Cooling Questions
10-22-2006, 08:32 AM
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Cooling Questions
Hi all, hope everyone had a safe and fun boating season this year. It's over up here in Western NY as far as I am concerned.
To the question,
Last spring I installed Stainless Marine exhaust manifolds and risers along with their thermostat housing and themostat that has the holes in it for a bypass so you only need to run two coolant hoses, one to each manifold.
Prior to this I was using the stock Mercruiser set-up with Glenwood Manifolds and Imco risers.
I've noticed that the temperature gauge barely goes above 100 until after a hard run when it will reach 140. Along with this the exhaust hose between the risers and tips is extremely hot ! You can barely touch it, and you can see smoke comming off of it and the cockpit smells like burning rubber.
Who else is using aftermarket exhaust with the bypass hose between the manifold and riser and how do you have the cooling plumbed ?
Changing this could be one of my many winter projects.
Thanks, Dave
To the question,
Last spring I installed Stainless Marine exhaust manifolds and risers along with their thermostat housing and themostat that has the holes in it for a bypass so you only need to run two coolant hoses, one to each manifold.
Prior to this I was using the stock Mercruiser set-up with Glenwood Manifolds and Imco risers.
I've noticed that the temperature gauge barely goes above 100 until after a hard run when it will reach 140. Along with this the exhaust hose between the risers and tips is extremely hot ! You can barely touch it, and you can see smoke comming off of it and the cockpit smells like burning rubber.
Who else is using aftermarket exhaust with the bypass hose between the manifold and riser and how do you have the cooling plumbed ?
Changing this could be one of my many winter projects.
Thanks, Dave
10-23-2006, 05:29 PM
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Re: Cooling Questions
Not enough water is bypassing the thermostat to cool the exhaust. You may want to consider drilling more holes in the thermostat or switching to a housing like the one from Hardin Marine that is a full-flow bypass when the thermostat is closed. Fred Cecil at Trick Marine might be able to help you.
Last edited by Crazyhorse; 10-23-2006 at 05:36 PM.
10-23-2006, 05:51 PM
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Re: Cooling Questions
Crazyhorse,
I thought about putting more holes in the thermostat which might solve the hot hose problem, but I think it might make the low temp problem worse. Can I get the best of all worlds with a two hose bypass ?
By U Boy,
This is an Alpha set up, but I never thought the impeller might be bad. It was replaced two years ago. Could it be bad already ?
I thought about putting more holes in the thermostat which might solve the hot hose problem, but I think it might make the low temp problem worse. Can I get the best of all worlds with a two hose bypass ?
By U Boy,
This is an Alpha set up, but I never thought the impeller might be bad. It was replaced two years ago. Could it be bad already ?
10-23-2006, 07:50 PM
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Re: Cooling Questions
Originally Posted by David Stotz
Crazyhorse,
I thought about putting more holes in the thermostat which might solve the hot hose problem, but I think it might make the low temp problem worse. Can I get the best of all worlds with a two hose bypass ?
By U Boy,
This is an Alpha set up, but I never thought the impeller might be bad. It was replaced two years ago. Could it be bad already ?
I thought about putting more holes in the thermostat which might solve the hot hose problem, but I think it might make the low temp problem worse. Can I get the best of all worlds with a two hose bypass ?
By U Boy,
This is an Alpha set up, but I never thought the impeller might be bad. It was replaced two years ago. Could it be bad already ?
10-24-2006, 07:28 AM
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Re: Cooling Questions
As By U Boy said, yup could be. Never hurts to check the impeller first.
It never hurts to backflush the cooling system from the thermostat housing back just to make sure no impeller pieces from the last impeller are blocking water flow.
Assuming you have sufficient cooling water into the engine you'll need to increase the amount of water reaching the exhaust system. How you do it is pretty much up to you, either by drilling more holes in the thermostat (or running a restrictor plate instead of a thermostat), changing to a two-hose setup, switching to a full-flow thermostat housing, you get the idea. I can't remember if you said whether or not you have a cooling system pressure gauge. If not, you might consider adding one, even if it's just a temporary installation. You might find that you're getting higher-than-normal pressure spikes when the thermostat is closed.
My Cigarette has crossovers in place of the stock water circulating pump with non-bypass thermostat housings. Restrictor plates take the place of thermostats to give me 23-25 lbs cooling system pressure at WOT. The cooling temps run about 120 when water temps are in the 60's, slightly higher as lakewater temps increase. Higher power settings will also increase the temps but I don't run the boat hard so I rarely see temps above 140.
Are you getting any condensation in the oil?
Yeah, I know. I had a fuel leak on the port carb when that picture was taken. New jet access gaskets cured that problem. The picture was taken during winter layup a couple seasons ago. Since then I've replaced the superchargers (I still have them though) with Hurricane 53035 intakes under the existing 1050 Dominators, along with hydraulic roller camshafts to replace the hydraulic flat-tappet cams.
The boat runs the same as when the low-boost pulleys (2-3 lbs) were on the superchargers giving the boat a top speed of 70 on flat water
It never hurts to backflush the cooling system from the thermostat housing back just to make sure no impeller pieces from the last impeller are blocking water flow.
Assuming you have sufficient cooling water into the engine you'll need to increase the amount of water reaching the exhaust system. How you do it is pretty much up to you, either by drilling more holes in the thermostat (or running a restrictor plate instead of a thermostat), changing to a two-hose setup, switching to a full-flow thermostat housing, you get the idea. I can't remember if you said whether or not you have a cooling system pressure gauge. If not, you might consider adding one, even if it's just a temporary installation. You might find that you're getting higher-than-normal pressure spikes when the thermostat is closed.
My Cigarette has crossovers in place of the stock water circulating pump with non-bypass thermostat housings. Restrictor plates take the place of thermostats to give me 23-25 lbs cooling system pressure at WOT. The cooling temps run about 120 when water temps are in the 60's, slightly higher as lakewater temps increase. Higher power settings will also increase the temps but I don't run the boat hard so I rarely see temps above 140.
Are you getting any condensation in the oil?
Yeah, I know. I had a fuel leak on the port carb when that picture was taken. New jet access gaskets cured that problem. The picture was taken during winter layup a couple seasons ago. Since then I've replaced the superchargers (I still have them though) with Hurricane 53035 intakes under the existing 1050 Dominators, along with hydraulic roller camshafts to replace the hydraulic flat-tappet cams.
The boat runs the same as when the low-boost pulleys (2-3 lbs) were on the superchargers giving the boat a top speed of 70 on flat water
Last edited by Crazyhorse; 10-24-2006 at 07:38 AM.
10-24-2006, 08:19 AM
#8
Re: Cooling Questions
I've been running the Revolution Marine exhaust, which has the hoses from manifolds to risers. The last few times out on the water this season I noticed that the manifold and riser on the starboard side was allot warmer than the port side. I pulled the engine a couple of weeks ago and it now sits in my garage. Last night I was in the garage puttering/cleaning things up. I got to cleaning up/checking out the oil cooler, and noticed the water inlet tubes were covered with sea weed/plant growth. Just a thin layer maybe 1/8 in. or so thick. Not enough to stop the flow but certainly enough to slow it down. This probably contributed to the warmer exhaust system temps.
I hear Oil coolers can get clogged pretty easy so I'd check that 1st and check sea pump impeller and thermostat housing too. Chit.....as long as ya have it all apart be a good time to back flush........
I hear Oil coolers can get clogged pretty easy so I'd check that 1st and check sea pump impeller and thermostat housing too. Chit.....as long as ya have it all apart be a good time to back flush........
10-24-2006, 10:54 PM
#9
Re: Cooling Questions
Cut off hoses in transom assembly.
Make sure you run thru hull pickups with strainers, and engine driven bravo style seawater pumps, you will have more than enough water , and can change an impellor in the boat easily. BBB
Make sure you run thru hull pickups with strainers, and engine driven bravo style seawater pumps, you will have more than enough water , and can change an impellor in the boat easily. BBB
11-02-2006, 11:55 PM
#10
Re: Cooling Questions
Also use a clear hose to see if there are bubbles indicating airation in the water inlet. Clear 1-1 /4" ID vinyl hose is avail at Home Depot.... BBB
