2001 Merc 240 EFI sportjet // first rebuild

[Mariciv]

Hello,
I am new to this forum and this will be my first 240efi rebuild. I bought the 2001 speedster with a busted cylinder (from a dishonest seller) and am now in the process of researching the rebuild. I found a place who will repair and re-sleeve #6 cyl and hone the others. Should I change all the pistons or keep the other 5 original ones? I ordered a full gasket kit, crank bearing kit, rod bolts and head bolts. Do I need to change the crank seal rings? They look ok to me but then again I am no expert. What should I use to replace the bleed hoses? I am sure I will have many more questions during this process so your help will be much appreciated. I will also need a step by step rebuild manual that I can follow during re-assembly. I am pretty handy but not much experience with these engines. I will post some pics of the faulty cylinder which is completely destroyed. The piston is missing about a third of itself.
Thank you
Ivan

 

[Dr Honda]

The crank seal rings should be fine, and if the old pistons are in spec... then I would be OK with re-using them. But... if you want to be a "Fresh" engine... I would replace them.


If it was my engine... it would get 6 new pistons.

 

[Mariciv]

Thank you Dr Honda. I also need to replace one reed as the peddles got bent. There was a lot of metal fro the piston in the reed. I cannot seem to find a single set of reed peddles. Is the only option to replace all 6 with carbon fiber reeds? What else do I need to check for this rebuild?

 

[Dr Honda]

I would check the crank very well. It should be smooth an shiny. It's normal for pits to start, and if you have them... it will eat the bearings. There are companies that can weld, and regrind the crank. Should be half the $ over a new one.


I would replace the oil gear on the crank. The new version is stronger, and it's not very expensive. FYI... when you order it... they list the parts as if you need to order 2 halves. But the Mercury part number will get you a new gear (both sides) nuts, and bolts.

 

[Mariciv]

Thanks, I will look into the gear. Mine is in perfect condition but I have read that they are known to give up sometimes. Is the new one "design II" ? The crankshaft has two straight scores on the lower weight. It must have rubbed on a piece of metal from the piston or sleeve. Will this throw off the balance?
Thx

 

[Dr Honda]

If the marks on the crank are just in the heavy part of the casting... I wouldn't worry too much about it. BUT... I would get a die grinder, and smooth any sharp edges. (Sharp edges can be a point to start a crack)

Yes... the gear you will get is "Design 2". I also agree that on some of these older engines... the gear is great, and not an issue. But they are known to have a finite life... and it's just better to put in a new one since it's open. The old style gear is just a thermo-plastic. Once you get into the surface... it eats itself quick. (gets hot and melts) The new gear is fiber reinforced nylon. So... even if it wears... it doesn't melt down.

 

[Mariciv]

Thanks. I will change the gear. As for the bleed system, can I use regular tygon tubing? Is the correct size 3/32"? Thx

 

[Mariciv]

I was wondering what the tolerance is for the reeds? Can I reuse if there is a small 1/16" chip on one of the peddles? Can the reeds be trimmed on top to rid of imperfections?
Thanks

 

[Dr Honda]

if there's any damage... don't use it. It will die quick.

 

[Mariciv]

Is there a trick to install a new lower main crank bearing or do I need to get it pressed? Thx

 

[Dr Honda]

Let me answer it this way........

 

[Dr Honda]

You can heat the inner race, and it may slip on... but you could damage the bearing. If you want to do it that way... put the bearing in the oven, and heat it to 400 degrees so it's an even heat.

 

[Mariciv]

Thank you. I think I will get it pressed in by a machine shop just in case. I was also wondering if I can lightly sand the pin side of the connecting rod? It's ok but edges are a little rough.

 

[Mariciv]

 

[Mariciv]

These are some pics of the faulty cylinder that prompted the rebuild. Thought I'd share the extent of the damage.

 

[Mariciv]

I think I figured out the origin of the blowout. I believe it is a piece of aluminum from the intake that broke off and entered the cylinder through the butterfly. I also found one of the TPS screws stuck in the reeds. I will post pics soon as reference.

 

[Dr Honda]

Using a file, or some emery paper to remove a burr is fine. But, if the bearing surface is damaged (even slightly)... then get a new rod. A lot of the parts for my rebuild were found on ebay, because a good used part is much cheaper. I think I paid $15 for a used rod.

The damage looks bad... but fixable. I see a chunk out of the sleeve in the picture of your block. That sleeve will need to be replaced. The new sleeve from LA Sleeve is around $100, and you will have to get a shop to install it. If you are brave... you can install it at home, but it will still need to be trimmed, and bored to size.

FYI... when you put it back together... DO NOT reuse the connecting rod bolts. Part of the torque spec assumes a stretch. So, they are a "One time Use" bolt.

 

[Dr Honda]

I'm not sure how a "TPS" bolt could get into the reeds, since the TPS is mounted external to the throttle body. Post a pic of what you found.

 

[Mariciv]

 

[Mariciv]

I bought a new set of rod bolts, head bolts and all bearings. The block is being re sleeves and bored over on all 6 with a new piston kit.

 

[Mariciv]

 

[Mariciv]

Can I get away with the crank without any work?

 

[K Rock]

What led you to realize it was bad? Was it making noise, no compression on that cylinder, or a lack of power?

 

[Dr Honda]

If you are planning on keeping the boat... the rod and crank need replaced. (or fixed) Otherwise, the bearings will die quick.


And yes... that looks like the TPS bolt. But how the heck did it get in there???? I figured it would fall down into the bilge. In openings for the throttle body face the block. It's almost like someone threw it in there on the last owner.

 

[Rickdug]

I was thinking the same dr honda! How does the tps bolt get back inside!