Flushing raw water side of 5.7GXi-HF

[HiWard]

I want to flush the raw water side of my 2007 5.7GXi-HF with Rydlyme or something similar. The drive is a DP-SM.

In order to do this, I had the idea of removing the lower unit, connect one end of a hose to the threaded fitting on the the gimbal housing and the other end to a ciculating pump placed in a large bucket under the exhaust bellows outlet. I might also remove the impeller to reduce restriction. In theory, this would allow me to circulate the Rydlime without running engine.

Has anyone tried this? I have some concerns with regard to the risers and the odd chance some of the circulating fluid can somehow find its' way into the exhaust.

 

[Scott Danforth]

no need to remove the lower

pump water into the hose from the raw water pump and push it thru the motor for a bit. catch everything that comes out the idle relief ports and the drive exhaust

then switch the pump to the inlet side of the raw water pump and push backwards thru the PS cooler, drive etc.

 

[BRICH1260]

What is Rydlyme and what is the purpose?

 

[HiWard]

no need to remove the lower

pump water into the hose from the raw water pump and push it thru the motor for a bit. catch everything that comes out the idle relief ports and the drive exhaust

then switch the pump to the inlet side of the raw water pump and push backwards thru the PS cooler, drive etc.

Thanks for your input. I would be doing this as a part of winterizing the boat so the lower unit is coming off regardless. This being a freshwater cooled engine, the flushing is for the heat exchanger, exhaust manifolds/risers and fuel pump. Is my concern for the risers unfounded? I would think the flushing agent will just go down the y-pipe and exit through the exhaust bellows relief ports. I would ideally have this circulate for a few hours.

 

[HiWard]

What is Rydlyme and what is the purpose?

It's a descaling agent meant to remove marine growth etc

 

[Bt Doctur]

I think your over thinking a problem that does not exist

 

[HiWard]

I think your over thinking a problem that does not exist

I have been known to do this from time to time… Thanks for settling my concern

 

[Scott Danforth]

why would you remove only the lower and not the whole outdrive for winterizing?

 

[HiWard]

why would you remove only the lower and not the whole outdrive for winterizing?

Sorry, my mistake, I meant the entire outdrive. There is a threaded fitting on the gimbal housing where the hose feeds raw water through the transom, thought I’d connect my flush hose there.

 

[Donald0039]

Is the engine RWC or FWC?

 

[HiWard]

Is the engine RWC or FWC?

Raw water cooled with heat exchanger so the block is fresh water cooled.

 

[tpenfield]

I take a marine de-scaler in through the muffs (about 5 gallons of it) and let it sit for about 6 hours. It cleans out the Heat Exchanger nicely. I do it once a year. Otherwise, the tubes within the H.E. tend to clog with calcium build-up.

There are a few product names for the solution, Rydlyme being one of them. Barnacle Buster does the same thing.

I think a have a thread or 2 here on iBoats about de-scaling the Heat Exchanger

 

[HiWard]

I take a marine de-scaler in through the muffs (about 5 gallons of it) and let it sit for about 6 hours. It cleans out the Heat Exchanger nicely. I do it one a year. Otherwise, the tubes within the H.E. then to clog with calcium build-up.

That is a good suggestion and a good way to descale the heat exchanger and the bottom half of the raw water cooling circuit. However, I wanted to get some circulation on this in order to also clean the passages of the exhaust manifold and risers as well as the fuel cell.

 

[tpenfield]

Sounds like you have a 'half' system, so yes you might want some circulation. The manifolds will get de-scaler solution, as long as you use enough of it. The risers may benefit from some circulation of the de-scaler.

Typically on the exhaust, it is more about rust.

 

[HiWard]

Sounds like you have a 'half' system, so yes you might want some circulation. The manifolds will get de-scaler solution, as long as you use enough of it. The risers may benefit from some circulation of the de-scaler.

Typically on the exhaust, it is more about rust.

Correct. Do you see any problems with the setup I described in my original posting?