787 Engine Teardown

[jimmaki]

Tearing apart a 787 but getting off to a slow start. Got the cooling lines off the head and the temp sensor out. All the head bolts are coming out except one. The bolt next to the port cooling outlet feels like it's getting ready to snap. I broke it free and put almost a whole turn out on it but any further movement springs back like the bolt itself is twisting. I've sprayed it with penetrating oil but so far no improvement. Is there a trick to getting the stubborn ones out? Heat the jug with a heat gun? I can't get an impact wrench on that bolt, not enough room above it.

Suggestions before I snap the bolt? It's in there so hard the 12 point socket was starting to round the bolt head. Luckily I got a 6 point on there in time.

 

[Coastiejoe]

Keep spraying and move it back and forth. If you absolutely feel it will snap, grind the head off and lift the head. Then you will have the stud to work with. Easier to get penitent to it.


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[jimmaki]

I tried tightening the stuck bolt but it wouldn't move. Tried a little harder and it moved, but what I thought was the threads started to loosen up turned out to be the molecules of the bolt letting go of each other. Got real easy to turn at that point.

Here is the head, the top of the jugs (left is PTO you can see the broken bolt at the 10 o'clock position), and the PTO cylinder wall. Also, not sure you can see the silicone on the ends of the bolds. It's like silicone sealant.

The MAG cylinder looks like it was running rich. The cylinder walls had a light orange tinge like varnish or rust. The PTO cylinder looked like it was running leaner, the walls looked like new only no visible crosshatch.









Now comes the jug and exhaust manifold bolts. <gulp> Can't grind off the tops of the jug bolts if they stick.

[EDIT] OK, the jug bolts ... well 7 of them ... all loosened without having to go through any gynastics. However, one is so buried in sand and water, I can't get the socket all the way on it and I don't want to round the head.

As I'm loosening the exhaust manifold bolts, the few that will loosen ... I'm noticing water dripping down the outside of the engine coming from the parting line between the bottom of the jugs and the top of the crankcase. I didn't realize there was so much water down in the bottom of the jug cooling cavities and it evidently is running out the loosened bolt holes and out the engine and I'm concerned, possibly into the engine. The exhaust bolts are giving me a hard time, they are making that squeaking seizing noise so I have to rock them back and forth a little at a time. I hope I can get to the bottom end quickly to dry it out if there's water in there.

 

[onlyadoo]

You could use a shop vac for the sand and water. Why are you tearing this down? Does it need a crank? If so I would pull the engine and the disassemble. Take the jug to competent machine shop, they'll remove that bolt.

 

[onlyadoo]

should be thread locker of some sort not silicone, at least that's what my manual says

 

[jimmaki]

You could use a shop vac for the sand and water. Why are you tearing this down? Does it need a crank? If so I would pull the engine and the disassemble. Take the jug to competent machine shop, they'll remove that bolt.

Couldn't get in there with my shop vac ... hose is too big and the angle and side of the seadoo make it impossible to get in there with the standard attachments. I had to duct tape a smaller diameter piece of 3/8" tubing into the shop vac hose and it got out all the sand and water. That bolt is now loose thank goodness. I thought it would be rusted solid sitting in water so long.

At this point I'm asking myself the same thing ... why am I doing this?? Certainly not for the fun of it, but I'm learning a lot. Especially learning what NOT to do.

Yeah, I guess removing this broken bolt is going to have to be taken to a shop and done on a mill.

The bolts underneath on the exhaust manifold are hard to see and hard to reach with any force so I'm taking the pipe off the manifold with the idea of taking the jugs off as a unit attached to the manifold. BUT, I can't get a wrench onto two of the bolts because the weldments won't let a wrench in there straight to engage the hex. I don't think a ball driver can put enough torque on them. I finally got the top one loose forcing the socket into the hole at an angle, but that's not going to work on the bottom one since there's no room to leverage it in. I'll have to cut down an L wrench and hope I have enough leverage on the handle end to loosen the bolt or come up with an extension handle for the L.

 

[jimmaki]

should be thread locker of some sort not silicone, at least that's what my manual says

I bought this new so I'm assuming whatever is on those bolts is what the factory used. It's definitely not any thread locker I've ever seen. It's translucent white, rubbery, and looks just like silicone sealant. But I can't see where it did any good since the threads are all garbaged up with corrosion anyway. Now that you mention threadlocker, I seem to recall seeing in the manual that these bolts need to be heated up to break down the thread locker. ooops.

 

[onlyadoo]

I cleaned all my threads with a tap and die kit lubed with oil. as for tearing down, much easier out of the hull. you can get that engine out in 30 min. Remove the flame arrestor, remove carbs leave the fuel lines and cables intact Remove curved pipe, I do it this way Leave the manifold on. Disconnect the cone pipe bolts, you'll need a long extension, or two short. leave it in the hull. Remove all water hoses spark plugs and the temp sensor. remove the pto cover and the pto boot. There's a hook on the manifold. I attach my hoist there. remove the three engine mount bolts that hold the motor and remove the front engine mount completely from the hull. jack it up slowly. pull forward it will separate from the shaft. come up slowly. I pinch the two oil lines with hemostats. I usually remove the starter and leave it in the hull, but you can undo the wires and leave it on. There's also the water line on the cylinders.

Now this is just a guess but this kept overheating? is that the reason for teardown?

 

[jimmaki]

No, it has never overheated. Top end is great, 160PSI both sides. I originally thought a spring had dropped down into the engine so I intended to tear the engine down from the top to try to find it. I'm beginning to believe the noise I'm hearing when I turn the engine over by hand is not the spring but a bearing so I may have to yank the engine anyway to replace the bearing or the whole crankshaft.

On my engine two of the cone pipe to manifold bolts are partially blocked by the plug weldments. It's not a straight shot to the bolts so a longer wrench wouldn't help. I'll have to cut down the short leg on an L wrench to fit inbetween the bolt and the weldment if that makes any sense. Looks like a handle of some kind on your hex wrench in the picture, what is that, does it help in tight spots and where did you get it?





Here is the allen wrench I had to cut down to fit inbetween the bolt head and weldment. I had to cut it twice since as the bolt came out I couldn't get the wrench out of the bolt head to get another reach. I had to tighten the bolt and get the wrench out and cut it again. The bold head actually hits the weldment before it is all the way out of the hole. Not sure how I'm going to get a torque wrench on it come reassembly time. I might put a hex head bolt in there instead and use one of those offset open end attachments and divide the torque reading accordingly.



On the inside radius of the pipe BRP was kind enough to use a stud and nut. I didn't have a 17mm open end wrench (socket won't fit) but luckily an 11/16 fit tight enough to get the nut off with any rounding.

 

[jimmaki]

Keep spraying and move it back and forth. If you absolutely feel it will snap, grind the head off and lift the head. Then you will have the stud to work with. Easier to get penitent to it.


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Well it snapped so now it's real easy to get penetrant on. Maybe between that and some heat it will back out.

If I take the jugs off will I need a ring compressor to get them back on over the pistons? Can I even use the same rings or will I need to put on new rings and hone the cylinders? I haven't measured them but right before I took it apart I was getting 160PSI on both cylinders.

 

[onlyadoo]

Okay, thought maybe the sand was making it overheat. It's a wrench use it for leverage. The cone pipe I'm referring to is the one behind the engine You do not need a ring compressor. Since compression was good you could just put it back together, but honing and new rings is safer than sorry.

 

[jimmaki]

Oh, a wrench, yeah I had to do the same thing to get leverage on that little allen wrench.

Either my engine is different than yours or I'm just not seeing your pictures right. What I would call a pipe cone sits along side the engine and they call it the tuned pipe. I guess the wave reflects off the cone. The pipe behind the engine is the muffler or what some people call the waterbox.

Because of the one stud in the exhaust manifold, the jugs will not slid off with the manifold because there is not enough play in the connecting rod bearings, to angle it back to clear the stud....at least I don't want to push it that hard. The tuned pipe elbow has to be removed or disconnected and moved forward so the hole in the pipe clears the stud, then the jugs and manifold can be removed as an assembly.

To do this, the manual says: "Remove the clamp no. 4 securing tuned pipe cone to tuned pipe head." What it doesn't say is how to do that. I don't see any way to remove the clamp. I did feel up underneath the pipe where I can't see but I did feel some kind of lollipop clamp with a soft piece of tubing attached to it. What's with that? I guess the tubing protects the threads on the clamp? Wish they had put the clamp on top instead of underneath

I'm not sure taking the engine out now would be much easier since the pipe elbow looks like it will hit the front edge of the engine bay as I try to slide the engine forward to clear the splines on the PTO end of the driveshaft. So if I don't want to take the pipe off, it looks like I may have to take the pump off to slide the driveshaft back and hoist the engine straight up.

I am beginning to so not like BRP design engineers. It's not so much that there isn't much room in there, it's the choice of fasteners that they make difficult to get to with standard tools or that aren't strong enough for the application. The jug bolts are nice hefty fasteners, but the head bolts blow.

 

[racerxxx]

I bought this new so I'm assuming whatever is on those bolts is what the factory used. It's definitely not any thread locker I've ever seen. It's translucent white, rubbery, and looks just like silicone sealant. But I can't see where it did any good since the threads are all garbaged up with corrosion anyway. Now that you mention threadlocker, I seem to recall seeing in the manual that these bolts need to be heated up to break down the thread locker. ooops.

The thread locker is yellow, the white is corrosion from the stainless and aluminum.

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[racerxxx]

You need ball end Allen wrenches.

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[mikidymac]

Please do yourself a favor and pull that engine LOL.

You are already this far so pull it and buy a complete gasket kit with seals. Then you will be able to inspect everything on a clean bench and install all new seals and gaskets and check for air leaks. Peace of mind on the lake is priceless.

 

[jimmaki]

The thread locker is yellow, the white is corrosion from the stainless and aluminum.

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Good to know, I couldn't imagine the factory using silicone sealant on the screws! But it sure looked and felt rubbery like silicone. The corrosion of which there is more than I hope to ever want to see again, is white, dusty and powdery.

 

[jimmaki]

I got the jugs and manifold off after taking off the pipe elbow. Didn't have a 14mm deep socket to get at that nylock nut on the pipe clamp but a 1/2 deep socket got the job done without buggering the nut.

Good news and bad news.

The good news the spring is nowhere to be found. The bad news is it looks like the forward rotary gear seal is leaking and the bearing is bad. The crankcase is nasty with oil on the MAG side, but no metal or bearing cage pieces. No signs of any metal going though the engine. Anyway, so it's new crank time ... maybe even new engine time. (or rebuilt engine) The PTO crankcase is squeaky clean, no oil, no rust, no noises, no spring.

Some of the water passages under the MAG jug were clogged with sand. I don't know if that caused a local overheating problem that may have contributed to the seal and/or bearing failure. We have a beach on our lot and park the Doo there during the day so when we back up and take off, sometimes the pump will bottom out and suck sand.

Everything on the PTO side looks cherry. The MAG piston has carbon buildup on the skirt by the exhaust port. The top ring is free but the bottom ring is partly seized on the exhaust side. The rest of the way around to the gap is still free. I don't think the ring is seized from heat or hammering, it looks like burnt oil, or some kind of carbon gook has it frozen in the groove.









Even though the compression was 160 on both cylinders I think by the time I replace the crank and clean up the MAG
piston/cylinder ... it is probably time to think "new engine" or rebuilt engine.


The kids are starting to outgrow wanting to be towed by the SeaDoo and want to be towed by the boat which throws a lot bigger wake. The little ones don't really like riding the X4 hull since to them it's too tippy when it stops or turns slow.

I'm not sure whether to sell the Doo now or put a rebuilt engine in there and run it for a year or two and sell it before the rebuilt can blow up. I already redid the whole fuel delivery system, rebuilt the carbs, put in a new agm battery and rebuilt the VTS. My 22' Hurricane deck boat with a 200hp Merc goes almost as fast as the SeaDoo so I'll use that as an alternate expensive hair blow dryer.

Any suggestions on where to get a rebuilt engine that will last a few years without spending more than the Doo is worth? I snapped one head bolt. Will most rebuilders take it as a core tradein?

 

[jimmaki]

You need ball end Allen wrenches.

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Yeah, I need those and a better set of metric wrenches.

 

[jimmaki]

This is all that's left in the engine bay. I'd like to check the crank and cb along with the rotary valve and gear. Might also pull the magneto cover and take a peek. Where would you hook onto to lift it out?

 

[soccerdad]

put it all back together and use the hook on the exhaust... LOL. At this point, you may just be able to muscle it out. Or strap around it once under the motor?

 

[jimmaki]

Ha ha. I guess I deserve that after all the advice to take the engine out earlier in the thread before taking the top end apart.

By "hook on the exhaust" do you mean this hook? It looks beefy enough if I take out the rubber grommet. But the exhaust itself it out already.



The manual mentions "Engine can be easily lifted by inserting a hook into exhaust manifold eyelet." But from the picture I can't really tell for sure what they're talking about. Is it the bracket with a rubber grommet in it that the exhaust elbow was supported by between the tuned pipe clamp and the four bolts at the exhaust manifold?



I notice SES lowered its prices and is now competitive with SBT but claims to use better parts. I'm not in any hurry to get the engine back (my knuckles have to heal from taking it out). I like that I can drive to SBT in a hour but from reading many resto threads, the way to go if you're putting in the time to take it apart is to go OEM. Although they're all OEM parts in there now and they only lasted 18 years. http://www.seadooforum.com/images/smilies/new/seeya.gif

 

[soccerdad]

By "hook on the exhaust" do you mean this hook? It looks beefy enough if I take out the rubber grommet. But the exhaust itself it out already.

The place the hook attaches to is on top of the exhaust manifold. The thing that you had so much fun removing... At this point, you don't have much weight left in it, so you can probably take out the grommet and hook it as you said. Or just run a choker strap under and around the motor.

 

[mikidymac]

If you want to get back in the water fast your only option is SBT.
If you don't mind waiting and want a warranty SES or FullBore.
If you want the best OEM parts and are willing to do it yourself buy from SeaDoo.

 

[jimmaki]

The place the hook attaches to is on top of the exhaust manifold. The thing that you had so much fun removing... At this point, you don't have much weight left in it, so you can probably take out the grommet and hook it as you said. Or just run a choker strap under and around the motor.

OHhhhhh, that lifting eye ... just went out to the garage and found it. Never noticed it for some reason.

Everytime I have to lift something with straps or what not, this video that I saw ages ago still haunts me.

 

[jimmaki]

As long as the boat keeps running no rush on the Doo. I only need the Doo to tow the boat back in.

I might try fixing it myself but I'd probably easily end up spending more in special tools, not to mention parts, than it's worth. These days I'm the only one that wants to ride it so putting a lot into a ski that old is hard to justify. I think the fact that it sat so much unused was the root of it's downfall. It doesn't have that many hours on it. Less than a hundred.