How long should (or could) a 4 stroke motor last?

[Sea Dood]

Yes; you can see them without pulling the head, or even the rocker arms. Just need to remove the valve cover and get in close with magnification; they are tiny numbers!

The number is stamped around the end of the valve, just above the spring retainer. You have to get up close, and at least one of the valves should be in a position where you can read it.

The early (bad) '04 to mid/late '06 valves are stamped:

Intake:72377
Exhaust: 72524TK

In late '06, they implemented the improved valves, which are stamped:

Intake: 72377 C2
Exhaust: 75219 TK

In '08 they improved the strength a bit, and have the following numbers:

Intake:- 72377 T2
Exhaust:- 75219 T1K and

Note that a number starting with "72" on the exhaust is bad, starting with "75" is good.....

They didn't make the hollow valves for weight reasons. They used a concept called sodium-filled. The hollow cavity is filled with sodium metal and the sodium melts and conducts the heat away from the top of the valve better than regular valves. The new valves are made from Inconel which stands the heat better.

 

[Michael211_2000]

They didn't make the hollow valves for weight reasons. They used a concept called sodium-filled. The hollow cavity is filled with sodium metal and the sodium melts and conducts the heat away from the top of the valve better than regular valves. The new valves are made from Inconel which stands the heat better.

Oh! Ok... didn't know that. I read that it was to reduce the weight of the valves previously. IDK.

We're supposed to have nice weather Saturday so I'm going to take a peek then and see what I've got here. Sure wishing it has 75 on those exhaust valves! Arghhh!

Why is 72 ok on the intake valves but not the exhaust valves? Are the exhaust valves more prone to breaking off?

Thanks for all the info! Greatly appreciated!!!

- Michael

 

[Sea Dood]

They have made some improvements to the intake valves, but they haven't been as big of a problem.

The failure mode of the exhaust valve is corrosion microcracking. This is because the valves get really hot, and then they are exposed to high humidity in the exhaust chamber (remember the waterbox keeps the exhaust chamber at 100% relative humidity when the ski is stored. Ever notice that exhaust manifolds on car engines are very rusty? Same principle.

There is some evidence that skis that are used very often don't drop the exhaust valve as often as those that are stored for long periods of time. I don't know how true this is, but it makes sense that the corrosion could be kept at bay by continual use. The same principle applies for fogging. It has been said that if you religiously fog the engine after riding, you stand a better chance of keeping the exhaust valves from rusting and breaking off. I don't know how correct this is; you need a lot of fogging oil going thru to get to the exhaust valve stems on its way out of the engine..

 

[Michael211_2000]

Well I don't know how much this helps, but I religiously crank the engine (of both jetboat and SeaDoo) and run them on the trailer dry for 10-15 seconds after use to dry out the exhaust system. The exhaust blows any standing water out of the system, and then heats up the system a bit so that any residual moisture quickly evaporates. This helps to keep the jetboat's exhaust headers from corroding inside, and I'd assume it should have the same effect on the SeaDoo's exhaust log and exhaust valves??

As I say, I don't know how much this helps on the SeaDoo's system. I realize it's a longer run out the exhaust to the outside world, and I can only run it dry for 10-15 seconds or so before overheating the exhaust log (I think it says up to 30 seconds dry in the manual, actually).

- Michael

 

[Sea Dood]

You cannot dry out the Sea Doo exhaust no matter how long you run it. The exhaust system contains a water-filled muffler (called a waterbox) that always retains some water in it. Therefore, the exhaust system is always at 100% RH.

 

[TundraLu]

You cannot dry out the Sea Doo exhaust no matter how long you run it. The exhaust system contains a water-filled muffler (called a waterbox) that always retains some water in it. Therefore, the exhaust system is always at 100% RH.

So to check the valves we need to pop the valve cover off. Do we need to buy a new valve cover gasket?

 

[Michael211_2000]

No, it's a rubber compression gasket... totally reusable.

- Michael

 

[seadooya]

I would like to clear up some confusion here. While the supercharged 4-tec's have not been very reliable due to supercharger clutch issues, dropped valves, broken flywheel bolts, etc. the naturally aspirated models have been very reliable. It is not unusual to get 1000+ hours on these, and there are plenty of rental outfits that can attest to that. There have been reports of 2-5K hours on some of them.

I'm not reading all the post, but i'll vouge to this statement. Buddy of mine, which has a fleet of mixed seadoos and yamahas, 4-strokes, are banging on 500+ hrs, and not thinking of it, to run them another 500+, all naturally aspirated.

Grant it, my brother has done the service to them, valve adjustments, pump assy..etc, but nothing that needed the attention, of pulling the motor and rebuilding them.

 

[TundraLu]

No, it's a rubber compression gasket... totally reusable.

- Michael

Michael,

Thanks again. I will look at mine and see what I have in their.

 

[unclejay]

Auto Engines

Lets see, a stock Corvette 7 litre engine produces say, 500 HP, which is 71 HP per litre.

A Sea Doo 255 engine at 1.5 litres produces 170 HP per litre.

If the Chevy engine were tweaked to produce the same power, it would be 1190 HP.

How long would a 1190 HP Chevy engine last ?

 

[TheChad]

Lets see, a stock Corvette 7 litre engine produces say, 500 HP, which is 71 HP per litre.

A Sea Doo 255 engine at 1.5 litres produces 170 HP per litre.

If the Chevy engine were tweaked to produce the same power, it would be 1190 HP.

How long would a 1190 HP Chevy engine last ?

That depends on ALOT of things....

1. A jet ski engine is either cooled by an endless supply of cool/cold water OR is a closed loop system which is being cooled by an endless supply of cool/cold water VS a corvette which is cooled by outside air temp which is most often not cool or cold.

2. A Corvette weighs atleast 3 times what a 4-stroke Jet ski weighs.

3. A V-8 engine is MUCH different.

4. It would be MUCH more fair and apples to apples to compare a 4-stroke 4 cylinder motor cycle engine like those founde on high performance street bike.

Doing that comparison, Street bike 4-stroke 4 cylinder engines running at high RPM's in street bikes last a really long time as long as they are well taken care of and not abused.

I would expect the same from a freshwater 4-stroke jet ski. A saltwater craft will ALWAYS have a reduced life.

-TheChad

 

[TundraLu]

OK I took off my valve cover and lo and behold my exhaust valves are the 72 ones. Do I have to pull the whole engine out to take off the head and swap all the valves to the new ones?

 

[Michael211_2000]

Ah rats! That suxs... I still haven't found time to pull my valve cover off to check mine out.

I am not positive, but I believe you can pull the head with the engine still in the hull... you are supposed to NOT re-use the head-gasket nor the head stretch bolts, they must be replaced with new ones (~$100 or so). A good torque wrench and some patience is required... the timing chain and gear is a PITA to get loose so you can take the head off: tie a string or something to that timing chain so that it cannot fall down into the engine out-of-reach! You also need the torque values and bolt order to re-install the head correctly. Oh and locking tools to lock the crank and head in the correct position's (I found 2 steel shafts in my parts box that just happened to fit into the locking holes perfectly). I'm guessing the jetpump will need to be pulled so you can use the drive shaft to turn the engine to the correct position to insert the locking tools???

If one has the sodium filled 72X exhaust valves and one isn't prone to running WOT frequently (no racing!), what kind of priority should replacing these valves be I wonder? It totally suxs that if just 1 exhaust valve fails, there goes your entire engine to 4-TEC Heaven! Grrrrrrrr!

- Michael

 

[TundraLu]

Ah rats! That suxs... I still haven't found time to pull my valve cover off to check mine out.

I am not positive, but I believe you can pull the head with the engine still in the hull... you are supposed to NOT re-use the head-gasket nor the head stretch bolts, they must be replaced with new ones (~$100 or so). A good torque wrench and some patience is required... the timing chain and gear is a PITA to get loose so you can take the head off: tie a string or something to that timing chain so that it cannot fall down into the engine out-of-reach! You also need the torque values and bolt order to re-install the head correctly. Oh and locking tools to lock the crank and head in the correct position's (I found 2 steel shafts in my parts box that just happened to fit into the locking holes perfectly). I'm guessing the jetpump will need to be pulled so you can use the drive shaft to turn the engine to the correct position to insert the locking tools???

If one has the sodium filled 72X exhaust valves and one isn't prone to running WOT frequently (no racing!), what kind of priority should replacing these valves be I wonder? It totally suxs that if just 1 exhaust valve fails, there goes your entire engine to 4-TEC Heaven! Grrrrrrrr!

- Michael

Yeah this sucks. I am begining to think for a couple grand more I could have bought a 08 RXP-X without these darn issues ...

 

[Emig5m]

Well, as far are the supercharger goes, they have made a number of changes since the the ceramic washer debacle. 04-05 have the worst case set up with ceramic washers, they switched to a heavier design in 06-07 (but still ceramic washers)

In '08 they switched to titanium coated (gold) metal washers and a new oiling system. They put out a total rebuild kit (420881100) with this setup, which included a shaft with a larger oiling hole in the center. In '09 they found that those gold washers still broke, and came out with a better grade washer. This kit is part number 420881101, and is considered bulletproof.

If you have a ski older than '09, the supercharger should be rebuilt using the 881101 kit, and the PTO cover should be modified to put the '08 style oil sprayer, which directs the spray of oil into the hole in the end of the shaft. This setup has been found to be very reliable.

Interesting. I just bought my first ever 4-stroke PWC, a 2008 RXP. It's brand new with 0 hours. Should I be ok for the first 100 hours and then rebuild with S/C the kit mentioned above?

I'm no expert on these PWC's (yet!), but it's been my observation that how the owner takes care of the machine has A LOT more to do with how long the machine lasts than how many hours/miles the owner puts on the machine.

My Sidwinder jetboat is 36 years old now, it's 454 BBC engine is a 1978 model (the hull a 1975 model), and since I bought it in 1989 I've never had any problem with the engine whatsoever. It cranks and runs like a champ, the boat can hit over 80 mph but is mostly used to pull skiers and I like to kneeboard at 35 mph with lake crusing in the mid-40's typically. Just because it can do 80+ mph doesn't mean I feel the need to go that fast all the time! I've always taken very personal care of the hull and engine, had the jetpump rebuilt by Mike's Pump & Speed in Houston just once and it's a solid running boat still as of this Fall. Only once have I ever had to be pulled back to the dock (after sucking up a rope somebody had left in the lake... grrrrr!).

I intend to treat the 2006 SeaDoo RXT I purchased this past Fall the same way... just because it can do 70 mph doesn't mean you'll find me running it that way very often. I'll do my own oil changes every season, keep good quality treated 93 octane gas in it and enjoy it like a responsible owner. The hour meter is just a way to guage when it needs maintanence items taken care of, like rebuilding the supercharger at about every 100hrs... it's not a measure of whether the engine is about to expire or not! If the engine ever does fail, it's only about $2K to replace it with a short-block (which I can install myself). There's 1 chip in the hull (from previous owner bumping a dock) which I'll get fixed early this Spring before 1st use and get a few light scratches buffed out as well.

ps. If a watercraft has been routinely "rode hard and put up wet" you'll be able to tell it! Things won't be tight or fit right anymore, parts that aren't real important will break and be left broken, chips and scratchs on the hull will be ignored etc. If it looks like it's been abused and not cared for then it probably has! Look at the condition of the machine more than the number of hours on the meter, IMHO.

So don't stress about it, enjoy it and have fun peeps! Life's too short ya knows!

- Michael

My father is always telling me the same exact thing, heh. Although I'm not going to constantly abuse my new ski, I'm not going to putt around at 30mph all the time either. I would of just stuck to my 94 VXR if that was the case, heh. For example, for those times I want to hit max speed, what's generally a safe amount of time to hold it WOT? I see some people on Youtube that hold them WOT for minutes at a time! Surely that can't be good for the motor or can it handle going WOT for that long occasionally?

So anyway, with the 08 RXP will it generally be pretty reliable out of the box if not constantly abused and should it make it to the first S/C rebuild before I should get the upgraded rebuild kit? And after broken in, what's a safe amount of time to hold it wound out when I want to take it to full speed? This is really the main type of riding I like to do:

[video=youtube;GZJdAVu7qJY]http://www.youtube.com/watch?v=GZJdAVu7qJY[/video]

 

[Michael211_2000]

No; most '06 skis had the hollow valves. They didn't switch until the very end of '06 production. The only sure way to know is to pull off the valve cover and look at the stems of the valves. The "bad" exhaust valves start with a 72 number, the good late ones start with 75...

I know it's been a few months, but I took the valve cover off just the other day and though I could NOT make out the numbers on the valve stems I took a high-res digital pic and lookie-lookie!

I could be mistaken, but that sure looks like a 75 stamped on this exhaust valve stem.... with only 74 hrs on the engine, any reason I should be concerned about the valves now?



ps. Something else has gone wrong this past weekend, but I'm working thru that issue in another thread... went to missing and surging really bad all of a sudden, but starts easily and makes no strange mechanical noises.

Thanks.

- Michael

 

[greggebhardt]

Here's where I am coming from and yes, it is different from where you are. I am doing about 100 hours a season on mine. The GTX is a big comfy couch and not really that much fun to run wide open all day and throw it around like a smaller 2 stroke. So how does someone prove that it was not ridden like it was stolen and that, relative to most skis, it was babied? Hypothetically, would you be more apt to buy a 200 hour ski that is 2 years old from a private owner (non rental) or a 5 year old ski with 200 hours on it from the same person. My guess is service records would help but see my other post on "Computer Printout" Would a clean billof health from a dealer's computer help sell it?

I agree with you. I know there is extra main needed on my GTX but expect it to last much longer that what people think here. If you do not abuse it and run it like it is stolen it will last MUCH longer than 100-200 hours.

If you run the piss out of your ski you can expect short engine life. It is why I bought new as I want to know what my engine has gone through. I can not imagine WOT on my GTX for extended periods of time, where I ride the conditions seldom exist where you could hold on at that speed!

 

[keltonks]

Everybody will begin screaming at me, but as my answer to your original question, a 4-TEC SEA DOO PWC will last 47 hours before its timing chain will break and you will have to perform a major engine overhaul that costs thousands of dollars unless you can do the repairs yourself. Even then it may cost you hundred of dollars in parts. If you purchase a 4-Tec engine from a SEA DOO dealer it can run $6,500.00. There are other sources that are less expensive.

From some responses I have received to the thread I started, I have gathered that a major breakdown of your SEA DOO PWC powertrain is "bound to happen." My 2006 GTI quit running due to a broken timing chain less than two months after I purchased it, with only 47 hours of total use. Broken timing chain = bent valves + bent push rods = major engine overhaul = $$$$$$$$$$$. The cost of rebuilding the engine is more than half of what I paid for the GTI, which had only 30 hours at the time of my purchase. And for those of you who haven't read my thread, the GTI was not abused or mistreated.

My advice, which I get yelled at for expressing, is: Don't buy a SEA DOO PWC unles you can afford the cost of a major engine overhaul without worry; unless you are a PWC mechanic who can perform a major engine overhaul in your own garage; or unless you buy it new with a warranty (and then quickly sell it when the warranty expires).

This may be the same advice for other brands of PWC, but my experience is with a SEA DOO 4-Tec and no other brand of four-stroke engine.

 

[greggebhardt]

Everybody will begin screaming at me, but as my answer to your original question, a 4-TEC SEA DOO PWC will last 47 hours before its timing chain will break and you will have to perform a major engine overhaul that costs thousands of dollars unless you can do the repairs yourself. Even then it may cost you hundred of dollars in parts. If you purchase a 4-Tec engine from a SEA DOO dealer it can run $6,500.00. There are other sources that are less expensive.

From some responses I have received to the thread I started, I have gathered that a major breakdown of your SEA DOO PWC powertrain is "bound to happen." My 2006 GTI quit running due to a broken timing chain less than two months after I purchased it, with only 47 hours of total use. Broken timing chain = bent valves + bent push rods = major engine overhaul = $$$$$$$$$$$. The cost of rebuilding the engine is more than half of what I paid for the GTI, which had only 30 hours at the time of my purchase. And for those of you who haven't read my thread, the GTI was not abused or mistreated.

My advice, which I get yelled at for expressing, is: Don't buy a SEA DOO PWC unles you can afford the cost of a major engine overhaul without worry; unless you are a PWC mechanic who can perform a major engine overhaul in your own garage; or unless you buy it new with a warranty (and then quickly sell it when the warranty expires).

This may be the same advice for other brands of PWC, but my experience is with a SEA DOO 4-Tec and no other brand of four-stroke engine.

I see that you have chosen to have a MISERABLE life! Enjoy!

 

[keltonks]

As in my other response, typing responses is rather enjoyable. And I hope others are enlightened, and educated, by my comments.

 

[greggebhardt]

As in my other response, typing responses is rather enjoyable. And I hope others are enlightened, and educated, by my comments.

Well then Don,

Keep swinging at that windmill as you are also part of the entertainment! LOL!

 

[keltonks]

My efforts do indeed seem to be equivalent to "jousting" at windmills. That doesn't make the cause any less "heavenly." Happy to be of service. Keep smiling.

 

[hackete]

I bought a 97 1/2 GSX limited kept it maintained. It currently has 438 hours on it. I have replaced the starter, couple batteries, and at 407-412 hrs I replaced the balance shaft. Think I paid around 6k for it. Single trailer.

I bought a used 97 GTI about 4 years ago. I put two batteries and a starter on it. We got it for 1200.00 single trailer

I bought a 95 XP about 3 years ago it lasted till this summer had to put a top end kit on it. Paid 500.00 for it. No trailer

Bought a 96 XP 2 years ago died beginning of this summer. Currently putting a top end kit on it. Paid 300.00 for it with a double trailer.

So from my experence the only way to know how it was maintained is to own it from the start or put a engine in it when you get it lol.

But the sad thing is I have run that unlimited so hard it should have blown up twice. I have summerged it, held throttle wide open while in air etc. I am the idiot you see lagging about 300 yards from the wake boats hitting the rolling waves wide open to see how high I can get. The only time they get tlc is when there on the trailer. My wife wants a newer one with brake and reverse etc. We may get one for her but when we test drove one of the smaller engine ones GTI, I didn't like it. I am sure if I drove one with the 255 I would have like it better. As long as they don't ban the 2 strokes I will stick with them. But hey were in Alabama we still have dry counties. Once the other states start getting banned it will take them 20 years for us to catch up.:thumbsup:

 

[opfor22]

My 2005 GTX 4-Tec Eng just took a major $hit on me. The #1 cylinder spark plug was totally destroyed and the dealer told me that he thought it may have dropped the exhaust valve and the gave me an estimate of $ 5500 to $ 6500 to replace it. I paid 3800 for it including a new Zeiman trailer so I'm toying with getting a rebuild Eng from SBT. Any suggestions or comments???