My Iwaki md-30rlt is getting louder and louder!

[PolakATL]

Hi, first i'd like to say its been a while since i have visited this forum but I know there are a lot of cooling experts here.

A while back I got a md-30rlt. It was a very quiet pump when I first used it but soon it started to make a rather noticable rumbling sound. Its not a sound that tells you something is about to bust but just an anoying rumble. I have a res that was ment to be a water filter for a house water supply. I took out the filter part and screwed it right on to the pumps inlet. I'm running 1/2 tubes all around. I heard somehing about large pumps "cavitating" (or something like that) when the inlet is rather restrictive like in my case. If this is the case would getting a larger less restrcitive reservoir make the pump quiet again or has the pump been damaged and will it continue to rumble? I'm trying to setup my cooling system/comp in an ams gtower (midtower) case. I want it to be completely inclosed so i'm willing to drop the massive iwaki for a l-50 hydor. If the pump cannot be bade quiet than i will get a l30 hydor wich is a huge downgrade in flow. I hope you huys can guide me in the right direction on this one.
Paul

[bigben2k]

Hi PolakATL!


Your problem isn't easy to resolve, because with only a text description, it's hard to figure out the actual problem. All pump problems are difficult to solve anyways!

#1: you may have some debris that slipped in your loop, or something that broke off, and is now lodged in the pump housing.

#2: you may have a broken impeller shaft.

#3: you may have a few loose screws around the pump housing.

and that's just off the top of my head, but either way, you're looking at taking out the pump, and taking it apart for examination.

If you do, let us know, and I'll advise further.

[PolakATL]

Thanx,
I get my rads towards the end of this week so I will take apart the pump. Currently I have a massive 22x11xin lytron rad so that definately isn't going into the case. I can rule out the possibility of debris. I would like to hear more about the cavitation theorey i read about on these forums a long time ago. I first had a wmd 30rlt hooked up to a 90deg elbow and 1/2tubing and this was really chocking and rumbling. The res and md pump is a lot better at staying quieter. Should i go ahead and take the pump apart when i open my system? I don't want to mess with any good seals and then have them leak.

[jaydee]

Originally posted by PolakATL
Should i go ahead and take the pump apart when i open my system? I don't want to mess with any good seals and then have them leak.

No. First run the pump without anything hooked up to it (except maybe a inlet and outlet hose) to give a free flow, and then see if it makes the same noise. If the noise stops it probably isn't anything in the pump and maybe just making noise from the system. Possibly the water heats up and builds a little pressure causing it to make noise? How sealed is the system?

[PolakATL]

I don't think the system can build up pressure since the res connected to the pump has a cork in the fill hole. Its not a perfect seal and i have taken it out before. I will definately try the pump in my bathtub (not submerged of course LOL) and see what happens. Keep ur ideas coming. I knew this was the right place to ask.

[pHaestus]

They put 3/4" NPT barbs on the pump for a reason, especially on the intake side. Your problem sounds like it may be NPSH issues due to restriction on the intake side. Read this for much more info:

http://www.cepmagazine.org/pdf/050252.pdf

Nice (and expensive!) pump. Don't hamstring it

[Blackeagle]

Iwaki recomended pump/fittings & pump performance

MD-15 = 1/2" NPT & 1/2" line size, gpm 5, max head 11.1 ft.

MD-20rlt = 3/4" NPT & 5/8" line size, gpm 8.2, max head 14.1 ft.

MD-20rlzt = 3/4" NPT & 5/8" line size, gpm 2.9, max head 22.6

MD-30rlzt = 3/4" NPT & 5/8" line size, gpm 4.6, max head 36.1

MD-30rlt = 3/4" NPT & 3/4" line size, gpm 10, max head 17.7

The gpm rates are at 0 head or free flow.

www.iwakiwalchem.com

Check the performance curve chart at this site. Note that the MD-30rlzt will still maintain 4gpm of flow at your MD-30rlt's shut off head rate. If you havn't had the pump to long your dealer might be willing to exchange the pumps impellor head, or the whole pump, for a Z type one at low/no cost. I can't imagine anything else you can do to so improve performance while also lowering noise.

Questions to increase info needed to better help you.

1) Are your lines in use now 1/2 copper or Tygon ?

2) What are the inlet/outlet sizes on the rad in use now & on the one you have ordered?

3) Do your blocks have 1/2" barbs ? Have they been drilled out to allow a less restrictive throughput ?

4) How many 45 & 90 degree fittings are in your system ? Are they plastic ones or copper plumbing type ?

PolakATL,

I'd suggest you also read the article, "Maximizing flow rates" by pHaestus. It's on the front page of this site & is a great article on getting the most you can out of a pump/system.

pHaestus,

Thanks for the interesting link.