Prior to this engine, the temp gauge seemed correct? Clean the canon connector and check all those gauge connections and try using one of those temp guns at the the points along the way.

On a hose mine takes a long time to warm up to 160. Maybe close to 10 minutes.

5 hours ago, derekt2 said:

Thanks for sharing! I just discovered I blew between 4 & 6 as well. Water in cylinders, and oil is tan. Thanks for posting the part kits - what shop were were you going to send the heads to where you ended up getting new ones? I'll likely have to do the same. 

This will be my first head gasket change - any tips other than disassemble and reassemble? 

Did you do a compression test?  You could have leaky exhaust manifolds instead.  Test it before you pull it apart.

Is your engine a multiport injected one, or throttle body injected?

5 hours ago, derekt2 said:

Thanks for sharing! I just discovered I blew between 4 & 6 as well. Water in cylinders, and oil is tan. Thanks for posting the part kits - what shop were were you going to send the heads to where you ended up getting new ones? I'll likely have to do the same. 

This will be my first head gasket change - any tips other than disassemble and reassemble? 

That sucks that it happened in the middle of the summer! Hopefully my experience will help you out and get you back out there.

1 hour ago, Woodski said:

cover your carpet before you start

Yeah definitely do that. I had towels covering every inch of carpet. I also removed the rear bench and the observer seat to minimize the chances of ruining something. I also pulled the doghouse out of the boat, that made everything way easier to work on.

For the torque specs and instruction, I used a Clymer's Indmar shop manual. This book has every instruction you need to take it apart and more importantly, back together. This thing has been super useful not just for the work I did on the head gasket, but on my friends' Malibus and their issues.  https://www.amazon.com/Indmar-Inboard-Manual-Engines-1983-2003/dp/0892879769

The name of the shop is Fast Times Motorworks INC. I never dealed with them directly. My buddy owns a mechanic shop who was helping me with the rebuild. He's the one who had previous business with them, so he was the middleman because he gets better prices with them.  https://www.fasttimesmotorworks.com/ 

While I was working on it, I ended up replacing a lot of stuff just because it was apart and I had the time. Some stuff needed it like my raw water pump looked pretty worn out and my exhaust hoses were collapsed. So just inspect everything as you take it apart to see if it has a lot of wear. My engine had 1150hrs on it so a lot of parts were at the end of their life span.

The only thing I can think of that wasn't in the book was to put the lifters in oil a day before you put it back together to pump them up. 

A good place to look for poor electrical connections is the engine harness connector.  Your model may have split male pins.  If so, use a small blade to very gently pry the split pins apart to get better contact with the female sockets.  Use a bit of grease or spray oil to keep oxygen away when you put it back together.