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#570757 - 04/28/18 05:36 PM Can I run engine with exhaust apart at elbows  
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Admiral
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Boise, ID
One goal this year is to figure out the cooling issue. One side suddenly began running warmer than the other. It's about a 20 degree difference, in the water and on the trailer, at idle and after a run.

One test that I am looking at doing is trying to measure the water flow on each side. Can I remove the exhaust at the end of the manifold where water and exhaust come together and run the engine? My only concern is water somehow running back into the manifold on shutdown. I don't think it would happen, but thought I would check.

I have a few other tests to complete first, but wanted to be prepared.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


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#570759 - 04/28/18 07:23 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Dave R Offline
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You can indeed do that.


"Mischief Managed"
2000 Regal 2550 LSC
7.4 MPI Bravo 3
#570764 - 04/29/18 11:20 AM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Are we talking the exhaust manifold or the exhaust elbow? . . . as far as disconnecting the exhaust.

If you took the elbows off and ran the engine, even for a short period of time, you will most likely get water inside the exhaust chamber and into the cylinders. . . . might even hydrolock it.

Do you plan of a visual comparison of the water flow, or do you have a means of measuring it?

I dn't recall where and how you were measuring the temperature . . . was that at the exhaust elbow?

Last edited by tpenfield; 04/29/18 11:21 AM.

Regards, Ted

Formula 330SS

My Boat Web Sites
#570765 - 04/29/18 11:50 AM Re: Can I run engine with exhaust apart at elbows [Re: tpenfield]  
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Originally Posted by tpenfield
Are we talking the exhaust manifold or the exhaust elbow? . . . as far as disconnecting the exhaust.

If you took the elbows off and ran the engine, even for a short period of time, you will most likely get water inside the exhaust chamber and into the cylinders. . . . might even hydrolock it.

Do you plan of a visual comparison of the water flow, or do you have a means of measuring it?

I dn't recall where and how you were measuring the temperature . . . was that at the exhaust elbow?


I would do it after the elbows and risers where the water and exhaust normally combine. Most likely i would actually go further down. After the elbow I have a rubber coupler and then another elbow, then rubber then the y pipe.

Plan was to divert into a bucket and then measure.

I have measured temp on risers and manifolds in several places using a temp gun.

I have already pulled the elbows to check for blockages, scoped the y pipe and exhaust, etc. Next test is to put some clear hose into the water system so I can see if I am getting air into the system somewhere.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


#570766 - 04/29/18 03:13 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Jack T Offline
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"Next test is to put some clear hose into the water system so I can see if I am getting air into the system somewhere."

Now, that's something that only a small percentage of people would think of in regards to a cooling system. Kind of like checking the fuel lines going to the fuel pump.


Have a great day of boating
2012 Monterey 224 FS,
300 HP Volvo Penta with catalytic converters

#570775 - 04/30/18 12:38 AM Re: Can I run engine with exhaust apart at elbows [Re: Jack T]  
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Originally Posted by Jack T
"Next test is to put some clear hose into the water system so I can see if I am getting air into the system somewhere."

Now, that's something that only a small percentage of people would think of in regards to a cooling system. Kind of like checking the fuel lines going to the fuel pump.



I actually saw a YouTube video of someone doing it. I'm wondering if I am getting some air at the raw water pump which I rebuilt 2 years ago. Also wondering if I am getting air at thermostat housing. It's a lot harder to insert clear hose than one might think.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


#570779 - 04/30/18 10:09 AM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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captkevin Online content
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What temp do you get on each side?


2004 Rinker 232
2010 Dodge Ram Crew Cab Laramie 4x4
#570781 - 04/30/18 11:06 AM Re: Can I run engine with exhaust apart at elbows [Re: captkevin]  
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Boise, ID
Originally Posted by captkevin
What temp do you get on each side?


I can't recall off the top of my head. I'll measure again this weekend. I do know on the starboard side. I can put my hand on top of the riser and it is comfortable. On the port side, it's hot.

Often times, these questions are answered with, "the difference is normal". My issue with that is that this is a change for this engine. Prior to this, the two sides were not noticeably different. Last time we were out, late 2016, it smelled hotter as well.

I'll solve it, one way or another. Either I'll figure it out or I'll take it in and write a check.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


#570783 - 04/30/18 12:58 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Guessing start with the simple things & go from there. Have you ever had an impeller that came apart & could be blocking anything? Might be worth it to change out impeller & back flow hoses with water to see if there is any debris. Also check exhaust flappers to see if you have a melted one.


2004 Rinker 232
2010 Dodge Ram Crew Cab Laramie 4x4
#570785 - 04/30/18 02:04 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Boise, ID
Been down the road.

No impellers have come apart and no flappers exist in this engine. Scoped the exhaust and nothing in there. Pulled the elbows last winter to check for blockages and corrosion. Really clean inside. I can and will back flush parts that I can.

In relation to back flushing, can I thread a nipple into.my block drains and push water up from there. I know there is some scale in the block as it comes out when I drain in the fall.

I haven't done much of it and am very fearful of forcing water somewhere its not supposed to be.

I'll change the impeller again just to be sure.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


#570786 - 04/30/18 02:25 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Frantically Relaxing Offline
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I remember draining the 350 in the Sun Runner for the first time, I found the starboard exhaust manifold was half filled with Lake Powell sand. I was able to get most of it loose with a coat hanger while flushing. And for what it's worth, I've noticed after driving the Regal around that the starboard manifold on the starboard engine is warmer than the other 3... Starboard thing?

Have you pulled the engine water pump and checked the water ports for rust or other obstructions? Those impellers have been know to divorce themselves from the pulley shaft too.

Any evidence of a replaced freeze plug? Sometimes old ones end up in the water jacket and they don't get removed...


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#570787 - 04/30/18 06:11 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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A blown head gasket will often put exhaust gasses into the cooling system, depending on where the gasket has failed.

Also, is there something that balances the flow of water out to the exhaust manifolds/elbows? If so that may be a place to check.

Also, you could check the temperature at various points throughout the cooling system to get a better idea of 'where' the heat gain is occurring.

FWIW - I chased a cooling system issue on my port engine for a whole summer . . . no fun.


Regards, Ted

Formula 330SS

My Boat Web Sites
#570788 - 04/30/18 07:23 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Do you have a laser thermometer? Using one to check the temp of the engine block, exhaust manifolds and risers and intake manifold at various points might help with locating where the extra heat starts--


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#570803 - 05/01/18 07:52 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Jack T Offline
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"I'll solve it, one way or another. Either I'll figure it out or I'll take it in and write a check."

I like FR's suggestion--Nothing to take apart.

Another no take apart suggestion. How hard would it be to close the cooling system where it won't hurt anything. Run the engine for a very short period of time and see if you have leaks. Is this thinking in Fantasyland?


Have a great day of boating
2012 Monterey 224 FS,
300 HP Volvo Penta with catalytic converters

#570805 - 05/02/18 03:36 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Boise, ID
Let me try to answer.

Chasing cooling issues and electrical issues are two I don't like. The latter is more despised than the former. My goal is to not fart with it the whole summer. I missed all of last summer and want to enjoy this summer. Hence then willingness to write a check.

I have a laser thermometer and have used it. I believe, if I remember correctly, that the added heat starts at the heads, but I'll have to recheck everything this weekend when I bring the boat home.

As far as flow balance, the only places that happens are at the thermostat and after the water and exhaust mix. The clear hose will be put in at the thermostat so I'll get a view there. I'll pull the hose in the exhaust and see if it is collapsed. Interestingly, the water ports out of the thermostat are different sizes. The one to the port side is bigger. I believe it is a longer run and as such is a bigger hose. I should pull those and inspect them as I believe they are original.

I have not pulled the engine water pump. Not that it wouldn't be a valuable exercise, but 90% of the raw water that comes in is diverted to the exhaust manifolds. If I pull it, I'll replace it.

No indication of replaced freeze plugs. We've owned her for 10 years and no issues with freezing stuff.

To flush the block and manifolds with some water from a hose, what precautions do I need to take?


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


#570808 - 05/03/18 01:59 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Dave R Offline
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Raymond NH
Originally Posted by Silverbullet
To flush the block and manifolds with some water from a hose, what precautions do I need to take?


I had success cleaning silt and sand from my 454 block by using muffs to run it and compressed air to flush it out. I ran it on the muffs and opened a block drain. I then alternated blasting compressed air into the block drain hole with letting it drain for awhile, while the engine was running. It stirred up a lot of crud. I've tried it a few times in the last few years and only rust comes out now. I think the lack of silt and sand now is a function of where I boat versus where the previous owner boated.

I like Ted's theory about he head gasket failure allowing exhaust gases into the cooling passages. I have seen that twice before, but not on boats.Due to the wide open cooling system you have, it will not manifest itself as an overheat under load, instead it would be localized near the leak and downstream of it. That sounds exactly like what you describe... A leak down test would find it quickly.


"Mischief Managed"
2000 Regal 2550 LSC
7.4 MPI Bravo 3
#570809 - 05/04/18 12:50 PM Re: Can I run engine with exhaust apart at elbows [Re: Dave R]  
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Boise, ID
Originally Posted by Dave R
Originally Posted by Silverbullet
To flush the block and manifolds with some water from a hose, what precautions do I need to take?


I had success cleaning silt and sand from my 454 block by using muffs to run it and compressed air to flush it out. I ran it on the muffs and opened a block drain. I then alternated blasting compressed air into the block drain hole with letting it drain for awhile, while the engine was running. It stirred up a lot of crud. I've tried it a few times in the last few years and only rust comes out now. I think the lack of silt and sand now is a function of where I boat versus where the previous owner boated.

I like Ted's theory about he head gasket failure allowing exhaust gases into the cooling passages. I have seen that twice before, but not on boats.Due to the wide open cooling system you have, it will not manifest itself as an overheat under load, instead it would be localized near the leak and downstream of it. That sounds exactly like what you describe... A leak down test would find it quickly.


Thank you for ending your post with how to find it. I was going to ask if it would not get into the oil.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


#570810 - 05/04/18 02:15 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Admiral
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Admiral

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Boise, ID
Apparently I already own a leak down tester. I wonder if my 2 gallon compressor is big enough? It still might be worth it to pay a shop to do it so I can move on.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


#570811 - 05/04/18 03:39 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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tpenfield Offline
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Leakdown testers use more pressure than volume, so even the smallest of compressors should keep up.


Regards, Ted

Formula 330SS

My Boat Web Sites
#570812 - 05/04/18 05:36 PM Re: Can I run engine with exhaust apart at elbows [Re: Silverbullet]  
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Admiral
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Boise, ID
I checked with local shop. They want $180 to do a compression and leak down test. It's not too bad so if I don't get to it this weekend, I'll take it in and check that off my list.

Thanks Ted for the tips on compressor size.


James
2002 Cobalt 226 VP 8.1GIDP
2007 Chevy 2500HD Crew Cab Duramax
1988 Suburban 3/4 Ton
2000 Subaru Forester


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