Running diesel without belt?

[Bunnellr]

My crankcase pulley has become corroded. I was thinking about running the engine without a belt for 10 to 15 seconds and using a brass brush to clean the grooves. Then spray with brake cleaner. Then run again for 10 seconds to put on rust-resistant paint.
Anybody see why not? Alternator and internal cooling pump on the belt.
Ciao!

[rbk]

If you do this, take video of you doing the painting and post here; I need a good laugh.

[valhalla360]

Be careful around the moving parts but shouldn't harm the motor.

I probably wouldn't paint that way...you could wind up sucking the paint into the engine and it's not as critical.

[Hesti]

No need for paint where the belt will run, it will prefer blank steel. The rest, you should be able to paint without the engine running. Apart from that - no, it should not harm the engine.

[a64pilot]

After you clean it off there will still be a very thin layer of rust, that will be a problem in the future unless you use a rust stop product, there are many and the good ones work very well indeed and make a great primer for paint too.

[meirriba]

Originally Posted by Hesti

No need for paint where the belt will run, it will prefer blank steel. The rest, you should be able to paint without the engine running. Apart from that - no, it should not harm the engine.

Exactly.
The engine may run some short time without cooling. More than 15 sec.
But do not let it get warm!
You can monitor the temp by your hand. Too hot to touch - shut down...

[sailing_gal]

Seems to me to be a really dangerous thing to do. Why not just remove the pulley and clean it properly? I added a serpentine belt kit to my Yanmar, had to remove the pulleys. Not that hard, and properly cleaned the crankcase pulley at the same time and painted it with yanmar paint to protect it while it was removed.

[Hesti]

As an afterthought: Likely, the exhaust hose temperature is going to be the first thing to become critical.

[AndyEss]

You could probably run it even about a minute with no harm. It isn’t as if none of us has forgotten to open the cooling water seacock at some point in our lives. Do it too often and for too long of course you will start burning things up.
Watch for other rotating parts so you or tools don’t get caught in them and cause injury and/or damage.
Probably safer ways of achieving what you want to achieve (risk/benefit ratio doesn’t seem particularly good) but it’s your fingers.

[a64pilot]

Depends on the engine, on mine the belt only drives the fresh water pump and alternator, my water pump">raw water pump is gear driven through the accessory gearbox. I could likely idle just about forever and not overheat anything. There would be some fresh water circulation through the heat exchanger from thermal siphon, and I’m betting it would be enough at idle.

Then if you have ever had a pyrometer on a Diesel the exhaust temps are very low at idle, the reason for this is a Diesel has no throttle valve like a gas motor does, so a Diesel takes in the same amount of air at idle that it does at full throttle, assuming no turbo, all this excess air isn’t heated very much at idle, so where you may have an exhaust temp above 1000F under a load, at idle it’s likely less than 200f or so.

[oleman]

I see a disaster in the making, The brush will hang on the rotating pulley and your hand will get wrapped around the pulley also. Recommend if you are going to try this to get a good pair of leather work gloves.

[GRIT]

The OP said internal cooling pump, I assume he means fresh water, and alternator on the belt.

Please re-read A64's post.

Note, please, that he said he could "probably" run it forever. I'd guess he's close to right, but I've not tried it, and I don't suggest you do.

Diesel engines used to be my job, don't fret, run it as long as it takes to clean the pulley.

Now, painting while the engine's running... at idle...may be...perhaps... I'd probably try it with paint on a rag... but I'm adventurous that way.

I wouldn't, personally, paint on the belt riding surface though, the belt is just going to wear it off. But I wouldn't worry if you did paint it, it won't hurt anything.

Cheers all.
Paul.

[CassidyNZ]

A corroded pulley is not going to be remedied with a brass or any other kind of brush and a corroded pulley surface will just generate a heap of black dust and worn-out belts.

Remove the pulley and have it cleaned up properly on a lathe taking absolute minimal material off and being absolutely anal about preserving the V angle. V-belts like a polished surface, not a clean one.

If you’re going to machine the old one, test-fit a new belt in the V to ensure it doesn’t bottom in the groove, if it does you’ll never stop the belts from slipping. Be aware that a machined surface on cast iron is not necessarily non-abrasive. You may sacrifice a belt or two polishing the machined face.

If any part of the aforementioned is dodgy, buy a new pulley.

[BruceS]

I've polished irrigation engine pulleys by using a file while the pulley rotates.
Easier to keep straight/flat. Move it back & forth to stop the file clogging up.
Most engineers finish on the lathe with a file?

[Brewgyver]

If I saw an employee attempting something like this, he'd likely get fired.

People lose body parts doing this kind of thing. Frequently.

Some of them have had the parts reattached, because their survivors want an open casket for the requiem.