Hole in exhaust manifold

[ebubeck]

I've got a 2001 90hp Merc. 4-stroke with a nickel sized hole in the adaptor plate or exhaust plate that connects the yamaha powerhead to the drive shaft houseing. The exhaust quickly fills the engine compartment and snuffs the engine. I've tried a jb weld patch but it doesn't hold. Mercury basically won't take any responsibility for their poor design. The part is $200 plus I've got to pull the powerhead, oil pump, lower unit, and replace all associated seals. I would really like to avoid that. Access is reasonable with the footing cover removed. Any ideas? The adaptor plate is aluminum. Is welding or brazing a bad idea? What about heat transfer - warping and melting seals, blowing electronics etc? Help please!

 

[arboatdr]

Re: Hole in exhaust manifold

Is the hole on the starbord side? If so there should be 2 plugs there(pipe) Did one of them possibly fall out? If not is the metal thick enough to run a pipe tap in and put a plug in it. A pic sure would help.

 

[fatpratt1996]

Re: Hole in exhaust manifold

Is that cast iron. If so good luck trying to repair that. I wonder of there is a cheap way to patch it with a small piece of metal and some very shallow sheet metal screws and some jb-weld. Kinda cheesy of a fix if you ask me, but if you don't want to spend the $200, it can't hurt. Take this with a grain of salt though

 

[ebubeck]

Re: Hole in exhaust manifold

follow this link to a post with some pics<br /><br /> http://www.2coolfishing.net/ttmbforum/showthread.php?p=68873#post68873 <br /><br />the metal is pretty thin ~1/8", it's aluminum and it's right in a corner. I tried to jam a short bolt in it but I just don't have space for the bolt head. Hey, if I'm going to spend the $ and time to fix it anyway I might as well try some "cheesy" fix first - nothing to lose. The short sheet metal screws might work.

 

[arboatdr]

Re: Hole in exhaust manifold

Yeah, thats nasty. probably will replace in the long run. No good fix that i can see.

 

[KCLOST]

Re: Hole in exhaust manifold

How did this happen?????

 

[ebubeck]

Re: Hole in exhaust manifold

Ask mercury. To me the metal was too thin - it corroded from the inside out.

 

[ebubeck]

Re: Hole in exhaust manifold

I run it in saltwater and rinse, flush after each use. All of the grey stuff surrounding the hole is the residue from the jb weld I've tried to patch it with.

 

[rabidfish]

Re: Hole in exhaust manifold

If you have it apart, replace the driveshaft bushing also. It can wear, causing oil pump failure promptly. I dont think Merc has a service bulletin on this, but it does need to be done. Also, be sure to never run the engine without the lower unit installed. The driveshaft splines are what turns the oil pump.

 

[Chris1956]

Re: Hole in exhaust manifold

LASpeckking, The entire manifold looks like it is about to fail. This shouldn't happen to such a new motor. Does it get very hot when running, it kinda looks like it is discolored from heat. Anyway, I would sand it rough, wipe it with Acetone and cut a piece of fiberglass cloth to fit the entire exposed side. I would then mix some Marine-Tex and trowel it onto the cloth and stick it over the manifold, and trowel it smooth. The Marine-Tex should stand up to the heat and corrosion for quite a while.

 

[ebubeck]

Re: Hole in exhaust manifold

I agree completely - this should not happen on such a new motor. There was no discoloration until I gooped up the area with JB weld and some junk I got at the autoparts store. It was a much smaller hole but I decided to try and get rid of the flakey stuff (just pushed it out and then drimmeled the edges a little). From the outside it looked perfect, just a hole in the metal - I've since mucked it up pretty good. I was trying to get on the water for a tournament.

 

[Hooty]

Re: Hole in exhaust manifold

I believe it can be welded but it's gonna have to be disassembled to access the inside.<br /><br />c/6<br />Hooty

 

[ebubeck]

Re: Hole in exhaust manifold

Just to let you know Mercury has declined my request for assistance. Apparently their products are not designed to last beyond their warantee - and they accept no responsibility. They have lost a customer - never again will I purchase a Mercury product.

 

[flips]

Re: Hole in exhaust manifold

Mate that looks very sick.<br />Look up Mr Stickys site and see if it will take the heat,My mate here has selling rights in australia and i have used this on many things and had great results.its made in USA, but i am not sure about that heat.<br />cheers Flips.

 

[ebubeck]

Re: Hole in exhaust manifold

Thanks for all of your help, I tried several different patches but none held up, so it's $475 and the exhaust plate will be replaced by the local shop. Hope to not have this problem agian four years down the road. Thanks again.

 

[Chris1956]

Re: Hole in exhaust manifold

Did you specifically try the MarineTex? I have used it on auto mufflers, exhaust pipes and catalytic converters for years. I also used it to glue a spark plug insert into the head of an air-cooled motorcycle. It never burned or fell off. The only time it failed was when the metal it was attached to rusted away from the inside!

 

[ebubeck]

Re: Hole in exhaust manifold

No, did not try the marine tex - thanks for the suggestion, I just wanted to get reliably back on the water ASAP. The shop has it apart right now, looks like I'll be relacing more than the exhuast plate. I will be looking for answers from Mercury. The area from just below the exhaust exit on the powerhead to about 3" down the exhuast tube is completely pitted. Totally clean down from there. That leads me to believe something in the exhuast is eating away at the aluminum or the heat is affecting the corrosion resistance of the aluminum. Any ideas? I will post a link to picks once I upload them - it looks really nasty.

 

[ebubeck]

Re: Hole in exhaust manifold

http://www.2coolfishing.net/ttmbforum/showthread.php?p=77430#post77430 <br /><br />pictures and post of the inside

 

[jim dozier]

Re: Hole in exhaust manifold

I have been following this post just because it was interesting. I am perplexed by it as I'm sure the owner is. It does look like a bad casting with a odd alloy batch but I'm no metallurgist. It looks like a combination of corrosion and heat have eaten through. The hole is not the only area either, it is widespread. Is there or has there been any evidence of ??<br />1. running lean<br />2. overheating<br />3. pre-ignition<br /><br />Perhaps a combination of high combustion temps due to lean mixture, overheating, and pre-ignition ran the temperature up in the exhaust housing and accellerated corrosion from salt deposits left there. I would be really interested in Mercury's explanation of what happened even if they don't cover it under warranty.<br /><br />Is this casting supposed to be cooled by the cooling system? If so is the cooling water flowing properly where it is supposed to?

 

[ebubeck]

Re: Hole in exhaust manifold

Jimd - thanks for the response.<br /><br />The cooling water does pass through the exhuast plate but I don't think it is intended to significantly cool the plate (no veins through the plate). No doubt had there ever been a problem with water flow through the plate I would have a seized block now.<br /><br />About 1 year ago, after setting idle for 3 months, I had carb problems and cleaned them out. Ran fine after that and have no reason to suspect a lean running engine, however, I would not rule that out. Any idea how I can verify that I am/not running too hot? Like I said, I have never seen any evidence of overheating or poor cooling water flow. Sorry - define pre ignition for me (my guess - firing before the sparkplug fires due to excessive heat in block). If so, I haven't ever noticed anything like that. Motor seems to perform 100% even after running wide open for 30 minutes.<br /><br />As far as Mercury, they will not talk to me about any technical issues. I have to go through my dealer, which I have asked that he give them a call. I'll let you know if anything comes out of it. At this point I've given up trying to get financial assistance from them - I really don't want to do this again in 4 years so I need some real answers.