No water through exhaust on 5.7 mercruiser

[rmonheim]

Just installed a reman 5.7 marine long block in my 99 Crownline 202BR to replace a perfectly functioning 5.0 that I failed to winterize properly (filled with AF but didn't drain). Also went through the Alpha One Gen 2 outdrive before the motor swap, did the bellows and installed EMP impeller kit.

My problem is that while running on muffs, there doesn't seem to be any suction from the water intake and no (or very little) water comes out of the exhaust/prop. Already melted the flappers in the exhaust during the first start when I didn't realize what was happening.

I have checked everything I can possibly think of to no avail. Double checked the impeller was installed correctly, water tube was aligned during lower unit install. Old impeller came out in one piece and was in good condition, housing seemed ok with no major grooves or anything. I have checked that water flows easily from tstat housing all the way out of the outdrive, and ran engine briefly with tstat inlet hose in a bucket and seemed to get a decent flow (didn't measure actual volume, maybe half a gal in about 10sec). Did the same test with the exhaust manifold inlet feed hose and got decent flow from it too. No apparent blockages or cracks in manifold or risers. Not sure how well engine itself is cooling because I can't run it for very long.

Long story short, the engine/exhaust seems to be getting water at a decent rate, yet the exhaust is overheating and no water seems to be getting sucked in from the muffs or comes out the exhaust. Just pulled a riser this evening after running and there was definitely water in the cooling passages, but I guess not enough flow to make it all the way out the exhaust. Maybe a water pressure issue, maybe a bad impeller? I'm stumped at this point and want to see if anyone has any insight. Thanks!

 

[Bt Doctur]

I have checked that water flows easily from tstat housing all the way out of the outdrive, That the first issue, that should no happen and ran engine briefly with tstat inlet hose in a bucket and seemed to get a decent flow I doubt you had flow from the impeller, you may have had flow from the water pressure of the muffs

 

[Bt Doctur]

Pull the drive and using a washing machine hose cut in half .insert into water inlet hole and run motor. If motor cools as normal operation , you have a imleller issue

 

[rmonheim]

If I pour water into the inlet hose at the tstat housing, should anything at all come out at the outdrive end? When I had the lower unit off, I ran water from the tstat inlet hose out of the plastic water tube that normally connects to impeller housing. With the lower unit on, water slowly comes out of 2 holes near the top of the lower unit as well as some out the intake holes.

It seems as if the impeller/pump assembly is not "water tight" when stationary, but I am not sure if it is supposed to be.

 

[achris]

You may find a little leaks passed the impeller, but it shouldn't be much.

Pull the drive, stuff a water hose into the water passage in the bell housing and turn the water on. You should get water coming out of the exhaust reliefs at the bottom of the gimbal housing, even with the engine not running. If you do get water flowing, and it should be plenty, not just a trickle, then the engine flow is ok. If you're not get any (or enough) then you need to find out what's stopping it. If you have plenty of flow to the hoses that go into the manifolds, but nothing coming out.... You did use full flow gaskets between the manifolds and the elbows?

Chris......

 

[rmonheim]

It sounds like pulling the drive and testing with a direct water feed should tell me what I need to know, thanks for the tip. I did use a full flow gasket, and as far as I can tell everything is clear as far as the water passages go. Nothing really changed with those parts since they worked just fine on the old engine.

If the issue is the impeller, I'm not sure what it would be other than a defective part...the boat cooled great last season, and I double and triple checked everything when I reinstalled the new impeller for the second time. I guess I could have missed something, not sure...

 

[Bt Doctur]

There are too many mistakes in doing an impeller from forgetting the impeller key or to burning up a new impeller from doing something wrong during assembly. Do the hose test to isolate the touble. When running on muffs with the engine off there should be a "splash" seen escaping from the muffs. The instant the motor starts 90% should immediately disappear if the impeller is doing it`s job

 

[achris]

You put the key on the shaft that locks the impeller to the shaft?

 

[AShipShow]

You put the key on the shaft that locks the impeller to the shaft?

Lol, was just going to say that

 

[rmonheim]

I definitely installed the key haha, I was worried I forgot it the first time but unfortunately the fix was not that simple. Also made sure the water tube was aligned when I installed the lower unit. Not sure if I kept the old impeller but if I can find it I will compare to the EMP impeller I put in, maybe try running it with the old impeller that I knew worked before.

 

[Scott Danforth]

if you burned the exhaust flappers, you also burned the exhaust hoses

many times when an impeller grenades, its pieces plug up the rest of the system.

 

[rmonheim]

No impellers have grenaded, the old one was 100% intact and the new one was fine when I took it out for the second time.

What will the symptoms be of burnt exhaust hoses? They still look the same inside and out, no blistering, seem to be flexible. I guess I will see if they leak but they sure seem to look and feel the same as before

 

[Scott Danforth]

if there is no blistering and burnt rubber, you may have gotten lucky.

 

[rmonheim]

Ok, Just tested the water flow with the drive removed. Plenty of flow out the exhaust port on bottom of gimbal housing so I think everything inside the boat is fine.

Pulled the impeller and found something odd...some fins were pointing in different directions (first pic). I also included a picture of how the fins were curled when I installed originally, as far as I know this is the correct direction (?). Not sure what would cause the fins to do what they did unless it was spinning backwards and I didn't run it long enough for them all to right themselves? I used healthy amount of silicone grease when installing. Am I just dumb and installed the impeller backwards?....

 

[Bt Doctur]

Is something up with the website again, no edit, no back page. Is it the site or me? 1 Avoid grease or silicones, try K-Y Gel , it works a lot better and is water soluble . You lubricate it because you turn the shaft backwards to align the splines

 

[Scott Danforth]

Dawn dish soap works, then you dont have to explain going to walmart right now wearing a mask and buying KY.

 

[JASinIL2006]

I wouldn't worry about the vanes looking like that on a Gen 2. They'll straighten out first time you run it. (I even recall reading something that suggested one or more vanes will flip backward when you stop the engine.) But lubing the inside a bit when you assemble it will help as BtDoctur says.

 

[rmonheim]

Ok so it sounds like backwards impeller likely isnt the issue. Correct me if I'm wrong, but I doubt the type of grease being used would cause the issue I'm having. I compared the new and old (working) impeller, they seem to have the same dimensions. I'm not sure what could be causing it at this point.

Like I mentioned, this is a reman engine and I'm trying to break it in. I have tried to keep the revs low per the break in instructions, I think the highest I've been so far was like 1500rpm. Maybe running it a little higher for a few seconds would get everything moving? I'm kinda stumped at this point

 

[Rick Stephens]

I'd be really worried too while breaking in a reman and having the cooling system misbehave. The expense probabilities are too big to ignore.

I see no problems at all starting up with muffs hooked and water on and hose off of thermostat housing to see what flow is any time you question the impeller. DO that again when you reattach the leg..

Your vanes getting discombobulated is just weirdness all of us have seen.

I was going to ask if maybe the motor circulation pump was the wrong one or damaged somehow, but your test with the leg removed and the hose stuffed in the bell housing port kind of resolves that.


I had a weird one yesterday just like this. Pulled the boat out to dewinterize. Hooked up the muffs, fired up and had water running out the bilge cause I forget to attach the big hose to the water pump. Water was flowing well. Shutdown, hooked up that hose, fired up again, no water from exhaust, lots of water around muffs. Waited a couple minutes and started getting steam out the exhaust. Shut down, looked over everything, turned water back on, started up and everything normal. Go figure. Going fishing tomorrow, so I hooked up again today and tested it, again, everything normal.

 

[Scott Danforth]

run the motor with the hose stuffed in the gimbal housing for break in if its a flat tappet motor while you are working on your lack off flow issue.

if its not a flat tappet, solve the problem and go boating.

have you verified the coupler is in good shape? if the coupler is gone, the drive doesnt turn....... if the drive doesnt turn, the raw water pump doesnt turn