Rotax 4Tec 1503 Rebuild

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backyardbuilt

New Member
Alright forum here's what i got. So recently my 2013 RXPX 260 dropped a valve, i replaced 3 pistons and rings and started assembly on the rest of the motor. Everything was going smooth until it was time to put the cases back together. I got everything torqued to spec, according to the manual, but the crank will not spin at all by hand. I split the cases and the crank started rolling pretty easy again. I used tons of assembly lube and like i said, torqued to spec. No visible damage to anything on the bottom end. Silly question is, could it be because im trying to rotate the crank with the motor being upside down? Im at a loss for now, and i don't really know what to do next. I am not a Professional engine builder, but i do have experience in building motors. Like i said, not sure what to do, hopefully you guys can help me out. Thanks in advance.
 
I am currently doing this on my 2005. Unfortunately I had to replace the head.

I would check to make sure the key on the main bearings are properly engaged with the key slot in the engine block and engine case bottom. Check the same for the counter balance bearings.

Make sure the bearings do not extend up beyond the engine block or case bottom. If they do, there may be debris trapped under the bearings.

Any chance you bought oversize bearings which are to be used with a crank which is ground under size?

If you do not find a problem. pull the counter balance shaft bearings out of the case bottom and assemble it again. If it now spins freely, look for a problem with the counter shaft bearings. Still no luck, pull the thrust bearings out and try to spin it. Maybe one is in wrong.

Rotating upside down should not be a problem. If rotating right side up you need to be careful the timing chain does not jam up.
 
dcm0123 said:
I am currently doing this on my 2005. Unfortunately I had to replace the head.

I would check to make sure the key on the main bearings are properly engaged with the key slot in the engine block and engine case bottom. Check the same for the counter balance bearings.

Make sure the bearings do not extend up beyond the engine block or case bottom. If they do, there may be debris trapped under the bearings.

Any chance you bought oversize bearings which are to be used with a crank which is ground under size?

If you do not find a problem. pull the counter balance shaft bearings out of the case bottom and assemble it again. If it now spins freely, look for a problem with the counter shaft bearings. Still no luck, pull the thrust bearings out and try to spin it. Maybe one is in wrong.

Rotating upside down should not be a problem. If rotating right side up you need to be careful the timing chain does not jam up.
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Thank you for the reply, i will check in the morning everything you have noted, i didn't replace main bearings, they seem to be in good shape still. I will pull the thrust washers / bearings out and check to make sure they are in right, i will also double check the main bearings on both cases and see what i come up with. Once again thank you for the reply. I also will check with the counter balance bearings / thrust washers.
 
Forgot to mention the "OEM" Main bearing bolts are torque to yield. If you already went to yield on re-assembly, you should probably replace them. Do not take up to the higher yield point until you check rotation.

If you still have problems, pull the crank shaft then remove all bearings and clean all surfaces (both sides of bearings, both cases, crank and counterbalance shafts), then re-lubricate the crank/counter balance sides of the bearings before reassemble.

I will need to remember to check rotation first when I re-assemble.

You may need more torque to rotate then you can apply by hand. If much more, maybe something wrong.
I saw a tool being used on line to hold the crank. Looks like the tool used to hold the shaft when you re-assemble the jet pump but I am not sure.

I am not an expert on Seadoo's but are trying to use common sense based upon many other engines I rebuilt over the past 45 years.
 

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dcm0123 said:
the "OEM" Main bearing bolts are torque to yield
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No, the case bolts are not stretch bolts. You can reuse.

Some assembly lubes are very thick and cause a lot of drag. I prefer to use oil only. There will be a little bit of drag but should rotate easily.
 
dcm0123 said:
Forgot to mention the "OEM" Main bearing bolts are torque to yield. If you already went to yield on re-assembly, you should probably replace them. Do not take up to the higher yield point until you check rotation.

If you still have problems, pull the crank shaft then remove all bearings and clean all surfaces (both sides of bearings, both cases, crank and counterbalance shafts), then re-lubricate the crank/counter balance sides of the bearings before reassemble.

I will need to remember to check rotation first when I re-assemble.

You may need more torque to rotate then you can apply by hand. If much more, maybe something wrong.
I saw a tool being used on line to hold the crank. Looks like the tool used to hold the shaft when you re-assemble the jet pump but I am not sure.

I am not an expert on Seadoo's but are trying to use common sense based upon many other engines I rebuilt over the past 45 years.
Click to expand...
Okay so, I tried everything you mentioned last night. No luck. I am gonna try and clean and lubricate the bearings and double check clearances and make sure bearings are seated. I guess I’ll try to spin the crank using a tool. How tight is too tight? I know the starter isn’t very powerful, I’m just worried when I get it all together the starter won’t be able to budge it.
 
backyardbuilt said:
Okay so, I tried everything you mentioned last night. No luck. I am gonna try and clean and lubricate the bearings and double check clearances and make sure bearings are seated. I guess I’ll try to spin the crank using a tool. How tight is too tight? I know the starter isn’t very powerful, I’m just worried when I get it all together the starter won’t be able to budge it.
Click to expand...
I guess I should also mention that the crank spins easily until the bottom case goes on.
 
Okay so I have the outer case bolts 4 of them in each corner with both cases together. Crank spins but it’s very tight. I’m thinking when I torque down the main bolts and put the rest of the bolts in the case it’s gonna be locked up again.
 
Have you taken a straight edge to the mating surfaces to make certain they aren’t warped/distorted?

Following bolt torque sequence? With proper lubricant to threads and under bolt head? (If called for in manual).

Are threads clean and chased with tap?

Were bearings marked as to where they came from during disassembly since they were reused?

Is torque wrench calibrated?

Can we assume all dimensions and clearances have been verified before assembly?
 
Here is a suggestion to try to identify if crank bolts-

Do not put in the case bolts until after testing crank bolts.
I would put all crank bolts in starting with the outer pair of bearings and torque. Then check for rotation (you may have already done this).
Then put in the other 2 pair. Turn again. If tight, loosen one at a time to figure out which causes the binding.

If still loose, with only crank bolts in, try turning the counterbalance gear back and forth to see if any rotational play between the CB and crank gears.

I have my doubt tightening the case bolts have anything to do with the main bearings due to the difference in the torque on the mains vs the case bolts.

Then start putting in the case bolts. When done, see if there is any rotational play between the counterbalance and the crank gears again. The case bolts are what clamps the counterbalance bearings in place. If this causes the binding, look closely at those bearings.

I can not tell you how much torque it takes to rotate the engine. The rings will provide the drag. A thicker oil on the bearings will add to the drag. Put a rorque wrench on with the case removed and see how much torque it takes to rotate the crank. I would not think tightening the bearings would add more than 1-2 foot pounds to the torque the rings require.. I will have a better idea when I install my lower case in a week or two.
 
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I had the same problem. But different situation. My engine was totally destroyed, so I bought another set of blocks. Turns out they were not a match! The hole line for crank was oval. You can tell if in front of the engine under oil pump block serials match or not. They should match.

But I understand you have your old engine, so that should not be it.
 
Alright I have been gone for a while. Life stuff got in the way. It im back at it again, I have tried everything dcm0123 has stated to try. Still nothing. It binds up really bad I even tried with no counterbalance in. I’m pretty much at the point of buying new main bearings. That’s the only thing I can think of. Will report back when I get new bearings in and seeing if that fixes it. I’m assuming it’s a clearance issue. But they are the original main bearings and were in good shape. I just really don’t understand. I have tried and tried to research and call a few mechanic buddies that do marine repair also and that’s what it’s looking like is bearing clearance issue. So I’ll go from there.
 
Okay I just noticed that when the crank is spun without the cases together. When you get to a certain spot one side of the crank lifts up slightly. And then doesn’t want to spin. Could that mean the crank is bent? Or bearings are shot?
IMG_0367.jpeg
 
Not likely. Probably just the resistance of the piston pushing it up. Can you push it back down?Take all the bearings out and clean them as well as the journals. Put them back in the same position making sure they are lining up properly with the groove. I would only put 1 drop of oil on each bearing. A machine shop will be able to tell you what's wrong pretty quickly.
 
ski-d00 said:
Not likely. Probably just the resistance of the piston pushing it up. Can you push it back down?Take all the bearings out and clean them as well as the journals. Put them back in the same position making sure they are lining up properly with the groove. I would only put 1 drop of oil on each bearing. A machine shop will be able to tell you what's wrong pretty quickly.
Click to expand...
Alright so bolted it all back up. Cleaned and lubed bearings, torqued everything I’m just gonna assemble it and run it. I was able to put vice grips on the end of the crank and was able to spin it. It’s tight but it’s not froze up like I thought it was. I’m just gonna roll with it and see what happens.
 
Pour oil into the oil filter housing to help bring the pressure up faster after you start it.
Would be a good idea to crank it for about 30 seconds without the spark plugs in to build oil pressure before starting.
Then check the oil level again.
 
I fully understand the do-it-yourself aspect of working on your own ski... BUT
I have to wonder: Is there not a reputable aftermarket supplier or machine shop somewhere that can or IS doing OEM quality short block remans or complete exchange for those that are totally f'ed up?
I figure "ski-d00" and the other regulars would probably have the pulse on this kind of thing?
Maybe the market is just not big enough to support that kind of operation?
Maybe it IS all about the $$$. In that case, there probably is no good alternative answer.

Having done this type of work (and seen the failures) for decades, I just hate to see so many of our well intentioned skiers struggling with these kind of MAJOR problems. I would also imagine that most of these motor failures were the result of some serious overall system failure or abuse.
Imagine if OEM dealers were fast, friendly and honest? Get out the rainbows and unicorns!... I know, I know.
Just wondering out loud.
 
I took the DIY approach because the 2005 RXT is only worth 5K and I have rebuilt many engines, transmissions and differentials but not Seadoo's. I also have engine building tools and a Candoo. The 2005 and 2006 Supercharged engines fail due to defective engine valves.

Best rebuilt price I found was .about $3K for a standard rebuild. Not sure what I will be getting for parts. If you hire someone to install it with additional parts you are probably spending another 3K.

For about $2.5K I can rebuild it with used parts (late model head and piston assemblies) from reputable suppliers on Ebay and some new from Seadoo. I will know what I have in the end.

There is a lot of good technical resources available between YouTube, this forum and the PWC Performance Forum (Greenhulk)..
The Seadoo service manual is excellent. It provide detail and a good technical overview to how the various systems of the engine function. If you have a technical background and are willing to take the time to understand it, you can figure out some issues for yourself.
 
Hey everyone, so I had some life things get in the way and I’ve pretty much been away from being able to work on the motor. I have the motor back together, and it does in fact turn over. Maybe it was just all in my head. But I appreciate everyone for help and guidance. Thank you all!
 
Okay so I'm back, did a compression test today before running the motor just to make sure everything is good. I poured oil in all 3 cylinders the compression readings I got were cylinder 1 135 psi, cylinder 2 150 psi, and cylinder 3 was 170 psi. Now i think that i might have put too much oil inside of the cylinders, BUT I figured I'd ask and see what you all think about it. I definitely think i put too much oil inside each cylinder but like i said not sure. 3 new pistons and rings, new head, new cam, new valves and seals. head studs stuff like that.
 
I would crank it for about a minute with the spark plugs out to blow out excess oil before starting.
This will also build oil pressure in the system before you start it.
Can not tell you if compression is OK since compression is usually tested without putting oil in.
 
Three questions for you.
  1. When you rebuilt, are you sure you got your ring gaps correct? If those are too tight I'm guessing it could cause binding and also cause high compression numbers (from less blow by?).
  2. Did you hone/bore the cylinders? If you bored, did you get your machine shop to match the bores to your new pistons?
  3. I'm going to ask, but hopefully this is a dumb question. When you were turning the crank by hand, the spark plugs were removed - correct? If no, then you're just fighting the compression of the engine and it SHOULD be hard to turn by hand.
I'll qualify this by saying that I'm wrapping up an engine rebuild myself (first ever) and others are much smarter than me in this area so I'll defer to them but figure I'll share in case I can help.
 
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