Do I convert to FWC , 454's with 250 hrs on them?

[Donzigo]

Well, the post is the question. Is there any advantage to converting to FWC with 454's , installed 1996 by previous owner? The engines have been run in salt water since new in 1996. Look and run great. I have a Donzi Z-33, 1989, with 250 hours on the engines.

I intalled a 454 with FWC on my Z-25 that I just sold to Dennis Bosch, of Vermont. I love the FWC; but, people tell me that once the engine has been run, even for a few hours in salt, that FWC won't help a thing.

[MOP]

My opinion why not, if you run a good desalinizer then the two part Dupont flush that should clean all the gunk out of things. The rust inhibitors in the anti freeze or Nal-Cool if you prefer should do the rest.

[Woodsy]

Donzigo...

If you choose to convert to FWC, I would start by flushing the motors thoroughly, just like MOP suggested. If you have 250hrs on your exhaust manifolds, I would replace them at this time, no need to spens all of this $$ on FWC, only to lunch a motor because of a bad manifold or riser. New water pumps & thermostats might not be a bad idea either.

Woodsy Von Donzi

[MR MAGOO]

Definatly not, with the age of the motors and 250 hrs of use, the blocks will have some scale in the coolant passages and will clog the heat exchanger with rust/scale. I had recently removed a fresh water cooling system that had been installed by the new owner of a 311 Formula with similar hrs for this exact reason.We also had to replace one motor because it had got too hot.(oil temp went to the moon!)and overheated badly.

[Rodger]

Mr Magoo has a good point. Four times I have put marine engines into cars and I had trouble with clogged radiators and heater cores. Backflushing corrected the problem but I had to do it several times over a few weeks until the problem did not re-occur again. I flushed each engine thoroughly also, before installing it in the vehicle.

[BigGrizzly]

First of all a heat exchanger has much bigger tubes than and auto does. It really depends how crusty the old block is, so I can't say yes or no at this point. However I would take the chance.

[Donzigo]

Thanks for alll the information. I forgot to say that I bought the boat about 9 monthes ago and took both engines out at that time and completely re-worked them.

New:
Water pumps
Exhaust manifolds
Raw water pumps
Risers
Power steering pump
Carbeurators
Starters
Alternators
Gaffrig dash guages and senders

Outdrives:
Seals
Steering arms
Transom plates
Gimbal bearings

The previous owner had installed the engines a while ago, as I stated; but, never put many hours on them. I did the renewals; bacause I wanted to be sure to start with new everything, within reason. Most of these things were in good shape; but, aged. Of course, the exhaust manifolds had to be replaced, for sure.

Now, knowing this new information, everybody still have their same opinions.

[Forrest]

It all depends on how much rust is now in the engine block and heads, and that better be close to none. I'll go with Magoo on this one. I personally wouldn't do the conversion until it was time for a rebuild. At that time I would go for another block and heads, used from the automotive world where the cooling passages have never seen salt water, or new. Once you old block is well seasoned and eroded with salt water, it's almost impossible to clean it all out like new again. Also, rusty blocks don't cool worth a darn. Oh yea, your temp gauge may show that it's normal, but rust is a great insulator of heat. In one diesel engineering handbook that I have, it states that 1/4" of rust in a cooling passage is equal to 4" of cast iron in heat transferability. That's a bunch!