looks like my riser gaskets are leaking

Back when I posted pics of my ignition swap someone questioned all the rust streaks coming from the riser gaskets.

The recommendation was to repaint the manifolds and look for fresh signs of leakage.

When I was messing with the boat yesterday I noticed some dried water streaks coming from the same area. I'm thinking I need to replace my riser gaskets.

Couldn't find any good How-To's.

I'm going to drop some 50/50 acetone/trans fluid on the bolts today and attempt to remove them New Year's Day.

I have hand, air, and power tools at my disposal. Should I start with hand tools (box wrench or socket)or should I hit the bolts with an impact first (air or electric)?

I know I may wind up having to heat the manifolds up.

Any tips or suggestions would be great. See below pics for new signs of leakage.

Thanks Pete.

So permatex each side of the gasket prior to installation?

I wasn't planning on messing with the manifold. Should I?

J - You might have to clean up the cast iron gasket surfaces.   Mine very very pitted, about 1/2 of the wall was gone.     I used some emory cloth stapled to an oak board to cut it flat. You can use a file too, but it won't cut very easy.

I would tap out the threads while you have it apart. Anti-sieze compound is always a plus for reassembly.

Make sure & position the new gasket so that the lower riser port is blocked.

Happy New Year!

JPass:

What you are doing is close to what I did recently. While skiing at Lake Powell in October, my muffler blew out. 1994 boat (351W) so I figured that the muffler didn't owe me much. While installing the exhaust gear, I noticed the tell-tale leaks on the risers. So I decided to replace the gaskets. I was concerned with bolt extraction, so I applied PB Blaster 2X per day for 3 days. To my surprise, the bolts came right out.

Then the fun started. Upon further inspection of the manifolds, I could see where the exhaust manifold bolts were badly corroded and rusted - directly under the riser leak. Can't have that now, can we? So I decided to pull the manifolds and re-work the exhaust system. My problem came with the exhaust manifold bolts. I did the same PB Blaster technique of 2X per day for 3 days. Of the 16 bolts, 12 came out fairly easily. The bolts are 5/16" hex cap bolts. On the 4 stubborn bolts, the corrosion was so bad that the allen key just spun. I used a big Easy-Out and they also came out relatively easy.

As for your question regarding air tools, I've had too many bad experiences with bolts breaking due to over-use/misuse of air tools, so I try to exhaust the "hand" method first.

The biggest challenge I had was cleaning up the surface on the risers and on the manifolds where the gasket mates-up. I also used Permatex on both sides.

I have a question for all you motor-heads: I bought the replacement exhaust manifold bolts from skidim. They appear to be stainless steel. The original bolts were carbon steel. I used a liberal amount of anti-gall / anti-seize during installation, but I'm a little concerned with stainless bolts in a carbon steel block...particularly in a high heat environment. Any thoughts?

Good luck.

JQ

Jonny Quest wrote: I applied PB Blaster 2X per day for 3 days. JQ

Funny you say that. I wound up going with PB Blaster too. Hit the bolts 3 times the other day and I'll be hitting them again today and tomorrow. I may wait until Sunday to attempt to remove them. Saturday is supposed to be around 80 and I may head out for a run.

Glad to hear your bolts came out intact. I hope I'm as lucky.


Happy New Year

JPASS wrote: [QUOTE=Jonny Quest]I may wait until Sunday to attempt to remove them. Saturday is supposed to be around 80 and I may head out for a run.

It was 2 degrees this morning at my place. I doubt that I will head out for a run on Saturday.

Cheers!

Jonny Quest wrote: I'm a little concerned with stainless bolts in a carbon steel block...particularly in a high heat environment. Any thoughts? JQ

What is your concern?   

After breaking some of the bolts on both my '85 and '95 I was able to get them out using a torch and penetrating oil heating the manifold and using vise grips on the remaining part of the bolt. The long ones in the front are the ones that will most likely break. I then replaced them with SS bolts coated with anti seize.
They are a odd length I think they were like 5 1/2" or 6 1/2" so I got the next size up and cut and retreaded. I also ran a tap in the thread holes to clean them up.
Now as part of the winterization process I remove them and re-apply a fresh coat of anti seize every year, no more problem.

5 of the 8 came out nice and easy. The other 3 (all on the starboard riser) are going to soak another day or so. I still haven't been able to get the exhaust hose off the riser yet. Going to try some heat tomorrow.

phatsat67 wrote: Ohhh common Pete!!! Vice grips are a life saver. Used that method successfully 100s of times.

Zach,
What would you think of a mechanic removing head studs from a engine block with vise grips?

8122pbrainard wrote: 8122pbrainard wrote: Jonny Quest wrote: I'm a little concerned with stainless bolts in a carbon steel block...particularly in a high heat environment. Any thoughts? JQ What is your concern?    Rob, I see you have been on site but maybe missed my question?

Rob,
Without an answer to your concern, I'll try to guess and answer.

Electrolysis between dissimilar materials? No, both cast and stainless are carbon steels.

High temperatures? Not a problem since stainless steels are the preferred choice even for extreme temperatures.

You have nothing to worry about and purchased a premium set of bolts.

OK, so here's where I'm at as of this morning. I got the three remaining bolts out, but snapped each one. They stick up less than a half inch and look pretty corroded. I've begun soaking them, but I think I'm going to have to drill them out and re-tap (which I completely suck at). May even have to remove manifold???

Suggestions?

Smoke wrench?

Pete, those work when you aren't lucky enough to have a McMaster right down the road ( I think you own stock in them ). But, since I have experience like you, I will usually try to drill it down below the thread size and pick all the stuck bolt out to re use the existing threads when possible.

phatsat67 wrote: Pete, those work when you aren't lucky enough to have a McMaster right down the road

Zach,
They do ship UPS!