Issues with an older Iwaki RLT4

reefknight · Feb 15, 2015

I have an older RLT40 , probably 15yrs old. Pump was only used for maybe 1.5-2yrs and lightly at that. Either way the pump is now making a loud growling noise, and is not really pushing any water. I have it installed as a recirculating pump on my salt mixing station. I have cleaned the pump well, but it still is not operating. Now if I remove the front and rear casing, o-ring and impeller and plug it in it hums along nicely without any noise. My thought is that the bearings are shot in the front/rear casings and should be replaced. Correct? Also can anyone verify whether or not the shaft in the impeller should spin freely or not? Its been so long I cannot recall.

Any thoughts would be appreciated, thanks!

reefknight · Feb 16, 2015

gcrawford · Feb 16, 2015

I have a few iwaki pumps in service and spares....this model's impeller does not spin on a shaft. The bearings are built onto the impeller which spin freely on the housing if they were made like the newer ones. If the impeller has red bearings on each end, they should be fixed on the impeller. Hope that makes sense.

pmorphb28 · Feb 17, 2015

I have a question as well. I purchased a iwaki md-100rlt for my 120 and its a beast. Started it today and my wife is really irritated. Its pretty loud. Can anyone help? Also, if I'm SOL is there a quiet pump you all would recommend for a living room set up?

Thank you for your time!

wangspeed · Feb 17, 2015

pmorphb28 said:
I have a question as well. I purchased a iwaki md-100rlt for my 120 and its a beast. Started it today and my wife is really irritated. Its pretty loud. Can anyone help? Also, if I'm SOL is there a quiet pump you all would recommend for a living room set up?

Thank you for your time!

If I were you, I would get a Jebao DC pump and be done with it. 6000 is probably more than sufficient for you unless it is pushing from the basement.

reefknight · Feb 17, 2015

pmorphb28 said:
I have a question as well. I purchased a iwaki md-100rlt for my 120 and its a beast. Started it today and my wife is really irritated. Its pretty loud. Can anyone help? Also, if I'm SOL is there a quiet pump you all would recommend for a living room set up?

Thank you for your time!

I agree with the suggestion of a DC pump, whether its Jebao, Waveline, etc. Also Unless you are pushing from a basement or operating a closed loop an external is just not practical due to noise and heat factors. I would also recommend the Eheim 1260 or 1262, ATB Flowstar ( or Askoll Laguna motor block pump). You can find these in pond sections of some stores or online. These are also extremely quiet pumps, very efficient. Same motor block that Red Dragon uses before modifications are made. For you situation, a submersible pump would be my recommendation. Less heat, less wattage less cost to operate 24/7/365.

Hope this helps

reefknight · Feb 17, 2015

gcrawford said:
I have a few iwaki pumps in service and spares....this model's impeller does not spin on a shaft. The bearings are built onto the impeller which spin freely on the housing if they were made like the newer ones. If the impeller has red bearings on each end, they should be fixed on the impeller. Hope that makes sense.

Awesome, thank you! I couldn't recall after all these years. Mine does have the red ends (bearings) on the impeller shaft. Since you have a few on hand and in service would you believe that the casings required replacement or the impeller?

pmorphb28 · Feb 17, 2015

Thank you so much for the help! Ill start researching those.

gcrawford · Feb 17, 2015

reefknight said:
Awesome, thank you! I couldn't recall after all these years. Mine does have the red ends (bearings) on the impeller shaft. Since you have a few on hand and in service would you believe that the casings required replacement or the impeller?

Possibly both, as a set. Bad news is I tried to get a replacement impeller and housing (not cheap) and the vendor could not deliver and ended up refunding my money. You might have better luck. I find that regular cleaning and NEVER running dry keeps them running for years.

reefknight · Feb 18, 2015

pmorphb28 said:
Thank you so much for the help! Ill start researching those.

You're welcome, good luck!

gcrawford said:
Possibly both, as a set. Bad news is I tried to get a replacement impeller and housing (not cheap) and the vendor could not deliver and ended up refunding my money. You might have better luck. I find that regular cleaning and NEVER running dry keeps them running for years.

Ugh, I was afraid of that. I was hoping of just being able to replace the front/ rear casings and due to age the o-ring and not have to replace the impeller. The impeller is almost half the cost of a new Pan World 100px, the equivalent to the Iwaki. Ugh...decisions, decisions.

Thank you for your suggestions, they have helped tremendously!