Thread: Silicone on pump
08-23-2014, 09:26 AM #1
Silicone on pump
So a few weeks ago I replaced my impeller, wear ring, and r&d pump seal. For some reason between 4-7k I was getting terrible cavitating until I got on top of the water. So I pulled the pump assy to check out the seal and it looks good. I siliconed the nozzle to the pump with black permatex silicone. It appeared ok. So I'm wondering if maybe I didn't have the pump tightened into the right sequence or the silicone I used is shit.
My my question is this. What's the pattern to tighten the pump? And is there a fast dry silicone as I want to be on the water today! Any other recommendation would be bad ass
side note. I'm not running a nose cone if that is possibly an issue
08-23-2014, 11:01 AM #2
According to my manual:
top left: 16nm (142 lb/in), bottom right: 16 nm 142 (lb/in)...12 lb/ft
top right: 31 nm (23 lb/in), bottom left: 31 nm... 23 lb/ft
Back to top left: 31 nm, bottom right: 31 nm...23 lb/ft.
Last edited by 1tommygunner1927; 08-30-2014 at 08:04 AM.
08-23-2014, 11:06 AM #3
Removing the nose cone is fine, lots of people delete that part and it 100% does not cause any problems - talking about the little nose piece that screws onto the FORWARD end of the impeller. I use the Speedfreeks piece with red loctight holding it on.
08-23-2014, 11:09 AM #4
Talking about the large cone on the REAR of the pump = if I remember correctly, that cone already has 2 seals around it (at least 1 seal) and therefore doesn't need any silicone sealant.
EDIT: and if your pump seal was seated properly and you still have obnoxious cavitation through all of that RPM, then it sounds like you have other shit going on besides what's mentioned in your first post here. Any more info you can throw out??
08-23-2014, 11:33 AM #5
not yet. i went to west marine and purchased 3m 4200 marine sealant/adhesive to seal the pump to the nozzle. it says it bonds in 15 min @ 90 degrees F and 90% RH. Im going to get a hot towel and wrap it for a while. Im going to leslies pool supply to get some gasket o-ring lube and tighten that bitch to spec. I'll get back to you guys in a while.
This all started when i sucked a shit load of mud and a framing nail into the pump. thats when i changed the parts out. i did notice an improvement but it was still cavitating. hoping i didnt fuck up the carbon seal or what ever seals the drive shaft to the boat. i dont think its that because my hull never fills with water.
Thanks TommyGunner and blkturbo for info!!!!
Last edited by kccb7; 08-23-2014 at 11:34 AM. Reason: spelling
08-23-2014, 12:06 PM #6
it says make the bond in 15 min at those conditions! i knew it was too good to be true. the guy at west marina said in a couple hours its gtg.
08-23-2014, 12:13 PM #7
IF you sucked up the crap you said you did i would pull the pump and check to make sure all the sharks teeth are still intacked on the pump shoe..IF 1 or more is chipped or damaged it will also cause cavatation and then all of them need to be removed...I would also check your carbon seal,when you sucked up the mud and crap you could have gotten some small debris between the seal and hat messing up your carbon seal....I would NOT silicone anything till you find the root of your problem..IF done correctly you should NOT need any kind of silicon on or near the pump area.,,especially with a R&D pump sea..Also check your props blades and pump stators for damage or debris also...And No, not running a nose cone will NOT cause cavatation...many of us do not run them...
08-23-2014, 12:49 PM #8
08-23-2014, 12:52 PM #9
08-23-2014, 05:39 PM #10
ok so i made 100% sure the pump seal was properly installed, sealed and torqued. put new silicone between the nozzle and the pump. the engine pulls fine to 4K around that spot the ski seems to fall on its face or hit a wall. then its like it slips and the rpm's rev if you are on the throttle. if you feather it around 6k the ski will get on top of the water once i get moving the rpms drop back around 4.5k the the ski pulls hard all the way through. my rpms are low (7700-7750) at full throttle i think because the impeller isnt pitched properly and the lake temp is 87 and outside is 95. I pulled my seat while on the water and watched the drive shaft. at idle the rubber boot seems to vibrate alot when i give it gas it seems to balance out. i didnt notice any water what so ever leaking from this area when rev'd up. could this just be due to a prop that isnt pitched right?
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