Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Existing motor is a B&S 3.5HP Model 92905 Type 1825-01 Code 77083004.   I have tried the B&S site and could not find a correct replacement.

Any direction on how to research for a direct replacement engine would be greatly appreciated.  I have had the mower for 16 years, I bought it used

it has been a great mower but the engine is pooped.

mml4 wrote:

Marc, I was able to get a NOS TVXL 840 Tecumseh off of ebay.  The only problem I see is the throttle control  on the 840 is up front instead of on the left (plug) side like the "old Briggs", this puts the throttle cable in a bind trying to make an abrupt 90 degree turn.  Will a longer cable work or is there something special that is used for the abrupt 90 degree turn?  Thanks again for getting me this far.

John

John-Congratulations on finding the engine. The stock throtle  cable from the Briggs won't work. You are going to have to find an aftermarket with a cable(longer) you can work with or see if you can mount the original on the other side and lower on the handle bar.. Another issue is going to be  disabling of the blade brake and grounding wire of the brake system. Place the engine upside down on a towel and look for the blade brake return spring . It is attached to the brake control lever that has the brake pad attached to it. Remove the spring and cable tie the lever so that the pad is not rubbing on the shaft. You will also see a shorting clip that would cut the ignition when the spring pulled the lever to where the pad contacted the shaft. I wired the clip to one leg of a  momentary switch on the handlebar so I could short out the ignition in order to shut the engine off. Which way do you have the muffler facing? Notice you can rotate the engine to several positions. You must find the position that allows you to mount the bag so it doesent get burned by the exhaust and also leave the pull start available to be used. I am sure you already figured this out-

Good Luck,

Marc

PS- If you got the manual with your engine you will see it suggests TC-W11 or TC-W3. From what I know these are the outboard motor variety of 2 stroke oils which are formulated to be run in engines that don't turn the high # of rpm that  a blower or string trimmer do and run at cooler temperatures. The manual also suggests 50:1 mix with DOUBLE the ammount of oil in the first gallon (25:1) No explanation but I bet it has to do with the cast Iron bore.

mml4 wrote:
I have never had a mower with a blade brake.  I have looked for the brake control lever that has a brake pad attached.  Is this a brake pad that will contact the drive shaft and stop the blade from spinning?  If so I don't see it.  Do I have to remove something to access these items?  I am looking around the carburetor linkage area.  I have downloaded a Tecumseh technician's manual which covers TVXL840 and other modeles and on page 16 & 17 it has pictures of the Self-Energizing Brake system.  I see nothing "exposed" that looks anything like the pictures in this manual.  Is it possible this NOS model I bought does not have a blade brake? To answer your question I have the muffler facing the left side and this places the throttle controls towards the front, and engine  also clears the discharge chute with the fuel tank and pull cord on the right side. These are the numbers that are stamped into the blower housing TVXL840-8405A  7301A.  

John- My bad!  I just went out to the shed and had a look. The pad contacts the inside of the fly wheel not the shaft. I did this several years ago so please forgive me. Turn the engine upside down and look in the area between the muffler guard and the corner of the tank. The spring I was speaking of is right there. You will also see the linkage that is attached to the spring. The brake pad and grounding clip is on the other side of the plate and not visible. If you want to access them you will have to do some disassembly.

You could just put a short self tapping screw in the plate so that the spring assembly is permanently in the run position but then you will have to rig some other way to ground the ignition to shut the engine down. If I was doing this again I think I would go that way if I could find an alternate way to ground the ignition.

My engine # isTVXL 840 849J 0013G, the 849J is the part of the # that indicates internal parts and is different than yours. It may be that your engine doesen't  have the blade brake/ignition cut off. I also think your engine may be older than mine because my #s were on an ID tag  and not stamped in the blower housing. The first digit of the  last four #'s indicate the year of manufacture which in my case is 0 so it was made in either 2000 or 1990. The day is 013 which would be Jan. 13 . Yours is the 301st day of a year that ended in 7-2007,1997,1987- Who knows?

Marc

mml4 wrote:

Marc-That's good news!  I did as you said turned engine upside down and looked in the area between the muffler guard and corner of the tank and I saw absolutely nothing.  It is entirely enclosed in sheet metal around blower housing.  You keep mentioning a way to ground out the ignition to shut the engine down.  What I see on my engine is that in the carburetor linkage there is a wire that is connected to a insulated mounting,  the wire becomes grounded when the throttle linkage is fully retarted and becomes ungrounded when throttle is advanced.  The wire runs from throttle linkage to an area above cylinder head, hopefully to the ignition.  Would this be what would have been done to shut the engine down if this is a pre-blade brake motor? Thanks alot for getting back Marc, I was very confused.

John

John- Sounds like you have an engine without the blade brake mechanism. Good for you. It also sounds as if the carb  linkage shorts out the ignition when you go to low motor  just as the Briggs did. One thing occured to me -did you check to make sure the shaft length and diameter are the same as the Briggs? If so you are almost there. Taking the blade adapter and the pulley off the Briggs and putting it on the Tecumseh is the next hurdle. My first Tech had key way in the shaft but my blade adapter had set screws I put the adapter on and marked where the screws contacted the shaft. I then filed some flat spots on the shaft where the screws from the adapter contacted it. As I said I did this a while ago and it is the second repower so I forget if the  blade adapter had a key as well. I also remember having a hard time the first time getting the adapter off the Briggs.

If memory serves me  on the second repower I went to the mower shop and bought an updated blade adapter because I didn't want to go through the trouble of trying to get the old one off. It can be done but it is a pain.

Marc    

mml4 wrote:

Marc, The shaft dia. and length are exactly the same on the old Briggs and the new 840.  My 840 has a keyway the full length of the shaft and at 90 degrees from that full length keyway are two individual slots for woodruff keys.  I have already fitted the blade adapter with woodruff key in the lower of the two individual slots and it fits perfect.  The only problem left is removing the old engine pulley from the Briggs.  It has a set screw holding it and it is stripped out.  It may also have a woodruff key can't tell yet.  I may have to get a new engine pulley if I can't get the set screw out.  Marc, I can't thank you enough for all your help, I really appreciate it.

John

 

 

John- It's been my pleasure!! I'm glad the shaft is the right size. Wait till you get that puppy running. You are not going to believe the difference between it and the Briggs. If you can get your hands on a tach try and set the governor to about 3550. I don't mean to lecture but be careful about the fuel- I can't tell you how many times I almost forgot to mix in oil . In addition I found the Snapper blades to be much better than the after market. They are much lighter and my engine runs better . Worth the extra $ in my opinion. 

Getting the old pulley off after all those years is going to be tough-probably not worth the effort..

Please let us know how you like it.

Marc