Another cracked head!

I want to drain and flush until clean but the PO tried that and I don't think did a good job. I'm told if I don't drain from the right places, crud won't flush out. Trying to learn the best way to do it.

The crack allows air to enter the cooling system on these. I suppose it could go into the oil, but it's not and I'm told this is common on DD 92s. Just the way it goes, I guess.

Still cheaper than some other things. My buddy has to do a service on his IPS drives and he will pay the marina almost as much as a head job will cost me (doing it with my own mechanic)!

Ok then, this is a good start.
I’ll flush the coolant and have the heat exchange looked at.
I’ll also replace the wires and senders. The bridge gauges are new(ish).
Would it be worth adding more senders for temp at different spots?

I'm seeing above 180 on the bridge gauges, but haven't seen above 165 on the murphy gauage. Now I can't be certain, because I slow down before running down to check the murphy gauge. My wife doesn't like to drive. It's possible it was up higher and dropped before I can get down.

What should running temps be? My DD truck guy says they'll run at 200 all day, but everybody here seems to think otherwise (and a series of cracked heads would support the lower number!)

What thermostats should I be using? Could the wrong ones cause this?

I think the PO had heat problems and that's why he did the flush. He told me he thought there was a build up in the coolant system, possibly from an incorrect coolant/water mix, or just from age. He used some chemical, ran the boat and hour or so, flushed with water and ran another hour or so, then returned to a coolant mix. That was shortly before I bought the boat and started to find crud in the overflow.

How should I flush the engines? Preferably a way I can do it while out of the water. I've got a few spare pumps of various sizes that I could use to circulate.

What else should I look at in the cooling system? The heat exchangers have been looked at and I'm told they're fine.

Thanks for all the help and support so far. This is frustrating, more so because I can't figure out what's wrong!

This may sound silly, so forgive my ignorance. I don't think I have raw water strainers. I see the inlet for raw water but there isn't a strainer there that I can see. Is it possible I don't have one? Maybe it's there and I'm an idiot and don't see it?

Beau,
I'm out of the water now. My gauges do run differently, we've verified that at warm up at the dock, what I'm not sure is how big the difference is at load.
I am taking everything said here and looking at it, everything!

Here's the raw water inlet. in case that is a strainer
https://photos.app.goo.gl/ssRhhAuHP7CW698YA

Since it's out of the water, that should be easy to check I'll try to get there tomorrow!

I've always suspected a wiring issue with the bridge displays. the mechanical gauge was tested accurate (at the dock).
The bridge gauge would go screwy when I turned on my engine synchronizer up until this year (I ran new wires to that). IT would go up 20 degrees as soon as I engaged it, drop as soon as I turned it off - only when the engine was running though.

Thanks. I’m planning on doing he ridlyme flushing for sure.

I’m going try to get there today or later this week and check the strainer. Not sure what I’m looking for but will look under the boat and hopefully it will make sense.

I'm pretty sure I don't have one of those.

Maybe I do t have one at all?