MCP 355 suddenly running at lower rpm's?

[mav2000]

Hi,

My mcp 355 is about 6 months old and now today all of a sudden the rpm on the pump has reduced from 4.4k/4.5k to 3.9k/4.1k

I have no clue how this has happened over night, without changing anything. Any ideas guys?

The loop consists of 1X360, 1X120, 1 EK cpu WB and 1 EK 5850 WB and an EK 150 res.

[Tetrafluorometh]

Check the loop for anything blocking it. You'd going to have disconect it all and look. What fuild you using?

[mav2000]

Distilled and silver coil.....maybe the silver coil has moved in the res...need to check that as well.

[Tetrafluorometh]

Distilled and silver coil.....maybe the silver coil has moved in the res...need to check that as well.

Sould well of done, hopefully part of it has not broken off and gotten into the pump.

[Waterlogged]

Check to make sure the pump didn't swallow some air and send it through the loop. It may be stuck in a rad somewhere if it did.

[Martinm210]

There are many versions, and not much RPM related info on the older models, but I do know the latest DDC3.25 reduces rpm with an increase in flow rate. I've also seen some sporadic impulses by some of the pumps like the D5 strong where it hops +- 120 rpm causing some fan controllers to read the high end..then switch to the low sort of back and forth.

I have also had an old DDC1 pump that operated at a reduced speed because one of the FET(not sure if that's the right term) was toast. I could see black burn on the pcb.

I would suggest taking it apart and looking for any signs of damage. I doubt there is, but I would check just for comfort. At a minimum set the rpm wire on the cpu header with a 2000rpm min shutdown in bios or other means of protection.

Could just be a flaky rpm sensor, but I wouldn't like that without opening it up.

Or as WL noted maybe a chunk of something broke loose which could also be fixed by open inspection.

[mav2000]

Thanks guys. I think it could be an air bubble as I recently drained and refilled the loop. Looks like one is stuck somewhere, but the funny thing is that it didnt happen the day I refilled the loop but seems to have started the next day....is that possible?

[matari]

Put a piece of tape on the reservoir where the fluid level is. Turn off your computer. If the fluid rises more than a few mm then you have an air pocket. When you tilt your computer does your radiator make a sound?

[mav2000]

I will have to check, but air pocket seems to be the best bet as of now. Will get back soon.

[mav2000]

Thanks guys, got it back to normal. I drained the loop and took the pump out. Cleaned it up, but there was no debris. Then put it back together and runs fine now...

[Sparky]

Probably had an air pocket in the radiator where you couldn't see it.

But keep an eye on it. My old MCP350 (the black impeller one) would drop about 300-400 RPM randomly for a couple seconds then increase back to normal. After a couple months of that, it stopped running while I was playing a game. Thankfully when the temperatures jumped it made the PC BSOD and restart, which gave me a "CPU fan error" from the bios and shut down before it killed anything. That pump was 9 months old when that happened. Got an MCP355 (the 3.2 with blue impeller) as a warranty replacement, and it has been running fine for 3 years now.