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#565562 - 08/05/16 11:54 PM Exhaust elbow leak  
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parrothead Offline
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parrothead  Offline
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wv
I had an overheat last week on my 1995 Searay 220 7.4 Bravo one due to a failed impeller. Not severe but enough that i heard a slight boiling sound when i opened the hatch. I trailered it home and replaced the impeller, o rings , and backing plate. Took it to the lake and noticed water leaking from the elbow gasket. I tried tightening the 4 bolts and got a slight amount of turn which took the leak down to a barley noticeable trickle that only shows up at 3000 rpm and up. I had someone drive while I watched it and it is bone dry until the higher rpms. I guess this is due to water moving at a higher pressure through the system. I am going to pull the elbow and replace the gasket. I have read the other riser thread and understand that I need to drain the system, pb blaster the heck out of the bolts,make sure that the mating surfaces are truly flat, and retourque the bolts to 25 ftlbs as per mercury manual. Am I missing anything? This seems like a pretty straight forward job. I am assuming I did no other damage to the engine as it ran fine for about 5 hours total running over the last two days. I checked the oil and it looks good, no other water leaks anywhere, and no mysterious new noises. I was unaware that the leaking gasket could put water into the engine. I believe that i got lucky there as I have had no hydrolock issues. Engine seemed to run as good as it always has. If water would have gotten into the engine I figure I would have known by now. Any suggestions and comments would be appreciated.

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#565564 - 08/06/16 01:36 PM Re: Exhaust elbow leak [Re: parrothead]  
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Argyle, TX
I think you are on the right track for the recovery from that. Warpage probably occurred on one or both of the surfaces at that joint and the gasket could no longer keep them sealed. Usually the rubber exhaust connections from the riser to the rest of the exhaust tubing suffer, but if you did not smell anything when you heard the boiling, and no leaks from those when running it hard then you may have been just lucky enough to skip that part.


2002 Bryant 188 4.3MPI Mercruiser
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#565565 - 08/06/16 02:57 PM Re: Exhaust elbow leak [Re: Maclin]  
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parrothead Offline
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I see no other leaks. I was all over the engine with a flashlight while underway and the leaking gasket was all that I found. We did some pretty hard wake boarding and knee boarding for about three hours. I would think that if there were other issues they would have shown themselves.again, I only notice the leakage past 3krpm. The engine was shut down immediately when the high temp alarm came on and was only started again to get it to the dock. That is roughly 50 yards or so and it was fast idled to the dock. I did not smell anything at all. The rubber tube that connects the elbow to the rest of the system seems fine. Not melted and no leaking.

#565567 - 08/07/16 10:00 AM Re: Exhaust elbow leak [Re: parrothead]  
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You are on the right track with your approach . . . Keep in mind that what leaks out may also leak in (to the exhaust chamber)

Also is this a closed cooling system (that includes the exhaust manifolds) or an open (raw water) cooling system?

Pressure in a open system is not all that high, so if you are leaking, then it deserves your immediate attention. Also keep in mind that Silverbullet's manifold mating surface looked really good (after he touched it up) . . . if yours does not look as good, you may need to replace the manifold/elbow.

Last edited by tpenfield; 08/07/16 10:03 AM.

Regards, Ted

Formula 330SS

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#565568 - 08/07/16 12:08 PM Re: Exhaust elbow leak [Re: parrothead]  
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Silverbullet Offline
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Boise, ID
Glad my post and pics provided some reference and help.

I'll add to do some research on the gasket and directions for it. For volvo they came out with a new gasket that was supposed to go on dry. It didn't work so they issued a tsb to do it differently. At least for a time they didn't update the instructions that came in the package.

While in there check for exhaust flappers.


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


#565571 - 08/07/16 02:58 PM Re: Exhaust elbow leak [Re: tpenfield]  
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parrothead Offline
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Mercury says install gasket dry and torque to 25 ft lbs which seems to have been superceded by 33 ft lbs from what I have read in a service bulletin. How do I know if I have had water intrusion into the exhaust chamber? As I stated, we did some hard towing and just general cruising and all seemed well. I am assuming based on what I know that water did no get into the engine. I'm going to spray the bolts today and try to change the gasket tommorrow. I will use a straight metal ruler to check for high spots.

I also forgot to mention that this is a raw water open cooling system.

Last edited by parrothead; 08/07/16 03:19 PM.
#565573 - 08/07/16 04:31 PM Re: Exhaust elbow leak [Re: parrothead]  
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Boise, ID
Below is based in my reading, not actual experience.

Water intrusion could show as signs of rust on the exhaust side of the manifold. Sometimes you can see small marks of rusthe on the inside when you pull the elbow. You also might notice part of the gasket is missing or rusty depending on the type.

Water intrusion into the cylinders at worst case would cause hydrolock which can resultry in bent things like rods and valves. You can also look at the underside of the oil fill cap for either condensation or milky oil. Both can indicate moisture in crankcase.

Hydrolock is usually heard when trying to start the engine and it has trouble turning over because the water won't compress.

It's also possible the waterm intrusion over time can rust the valve causing it to not seal correctly.


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


#565579 - 08/08/16 12:00 AM Re: Exhaust elbow leak [Re: Silverbullet]  
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parrothead Offline
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So I went ahead and started disassembling the joint today. I drained the system, removed the clamps, removed the 4 bolts and took off the elbow. Pretty easy so far. The riser mating surface looks good. Nice and shiny. The manifold surface is slightly pitted. I filed on it with a large flat metal file and was able to remove some of the pitting. I'm going to make a sanding block as was suggested in the other riser discussion. I would assume that as long as I sand evenly and check with a straight edge frequently then the gasket will seal. I am tempted to use a gasket sealer when I reinstall even though merc says dry is fine. My father has a high temp gasket sealer that contains copper. Any issues with doing anything that I have mentioned? Upon removing the elbow, I'm pretty sure no water has entered the engine. The exhaust passage had no rust in it at all.

Last edited by parrothead; 08/08/16 12:02 AM.
#565590 - 08/08/16 10:50 AM Re: Exhaust elbow leak [Re: parrothead]  
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Lowrider78 Offline
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A gasket will tolerate a VERY LIMITED amount of non-flatness.

A gasket sealer such as Copper Coat is always a good thing, especially where water is concerned. paper/fiber gaskets last longer when basically "waterproofed" with C.C.
When intake gaskets (fiber) are installed into an engine, every guide I ever saw advises to add a SMALL bead of RTV around the coolant passage, front and rear, both sides, it is insurance against them leaking there. They SHOULDN'T dry, but, sometimes they do.

If the mating surfaces are warped too much (iron is much better at this that Aluminum, Al. warps terribly), Red High-Temp RTV.
Apply a bead, to one part only, no difference which, let it cure for about 3 days, bolt the parts together. I had to seal exhaust leaks on the old Taylor's Aluminum exhaust logs this way at the head once. Then I installed her headers this way, lasted great both times.

I would still be worried about those flappers, but, maybe you get lucky.

When I had the heads ported on the Taylor's 454, I discovered that one exhaust valve guide had developed a small water leak, which resulted in a cracked valve seat (dripping on hot seat). Never knew it from driving. Wasn't that big a deal, was no way without pressurization for it to seep enough to hydraulic a cylinder, but it DID show a bit of rust on that one exhaust port.


That streak that howled by? That was me. Did ya like the roostertail? Big Blocks and Jets Forever
1978 Hawiian 20' Bowrider, 454, Dominator pump
1990 Magnum Mach 1 24' Cuddy Cabin Cruiser, 454, Bravo 1 drive.
1993 Suburban 454 tows the Mach 1 to water.
2001 Blazer 4x4 4.3L gets the Hawaiian wet.
#565592 - 08/08/16 11:32 AM Re: Exhaust elbow leak [Re: Lowrider78]  
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parrothead Offline
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wv
Lowrider, I'm going to try and sand on the manifold surface with a flat block and wd40. Neither surface appears warped. When I run a straight edge across them the most gap I have at any given point is no more than the thickness of a piece of heavy notebook paper. I would think that a good polishing should take that out. I will probably use the copper coat and see what it does. If it leaks I'll have to go to the high temp rtv. I was able to stick my hand down to the flappers and the feel ok.

#565593 - 08/08/16 01:42 PM Re: Exhaust elbow leak [Re: parrothead]  
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Lowrider78 Offline
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Sounds like it should go together OK for you then PH, I do hope so. smile


Realize, you aren't working with a "high-temp" area in a boat, not with everything there being water-jacketed.

If those manifolds ever got much above 175-180*, then you have a real water flow problem.

It's not like dry exhaust in a car.

My only justification for hi-temp red RYV where I use it is against head flanges. Against the exhaust ports themselves, they are not very close to the water jacketing, and the header/manifold flanges again move the actual water-cooled area away, that little zone right there at that gasket could get 400-500 degrees when running hard.

Out on those jacketed elbows, you'd be able to use any RTV gasket maker you wanted to, same as on an oil pan, a timing chain cover, and so forth.


That streak that howled by? That was me. Did ya like the roostertail? Big Blocks and Jets Forever
1978 Hawiian 20' Bowrider, 454, Dominator pump
1990 Magnum Mach 1 24' Cuddy Cabin Cruiser, 454, Bravo 1 drive.
1993 Suburban 454 tows the Mach 1 to water.
2001 Blazer 4x4 4.3L gets the Hawaiian wet.
#565601 - 08/08/16 08:47 PM Re: Exhaust elbow leak [Re: parrothead]  
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Jack T Offline
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Since I have been in sacrificial anode mode, is it likely that the copper may have an adverse effect as far as corrosion is concerned, either the drive or engine components?


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

#565602 - 08/08/16 10:10 PM Re: Exhaust elbow leak [Re: Jack T]  
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Silverbullet Offline
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Boise, ID
Originally Posted By: Jack T
Since I have been in sacrificial anode mode, is it likely that the copper may have an adverse effect as far as corrosion is concerned, either the drive or engine components?


I don't know the answer to that question. I only know that VP changed their gasket instructions from installing dry to coating the surfaces with copper spray gasket.


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


#565604 - 08/09/16 12:19 AM Re: Exhaust elbow leak [Re: Jack T]  
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Lowrider78 Offline
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Newton Ks
Originally Posted By: Jack T
Since I have been in sacrificial anode mode, is it likely that the copper may have an adverse effect as far as corrosion is concerned, either the drive or engine components?


I do not know the answer for certain, but, I consider it this way.

Copper will not have much different effect than Brass. The base material of Brass, is Copper (alloyed with a few things).

The amount of metal contained in a gasket sealer is miniscule, not enough to alter anything.

Also, copper/brass is much less "corrosive" to your aluminum parts than the stainless steel propshaft and prop(s).


That streak that howled by? That was me. Did ya like the roostertail? Big Blocks and Jets Forever
1978 Hawiian 20' Bowrider, 454, Dominator pump
1990 Magnum Mach 1 24' Cuddy Cabin Cruiser, 454, Bravo 1 drive.
1993 Suburban 454 tows the Mach 1 to water.
2001 Blazer 4x4 4.3L gets the Hawaiian wet.
#565605 - 08/09/16 12:25 AM Re: Exhaust elbow leak [Re: Silverbullet]  
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parrothead Offline
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parrothead  Offline
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wv
I don't believe the copper spray gasket would have much corrosive effect especially if vp specs it. Im dealing with mercruiser but I wouldnt think that the exhaust systems are that much different.I may use rtv instead though for assurance. Would there be anything wrong with filling the pits with jb weld and smoothing it up level or should I just sand it? I know machining would be best but I really don't want to pull the manifold. I fear I would create more problems in doing so. The pitting is minor and I don't think machining is warranted. I would post a pic of my manifold but I am unsure how to do so.

Last edited by parrothead; 08/09/16 12:27 AM.
#565606 - 08/09/16 03:21 AM Re: Exhaust elbow leak [Re: parrothead]  
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Silverbullet Offline
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Silverbullet  Offline
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Boise, ID
I would sand it flat with a glass block. It may not take much to get them out.

To post pic, upload to photobucket or something similar. For photobucket, they generate a link for you. Wherever you post them, get the link that ends with jpeg.


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


#565607 - 08/09/16 09:09 AM Re: Exhaust elbow leak [Re: Silverbullet]  
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parrothead Offline
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wv
This is my manifold after using a wire brush on a drill to clean it. At this point I have also filed the bumps off of it with a large flat file.

Last edited by parrothead; 08/09/16 09:11 AM.
#565608 - 08/09/16 09:34 AM Re: Exhaust elbow leak [Re: parrothead]  
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Lowrider78 Offline
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Awm heck, bolt that up and run it, it probably didn't look that good brand new.

That pitting it running between 2 fluid openings, no problem.
If that run of pitting was headed outside or inside, I'd think differently.

If you REALLY wanted to get wacky about it, you'd put a layer, or 2, of epoxy primer over that shiny clean iron.

On an airplane, we'd paint that with epoxy primer (both parts), then cover it in a catalyzed liquid butyl rubber sealer (both parts), with the gasket sandwiched in there too.

No leaks, ever, but a holy mother to get apart eventually again after the sealer sets up.

If the gasket is a really nice fit, copper-coated, it should be fine. Those spaces to the exhaust passage are not real wide. If it's a bit sloppy, I'd run a set of 1/8" RTV beads around everything there, go ahead and go into the pitting (to seal it over), let it sit (apart) and cure 24 hours in the warm, and bolt it up.


That streak that howled by? That was me. Did ya like the roostertail? Big Blocks and Jets Forever
1978 Hawiian 20' Bowrider, 454, Dominator pump
1990 Magnum Mach 1 24' Cuddy Cabin Cruiser, 454, Bravo 1 drive.
1993 Suburban 454 tows the Mach 1 to water.
2001 Blazer 4x4 4.3L gets the Hawaiian wet.
#569103 - 09/11/17 08:00 PM Re: Exhaust elbow leak [Re: parrothead]  
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Lou C Offline
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Long Island NY
Wow I'm amazed what fresh water manifolds look like. Great! I would advise after you get done sanding, to use a straightedge and some feeler gauges to make sure there no low points. An area like this should be flat within about .002". So if you use a good straight edge and a .002" feeler gauge, it should not fit in anywhere under the edge. If its more than that and you can't get it out by sanding, consider taking the manifolds and risers to a machine shop and having them true up the mating surfaces. They can do a really good job on things like this...


88 Four Winns 200 Horizon 4.3 OMC
98 Jeep Grand Cherokee 4.0 Six Selectrac
07 Jeep Grand Cherokee 5.7 HEMI Quadradrive II
#569230 - 09/20/17 04:03 PM Re: Exhaust elbow leak [Re: parrothead]  
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WayWeGo Offline
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Oakton, VA
When I did mine, I put some wet dry sandpaper on my granite countertop with a little water to hold it in place. Carefully moving the elbow back and forth left a very flat and clean surface.

Of course, I did that when my wife was not there...



1975 Trojan F36 Convertible, Twin Chrysler 440's
2014 West Marine AL360 Inflatable, 1966 Mercury 6HP, 1992 Mercury 20HP
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