Engine making a loud clangy sound while running

[Red Stallion 217]

Before I start ripping things apart, my Wheelhorse 520HC has a particular loud changy/clanking sound while running. I'm guessing one of the valves are probably need adjusting as there are about 400hrs on the clock.

 

Other than that, what would be the other things I should look at? Typical of that run time?

[sqrlgtr 1,687]

Hard to diagnose without hearing it in person. Hopefully its nothing serious but I wouldn't run it until you figured out what it is. 

[c-series don 10,913]

A simple compression check might be a good start. 

[Bill D 2,484]

I'd take the drive belt off then run it briefly to see if the noise goes away.  Could be the drive belt tensioner banging.

[c-series don 10,913]

Good point @Bill D I didn’t think about that! 

[Ed Kennell 44,029]

Pull each plug wire to see if the noise is from a particular cylinder.

[sqrlgtr 1,687]

19 minutes ago, Bill D said:

I'd take the drive belt off then run it briefly to see if the noise goes away.  Could be the drive belt tensioner banging.

Could be, hope that's all it is. 

[953 nut 63,510]

I would begin by removing the engine tins to see some cute little critters have set up housekeeping in there, an acorn in contact wit a flywheel can cause quite a racket.

Onan valve seats have been known to be troublesome. A compression check as suggested by @c-series don will let you know if this is a probable cause.

[Red Stallion 217]

Its unlikely to be any animals in there. I've spent the last year stripping it apart and blasting it clean.

 

I'll try the compression test first. My gut tells me that its only one half of something, as I'm not hearing the sort of frequency that correlates to engine speed.

 

I'll also check the tensioner. That's a nice easy thing to check.

[peter lena 9,630]

@sqrlgtr   hate those tiny bearing idler pulleys , consistent   noise / failure  , lubrication failure is assured , also helps to  eat  pto drive clutch ,pete 

[Blasterdad 3,145]

I just repowered my my C-161 snow machine, when I started it there was a racket from hell, turned out I left one bolt loose on the belt guard. 

Hopefully yours is something silly simple too...   

[Red Stallion 217]

Okay, so I dived in and pulled it out to adjust the valve lashings. In my heart I know that's the problem, so just commit to it.

 

Front cylinder wasnt too bad, but the back cylinder clearance was probably 2-3mm! Adjusted them all back to .013 and .005 thou.

 

But while I had it open I peered inside and it looks like there is a big crack around one of the valve seats? I'm no expert, but my vahue understanding is that engines and cracks generally dont go together to improve performance?

 

Its the same valve that had the massive clearance, which makes me think its pretty toast? Is the valve seat section repairable? Or it looks like its part of the engine block casting so its new engine material?

[RED-Z06 2,700]

I cant see the crack, but given the P220 engines nasty habit of losing intake seats on the right/rear cylinder...id pop that head off and have a look.  The block typically needs to be machined to accept an oversize seat, then the seat has to be faced/cut to the right height.

[Red Stallion 217]

If I'm not mistaken, that is the seat of the valve. And you can see the crack in the seat or the block just to the right. I still haven't done a compression test... maybe the engineering gods will shine down upon me and I'm misidentifying everything?

 

It's not a small job to fix that, so I'm starting to have a poke around to see who can do the valve seats.

 

 

[wallfish 18,844]

And this looks like a piece peeling off

[Red Stallion 217]

I'm not sure exactly what it is, but I'm not hopeful that it's going to be a positive benefit.

[lynnmor 8,328]

58 minutes ago, Red Stallion said:

If I'm not mistaken, that is the seat of the valve. And you can see the crack in the seat or the block just to the right. I still haven't done a compression test... maybe the engineering gods will shine down upon me and I'm misidentifying everything?

 

It's not a small job to fix that, so I'm starting to have a poke around to see who can do the valve seats.

 

The valve needs to come out so we, or a machine shop, can see the extent of work needed.

[Red Stallion 217]

6 minutes ago, lynnmor said:

The valve needs to come out so we, or a machine shop, can see the extent of work needed.

It's on my list of next jobs... it was too disheartening to make all that progress, and then find this major issue. As you are aware, it's not a 10min exercise to get that head off, and my new head gaskets have not arrived yet.

[RED-Z06 2,700]

If you have a tester, do a compression test, usually you like to see 115-125 on P engines, when a seat steps out, that number will typically drop to low double digits 

[Red Stallion 217]

7 minutes ago, RED-Z06 said:

If you have a tester, do a compression test, usually you like to see 115-125 on P engines, when a seat steps out, that number will typically drop to low double digits 

Before I pull the head I will do a compression test. If by some miracle it does have decent compression, it really only buys me a little time before I have to fix the obvious. 

 

But at least I can drive it around the paddock once and enjoy.