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Leaky elbows?

C

CaboJohn

Regular Contributor
I am back in Cabo for the season and have several questions. I will start with the easy stuff. Engines are 2003 5.7 Captain's Choice MPI with heat exchangers and “fresh” water cooling on the block and exhaust manifold . I changed out the elbows a little less than two years ago. I used the new Crusader gaskets that are black and sort of shiny. The instructions were to not use any sealer. Surfaces on the manifolds and risers were clean and flat, block off plates were new. I now see that I have a powdery rim of salt (tastes that way) around the edges of all four risers. The powdery rim goes completely around, not in just one spot. No external signs of a liquid leak. It just looks like small salt crystals that have condensed from escaping vapors.



Has anyone ever noticed this before? Is it a sign that the gaskets need to be redone (with RTV)?


Thanks for any advice.
 
No doubt some salt water leakage. A thin coat of RTV may have helped prevent this. Did you retorque after the second run? These are at half life, I don't think I would break them down at this point.
 
I've learned the hard way to disregard OSCO and Barr instructions and put a thin coat of RTV on both sides of the gaskets. Their objection is apparently based on a "mechanic" gobbing so much RTV that it plugs the restrictive water exit holes downstream and causes overheating problems. What they don't figure is warpage from heat and hours of operation.

The bottom line: RTV those gaskets or they WILL leak.

Jeff
 
What are the best gaskets to use? I just received new risers and they came with the green gaskets. I do have a set of the black ones. The black ones just look of better quality.

What RTV is the best? Red, black, or??
 
John,

Were the gaskets Crusader part #98127 and the blockoff plates the wing style that are now recommended part #98124?? The 98127 gaskets are sort of a silver color and from what I have seen are fairly soft and compress pretty well to seal any minor imperfections in the mating surfaces. Check out marine parts source (am I allowed to say that?).
 
@erich The very same. On the side I just took apart the black gaskets still looked like new where they separated from the new stainless block off plate. When I tried to separate them from the cast iron they seemed almost welded on and had be be scraped to be removed. So the RTV could be useful between the plate and the gasket. And if I wanted to try I might be able to pull apart the other three, RTV both sides of the block off plate and reassemble without importing new gaskets. Does not look like RTV would be needed on the cast iron as the gaskets clearly have a really good seal there.

Of course the gaskets have these stupid slots cut in it in case one wants to use them on a non fresh water system without the plate (or do they come solid and I bought the wrong ones?) The slots give the salt water access to the stainless plate and from there it is a very short trip (maybe 3/8") either to the outside or into the engine. Without the slots the seal would be 3/4" wide over the stainless and the good bond between the gasket and the cast iron looks like it would seal leaks from the top.
 
John,

There is only one style of gasket with the holes for that engine. I am not absolutely positive but I believe the holes are there to provide some cooling for the blockoff plate. I ran into this same type setup with the 454 engines. There were 3 hole gaskets on each side of the blockoff plate but only one hole (at the top) between the riser and elbow. The one hole insured that the cooling water would just about fill the riser before flowing down and out the elbow.

Erich
 
The new block off plates I got are the 'winged' type. Question.. What way does the 'wing' go? Up in the elbow or down in the manifold?

Also. Can I go to our local gasket maker and get the mounting gaskets made with out the holes??
 
kevin_z said:
The new block off plates I got are the 'winged' type. Question.. What way does the 'wing' go? Up in the elbow or down in the manifold?

Also. Can I go to our local gasket maker and get the mounting gaskets made with out the holes??
Click to expand...

The wing goes up to catch and boil off any condensation. I imagine you could get gaskets made but why? The ones from Crusader are fine.
 
What's the torque for riser bolts? I know that I need to re-torque after first run, but none of my manuals state initial torque.
 
Toss out that torque wench and use common sense instead. (Unless the threads are dry or lubed--and you have to determine which FIRST--you will either make 'em to loose or snap 'em of.) Then there's 'bolt drag' caused by the weight of parts on the joint, causing unexpected friction.

The mechanic's method is way to tighten them "nice and snug" (granted, by experience) then add a flat or two as needed. (A hex bolt has 6 flats.) When the motor is hot, add a few more flats and you're all set.

Jeff
 
Timely response as I am in the midst of doing an elbow. I finally, after four tries,found a head that was not cracked and put it on yesterday. I also searched the net on the elbow methods and torques. Opinions vary and the torque specs have been changed several times over the years (generally going down a little). The whole thing, IMO, is a crappy design that lends itself to problems.

I noted how in my earlier installation, using the black gaskets, it seemed to seal very well between the gasket and the cast iron, but not between the gasket and the stainless block off plate. This time I carefully put a very thin layer of high temp RTV on the gasket to plate surface (coating the gasket not the plate so as to leave the steel surface open to the coolant and salt - based on erich's theory of the need to cool the block off plate). I then torqued the whole thing to about 15 pounds. I like to hold the shaft of the torque wrench at the same distance as the length of a 9/16" open end. That way when I do the two nuts that you must use an open end on I have a feel for how hard to pull the wrench. I have allowed the layer of RTV to cure over night at the lower torque and I will soon go down and finish torquing to 28 ft. lbs. After a heat up and cool down (assuming it starts!) I will re-torque. Hopefully this time it will remain tight.

Thinking about what seems to me to be fairly low torques with soft gaskets for such a critical joint I wondered why it isn't a hard gasket with high torque, like the head gasket I just installed. I think possibly the problem is the expansion of the elbow in normal operation (and even more so if the elbow runs hot with poor water flow). This will put additional stress on the long bolts, that run much cooler, and could snap them or cause a permanent yield (stretch). So the bolts may have a much higher torque when the elbow is hot than when cold. Combined with the soft gasket this creates the need to re-torque after installation and use.

Also I did find that I needed to run a tap in the two long bolt holes to clear out the rust that would have messed up my torque readings.

I should be fishing tomorrow.
 
I've learned the hard way to disregard OSCO and Barr instructions and put a thin coat of RTV on both sides of the gaskets.

I bought a full set from Barr just last week. They advised to use aviation sealer on BOTH sides of the gasket ... :)
 
I installed the new risers yesterday. The old ones were three years old with 250hrs. Never flushed them. The replacement went o.k. No broken studs or 911 calls. I tried to post pictures with no success. The old ones looked o.k. All of the water ports looked clear. I used aviation sealer on both sides of BOTH gaskets. What really amazed me was after every thing was re-assembled, and engines were warmed to operating temperature, I was able to get almost a full turn on all bolts and nuts. A torque wrench was not used. You can not get one on the nuts anyway. Just the long bolt heads. I will continue to try to post the pictures. Going for a boat ride today!!!
 
.."I bought a full set from Barr just last week. They advised to use aviation sealer on BOTH sides of the gasket "

Ah-hah! They have woken up.

Jeff
 
kevin_z said:
I installed the new risers yesterday. The old ones were three years old with 250hrs. Never flushed them. The replacement went o.k. No broken studs or 911 calls. I tried to post pictures with no success. The old ones looked o.k. All of the water ports looked clear. I used aviation sealer on both sides of BOTH gaskets. What really amazed me was after every thing was re-assembled, and engines were warmed to operating temperature, I was able to get almost a full turn on all bolts and nuts. A torque wrench was not used. You can not get one on the nuts anyway. Just the long bolt heads. I will continue to try to post the pictures. Going for a boat ride today!!!
Click to expand...

You would have to use a "crow's foot" on the torque wrench. It would have to be positioned at 90 degrees to the wrench axis for a true torque setting/reading. I also applied av sealer to both sides of the gaskets two years and have no issues.
 
Better off modifying the wrench setting (reading) to account for the longer moment arm with the crow's foot....FWIW, Aviation sealer ~ Permatex #3 ~ quicksilver perfect seal ~ gm engine assembly compound = good stuff, especially for joints known to have CTE issues/concerns....
 
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