Thermostat Housing Replacement - 1993 7.4L/Bravo 1

[FuelishBehavior]

Does someone know of a stainless steel replacement for the big bulky thermostat housing part no. 16413A 3? There seems to be a stainless steel equivalent but it doesn't seem to have enough outlets. It seems to be missing two. Is this the right one or is there something else out there that can be used besides the huge bulky rusty clunker on the stock 7.4L's?

 

[alldodge]

The 16413A9 housing is NLA but can be found on ebay and the like sites. Don't know of anyone making a stainless for them and my guess would be very few would be sold. You could use the one shown in your post but would also need to redo plumbing

 

[FuelishBehavior]

I'm ok with re-doing the plumbing,can you elaborate?

 

[alldodge]

This is what you have now. It has hoses connected to the top elbows and bottom manifolds. The two hoses with arrows are removed.



Once removed the openings are plugged. If you have screw in fittings, just remove fittings and install pipe plugs. If it is part of the elbow, then use item 12 in link below to cap off
http://www.mercruiserparts.com/bam/subassembly/31914/1621/150

Then install new housing so it looks like this. You won't have item "C" it is cool fuel module

 

[FuelishBehavior]

That's what I thought would happen. So the upper hoses are completely eliminated. I assumed this was some kind of return. Now the water pumps through the bottom of the exhaust manifold then up and out through the exhaust riser? Seems like a much cleaner installation and less bulky plus two less hoses. Does this have any negative cooling or heating effect that you know of?

 

[alldodge]

Cooling flow is better and will have no impact so long as everything else is in working order. If you notice item 10 in the old housing, these are check balls to help keep the manifolds/elbows full of water but allows water to leave thru the elbow. Without them the new style sends all water thru the manifolds and out the elbows so there is no backflow problem.

 

[FuelishBehavior]

Awesome, thanks AllDodge, I'd hate for my new 496 stroker to get hot. It has been an interesting build going from a Gen V 454 to a Mark IV 496 stoker. I've switched sea water pumps to the cheaper ones that came on the Mark IV's and then utilized the Gen V tensioner pulley for ease of belt tightening and removal as well as had to change the oil adapter because of the bypass valve differences but it's been an interesting build to get the best of both worlds when it comes to an engine with the best upgrades with the lower costs for aftermarket parts on the Mark IV's. Plus I like how stainless steel keeps my parts from rusting.

 

[alldodge]

Sounds like a great build, is there a thread with build to look at?

 

[FuelishBehavior]

I have not done one but I probably should do one in case someone wants to do a Gen V replacement with a Mark IV block and use parts from one to improve on the other. I'm also experimenting with aluminum heads (low cost ones) since I run in fresh, brackish and salt water but I'm a stickler for flushing and using salt away. I want to see if they really fail like some have indicated but that's for another day. I may be mistaken but pretty much every outboard I've ever seen is made of aluminum (I know they drain better). Where would I start this thread?

 

[alldodge]

For a Merc build it would be in this same section for Mercruiser

Your going to need to run the motor for some time to get all the salt out of the bloc. The thermostat opens and lets in some cool water then closes off until it needs to open again. If you were running on full plane in fresh water it wouldn't take as long. Running just at idle on muffs it will take awhile.

 

[FuelishBehavior]

Yeah, I would agree with you on that regarding the thermostat. However I do run my engines on the muffs for the better part of 15-30 minutes just as a precaution. Also, since I live on a fresh water bayou, my trip from the Gulf goes from salt, to brackish to fresh so I have a bit of an advantage on flushing. It probably makes more sense to do a closed cooling system. It's on my list of to dos.

 

[alldodge]

It probably makes more sense to do a closed cooling system. It's on my list of to dos.

:thumb:

 

[Scott Danforth]

I would do at least a half system.

 

[FuelishBehavior]

Hey Scott, what is the difference between the half system and the full. From what I can see, the half only uses closed cooling on the block and then uses the raw water for the exhaust system, is that correct?

 

[Bondo]

Hey Scott, what is the difference between the half system and the full. From what I can see, the half only uses closed cooling on the block and then uses the raw water for the exhaust system, is that correct?

Ayuh,.... Correct,.... The full system also cools the manifolds, 'n exhausted raw water is dumped into just the risers,...

 

[kdt]

actually this is what they call a "cool exhaust manifold thermostat housing" it allows coolant to flow to your exhaust manifolds during engine warm-up before the thermostat opens, notice the position of the thermostat in relation to the other style,they do make a ss model