No I leave it in about 2 weeks at a time. i just wanted to clean these in the water so I can test run it afterwords to see if it worked. The bag idea is really smart

Put the ears for flushing on it with a short hose kept above the waterline.

^^^ Agreed. Don't just change the impeller.

Ok so now I have

1. Changed Impeller with housing
2. Replaced H20 sensor
3. Cleaned Sea Strainers
4. Flushed The Oil Cooler & Heat Echanger out with water
5. Back Flushed lots of Hoses off everything

Still have a water pressure issue. Next Step?

My friend said to get a 22 cal rifle cleaner, and run it through the tubes of the heat exchanger. Anyone try this?

Just checking, but you removed the ends of the Heat Exchanger. and made sure all of the passages are clear, correct?
You have all of your cooling coming through the drive, correct? You do not have through hull pickups, correct?
You have verified with SmartCraft or Scanner that the computer's reading of water flow is low on that side correct, just not the
Problem exists 100% of the time, correct? Idle, and when running at different speeds?

One last test while in the water: Start and idle both of your engines. Does the water flow look even across all four exhaust pipes?
The 600SCi, also has separate cooling thru-hulls too I believe. If so, does the exiting water flow look even across both engines?

I think it's time you pull the boat, and start checking the outdrive and transom assembly. I have seen the transom assembly passage and hose on a (33') Baja get so corroded and full of crap that it had to be replaced. You could also have Zebra mussels or other growth in there. I pulled the motor OB motor off of my 17' catamaran and found Zebra mussels that had made their way into the transom bracket's nooks and crannies, that were never visible when the motor was on the boat.

Pull the ends off of the heat exchanger, and look across it with a droplight or sunlight on the other side. You will be able to see if you have blocked passages.
If you can't do this when installed, remove it. and do it on a bench. I feel like you could do this with the boat still in the water as this is way above the water line.

I have not looked through the passages yet. im going to look, and clean them with the rifle cleaner this evening I suppose. I only flushed it out with water so far.

All the cooling is through the drive, and the drive is def not the issue.

The problem is def not in the smart craft it is def a clog somewhere

Yes at idle the boat has very similar water flow on both engines. it only when you are moving and give it more RPM when you notice and see H20 loss on thr smart craft and it put it into guardian

The outdrive is brand new. Does even have 1hr of run time. The transom/drive are already checked.

Just be careful with the 'rifle cleaner' in the tubes of the heat exchanger. They are quite thin brass tubes. You don't want to damage one forcing having to braze it shut, or a replacement h/e. Flushing with water isn't really going to do much as that's all running the boat does: pushes water through them.
It's pretty much mandatory to replace the large flat rubber washers that seal the ends of the Heat Exchanger when you take them off. Make sure you source these from your dealer before you take the ends off.

In looking at a few pictures of that motor online, and knowing how tight the bilge is on a 30' Baja, I don't know if you are going to be able to do much with the ends off of the heat exchanger while everything is still on the boat. Good luck.

I tried this spring but it was too large. Ended up finding a small diameter length of Dowling.
agree with sydwayz on the transom hose.
ok isee this has been checked or changed.