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View Full Version : Exhaust riser leak, how do manifolds look?



bsloop
12-04-2011, 08:56 PM
I had a leak on the outside edge of my exhaust riser, not bad but little squirts under full throttle. Motor got pretty hot a couple months ago due to a break in my perko fresh water flush intake (old design) which is where I suspect the leak originated.

Finally got it off (rear bolts were tough angles) and cleaned up.
Concerned if there will be any problems due to corrosion, especially on the front fresh water ports? Definately thinned a little, probably 3/16" at the thin points.
Exhaust manifold side looks pretty flat, maybe a slight pit or two. I have not cleaned up the riser yet.

A little trouble locating the gasket too. 91' Indmar 454 BB, narrow risers 53-1020. Measure 7" long exterior, 5" inner. 4 3/4" wide exterior, 1 3/4" interior.
Cant find a cross reference in Land n Sea for some reason? Here is a link to what looks like them but no measurements for sure.
http://www.hardin-marine.com/p-15906-exhaust-manifold-to-riser-gasket-bbc-indmar-riser-gasket-with-slots.aspx

When I remount, it was suggested I use a little permatex high heat sealant?
Lock-tite for the bolts? I will be replacing them with new stainless as two of the four existing have lost some of their threads in the middle.

John P
12-04-2011, 09:31 PM
Looks like its time for some new manifolds or take them off and get them surfaced. Getting pretty thin in spots.

eddie
12-04-2011, 10:33 PM
I just got some BBC manifolds in the store on Saturday $275 each. Let me know if you want some part numbers.

bsloop
12-05-2011, 08:16 AM
Apparently my IB application is a little unique. Indmar produced a compact manifold for straight inboard applications that resulted in a narrower motor package to allow more walk around room. Most BBC manifolds stick out further and are a square 4" which will not clear my IB dog house motorbox. The risers are also usually shorter and a different angle which could be a problem going into my existing exhaust. There is about a 3' section of 4" flex that drops into what appears to be a fiberglass elbow and then runs another 4' to exit out the transom below the water line.
Cast Iron manifold with square ports 53-1019 and riser 53-1020 are fairly specific. There was also an oval port manifold for lower 330hp 454 motors instead of the square port 390hp. I really dont know if this is a 330 or 390hp motor. I dont know if PCM had a similar set up?
I have been able to find some aluminum 53-1078 and 53-1077 manifolds and risers that may be compatable.
http://marineengineparts.com/shopsite_sc/store/html/page287.html

With a 20+ yr old engine, I almost hate to keep taking things a part for fear the repair/replace cancer will just keep spreading back further.
Pulling the exhaust for honing would be in that realm.

John, is "thin" a problem yet or something in 5 years? I know this was a brackish boat for some time of its life. It was originally sold in NY state and I bought if from a guy in NJ that used it on fresh and brackish water, hence the perko flush. I have had it 7 years now and do clean out rust flakes each fall when I pull the plugs to winterize.
I believe the motor has been out of the boat at some point since there is a 12 qt oil deep pan dont know what else may have been done.

John P
12-05-2011, 12:24 PM
98675

BDM
12-05-2011, 01:47 PM
Would it be an option to have it welded up and then resurfaced? Just thinking out.... type..... so to type.....

baja22
12-05-2011, 07:41 PM
Would it be an option to have it welded up and then resurfaced? Just thinking out.... type..... so to type.....

umm, no.

Griff
12-06-2011, 01:17 AM
A couple of the ports are thin, but with 20 years of use and some in salt, I would think they still have several years of freshwater life left in them.

bsloop
12-06-2011, 06:38 AM
Would a cautiously used flat file and hone stone work to remove enough to improve the surface?
I have seen them at 220 grit, can I use more coarse? need to finish with finer?

I could work it an hour or two vs the effort of pulling the manifold and associated hassles.

I talked to the shop selling Aluminum exhaust. He recomended if I went AL, to replace both the exhaust and riser due to uneven expansion over time. Cited a prior mercuriser case where they had problems with leaks from Iron and Al comobos.
Wouldnt I still have different materials between the block and manifold that could lead to a similar issue?

BDM
12-06-2011, 10:13 AM
umm, no.

Just wondering.... I remember doing that on some heads at a machine shop back in high school... didn't know if it was right or not... hence the question. :)

BDM
12-06-2011, 10:14 AM
Would a cautiously used flat file and hone stone work to remove enough to improve the surface?
I have seen them at 220 grit, can I use more coarse? need to finish with finer?

I could work it an hour or two vs the effort of pulling the manifold and associated hassles.

I talked to the shop selling Aluminum exhaust. He recomended if I went AL, to replace both the exhaust and riser due to uneven expansion over time. Cited a prior mercuriser case where they had problems with leaks from Iron and Al comobos.
Wouldnt I still have different materials between the block and manifold that could lead to a similar issue?

I think it'd be very difficult to maintain a completely flat surface without taking the manifolds off and to a machine shop.... even then I'm not sure if it'd work or not...

bsloop
12-06-2011, 11:14 AM
More potentially bad findings when I started digging into the exhaust riser.....

Passages were very blocked with corrosion. I am almsot suprised any water was getting though but it did seem to have flow the last time I had the motor on a hose.
I pulled significant debris from the riser by working a screwdriver into the ports and back though the exhaust.

There is still some debris I could probably continue to work out but thought I would make some determinations before spending more time.
The riser port walls are in better shape than the exhaust manifold but as you can see from the straight on shot, there is perforation of the separating wall between the exhaust and water. The perforation is after the turn down so no water should flow directly back down the exhaust into the engine but does not look good?

Griff
12-06-2011, 12:12 PM
I think it'd be very difficult to maintain a completely flat surface without taking the manifolds off and to a machine shop.... even then I'm not sure if it'd work or not...

Agreed.

Those risers are in pretty bad shape. Based on the corrosion inside them, I would guess the insides of the manifolds could be the just as bad.
It's probably a good time to start shopping for some replacements.

bsloop
12-06-2011, 03:54 PM
Ok, looks like we will be going the replacement route.

Can I get away with just the one side?
A concern would be with one new free flowing side and the old, clogged side; too much water would take the route of least resistance and there would not be enough presure to force water to the old side resulting in even less flow than when both sides were "evenly" clogged?

BDM
12-06-2011, 04:07 PM
In terms of fluid dynamics in other situations, your assertion that water would flow more through the new side and not as much through the old is correct. The flowrate would be higher, but the water pressure itself should be the same on both sides. At least that's how it works in other fluid pressurized systems... should be the same in an engine, I would think.

My .02 (for what it's worth) would be to replace both sides if you can.

Griff
12-07-2011, 11:38 AM
Replace both sides for sure.

baja22
12-07-2011, 08:50 PM
Replace both sides for sure.

no doubt! replace just one, come on Sloop you only have one motor! [smilie=crazy]

bsloop
12-07-2011, 08:59 PM
Pair of new exhaust and risers ordered.
Hope the exhaust bolts are not too rusted that I break bolts or uncover more problems :(

Should I be checking my trans cooler as well?

bsloop
12-07-2011, 09:29 PM
no doubt! replace just one, come on Sloop you only have one motor! [smilie=crazy]

I have some fuel wetness around the top of my Holly carb which also ran a little rich this year. Have a feeling a rebuild is in order there too.
Pulled drain plugs but have not fully winterized yet as I was expcting this to a simpler repair and figured I would be running it to check for leaks.
Sitting in the shed with the bilge heater, hoping there is no electrical interuption........

motor repairs are cutting into 2012 stereo upgrades [smilie=balls.gif]

Griff
12-08-2011, 02:05 AM
I don't think you will break the bolts, but the heads on the bolts could be rusted and create some problems. I would start soaking them with some PB Blaster now.

bsloop
12-19-2011, 03:20 PM
New exhaust and risers were installed over the weekend. Lucky weather!
Shinny and smooth. They felt cooler than my cast iron, dont know if that was due to better flow and heat transfer or just the cooler hose water?
First opportunity to use torque wrench received as birthday present. First torque to 30# had a small leak on each side so bumped to 38# and leak stopped.

Only other suprise was a threaded port on the front of the riser that was not on my OEM riser.
Its a 5/8" 18 fine thread.
Since UPS delivered late Friday, I didnt have a lot of choices and Ace only had the one series of bolts that would work temporarly. The bolt leaked, so I used some teflon tape to seal for now.

I expect Fastnal would have a plug like is used for the rear of the manifolds (manifold plug which I have 4 extra, is larger than riser)
Is this a tapered plug that is designed to seal tighter?

tko232
12-21-2011, 07:38 PM
The hole is most likely tapped for a 1/2 inch pipe fitting. you should be able to get them, in brass, at the hardware store.

bsloop
12-21-2011, 08:59 PM
Close, it is 3/8" pipe thread.

Placed a call to John P while at NAPA yesterday. [smilie=042.gif]
Between him and the parts man we worked it out.
Have not been back out to the boat to confirm but we tested on thier sample board.

arisenagain
07-24-2013, 05:02 PM
I have the same engine. Indmar model 350 which is a 454 GM big block. I'm having the same issue as you with finding the right replacements risers and exhaust. Can you tell me the part numbers of the Aluminum exhausts & risers you ordered? Also where did you get them? Are they the aluminum units you mentioned a few posts back?

Thanks a bunch for this post as there is virtually no information for this engine setup.






New exhaust and risers were installed over the weekend. Lucky weather!
Shinny and smooth. They felt cooler than my cast iron, dont know if that was due to better flow and heat transfer or just the cooler hose water?
First opportunity to use torque wrench received as birthday present. First torque to 30# had a small leak on each side so bumped to 38# and leak stopped.

Only other suprise was a threaded port on the front of the riser that was not on my OEM riser.
Its a 5/8" 18 fine thread.
Since UPS delivered late Friday, I didnt have a lot of choices and Ace only had the one series of bolts that would work temporarly. The bolt leaked, so I used some teflon tape to seal for now.

I expect Fastnal would have a plug like is used for the rear of the manifolds (manifold plug which I have 4 extra, is larger than riser)
Is this a tapered plug that is designed to seal tighter?

bsloop
07-24-2013, 08:40 PM
I replaced the manifolds, risers, gaskets and bolts. With other engine advice I ordered an extra set of gaskets since they are so cheap relative to one being damaged upon install. Barr is the OEM casting company for much of the industry.

Parts ordered were -


109-531017 4

RISER GASKETS

EA


4

4









109-531077

RISER E-COATED

EA


2

2









109-531078

MANIFOLD E-COATED

EA


2

2









109-CHVA184P

MOUNTING PACKAGE 2 EA




Plus the two 3/8 brass plugs and engine to exhaust gaskets.