CV740 27hp bogs severely under average load

[Turbodriven]

What I hear with headphones on, from your video OP, is normal RPM's in the first video. Low idle is lower than you will ever use and high sounded fine to me.

Your next video, sounded like, you have one or several bad bearings in the deck. Sounded awful mechanical when you engaged the blades. Heard a lack of engine rpm with the blades on. Like you have some aftermarket blades or some high lift wonder blades of the week on her. Are you running OEM blades?

Summation the engine sounded fine until you loaded her up. I would be looking into the deck then the engine if it was me. Or your Chinese tachometer is not reading proper rpm's. All this valve and such talk is getting you no place fast.

I currently have the belt off so I could take a video of the spindles spinning by hand. They don't sound gritty to me like bad bearings would. I'll check again though with some side tension applied. And I'll take a pic of the blades but I did sharpen them. No idea what they are though.

It's also important to note that I'm getting a slight power loss even without blades engaged. I'm at about 2500 rpms on flat ground just driving around. I haven't focused on blades/spindles because of this.

 

[slomo]

It's also important to note that I'm getting a slight power loss even without blades engaged. I'm at about 2500 rpms on flat ground just driving around.

Have you checked the weight of that mega mower with YOU on it? Talking thousands of pounds guy. So you have this issue without the deck on. Okay that "could" rule out the deck. What is next? Something hydro related dogging the engine down? Is your mower hydro driven or a belt? Rule these out then look back into the engine.

 

[Turbodriven]

While you have it apart, look at the crankshaft gear very closely for anything resembling a crack.

I'm in the office today, I'll look when I get home. Are you implying that a crack could allow the gear to slip? I thought we ruled that out when we verified exhaust tdc to be correct?

 

[Turbodriven]

Have you checked the weight of that mega mower with YOU on it? Talking thousands of pounds guy. So you have this issue without the deck on. Okay that "could" rule out the deck. What is next? Something hydro related dogging the engine down? Is your mower hydro driven or a belt? Rule these out then look back into the engine.

It's belt driven hydros. I've definitely considered malfunctioning hydros externally putting too much load on the motor, but that doesn't explain my carbon fouled cyl #1 (only). And this thing should normally run at 3300rpms under normal loads. I only weigh 175lbs . Back to the blades.. When I'm sitting with the blades engaged my rpms actually go up. It's in the second video. When I pull back the sticks the rpms come back up to 3300 rpms (blades still engaged). That said, when I first engage the blades in the beginning of the second video, the engine first struggles, then climbs back up to 3300. This is all pointing to the engine in my opinion. Whenever a load is applied (no matter what it is) the engine struggles.

 

[VegetiveSteam]

I'm in the office today, I'll look when I get home. Are you implying that a crack could allow the gear to slip? I thought we ruled that out when we verified exhaust tdc to be correct.

Yes. A crack would allow the gear to slip and yes that should have been ruled out by checking overlap, but since you're in there I figured it couldn't hurt to take a look.

And if you could clarify something for me. When you ran the engine on one cylinder at a time you said neither side would hold idle. I'm not quite sure what you meant. Was this with no load the engine wouldn't idle running on just one cylinder?

 

[Turbodriven]

And if you could clarify something for me. When you ran the engine on one cylinder at a time you said neither side would hold idle. I'm not quite sure what you meant. Was this with no load the engine wouldn't idle running on just one cylinder?

Yes. I should have taken a video. When I unplugged either side, it was difficult to start. With both cylinders it's usually it's a pretty easy crank or two even at low idle throttle position, but with one side unplugged it struggled to start. A little 50-75% throttle feathering and she would though.

During normal operation with both sides running I can throttle all the way back to the stop and she'll easily hold 1150-1200 rpms (you saw the video). However when one side was unplugged, that action would kill the motor. To keep her running on one cylinder I would have to be at about 40% throttle (if I remember correct) and it was lumpy.

This was consistent of both sides. Neither idled well or started easy. The only difference I noticed between the two was that while running with #1 plugged in, I saw a noticeable sooty colored exhaust coming out. I don't normally see this with both running and not with just #2 running either.

 

[Turbodriven]

How do the lifters look? Can you post a pic of the side that runs on the cam?

See the pic. It's hard to get a good one as the mating surface of the lifters are almost chrome and it reflects my led shop lights.
On this subject, in your experience are these Kohler lifters the exact same as GM/Chevy small block lifters? I've heard they're the same (and they look the same) but Kohler charges 2x+ for theirs. LOL. Reminds me of a real world story where $200 Lamborghini side markers are literally off a Ford Fiesta or something and cost $20 at the Ford dealership.

Kohler says to replace the camshaft and crankshaft together. Never just replace one. So you'd be looking at a cam, crank and new lifters.

If I didn't hate Kohler engines before... I do now. This is just bad.

 

[VegetiveSteam]

See the pic. It's hard to get a good one as the mating surface of the lifters are almost chrome and it reflects my led shop lights.
On this subject, in your experience are these Kohler lifters the exact same as GM/Chevy small block lifters? I've heard they're the same (and they look the same) but Kohler charges 2x+ for theirs. LOL. Reminds me of a real world story where $200 Lamborghini side markers are literally off a Ford Fiesta or something and cost $20 at the Ford dealership.



If I didn't hate Kohler engines before... I do now. This is just bad.

See the pic. It's hard to get a good one as the mating surface of the lifters are almost chrome and it reflects my led shop lights.
On this subject, in your experience are these Kohler lifters the exact same as GM/Chevy small block lifters? I've heard they're the same (and they look the same) but Kohler charges 2x+ for theirs. LOL. Reminds me of a real world story where $200 Lamborghini side markers are literally off a Ford Fiesta or something and cost $20 at the Ford dealership.



If I didn't hate Kohler engines before... I do now. This is just bad.

From what I see in the pics the cam lobes and lifters look fine.

As far as the lifters being the same as a small block GM, they are the same external size but according to Kohler they oil hole sizes are different. I can't say if GM lifters will work or not. I've never tried. They might work just fine.

 

[Turbodriven]

From what I see in the pics the cam lobes and lifters look fine.

As far as the lifters being the same as a small block GM, they are the same external size but according to Kohler they oil hole sizes are different. I can't say if GM lifters will work or not. I've never tried. They might work just fine.

Yeah, and although I'm sure they're not perfect, as mentioned before... I don't think this is my problem. So with that being so, I'm not willing to drop $500 on a new crank/cam/and lifters for sure.

I'll bleed the lifters like you mentioned, hone and ring job the cylinders (need to make sure I order the right rings), and then slap this bottom end back together per the manual. I still have to pull my valves out of the head too and clean them up. Although they don't look super bad through the ports, I still want to check the guides and everything so I can say I touched everything.

Thanks for your wisdom.

 

[VegetiveSteam]

Let me ask a silly and probably useless question but, do you still have the spark advance module you took off this engine? If so, what's the number on it?