Impeller housing overheating

[DGMan80]

First post for me, there seems to be a ton of knowable people in here. I've searched for quite some time and nothing this specific has shown up so far. Any help in the right direction would be amazing! I've got an '88 4.3L seaswirl with a cobra outdrive. I was told it leaks from one of the freeze plugs. While trying to diagnose this I've gotten everything running on muffs. My first issue was I noticed the impeller housing started smoking after about a minute of run time with the muffs on. Shut it down. Pulled the impeller, looked rough. Worn out pretty badly. I Replaced it with a whole new kit. Prior to installing I ensured that there was flow from the intake to the pump. There was. Then I disconnected the water line at the thermostat and ran an airline to it. Pushed air out to ensue no blockage, as far as I could tell, no problem no debris just some water. I installed the impeller, bolted it down, turn on the muffs I get flow all the way to the thermostat inlet. Hooked everything up again. Fire it up, impeller starts smoking again gets very hot at the housing within a minute. Shut it down again. I disconnected the hose at the thermostat. I can see increased flow from before and after I start the engine at the end of the hose where it goes to the thermostat. Logic would indicate the pump is working? Any ideas on why it's getting so hot so fast and what I can look at to fix this?? It's super hard to diagnose the water leak in the engine if I cannot run it without burning up impellers. One final question..the hose that hooks to the outside of the housing on the impeller housing, What's that do? Should water flow through that to cool everything? Thanks in advance,
Dave

 

[alldodge]

Hey @Scott Danforth

 

[Bt Doctur]

Remove the drive, stick a hose in the inlet and run the motor

 

[Lou C]

You're saying you get flow up to the impeller mount when you install your water muffs, and then when you start the engine, the impeller overheats?
well one possibility is the that little nipple on the impeller housing, (connected to the hose that plugs into the gear housing) that has to be open to allow air out of the impeller housing so it can prime. Try running a thin wire up it and blow out with compressed air. That hose is like the pisser on outboards, it lets you know the impeller is pumping water. So make sure the nipple and hose are clear, leave the cover over the impeller housing off and hose disconnected when you turn on the water to the muffs. You should see water come out the nipple when the water is on, and after you start the engine.
Otherwise, I have had problems with some of the muffs sold recently, the rubber is too stiff to conform to the lower unit shape. I have had the best results with the Merc/Quicksilver round muffs with the metal rod clamp. You can see the nipple in on the bottom right side of the impeller housing, this must be open the hose not clogged.

 

[Scott Danforth]

First post for me, there seems to be a ton of knowable people in here. I've searched for quite some time and nothing this specific has shown up so far. Any help in the right direction would be amazing! I've got an '88 4.3L seaswirl with a cobra outdrive. I was told it leaks from one of the freeze plugs. While trying to diagnose this I've gotten everything running on muffs. My first issue was I noticed the impeller housing started smoking after about a minute of run time with the muffs on. Shut it down. Pulled the impeller, looked rough. Worn out pretty badly. I Replaced it with a whole new kit. Prior to installing I ensured that there was flow from the intake to the pump. There was. Then I disconnected the water line at the thermostat and ran an airline to it. Pushed air out to ensue no blockage, as far as I could tell, no problem no debris just some water. I installed the impeller, bolted it down, turn on the muffs I get flow all the way to the thermostat inlet. Hooked everything up again. Fire it up, impeller starts smoking again gets very hot at the housing within a minute. Shut it down again. I disconnected the hose at the thermostat. I can see increased flow from before and after I start the engine at the end of the hose where it goes to the thermostat. Logic would indicate the pump is working? Any ideas on why it's getting so hot so fast and what I can look at to fix this?? It's super hard to diagnose the water leak in the engine if I cannot run it without burning up impellers. One final question..the hose that hooks to the outside of the housing on the impeller housing, What's that do? Should water flow through that to cool everything? Thanks in advance,
Dave

first, what is your water pressure?
second, what size hose are you using
third, what muffs are you using
4th, do you have your hose turned up all the way? you should have water spraying a good 6-8 feet until that motor firs up

@Lou C is already hear to comment on the nuances that are the breather system

 

[DGMan80]

Remove the drive, stick

You're saying you get flow up to the impeller mount when you install your water muffs, and then when you start the engine, the impeller overheats?
well one possibility is the that little nipple on the impeller housing, (connected to the hose that plugs into the gear housing) that has to be open to allow air out of the impeller housing so it can prime. Try running a thin wire up it and blow out with compressed air. That hose is like the pisser on outboards, it lets you know the impeller is pumping water. So make sure the nipple and hose are clear, leave the cover over the impeller housing off and hose disconnected when you turn on the water to the muffs. You should see water come out the nipple when the water is on, and after you start the engine.
Otherwise, I have had problems with some of the muffs sold recently, the rubber is too stiff to conform to the lower unit shape. I have had the best results with the Merc/Quicksilver round muffs with the metal rod clamp. You can see the nipple in on the bottom right side of the impeller housing, this must be open the hose not clogged.
View attachment 328033

That makes sense. I never did pull that off the nipple to see if there's anything flowing out. To clarify, the water should come from out of the housing not the hose? Another suggestion was brought up. Is there any chance that the kit I bought is wrong and the impeller is wider than the original? Just a thought. When I put the housing back on should it sit flush against the housing? I believe I had to grab it with the bolt threads and cinch it down.

 

[alldodge]

should it sit flush against the housing?

Yes, there should be no need to use bolts to bring the housing flush

What was the kit part number your using?

 

[Lou C]

when the hose is disconnected water should flow out, and when its connected it should flow out of the end of the hose
Sometimes what happens is people mix and match OE and aftermarket parts. If you have an OE housing, use an OE impeller kit, if you have a Sierra impeller kit use a Sierra impeller housing. Mix and match can cause problems....

I have both, but keep them clearly marked as to what is what. I use mainly OE stuff and they will easily last 3-5 seasons, as long as it primes well and you use good muffs.....

 

[DGMan80]

Yes, there should be no need to use bolts to bring the housing flush

What was the kit part number your using?

Through Amazon UANOFCN 984461

 

[Lou C]

Who makes it? Sierra or GLM ?
I"d try ordering an OE OMC/BRP housing and impeller kit. I never had that problem with theirs.

 

[alldodge]

The part number is correct but coming from Amazon it can be rolling the dice. Might be good but may also be counterfeit. It says replaces that number.

Does list sierra impeller 18-3058

Might also be how your assembling. The housing should mount flush with no need to press and pull into place

 

[DGMan80]

The part number is correct but coming from Amazon it can be rolling the dice. Might be good but may also be counterfeit. It says replaces that number.

Does list sierra impeller 18-3058

Might also be how your assembling. The housing should mount flush with no need to press and pull into place

I'll double check to see if it sits flush or not. I'll report back. I don't believe it referenced the Sierra number. I'll order the oe omc part number even if the old setup does sit flush. Worst case scenario if it ends up being the same and its something else is wrong I'll have a backup.

 

[alldodge]

 

[Lou C]

We can't post websites here but what you need:
OMC part #s
0984461 water pump repair kit $48.95
0984745 impeller housing $39.95

this way you're starting out with the right parts that will work well together. If you have an Evinrude dealer local to you, they might be able to get them in a couple of days.

 

[DGMan80]

You're saying you get flow up to the impeller mount when you install your water muffs, and then when you start the engine, the impeller overheats?
well one possibility is the that little nipple on the impeller housing, (connected to the hose that plugs into the gear housing) that has to be open to allow air out of the impeller housing so it can prime. Try running a thin wire up it and blow out with compressed air. That hose is like the pisser on outboards, it lets you know the impeller is pumping water. So make sure the nipple and hose are clear, leave the cover over the impeller housing off and hose disconnected when you turn on the water to the muffs. You should see water come out the nipple when the water is on, and after you start the engine.
Otherwise, I have had problems with some of the muffs sold recently, the rubber is too stiff to conform to the lower unit shape. I have had the best results with the Merc/Quicksilver round muffs with the metal rod clamp. You can see the nipple in on the bottom right side of the impeller housing, this must be open the hose not clogged.
View attachment 328033

If this hose was clogged
A. It would cause the impeller to housing to overheat?
B. If it doesn't unclog with a wire/compressed air how difficult is it to replace?

Thanks,
Dave

 

[Lou C]

possibly
easy to clean out

suggestion:
get an OMC factory shop manual.
I have the same engine as you and have used the manual every year saved tons of money.
BTW do you still have the one piece batwing exhaust manifolds on yours? If so and you are going keep the boat consider up grading to the 2 piece system. I did this 3 years ago....there can be problems with the one piece units, I didn't have problems but some have....

 

[DGMan80]

possibly
easy to clean out

suggestion:
get an OMC factory shop manual.
I have the same engine as you and have used the manual every year saved tons of money.
BTW do you still have the one piece batwing exhaust manifolds on yours? If so and you are going keep the boat consider up grading to the 2 piece system. I did this 3 years ago....there can be problems with the one piece units, I didn't have problems but some have....

View attachment 328062

I've owned the boat for about a month now. I traded a little aluminum fishing boat (I got a smoking deal on!) for the one I currently have. I was told all it needed was a new outdrive tilt solenoid and a freeze plug replaced. Turned out the solenoid connections were just not tight. Got that working right away. This freeze plug has been more of a pain as upon inspection they all looked good. It wouldn't start after getting it home, turned out the coil was shot too. The only freeze plug I couldn't inspect was behind the starter. That turned into a starter replacement and no leaking plug. I've just gotten it running and now this impeller. I will definitely be getting a manual. Even though I'm super bummed I traded a running boat for a non running boat during salmon season in the Pac NW I feel I'm still ahead in this deal. My plan was to get it running and working fish it for about another 6 weeks then start fixing it up at this point I just want to get it tuned running, take it out and run it through the paces park it and start improving it till spring. It's an '88 20' seaswirl topaz. It's in decent shape, but definitely needs some work. I think this is something I'll hold onto for a few years. My plan was to eventually trade up to a boat like this. I never expected to trade straight to this. I've never worked on anything like this before and have some knowledge of boats but it's quite limited. Every time I pull something off and do work I am learning something new. As far as the manifolds it does have the one piece bat wings. I would be interested in doing that conversion. I'm sure there's plenty of info on how to do it, any advice or links to complete conversion assemblies would be greatly appreciated.

 

[Lou C]

About the conversion...the issue with the one piece design is due to the difficulty in casting them sometimes the wall thickness is irregular and so thin they can crack or rust through easily. With the result that you get water in a cyl. Same thing happened with Mercs one piece V6 manifolds. I had 3 sets of these on my engine from 202-2017 and never had a problem though. We are in salt water so you have to replace every 5-7 seasons. I’d look at the spark plugs and check for signs of water in a cylinder (rust on spark plug electrodes water in oil etc).
If you do a search on my user name & exhaust conversion I posted the parts needed. I used Barr aftermarket manifolds and elbows and Volvo Penta hoses and 90* exhaust pipes that adapt the 4” elbow exit to the 3.5” y pipe. The VP stuff is expensive but fits perfect. These can be found used and they are in the aftermarket (GLM)....

 

[Lou C]

here's some pix....OMC actually changed to this design in 1991 or so, then during the joint venture with Volvo 94-98 they both used it, and after OMC was totally bought out by Volvo they continued using the same design till the exhaust was changed when cat converters became required. Those 90* exhaust pipes are not available from OMC any longer but V/P sells them (same exact part and part #) and GLM sells a knock off copy of it for way less $$$ .
You can see the 90* exhaust pipes in the 2nd and 3rd pic....

 

[DGMan80]

here's some pix....OMC actually changed to this design in 1991 or so, then during the joint venture with Volvo 94-98 they both used it, and after OMC was totally bought out by Volvo they continued using the same design till the exhaust was changed when cat converters became required. Those 90* exhaust pipes are not available from OMC any longer but V/P sells them (same exact part and part #) and GLM sells a knock off copy of it for way less $$$ .
You can see the 90* exhaust pipes in the 2nd and 3rd pic....

Thank you very much for the info! I'll be tackling this in the spring I think.