FWC Initial Operation

[Ando]

Is there a protocol to follow prior to introducing antifreeze into a heretofore raw water cooled A4?

Fresh water flush, I assume? Muriatic acid too maybe?

Is there an issue with just putting in the antifreeze without a flush (ie intro antifreeze with whatever remnants of raw water may be in the engine)?

[ronstory]

My two cents would be to try and clean the block the best you can before you add the HX and antifreeze.

I didn't go that on my 2nd new-to-me engine and there was a bunch of residue from the engine that coated the HX and the catch reservoir with a black sludge in the antifreeze. It was sludgy enough that it permanently stained the reservoir, and looking gunky. (those are technical terms )

I ended up draining and replacing the antifreeze twice and running it before the before it maintained the correct Mountain Dew color. When I replaced the anode 18 months later I pulled the HX and filled it with vinegar to get the rest of residue out of the raw water side. The reason I did that was it didn't seem to be cooling as good as it should with 50 degree water, and once the HX was cleaned... all was nice and cool.

Live and learn.

[sastanley]

Ando, Now that most of us are just about safe from worrying about blocks freezing...
After FWC conversion, I ran my engine for several hours with plain water and some vinegar to try and clean things out before adding antifreeze. I had an entire cruising weekend where I brought a couple gallons of vinegar and a 5 gallon jug of water and ran for a couple hours, drained, re-filled and ran again. If you are lucky enough to get the plain water/vinegar clear, you can probably be safe adding antifreeze.

Agree with a muratic flush before introducing the HX, etc. The risk to simply adding antifreeze is it will be muddy and it is $12/gal and plain water is free and vinegar is cheap.

[ronstory]

Yes, I wish I had done that. (sigh)

EDIT: What ratio of water to vinegar did you use?

[sastanley]

I don't remember..I bought a couple gallons of cleaning strength vinegar from Walmart...Probably like 3:1 water to vinegar. Anymore than that and the smell drove out of the boat.

[ronstory]

Got it and thank-you!

[Ando]

Ando, Now that most of us are just about safe from worrying about blocks freezing...
After FWC conversion, I ran my engine for several hours with plain water and some vinegar to try and clean things out before adding antifreeze. I had an entire cruising weekend where I brought a couple gallons of vinegar and a 5 gallon jug of water and ran for a couple hours, drained, re-filled and ran again. If you are lucky enough to get the plain water/vinegar clear, you can probably be safe adding antifreeze.

Agree with a muratic flush before introducing the HX, etc. The risk to simply adding antifreeze is it will be muddy and it is $12/gal and plain water is free and vinegar is cheap.

I know that I need to remove the thermostat for a muriatic acid flush, but how about a vinegar flush?

[ndutton]

I know that I need to remove the thermostat for a muriatic acid flush, but how about a vinegar flush?

Yes. The only difference is the concentration of the acid.

[Ando]

Flush completed. Now what?

Fill the hx with coolant and keep the cap off to add coolant as necessary during initial operation, ok. But:

1. Do i need to put coolant in the overflow tank?

2. Do I open the thru hull valve before or after the engine is running?

3. Prior to installing the FWC system, I had an anti-siphon installed in the exhaust discharge. Is that still a good thing to have or is it no longer necessary?
If it is good to have, does it still go at the high point of the raw water discharge leading to the exhaust or somewhere else?

Thank you all for getting me this far. I do appreciate it.

P.S. I did have a hiccup during the muriatic acid flush. Engine stopped running after taking in ~2.5 gallons of the fresh water/acid mixture and wouldn’t turn back on. All I was thinking was that the mixture that was still in the engine was going to melt it. Ndutton advised me to disengage the water discharge hose and put a garden hose to the coolant input to flush out the mixture from within the engine. Thankfully, I have a hose that fits to the input barb on one end and that has a fitting on the other end that attaches to a garden hose. So the process look less than 10min from when the engine stopped to complete mixture removal.
I then had time to track down the non operating engine. The fuel pump would engage for a second and immediately stop so I removed the + at the starter and the. bypassed the OPSS and then ran the gas line to a clear jug to ensure gas is flowing. It was. Reinstalled the gas line and this time the engine started right up. OPSS is still bypassed for the time being. I left the jug with the gas in it overnight and there is no water in it, which is nice. What can I do to reduce oil pressure so that the OPSS is happy?

[edwardc]

Don't worry about the overflow tank until the main coolant loop is full (no air).

Start the engine with the valve closed, as usual, and open it after starting.

The anti-siphon should remain, in the same place it was, in order to avoid the possibility of starting a siphon and back flooding the manifold.

The OPSS goes off on LOW pressure, not high. Usually somewhere below 5 PSI. But it is a strong possibility that the OPSS itself is bad. First check that your oil pressure is OK and then replace the OPSS. (Rule of thumb is a minimum of 1 PSI per every 100 RPM).