Craftsman 19.5 hp engine swap

I just bought a Craftsman LT1000 with B&S 19.5 hp mower for $50. From the seller's account of what happened, I thought that it sounded like a fuel pump leaking gas into the oil. Easy fix that I have had good luck with before. Well, not this time. After checking the oil, there was none. Took the chance and put fresh oil in and got the engine to start. It made some funny noises and then settled into a nice smooth idle. Thought I had it made. Then it made some really sharp clangs and bangs, and started idling smooth again. Then is started getting slower and slower till it just stopped. Locked up tight. I found a rod bolt and two pieces of a piston skirt laying on the frame outside the engine. Then I found the hole on the backside of the access cover. Not good at all.
My question now is this. I have an older 19.5hp B&S motor in another Craftsman mower that the deck is worn out and the transmission is shot. I would like to know if anyone thinks this engine would swap out. The newer mower has the automatic transmission in it and the deck is in really good shape. A quick look at the engines appears that they are close to identical, although the numbers I have for the older one says it is obsolete. Both are the opposed twin cylinder flathead engines.

Guess I'll find out when I get there.

About two years ago I saw one of those engines lock up. (Brought to me 'not running right' and I ran it for about 30 seconds THEN it locked up.) I have also opened up one that was on the verge of locking up. What is going on it the oil slinger gear just barely mates with the cam gear when it is new. Since the slinger gear is plastic it eventually wears a notch in every tooth that clears the cam gear teeth and then the engine locks up because its not getting lubrication.

If you want your replacement engine to last, open it up and check the oil slinger before mounting it.

Thank you very much for that important information. I sure would hate to go through all the work just to have it die shortly.

Should I pull the heads and clean the carbon out? A friend of mine told me I should. I personally don't know a lot about these engines. I have mostly dealt with cars and full size tractors. Can't be much of a job, this being a flathead type engine. Just want to do anything that will help keep this one going a long time.

Down load the parts manual at Briggs website and compare parts number on parts you are concerned about.

I would have done that, except I can't read the numbers on the older engine and mower. The tags have gotten a little too beat up. Both engines are 19.5 hp and opposed flathead engines. I am guessing that the older one was built in the early 1990's and the one I just bought was built in 2001. I have the manual on the newer one. The engines look practically identical. The main difference is the type of transmissions (newer one is automatic) and the mower decks. Newer one is 42" and the older one is 46".

Answered my own question finally. Tracked down a number for a 1996 Craftsman 19.5hp twin with 46" cut. Then went to the parts page and crossed numbers for gaskets and oil slinger. Part numbers crossed between the two so it looks like the engines will interchange. Thanks for the replies.

Glad you got it figured out.

I answered a similar question somewhere on the www. I found that OEM mfgrs "seem" to have standardized their frames to accept
different types of engines and engines from different mfgrs who seem to have standardized their mounting dimensions and placement of
necessities.

As a result, using the 10" bolt diameter on the frame, I easily removed single cylinder Kohlers and replaced with V twin BS engines with
everything matching up, everything, but the throttle and choke cables which were too short since they were located on the left side with
the single and around in front of the V twin.

Four main things on an engine swap..

Engines bolt pattern match.

Output shafts the same diameter (can be different if you are willing to buy pulleys and/or PTO that fit).

Output shafts the same length.

Output shafts Key ways match (again can be different if you are willing to locate pulleys and/or PTO that fits).

Everything else can be rigged to work. May have a litle trouble with the exhaust depending on it's location and set up. But it can be worked around.


I have two Lawnboy push mowers that were bought new and at the same time in 2005. Both are the same models and have 6.5 hp Tecumseh engines. One has a keyed output shaft while the other has a tapered shaft. The engines would be an easy swap while the blade adapters will not interchange at all.

Let me add something that may apply to your engines.

If they are Over Head Valve engines. Pull the valve cover and look at the intake valves push rod.. For some stupid reason B&S thought that it was a good idea to put Aluminum intake push rods on their OHV engines while leaving the exhaust one steel. Both are the same diameter and length.

If you find this to be the case remove the steel one from the bad engine and use it on the good one..

The B&S aluminum push rods are know to fail on a regular bases around the small oil hole near the top.