RAW To Closed ?

[starsnstripers]

Have a 1979 5.7 Mercruiser raw water system. Found a Heat exchanger for the change over. My question is do/will i need a different themostat housing/housing cover setup also ? Thanks, for any info, pics, diagrams. Cant tell in the parts diagrams or service manual.

 

[Fishermark]

Re: RAW To Closed ?

If you are changing over an engine that has been raw water cooled for a while, I understand it is NOT a good idea to try this change over. The damage has already been done, and once salt settles into the block it will continue flaking off pieces which will clog the heat exchanger.

 

[starsnstripers]

Re: RAW To Closed ?

This Boat has always been in fresh water and i am going to use it in salt, so i would like to get some longevity from it by having a closed system. Thanks Mark, i agree.

 

[starsnstripers]

Re: RAW To Closed ?

Does anyone have a picture of the front portion of their 5.7 Mercruiser closed system with the therm. housing and heat exchanger setup/plumbing? Thanks

 

[starsnstripers]

Re: RAW To Closed ?

This is what i have, What do i need? (see attached) Can i use this therm. setup or do i need a different one? Plumbing diagram? Thanks

 

[Don S]

Re: RAW To Closed ?

This Boat has always been in fresh water and i am going to use it in salt, so i would like to get some longevity from it by having a closed system. Thanks Mark, i agree.

It may have been in fresh water, but it was not in antifreeze, so you will have rust in the cooling passages of the block. When you convert to FWC, you MAY end up plugging up the heat exchanger, and it won't be the side you can flush out and get to to clean. I have installed them before for customers and had about a 50% success rate. Then you either replace the heat exchanger or possibly have a radiator shop take it apart and clean around the tube bundle if possible.
If it works, fine, if not, you will probably plug it more than once and it just won't be worth the expense, especially if it's a trailer boat, and you just flush the engine after each use.
If you want to try it, go for it, I will answer your t-stat housing question in a seperate reply.

 

[starsnstripers]

Re: RAW To Closed ?

WELL, Thats something to think about. Thanks Don, I would still like to know on the therm. incase i decide to try it and/or if i repower this or another boat? I'm getting a 25' Cruisers this spring so i may need to know for that boat too. Can this housing be used or? And any plumbing sketches would be helpful. I found a good exchanger for 150. which i'm going to get anyway. Good info Don, Maybe i'll flush the engine and see what comes out if it's alot of rusties i may pass. It is going to be trailered also. thanks

 

[Don S]

Re: RAW To Closed ?

Haven't got to it yet, but I will

 

[Don S]

Re: RAW To Closed ?

It all depends on how your heat exchanger is setup as to what thermostat housing you would need.
That's why when you convert from a raw water cooled system to a FWC system it comes as a kit. Different thermstat housing, different hoses and fitting for either a half or full system.

 

[starsnstripers]

Re: RAW To Closed ?

The exchanger is the mount on front of engine style with top tank smaller with pressure/fill cap and bottom tank larger. I wanted the diagram for full sytem Don. Let me guess, there;s still diferent style exchangers that mount on front of motor, right? Can i use my existing therm. housing or? Whats the typical full closed system diagram for 1979 5.7 I guess is what i want.

 

[Don S]

Re: RAW To Closed ?

Let me guess, there;s still diferent style exchangers that mount on front of motor, right?

Lots of different ones. Dependes on Volvo, OMC, Mercruiser, full, half, mostly where the ports are and which way they are pointed, along with how many. Just all sorts of different things. You can't use a half system HE for a full system. Not enough ports.

Service manul #3 has diagrams of a closed cooling system in it

 

[FreeBeeTony]

Re: RAW To Closed ?

see if this helps..............

 

[starsnstripers]

Re: RAW To Closed ?

HOLY! This would be a Mercruiser 5.7 Don. So it has to be a full heat exchanger as well. I have no clue what exchanger it is. Ok, Does the haf system HE have 4 in/outs? and the full have 6 ? How are they determined? I guess we'll start there so i know what i'm buying. I'll have to call him and determine it somehow with out seeing it. Do i ask 4 or 6 ports?

 

[Don S]

Re: RAW To Closed ?

Let me ask this, is it an OEM Mercruiser HE or aftermarket, if aftermarket, which one? Then, are you sure it's Chevy or Ford, and the type manifolds may dictate what goes where.
I get this all the time at work. Someone comes in with a boat and a heat exchanger and says "Here's what I want"
Never had to hook one up yet. Either wrong ports, won't fit, no brackets to mount to engine etc.
Look at manual #3 in section 7C, there are different diagrams.

 

[starsnstripers]

Re: RAW To Closed ?

Ok Don I'll do some homework. The guy i was getting it from probably doesn't even know that. He'll hang up on me when i ask him. LOL I'll check the manuals and see if i can distinguish which one i need. Or which system i need. Thanks Don I'll be back!

 

[starsnstripers]

Re: RAW To Closed ?

Thanks Tony, I need a diagram though can't tell by that what therm housing i need or where all the lines go. Nice engine though

 

[Don S]

Re: RAW To Closed ?

Ok Don I'll do some homework. The guy i was getting it from probably doesn't even know that. He'll hang up on me when i ask him. LOL I'll check the manuals and see if i can distinguish which one i need. Or which system i need. Thanks Don I'll be back!

Pictures are your friend

 

[starsnstripers]

Re: RAW To Closed ?

Thats what i wanted Pics and diagrams. Gotta love em.

 

[Don S]

Re: RAW To Closed ?

I'm talking about pictures of your heat exchanger, I gave you diagrams to look at, did you look at em? With some study, it will become obvious what each port does and why.
Of course, with way over 20 years of experience with a lot of different cooling systems, makes it a lot easier to see problems that others might miss.

 

[FreeBeeTony]

Re: RAW To Closed ?

My therm housing has 2 outputs.............each go to the bottom of each manifold............the return of each manifold returns to the H/E............this is a full system. Not sure if this helps you.