Help I lost compression in 1 of my cylinders on my 96 challenger.

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Talley43

Talley43

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Alright first I want to thank anyone who helps me figure this thing out. I'm brand new to boats and I've only had this one a month.
I took my wife and 2 nieces out and about 2 miles down the river it died 2 twice full throttle no warning sign or nothin. So we went back to the boat ramp in the process it died again and couldn't get it started so I just loaded it up and took it home. We hooked a water hose up to it after 15 minutes it fired up. I decided to trade it for a bigger boat I went to trade but thinking it was ok I didn't start it up I just took it. I put it in the lake to show the guy it ran and I couldn't get it to start he hooked up a pressure gauge and it said the back cylinder had 24psi and front had 150psi. I was told it it need a rebuild. How much would it cost to change out the motor or should I just pull this one out and rebuild it? Any suggestions on the easiest and cheapest way to get this thing goin again?
 
Ok, it is hard to say much with this information, and without more background, but I will give it a shot. Chances are something went very wrong and you need a new engine or a rebuild, however the only way to know how bad it is will involve inspecting the engine. Worst case that I can think of would be that a carburetor went lean (I think your boat is a 787 engine with dual carburetors) and you melted a hole in the back piston. If this is the case and even if it is not it would be a good idea to test and possibly rebuild the carburetors or else this may happen again with a new engine.

Now down to the all important dollars, the amount will depend on if you do it yourself, get a shade tree mechanic to do it, or take it to a professional shop. From the way you worded things, I assume you will not be doing it yourself, the cheapest route to go would be the shade tree mechanic option, there are a lot of guys out there that work on PWC's in their spare time, and in essense this boat engine is a Sea Doo PWC engine placed in a boat. Finding a good one is the hard part, but they are out there, and perhaps if you share your location more precisely than the US we could help you find one.

Engine Swap Labor $400-$800

Premium rebuilt engine with 2 year warranty $1,200+ shipping from SBT if your core is accepted as rebuildable (you might find a good used engine for half that, but those are a dice roll)

Carburetor Rebuild while you have them pulled $250-$450 (pulling them is half the labor)

There are a few other things that should be checked while this is being done, I would budget an extra $400 on unexpected stuff they may find (wear rings, pump oil change, shaft seal, etc.). Again this is a ballpark number and depends on local labor rates, all bets are off for the left coast.

Ike

p.s. best case is you may get away with just a top end rebuild, and not a whole new engine
 
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Thank you for trying to help out. I can work on it myself. I'm just trying to figure out what I need to do. I was told that since I did not use seadoo oil is what caused the cylinder to stop cause the oil was too thick to run through the engine like it's supposed too. I don't know how true that is, but that's what the guy who rebuilt it last year told me. So I should be looking to spend $3000 on gettin this thing fixed and back out on the water?
 
clmboating said:
Your rave valves have a lot to do with compression, try cleaning those once, and give it a go.
Click to expand...

HU ?????????


RAVE valves have NOTHING to do with compression. It just changes the port timing on the exhaust.

The only time they mess with the compression, is if one breaks off, and takes out a piston.


Tally: Unfortunately... you have a roasted engine, and there's no patch for that.
 
Dr Honda said:
HU ?????????


RAVE valves have NOTHING to do with compression. It just changes the port timing on the exhaust.

The only time they mess with the compression, is if one breaks off, and takes out a piston.


Tally: Unfortunately... you have a roasted engine, and there's no patch for that.
Click to expand...

Alright thank you. I was thinking it was done for. That's what 2 different mechanics told me. Would it be better to rebuild this motor or replace it?
 
Dr Honda said:
HU ?????????


RAVE valves have NOTHING to do with compression. It just changes the port timing on the exhaust.

The only time they mess with the compression, is if one breaks off, and takes out a piston.


Tally: Unfortunately... you have a roasted engine, and there's no patch for that.
Click to expand...

+1 on rave valves having nothing to do with the compression.


If you replace it you don't have to worry about any of the engine work plus you get a warranty.
 
[MENTION=76236]clmboating[/MENTION] No worries man simple mistake.
[MENTION=79199]Talley43[/MENTION] what engine do you have? SBT is in Clearwater Florida. They sell already rebuilt engines you just ship them your core when you are done with it. This is the fastest route. SES is in PA, they will rebuild your actual engine. Takes more time though.

Other members have different thoughts on both rebuild shops do some research and find out what is best for you.
 
Also when you get a new one you will need to flush out your oil tank, change your oil filter and use the right kind of oil.
 
Alright cool. I think mine is the rotax 787.

Isaac-1 alright Thank you. I guess make sure I use the seadoo oil that it requires?
 
The short answer is yes only use the Seadoo oil, the long answer is there are a couple of alternatives that some people use and get away with, but they are specific brands and a topic you can research when you have time.

ps I just sent you a PM
 
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I have a SBT 787 in my ski now. Runs great but I do a lot of preventative maintenance. I run XPS2, it's what the PO ran in it.
 
The link does not work, but remmeber you may not need a whole new engine, you may just need a top end rebuild.

If it were mine I would pull the head off and take a look. (well actually if it were mine I pull the spark plugs first and stick a fiber optic inspection scope inside to see what was going on.)
 
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Yes you might just need a top end, but you will never know until you pull the head (very easy) and check out the condition of the pistons. Now with a fresh strong top end you are working with a tired bottom end which in my opinion will soon fail.

The 787 is a very common engine.

If the link is to a used engine be cautious. Also, remember something took out your engine. Change out fuel lines if they are gray and rebuild carbs while doing engine repair or you run the risk of ruining another engine.
 
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