Replacing Rave Valves in 97 Challenger 1800

[hiletm1]

We recently pulled all 4 rave valves to clean them on our recently purchased 1997 Sea Doo Challenger 1800 (twin 787s) two find that a valve on each motor had broken--both corners on the blade ends. On the one, we found the piece in the slot and it looked like a recent breakage. On the other, the piece was gone and there is evidence that the break is older--there is carbon covering the broken surface. There is quite a bit of carbon buildup and we were getting oil out of the raves prior to pulling them.

We have been told that the broken piece more than likely went out the exhaust into the water box. We have not noticed any significant loss in power or RPM.

We are going to replace all 4 valves and install new gaskets, seals, etc. Should we purchase the OEM valves or the SBT? There is a price difference of about $50 per valve, OEM obviously being the more expensive.

Also, should we attempt to clean the slot where the valves slide down into? Should we pull the top half of the motor? Again, we have no loss in compression and the boat was running with plenty of power/rpm prior to pulling the valves.

Thanks for any help you can give. In the future, we plan on pulling and cleaning our RAVEs twice a summer.

 

[jhjesse]

We recently pulled all 4 rave valves to clean them on our recently purchased 1997 Sea Doo Challenger 1800 (twin 787s) two find that a valve on each motor had broken--both corners on the blade ends. On the one, we found the piece in the slot and it looked like a recent breakage. On the other, the piece was gone and there is evidence that the break is older--there is carbon covering the broken surface. There is quite a bit of carbon buildup and we were getting oil out of the raves prior to pulling them.

We have been told that the broken piece more than likely went out the exhaust into the water box. We have not noticed any significant loss in power or RPM.

We are going to replace all 4 valves and install new gaskets, seals, etc. Should we purchase the OEM valves or the SBT? There is a price difference of about $50 per valve, OEM obviously being the more expensive.

Also, should we attempt to clean the slot where the valves slide down into? Should we pull the top half of the motor? Again, we have no loss in compression and the boat was running with plenty of power/rpm prior to pulling the valves.

Thanks for any help you can give. In the future, we plan on pulling and cleaning our RAVEs twice a summer.

Get the ones from SBT. They work well.
Clean the slots really good before installing the new rave valves.

I would go ahead and order the housings, as well.

 

[Sportster-2001-951C-Stock]

More than likely your base housing bores are worn out. No comment on the SBT's really, I've only seen the pics but I'd go OEM, probably, depending on how close I thought I was to an overall overhaul.

If your cylinders have been bored, the raves may be too long and thus, snag the piston rings.

 

[hiletm1]

To what extent should we inspect the motor to find the missing piece of the rave valve? We're thinking it got blown out through the exhaust, but haven't checked.

We found the oil leaking was from a bad seal.

 

[Guest_User]

if you can get a deal on OEM, that would be good, but if no find on fleabay, then SBT is a very good alternative.
I run all 4 housings, guillotines and parts with no issues... Use all new, don`t skimp, bc one worn item will make it leak oil or melt down...

look at the piston skirts thru the hole from the guillotines, if they look good, and compression is good, do not pull the top end.
if there is NO evidence of a past rebuild, then most likely it is the stock bore, if you have any doubts, I`m pretty sure you can already get the valves cut from SBT... you`ll need to call SBT, ask for Jeremy!

good luck...

 

[Sportster-2001-951C-Stock]

To what extent should we inspect the motor to find the missing piece of the rave valve? We're thinking it got blown out through the exhaust, but haven't checked.

We found the oil leaking was from a bad seal.

Short of a tear down or removing the head to get a look at the piston crowns, about all you can do is inspect the pistons sides for signs of damage. I guess you should concentrate on inspecting the ring lands since the rings will most likely snag on the rave blade first.

I doubt you'll find any missing pieces of rave though, why dig the waterbox out for that confirmation? As long as compression is still good and the rings/lands don't show damage, then count your blessings! Might look on the piston crown to see if any dents on top, objects in the cylinder can smash the perimeter of the piston in the squish area and cause the ring lands to pinch the rings. Bottom line, I wouldn't tear it down if it was running well and the compression is good, unless my life depended on the motor. Retest compression after a few hours of running maybe, to see if it's deteriorating.

 

[martin18152]

I thought I just jump into this discussion. I just had a RAVE fail, the engine would just start to cut out at top end, and then the engine would stop all together. I looked under the hood, and saw the red spring adjuster, and spring laying on engine block, and the engine was making a rattling sound. Pulled the plastic assembly and found that the case was melted. When I pulled the lower metal case off, heard something fall into the void of no return - that’s the hull below the engine. Pulled the valve out, and discovered that the small threaded stud that holds the valve to the rubber baffle was sheared off and gone, guessing the nut and stud are in the void of no return, and the valve was just sitting in the slot. I am not sure how they designed this system, but if I was the engineer, I would design it so that the slot was tapered, and the valve could not hit the cylinder or rings. Would this be a good assumption? or was the valve hitting the ring as it was free in the slot? It did not appear that the valve edge was damaged or worn. I ordered all the new parts necessary, OEM, cost a fortune, about 175 bucks total.

I have kind of a silly question, what will happen if I just put a plate and gasket over the RAVE port, and run the engine, it will have a full open port, I am thinking it won't run optimally, but should not be too bad, or will it lean out on the low end. Another question, it was probably answered in another post, but what direction does the valve go? I did not pay attention when I pulled it out.
Does the replacement valve come with the nut? I could not find one on the parts diagram I used to order from, and mine disappeared.
Thanks for any help or advice, I am a total newbe working on this engine, I do have a shop manual and I’m not too bad at following directions.

 

[Sportster-2001-951C-Stock]

I thought I just jump into this discussion. I just had a RAVE fail, the engine would just start to cut out at top end, and then the engine would stop all together. I looked under the hood, and saw the red spring adjuster, and spring laying on engine block, and the engine was making a rattling sound. Pulled the plastic assembly and found that the case was melted. When I pulled the lower metal case off, heard something fall into the void of no return - that’s the hull below the engine. Pulled the valve out, and discovered that the small threaded stud that holds the valve to the rubber baffle was sheared off and gone, guessing the nut and stud are in the void of no return, and the valve was just sitting in the slot. I am not sure how they designed this system, but if I was the engineer, I would design it so that the slot was tapered, and the valve could not hit the cylinder or rings. Would this be a good assumption? or was the valve hitting the ring as it was free in the slot? It did not appear that the valve edge was damaged or worn. I ordered all the new parts necessary, OEM, cost a fortune, about 175 bucks total.

I have kind of a silly question, what will happen if I just put a plate and gasket over the RAVE port, and run the engine, it will have a full open port, I am thinking it won't run optimally, but should not be too bad, or will it lean out on the low end. Another question, it was probably answered in another post, but what direction does the valve go? I did not pay attention when I pulled it out.
Does the replacement valve come with the nut? I could not find one on the parts diagram I used to order from, and mine disappeared.
Thanks for any help or advice, I am a total newbe working on this engine, I do have a shop manual and I’m not too bad at following directions.

From skimming through, you just need all the upper parts and not the blade itself. There's an o-ring that seals around the blade shaft and keeps exhaust from entering the upper housing, which can melt almost everything except for the spring(s) And, the base housing itself has a bore in it which the blade shaft slides up and down inside of, this bore can wear, which allows exhaust to travel up inside the upper housing and melt everything.

So, you see this happen, it means you need all the obviously damaged parts and the housing base as well, b/c excessive bore wear was the root cause of the exhaust leak into the housing and melting of the plastic bits and pieces.

As far as running without the valve blade installed..... I doubt you'll like the results, assuming you can get the engine started. I've never tried this and don't see any reason to.

 

[martin18152]

Pulled the valve out, and discovered that the small threaded stud that holds the valve to the rubber baffle was sheared off and gone. The valve stem was sheered off, no rubber oring to be found, this the most likely cause of the melting. If I could get away with out buying the valve, I would be 114 dollars richer.

 

[Sportster-2001-951C-Stock]

Pulled the valve out, and discovered that the small threaded stud that holds the valve to the rubber baffle was sheared off and gone. The valve stem was sheered off, no rubber oring to be found, this the most likely cause of the melting. If I could get away with out buying the valve, I would be 114 dollars richer.

Okay, your rave valve stem broke off. Yep, that happens sometimes as well.

 

[martin18152]

The engine that the valve failed on was rebuilt, and slightly over bored. I did not rebuild the engine. My question is, is it possible that something was incorrectly done to cause the valve stem to break? The broken valve that I pulled out did not have any damage on the edge, so I think they shaved it to match the new bore, but I am not entirely sure of that. When I replace the valve with the new OEM, I was going to use the old valve as a template to shave the new valve. Do you have any suggestion on how to shave the OEM valve to fit?

 

[Sportster-2001-951C-Stock]

The engine that the valve failed on was rebuilt, and slightly over bored. I did not rebuild the engine. My question is, is it possible that something was incorrectly done to cause the valve stem to break? The broken valve that I pulled out did not have any damage on the edge, so I think they shaved it to match the new bore, but I am not entirely sure of that. When I replace the valve with the new OEM, I was going to use the old valve as a template to shave the new valve. Do you have any suggestion on how to shave the OEM valve to fit?

The service manual recommends trimming a rave valve in any motor with a .50mm overbore, so the valve need to be trimmed half that amount.

Look through the pocket the rave slides in, at the piston to see if there are any signs of rubbing. If rubbing, bright lines should show up near the corners of the pocket on the piston first, b/c if the bore was increased the diameter is larger. It's still possible for the rave to rub anywhere on the piston though, if it's too long.

I would definitely compare the length between new and old valves and trim any extra from the new ones using a largish round file or a sanding drum on a dremel tool to match the cut, if any. You could try sliding a thin flat piece of metal down into the pocket and against the piston while the rave is installed and then retrieve them together to see the physical clearance.

Also, slide the new valves into their pocket and hold them down tight while rotating the engine back and forth by hand, to make sure the piston/rings don't snag.

If you know the new bore oversize, you should be able to remove half that amount from the new raves. The other way to do it is to remove the head and measure the relief.