Exhaust Log Question

[83Dana454]

Purchased my first boat last weekend, a 83 Dana with a 454, berkeley pump with place diverter. My question is what is the proper way to route the cooling lines though the exhaust logs. It is Indmar Marine Engines Exhaust logs with 3 ports: 1 in the front, 1 in the rear, and 1 on the riser. How it is hooked up from the previous owner is from the pump it goes though a valve, from there it goes though a T, then to both water pump inlets of the block, from the waterneck it goes to the front of the exhaust logs, from the rear of the exhaust logs it is connected to the top of the risers. From what I read in previous posts this is incorrect and should go though the bottom of the logs first. Is this correct? And if so what makes the water flow though the block instead of just flowing though the logs and out the exhaust because all of the 3 ports on the exhaust are connected. Any info or a possible picture of a indmar setup would be appreciated.

[Jordy]

This is the correct way to do it (thanks Flat Broke):
http://www.liquidaddiction.net/images/logs.jpg
On my Schiada jet with the logs, it ran from the pump to a T, from the T it ran to both of the rear fittings on the logs. From the front fittings on the logs it ran to the water pump inputs. Then from the t-stat housing it ran back and dumped out behind the snails.
Hope that helps ya out.

[flat broke]

Don't thank me, I merely posted what other jetters supplied for the site ;)
I've seen the setup above, and a setup without the preheat by routing to logs before the block work just fine. Just depends on what you're looking for.
Chris

[sidewound]

I preheat my water through the logs but that's cause I live where the agua is pretty cold in spring and fall. I think if you only boat in warm water you don't need the preheat.
Peace Man!:cool:
CESAR

[83Dana454]

Ok maybe I'm thinking too hard, missing something, or a combination of the 2.......but what keeps the incomming water from just going up though the logs and out the exhaust and not going though the engine if I send the water though the logs first? I have 3 ports on the exhaust: 1 in the front, 1 in the rear, and 1 on the riser.......and they are all connected to the same waterjacket in the exhaust. Is the water jacket supposed to be blocked off between the log and the riser? I could see it working that way because the water would be pushed though the log then into the engine because there is no other path for it to take. But without it being blocked the water could go though the engine or flow up though the riser without going though the engine. As you can tell I'm new at this and don't have anyone around here to point me in the right direction and I would hate to starve my cooling system due to lack of my knowledge on the subject.

[83Dana454]

Here's a pic of how it is plumbed now:

[Jordy]

From the looks of it you're running cold water into the water pump inlets and dumping the water out of the t-stat, through the logs and out the exhaust. That's certainly one way to do it, but it all kind of depends on the water temp in the area you boat.
As far as the ports, the one on the back of the log is attached to the front, as there is a tube that runs through the log to preheat the water before it enters the engine. The one's up top are just a dump.

[83Dana454]

My logs must be messed up then because when I disconnected the lines and blew though the front port with compressed air and covered the rear port with my finger the air would come out though the water jacket.

[Jordy]

Well you got me on that one. The boat I had with the logs on it weren't that style, but I didn't figure that there would be that much difference.
Have you ever had the snail part off? Did air blow out the back port when it was uncovered? I'm thinking now after seeing the pics that they are more water jacketed style rather than the older jet boat/v-drive logs.

[King Kuracz]

Originally posted by 83Dana454
And if so what makes the water flow though the block instead of just flowing though the logs and out the exhaust because all of the 3 ports on the exhaust are connected. Any info or a possible picture of a indmar setup would be appreciated.
I have seen those manifolds on another setup and it was plumbed similar to that.
If the lines are routed as you say, the water has to pass through the block before it can exit. Here's the flow through that system:
COOLING THE BLOCK:
pump to tee, tee to front of block, through block into heads, heads to intake manifold, out thru the stat housing (for lack of a better term, there is no stat in there) to the front of the exhaust manifold. From there..............
COOLING THE EXHAUST:
from the stat housing into the front of the ex manifold, thru the manifold, out the back of the manifold and into the risers where it dumps out with the exhaust flow.
Since these are not the usual logs we deal with in a jet, I think that is where some of the confusion comes from. The only downside to this routing is there is no preheating of the water.
Looks like a sano setup to me. IMO, I wouldn't change it out and loose all those and nice routing unless you do a lot of boating in very cold water.

[83Dana454]

I took the riser off and it does look just like a cylinder water jacket to me, about 6 ports for the water to flow from the logs up and though the risers.

[Moneypitt]

The back of the logs should be blocked from the risers with thin stainless with gaskets on both sides. This keeps the water from entering the "snails" in the area where ONLY exhaust gasses should be. The inlet/hose on the risers lets the water into the exhaust passage AFTER the rise. This prevents water from getting near the exhaust valves. Preheated or not, the water leaving the boat goes out the risers, after the rise..........If the metal is missing the water will erode the gasket paper and enter the riser in the wrong place, which could be a bad thing.........

[King Kuracz]

I'm thinking that the reason for the rear exit to the riser is that if all the water passed into the exhaust at the riser connection, it would starve the rearmost portion of the manifold for water. This way it keeps a consistent flow thru all areas of the manifold and eliminates hot spots or vapor pockets.

[83Dana454]

King: I think I'm gonna take your advice and leave it alone although I would like to get the water temp up alittle bit. I have had the boat out only once since purchase. Max tem was 150 at idle and about 130 at cruise. I am thinking about installing one of the thermostat kits that I have seen mentioned in a few of the other posts. Thanks for all the responses.

[King Kuracz]

Moneypitt, not trying to be a smart ass, but did you look at the pic? There is no "back" of the manifold. These are not the usual logs, and no snails to speak of. The riser pipe is at the top. You got me thinking about the gasket deal tho...............

[83Dana454]

ya you got me thinking about that one too haha......but why would the single gasket between the long and the riser have perfect cutouts for the water to flow though the water jackets if it's supposed to have a plate to block the water flow?

[King Kuracz]

Dana, another thing to keep in mind is that the 150/130 temps you're getting can't be compared to an automotive engine with a closed cooling system. Getting proper oil temps are more critical than looking for the kind of temps you get with a closed system, IMO.

[King Kuracz]

Also, I believe the riser is jacketed as well. The water does not enter the exhaust area (from the jacket) until it's near the lowest part at the end of the riser.
I'm almost positive that riser gasket should have those holes in it for that type of system..
That system is very similar to what you would find on a Mecruiser.

[PE 316]

Originally posted by Moneypitt
The back of the logs should be blocked from the risers with thin stainless with gaskets on both sides. This keeps the water from entering the "snails" in the area where ONLY exhaust gasses should be. The inlet/hose on the risers lets the water into the exhaust passage AFTER the rise. This prevents water from getting near the exhaust valves. Preheated or not, the water leaving the boat goes out the risers, after the rise..........If the metal is missing the water will erode the gasket paper and enter the riser in the wrong place, which could be a bad thing.........
Who makes these "thin metal gaskets" and/or where can I get them???
I'm running only gaskets that I purchased from Rex Marine (with Permatex "Ultra Grey" silicone added)...

[spectras only]

make the gaskets out of aluminum yourself and just use the high heat copper gasket maker on the surface.The surface of the exh manifold & riser where it joints should be trued ,especially if it's corroded . For salt water operation the gasket should be made out of copper and annealed to make it soft to conform irregularities.