Rebuilding questions on carbon removal and reinstalling a crank merc L6

" Hi,

I'm a coupl

" Hi,

I'm a couple days away from having the parts to swap a crank in a merc L6. Currently I am attempting to clean the carbon off the pistons/rings. There is nothing wrong with the rods, pistons, rings or cylinders, and becuase of that I just removed the rod caps and am treating the pistons and rods as an assembly.

I have a bucket of chem-dip parts cleaner, and have attempted just soaking the head of the piston to loosen the carbon from the pistons and rings. I'm weary of melting the coating that prevents corrosion on the pin and rod, and also the instructions on the chem-dip tell you to rinse the parts in water, which is not something I would like to be doing with the bearings. After minimal success this way I have begun soaking the parts in gasoline, and then using a wire brush. Are there any tricks out there that may speed this process along?

Also, the book I'm reading on this merc L6 is telling me that the crank/rods/pistons should be installed as an assembly using 6 ring compressors that are shaped like a U. It looks like I can just spin the crank as I install the rod bearings/cages/rod caps and get the crank installed with the pistons in the cylinders.. if anyone out there has done this or knows if things can or can't be done this way please reply. Thanks in advance,

Jon "

" Jon,

I'm in the same

" Jon,

I'm in the same boat (bad pun) as you. I'm rebuilding an inline six as well. I've seen posts on other boards about using band type clamps and aluminum roof flashing to make compressors that can be removed. I've also been told that with a helper to hold the crankshaft, it is possible to work the pistons in using wooden paint sticks to compress the rings. There is a taper on the cylinder bore that should make it easier. I've gone the crazy route and bought two sets of compressors since that is what the manual indicates and it sure looks easier. You might want to check with your local marine repair center and see if they will rent you a couple of sets. If you are intent on putting the pistons in first, it can be a bit tough to torque the rod nuts (unless you have the later design with bolts only) and install the bearings on the rod throws.

Where are you located? If you are close, you could bring it over and I'd be happy to help out if I can.

As far as the carbon goes, I got a soft brass brush and used that along with parts cleaner to get most of the carbon off. A good soak overnight and brushing with extra solvent works well. Wear gloves since the solvent is rather nasty. The piston ring grooves have proven to give me the most trouble. I've used soapy water and an alcohol rinse followed by lots of engine oil on parts without any problems. I would be more concerned with using gasoline since it will remove all the oil and leave the parts open for rust. Gasoline is not a good parts cleaning solution.

Kirk "

" Kirk,

Well it's

" Kirk,

Well it's nice to find someone out there in the same boat (I'll accept the bad pun). Without the crank on it isn't very difficult to just use your fingers in those indents to get the rings compressed. The only tricky part is not to spin the rings, and I have not removed any other covers/jackets from the block so there is no way of double checking the installation. My rods are threaded, so it is just a bolt to torque, no nuts.. mabye that is why the book is saying to put it all in as an assembly?

As for using gasoline to clean the carbon, what I am trying to avoid is melting the reddish coating off of the rods, as they are still attached. That coating comes off in chunks in the parts cleaner (tried it on a junk rod/piston).. and I think it is supposed to be there for corrosion resistence or something. I know what you are saying about the gasoline, I didn't mention it, but I mixed a fairly liberal amount of two-stroke oil in to keep everything lubed. I agree on the rings being the hardest part, I'll be picking up a nice soft wire brush today. And man, that solvent is nasty -it doesn't hurt immeadiatly, but it will make you dizzy in short time .

As for the ring compressors, don't feel bad, I bought the magical mercury marine flywheel puller. Are the compressors you have shaped like a U, with tabs on the tips that adjust to the rings, like the book? What do they call them - just "marine ring compressors"? Anyway,
I am located in southern NH; if you are in the area, drop me a line at my email.

Jon "

"Hi Jon and Kirk,

I have re

"Hi Jon and Kirk,

I have rebuilt quite a few Mercurys and can tell you that you can definitely install the pistons without the ring compressors. The bore is a little bit wider at the forward end, as Kirk said, which makes it easier. Just make sure the ring gap lines up with the pin in the groove. This part is really not a problem. A little patience is all that it takes. I have done this alone, using wood spacers between the block and crank as necessary to keep the crank in position.

I would advise you to change the rings if there was a lot of carbon , especially if the rings were stuck in the grooves in a few places. Make sure you check the ring gap before putting them on the pistons.

As for the reddish coating on the rods, I don't ever recall seeing a coating like this, that ever came off in chunks, no matter what it was soaked in. This part puzzles me.

The reason they advise you to install the crank and pistons as an assembly ( I think ) is because it is easier to do it that way. Because these engines have no cylinder head, it can be very difficult to position cylinders as you are assembling the rod bearings and caps. If you get a few rods connected to the crank and an unconnected piston gets out of whack you cant reach in from the other end of the bore to help align it. All you have to work with is the end of the rod, and that can be a problem. Of course, if you have the older rods, which you mentioned, you probably have no choice. Assembling the rod bearings and caps in place might be possible, but I wouldn't advise doing it. If you drop one or more of those nuts, it could result in a lot of aggravation.

Cleaning ring grooves, I would agree, can be real nuisance if carbon has built up. You don't want to damage the grooves, but you have to get all of the carbon off. You can use an old piston ring to scrape the groove. Break it into a few pieces so that you have a supply of scrapers. You can clamp a piece of ring in a vise,and work the piston against it. This works very well for rectangular grooves. For a cone-shaped groove, you have to do some grinding on the tip that you are using as a tool so that it matches the shape of the groove.

Hope this is useful to either of you.

"

" Tony,

I was hoping

" Tony,

I was hoping to hear from you on this, and yes the advice is very useful. I'm not sure what to think about the reddish coating on the rods, but it is there on the 115 rods and the junk rods I pulled off an older 90 L6. The rings I'm cleaning arn't carboned too badly, but while practicing putting the #1 piston back in (to be sure I could do it correctly by hand) I managed to get the bottom ring to stick, so I figured I better clean them all off while it's apart.

I was planning on changing all the bearings as well, with the exception of possibly the uppper and lower ones on the crank, until I saw what mercury was charging. They wanted $64 a set for the rod bearings, and something equally as ridiculous for the main bearings. Well, I got a cataloge last night from Precision Mfg and they advertise those rod bearings for $6 and change.. the mains are also about as cheap. Rings through them look to be about $20 (I think for sets of 3), but this engine has had a rebuild prior to this one (I'm replacing a stripped crank) and I'm figuring with 122-127 cold compression they are probably OK. I also lack the tools,knowledge, and confidence to accuratly measure the rings/pistons so I think I better just go with what works this time.

There are a few things I wanted to run by you, the first was that there is a scuff on the stator. There is no exposed metal from the wires inside, but it did expose a few different colored wires a bit. The flywheel looks fine, and the stator was definitly on there right.. do you have any idea what could cause that? The second is that the heads of the pistons are completely covered in carbon, with the exception of a bare spot in the edge in the same place on each one. The pistons are not damaged, but does this sound like pre-ignition,or is it normal? Last, do you have any idea what causes the splines on the crank to strip, and/or how to prevent it? Thanks for any/all advise,

Jon "

Splines will wear out if ther

Splines will wear out if there is a bent exhaust housing. It is important to grease the splines on assembly to prevent them from rusting out.

"Jon,

I agree with Sparky,

"Jon,

I agree with Sparky, a little water proof grease is important on the splines. If the splines on the shafts rust together, taking them apart can be very difficult, and usually there is some damage. It might seem alright, but at some point the splines on either shaft can fail.

Frequently, metal objects ( washers, screws,etc. ), are drawn into the magnets on the flywheel, due to carelessness when working on the engine. This would explain the scufffs on the stator. As long as the windings are still intact it should work fine.

The carbon on the pistons is not uncommon. It can be the result of many things. I wouldn't worry about that.

"

" Hello all,

Well, I bought

" Hello all,

Well, I bought quite a few of the tools required for this project. I've got a couple other motors that I will be working on that I can use them on. You might want to pull the intake port covers off to check the rings since if one breaks, you will probably be looking at some more money in machine shop work and oversize pistons. I got my parts from the Mastertech and got a pretty good deal on the parts. I've had to replace most everything on my 1350 and Mercury parts are very, very expensive.

I'll be interested to hear how it goes.

Kirk "

Do not forget to check the bl

Do not forget to check the bleed inserts. They are often missing on older motors.

" Guys,

Thanks for t

" Guys,

Thanks for the help, it's allways appreciated,

Jon "

" Sparky,

I don't see t

" Sparky,

I don't see those on my 1350 parts list, when did they start using them?

Thanks!

Kirk "