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DYT 4000 Engine 31P777 0348-E1 replacement recommendation

3835 Views 10 Replies 4 Participants Last post by  northbama
Hello all. The engine on my DYT 4000 917.275640 gave up and I am looking to do a swap with a new engine. The engine is a 18.5 HP, Briggs & Stratton Model 31P777 0348-E1.

I called the local Lawn Mower Service store and and they quoted me $1300 for it. Then, they mentioned of a 33S877-0019 engine for about $700 but it is on back-order and there is a waiting list with 28 people.

I then searched the internet and found engine 33S877-0019-G1 at my local Northern Tool store for $560. When I chat with them online the person told me that the direct replacement for my tractor engine 31P777 0348-E1 is the 31S977-0005 and that they did not carry it.

Does anyone know of another engine model that will be a direct replacement for this one? Will 33S877-0019, 33S877-0019-G1 or 31S977-0005 work?

Thanks in advance.
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the main things on engine replacement
1 - engine crankshaft length and diameter
2 - fuel pump or gravity flow
3 - size of alternator on original compared to the new engine (electric PTO requires more amps)
4 - is the mounting hole pattern on a 33 series the same as a 31 series
5 - also the exhaust muffler
This was very informative.Now I can reference the first 6 characters of the engine numbers. Thanks.

I called Jack's Small Engines and they also referenced the 31S977-0005-G1 that Northern Tool. Being a newer model engine the price is high at $1200.

I called another website, EnginesForLess that I found on the internet. They have a 33R877-0029-G1 that said is a direct replacement for $675. The second picture below is that engine. But is a 33-series. Now I need to find out what is the difference between a 31-series and a 33-series.


looks like you are doing your research which is good
I think that engine will bolt into your machine just fine
No difference which should affect you. Alternator parts will interchange IF there is a difference. I can send you a Service Manual covering both IF you like, address below, put in proper format and remind me what you want.
Walt Conner
wconner5 at frontier dot com
Great. Thanks to both of you. I am ordering the engine tomorrow. I already took the old one out. I took the opportunity to do a frame clean up. While at it I am going to replace the belts. The engine belt has two big cuts in it.
My DYT4000 came with a 21hp courage, I swapped that with a Briggs platinum 21hp(both single cylinder) I’m doing another swap to a 24hp v-twin briggs XRD now

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Great glad to hear you are taking on the challenge I think it will work out. Keep us informed on how it works out
Engine replacement complete 2.5 weeks ago. I used the mower a total of 2 times. Engines feels strong and wants to go fast. I have not had to disconnect the battery after each use like with the other engine. I always had a problem with the slow start issue even with the installation of the relay. It looks like battery charges well now and does not get drained.

I have 2 issues that I will post separately next time I run the mower and take pictures and video. It has to do with 1) the idle moving up and down and 2) oil found coming out of the fuel pump.


I also changed the drive belt as I found it cracked in different places. Changing the belt makes it easy with no engine and you can turn the mower 90 degrees up. :) While at it, I also took the opportunity to do a pressure wash.


Lastly, thanks to a gift from my son, we installed an electrical hour meter. It took us some time to look get it connected and running and installed on the dash but it works well.


I hope this engine lasts me as much or more than the original. The original lasted me for 12 years of not so good maintenance from me.
looks great thanks for the update
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