Exhaust mani gasket
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=649
Printed Date: November-22-2024 at 4:25am
Topic: Exhaust mani gasket
Posted By: Guests
Subject: Exhaust mani gasket
Date Posted: July-21-2004 at 11:00am
While investigating my intake manifold tightness I realized I also have an exhaust leak where the mani meets the head. Just enough to make a tippity-tap tap tap noise. Nothing like finding two problems for the price of one! Anyway, I would imagine the whole thing would unbolt from the engine and I would replace the gasket. A few questions on this (351 W, 90 SN):
1. What are the chances of the bolts breaking off in the process? I've heard nightmares on this.
2. How is the surface of the header and the head prepared/cleaned for the new gasket
3. How many ft/lbs should the hex bolts be taken to upon reinstall?
4. How is the surface of the elbow/riser prepared for that gasket- do you use goop of some sort on it?
Thanks in advance,
Joel
|
Replies:
Posted By: AWhite70
Date Posted: July-21-2004 at 12:55pm
I'll answer your questions the best that I can.
1. I took the manifolds off my '79SN at ~1000hrs and the bolts came out fine. They had been removed about 500hrs prior to that. If the bolts were originally installed with anti-seize you should be ok, otherwise you might be in trouble.
2. I used a razor blade to scrape remnants of the old gasket off the manifold surface and also used a wire brush. Then I cleaned the surface with solvent. I would have done the same for the heads but they were newly rebuilt and already clean. Be careful not to get gasket fragments and debris down the exhaust ports and into the cylinders.
3. I believe the exh. manifold bolt torque is around 24lbft but I can't remember for sure.
4. I haven't had to mess with this yet, but I'd probably use RTV or some other gasket sealer along with the gasket just for some insurance especially if the 2 sealing surfaces aren't perfect.
|
Posted By: David F
Date Posted: July-22-2004 at 5:41pm
All good advise above. If you are worried that the bolts will break, then loosen each bolt one at a time. If it breaks loose, then snug it back down and go to the next. Repeat this process until all are loose. This way, if you brake one bolt, you can still run the boat without too much worry until you have to spend on it this winter. If you twist a bolt off, it will have to be drilled out and tapped. Chances are slim this will be a problem.
I recommend Hylomar sealant at the exhaust riser only. No sealant at the manifold to head gasket. You really do not need to remove the exhaust riser, but if you do, pay attention to how the gasket is installed, one water passage is blocked by the gasket and I cannot remember which, but I believe it is the lowest (back/stern) one.
|
Posted By: tommer12
Date Posted: July-23-2004 at 1:25am
|
I also recommend above, but for the gaskets, go to SkiDim and get the $4.00 gaskets... The backs are metal plated and the fronts are paper... I used some auto gaskets from the local autoparts store, they burned off in about 25 hours... Marine blocks I guess just get too hot for the normal paper gaskets... but just call SkiDim, they have the right ones, and very high quality!
|
Posted By: nms1991
Date Posted: July-25-2004 at 1:42pm
|
on the exhaust riser gaskets the tab points toward the front of the manifold blocking off the rear cooling port. Try a allen head socket to take out the manifold to block bolts, make sure the socket is all the way in the haed to keep from stripping out the head, with the socket on a extenstion tap it in with a hammer and soak the bolts down with a good penetrating oil a couple of days before you start.
|
Posted By: Guests
Date Posted: July-27-2004 at 3:08am
|
UPDATE: The previous owner had used never-sieze on the bolts and they came out very easily. All the parts are off and cleaned and ready for reassembly. Now, getting that 25 pound manifold held steady while bolting it in is another ordeal- any tips here?
|
Posted By: Rick
Date Posted: July-27-2004 at 3:12pm
You could use one stud. hang the manifold on it with a nut, put the other bolts in remove the stud and put the last bolt in
-------------
http://www.correctcraftfan.com/diaries/details.asp?ID=250&yrstart=1996&yrend=2000%20" rel="nofollow - 2000 Ski
|
Posted By: Guests
Date Posted: July-31-2004 at 10:14pm
Here are some pics from the project
http://m3fan.ath.cx/~joelhughes/boatweb/index.htm
|
Posted By: 77stang
Date Posted: August-01-2004 at 4:45am
|
those things are a bear to handle. I have a couple bolts that are an inch longer than the manifold bolts. I always insert them on the end ports and literally hang the manifold on them to steady and align. works just as well on removing as on installing.
|
|