin. If you can’t find all the bits in the sump, take the cam out and flush out the inside of the crankcase  over a clean receptacle  and hope to find the missing part of rock hard roll pin that will do serious damage if picked up between cam and crank gears or the worm gear and the bronze worm wheel. 
This is not from the official manual but we used to replace the standard roll pin with a stronger “ spirol” - especially on contractors’ machines. BUT don’t upgrade the pins outside the engine such as in the dog clutch fixings. You need to maintain a weak link and a lot easier to replace.

 

[NickB 0]

25 minutes ago, Wristpin said:

Just make sure that you can account for every bit of the failed roll pin. If you can’t find all the bits in the sump, take the cam out and flush out the inside of the crankcase  over a clean receptacle  and hope to find the missing part of rock hard roll pin that will do serious damage if picked up between cam and crank gears or the worm gear and the bronze worm wheel. 
This is not from the official manual but we used to replace the standard roll pin with a stronger “ spirol” - especially on contractors’ machines. BUT don’t upgrade the pins outside the engine such as in the dog clutch fixings. You need to maintain a weak link and a lot easier to replace.

 

Fortunately, the roll-pin parts remained in place (two in the gear and one on the shaft) but unfortunately the gear teeth have been damaged), so I’ll have to replace it.  Also, the legs of the shaft stop had broken (I think I’ve located those parts too), but I’m not sure if the two failures are connected - ie. shaft-stop failure caused or contributed to failure of the roll-pin, or vice-versa.

 

Incidentally, do you know if the roll-pins (gear and clutch-dog) are metric or imperial ?  My measurements suggest imperial - 3/16”, but I wondered if they might be 5mm … ?

 

It did cross my mind to replace the gear roll-pin with a spiral type pin to increase durability, so it’s good to know it’s a tried and tested modification.

[Wristpin 400]

My guess is imperial but I’ve been away from things for a while. A bit of Model , Type and Code digging may reveal something as would a bit of probing through the shaft drilling  using the two sizes of twist drill as slip gauges may suggest something.