Would someone please explain how the exhaust logs are supposed to work?Last month I bought a 73 Marlin Taurus. This is my first boat so I am pretty green. The motor has a water leak that I am trying to track down. A guy from work suggested I pressure test the exhaust logs before I tear into the motor. I pulled them off tonight and the first one I checked filled up the exhaust ports? Is that normal? What keeps the water from going into the engine? Where do the little flapper doors go? How do they work? My exhaust does not seem to have any :2purples: I take it that is bad? Any help would be appreaciated.
First remove the manifolds from the engine. Plug the one water inlet. Now take about 5-10 psi of air and blow it in the other water inlet. If you can hear air coming from inside the manifold it is cracked inside. It either has frozen or got real hot then was hit with cold water.
The flappers go on the back of the boat on the outside of the exhaust tips. This keeps water from coming in when backing up.
What motor do you have?
I pulled them off tonight and the first one I checked filled up the exhaust ports? Is that normal? ................. What keeps the water from going into the engine?
If the first one you checked was the one on the riser (snail) then that is normal, that's where the water gets dumped into the exhaust to cool the hoses.
The fact that the water is injected into the outlet side of the riser is what keeps the water out of the engine. Water would have to flow backwards & uphill past the riser to get to the engine. Not likely unless you stand the boat on it's nose. Even without the flappers on the exhaust, it's not likely that you could get water past the risers by backing up, but it can, and has happened.
If you're seeing water in the exhaust ports you will probably find a cracked manifold.
Its an Olds 350 and the exhaust logs do have the snail ends. So let me understand. If these were installed on my engine, the water would not backup into the motor because of the way the snails are designed? It is because I had them laying on the driveway that they filled the exhaust ports? It looks like the snails unbolt. Should I take them apart and check for cracks? Where do I get the gaskets? Should I install the flappers? Can I adapt what I have or do I need to purchase new tips?
you dont neccesarily need the flapers, the snails do a pretty good job of keeping the water out, its a pretty good rise the water would have to go up to come into the exh ports. Pull the manifilds, keep the snails on and blow water or air into them. You need to build up some pressure though, if one/both are cracked, it might not leak till you get some serious pressure built up. Keep this setup though, dont waste your money on water jacketed headers, or if you have an open engine compartment, you can get the non water jacketed headers from rewarder that are kind of cool. Logs rock for motors that arent built up. Post a pic of your tips, you might be able to adapt flappers onto them. Go to rex marine for the gaskets, but if you take them apart, you wont need to change the gaskets. Talk to Rexone on the boards, he owns rex marine and can point you in the right direction, he is a great guy and is very very helpful, I go to them for all my boating needs (can I get some advertisment money here Mike? :rollside: )
I am still confused weather water is supposed to end up in the exhaust manifold or not? This is what I did to test them on my driveway. I used some heater hose and connected two of three nipples together. The third nipple had the water hose connected to it. The end of the snail was left open. The log was laying with the mainfold ports facing up. When the water was turned on the manifold had a little water running in it. WHen I cupped the snail end with my hand the manifold filled right up. Is that good or bad?
I am still confused weather water is supposed to end up in the exhaust manifold or not? This is what I did to test them on my driveway. I used some heater hose and connected two of three nipples together. The third nipple had the water hose connected to it. The end of the snail was left open. The log was laying with the mainfold ports facing up. When the water was turned on the manifold had a little water running in it. WHen I cupped the snail end with my hand the manifold filled right up. Is that good or bad?
OK, I think I can visualize what you've done - you've hooked the inlet and outlet for the water jacketing together, then run water into the snail outlet - what you need to do is pressurize (water or air, air is better for this test) from the lower of the two water fittings (again, I'm assuming here, but if I'm correct, there are two fittings on the front of the log, one over the other), then hook the upper fitting to the snail fitting, this will most closely approximate the water routing in the boat - when you plugged the snail end, you just imitated a blocked exhaust, the water had nowhere to go - you also saw what happens when water comes back through the exhaust (causing a condition called hydrolock), but this does not give you a picture of whether the logs are "good" or not - it's best to do your testing with air, pressurize the log, then do "the Windex trick" to check for leaks - Good Luck!
Tigger,
Forget about the snail, or riser.
Plug one of the water ports on your log and pressurise the other port...
I would prefer to do this with a radiator tester or compressed air...
submerge them in water and watch for leaks.
Tim
Lay the logs on the side where you can fill the exhaust chamber with water. hold your thumb over one water fitting and put the air pressure to the other. mine had bubbles coming in. it was the gasket between the snail and the log. easy fix. :sleeping:
hey if need new logs i have a pair for an olds 350 i you want them.
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