520-HC no compression

[cafoose 3,747]

I was mowing with my 520-HC and I noticed the oil light came on. I promptly added oil to the full mark and it seemed to have lost power and started missing. I checked compression and the front cylinder is 85 and the rear is 0. It still starts and no loud knocking like a broken rod. I did notice wet oil drips underneath but nothing like a vented block. I hear they're expensive and difficult to rebuild. Thinking of a possible repower. 22 HP predator is $950 and 16.8 is $450. Is there really much difference in performance between the two for just running a 48 inch deck? Any other options or suggestions?

[Sparky-(Admin) 25,780]

Might just be the valve seat let go. Is it the rear cylinder that’s at 0 psi? 

[ri702bill 12,344]

19 minutes ago, Sparky said:

Might just be the valve seat let go. Is it the rear cylinder that’s at 0 psi? 

YUP - does it have over 1100 hours on it? That seems to start the countdown clock on them to the issue at hand.

[sqrlgtr 3,100]

@cafoose I would be interested in taking it off your hands if you decide not to pursue the repower. Would like the extra speed for running around the farm   .

[cafoose 3,747]

56 minutes ago, sqrlgtr said:

@cafoose I would be interested in taking it off your hands if you decide not to pursue the repower. Would like the extra speed for running around the farm   .

I like the speed myself and would like to fix it 

[cafoose 3,747]

Just saw this on marketplace. Will it work in my 520-HC? Description:

Good running horizontal shaft v twin off a cub cadet 2160. It’s got electric start & vacuum fuel pump, it’s ready to go on a mower similar to that or a gokart if you remove the governor. $250 or best offer.

[cafoose 3,747]

From Grok AI:

 

**The engine was manufactured on September 14, 1994** (based on the code **94091411**).

### Breakdown:
- **94** = Year (1994)
- **09** = Month (September)
- **14** = Day (14th)
- **11** = Plant/assembly line code

### Tractor Context:
The **Cub Cadet 2160 (AGS)** was produced from **1994 to 1997/1999** (depending on exact variant), so this engine is original to that era tractor — roughly **32 years old**.

At that age, these Vanguards are known for longevity **if** they've had decent maintenance. At **$250**, it's still a reasonable price for a complete, running take-off engine, but inspect it carefully for wear (bearings, compression, oil leaks, carb condition).

Ready to pull the trigger? I can walk you through a quick pre-purchase checklist or what to expect when mating it to the 520-HC.

[cafoose 3,747]

On 6/30/2026 at 6:04 AM, ri702bill said:

does it have over 1100 hours on it? That seems to start the countdown clock on them to the issue at hand.

Showing 1237 hours.

[Sparky-(Admin) 25,780]

5 hours ago, cafoose said:

Showing 1237 hours.

That 16 twin is a Kohler right? I don’t think that 1100 hours that Bill @ri702bill mentioned applies to that Kohler 

[cafoose 3,747]

6 minutes ago, Sparky said:

That 16 twin is a Kohler right? I don’t think that 1100 hours that Bill @ri702bill mentioned applies to that Kohler 

5 hours ago, cafoose said:

Showing 1237 hours.

Nope, it's the hours on the original Onan on my 520 The 16 I'm looking at is a Briggs Vanguard

[Handy Don 16,841]

A key difference might be the crankshaft bearings. The Onan on the HC had bearings able to handle the horizontal thrust from the PTO clutch. Cubs don’t work the same way and wouldn’t need that type of bearing so you might need to use an electric clutch for the PTO with the Briggs. 

@cafoose, can you tell from the Briggs specs what bearings it had?

[cafoose 3,747]

52 minutes ago, Handy Don said:

A key difference might be the crankshaft bearings.

From Grok AI:

Yes, the Briggs & Stratton Vanguard 303447-0447-01 (16 HP, code 94091411) is a popular candidate for a repower on the Wheel Horse 520-HC.

Why It Fits Well:

• The 520-HC originally came with an Onan 20 HP twin (or similar). A 16 HP Vanguard is a bit smaller in power but is a common, reliable swap for these tractors. Many owners report successful installs on 520-H / 520-HC models.
• It's a horizontal-shaft engine with ball bearing PTO side (as we discussed), flange mounting, and pressure lubrication — good match for the tractor's drive system.
• Physical mounting dimensions are close enough that it bolts up with minor (or no) adapter plate work in many cases. The crankshaft PTO end usually aligns with the existing pulley/clutch setup.

Things to Check / Common Adaptations:

1. Mounting — Verify bolt pattern and height. Some swaps need a simple adapter plate or shims for perfect alignment.
2. PTO / Pulley — Ensure the crankshaft diameter and keyway match your mule drive or deck drive pulley. You may need to swap or modify the pulley.
3. Exhaust / Muffler — Original Onan exhaust may not fit; many use a universal or custom muffler setup.
4. Wiring / Controls — Electric start, alternator output, and throttle/choke cables usually adapt easily. There are dedicated wiring harness kits for Vanguard conversions on Wheel Horse

[WHX?? 57,185]

On 7/1/2026 at 1:15 PM, cafoose said:

Just saw this on marketplace

Scrap price or a big roll of the dice you can't see it run... just sayin. 

[cafoose 3,747]

11 minutes ago, WHX?? said:

Scrap price or a big roll of the dice you can't see it run... just sayin. 

Seller sent me this video