Low water pressure 85 johnson 40

[damonlbcmiller]

Hey guys I have a 85 johnson 40 that I ran up on a sand bar during duck season and just got back to work on it. When I ran it on the sand bar I noticed it wasn't peeing like it normally did. So I quit running it. I pulled the lower and the Impeller was in good shape but the wear plates were scarred. At the same time I checked and flushed my power head to ensure it was unclogged which it is. I just put a new water pump in it and it still has low pressure. The only thing that was odd was my foot oil was real milky so I took it to a shop to be pressure tested and it was fine. Can my water pump be blowing down into my foot through my seal?? Any help is welcome and appreciated I'm just at a stand still and need some ideas to what it can be. Thanks in advance

 

[boobie]

Re: Low water pressure 85 johnson 40

Is the low water pressure coming out of the overboard water indicator ?? If it is, it may be plugged.

 

[FishinDave]

Re: Low water pressure 85 johnson 40

One of the things that I like to do is back flush the water system with the lower unit off. It is easier for the sand/etc. to leave the way it came in. Some things to make sure of(none to be insulting)= make sure that there are no cracks in the water pump housing, the impeller fins are bending in the right direction(rotate the drive shaft so that the prop is turning in the direction that it would move the boat forward), make sure that you have the impeller key in so it locks the impeller in position on the drive shaft, you can use a high speed drill at the top of the drive shaft and submerge the lower unit while turning the drive shaft to rotate the prop in a forward direction and see if the water pump is operating properly but be careful not to damage the drive shaft(I put tape on it so it doesn't get scarred). Also make sure the ports/water inlet holes in your lower unit are clean and flushed out. If you flushed the powerhead and did not clean the lower unit out it may be clogged again. Hope this helps

 

[damonlbcmiller]

Re: Low water pressure 85 johnson 40

That was the very first thing I did was back flush the foot to get it all clean. While it was apart I checked my t stat and shoved a water hose on the tube the water pump pushes the water through and water came pouring out where the t stat was freely so the head is unclogged along with the tube. I replaces the impeller made sure it was turning the rite way and replaced the wear plates also. I've done everything as you mentioned. Just not to sure what yal are talking about a overboard indicator. Thanks for the help

 

[dazk14]

Re: Low water pressure 85 johnson 40

That was the very first thing I did was back flush the foot to get it all clean. While it was apart I checked my t stat and shoved a water hose on the tube the water pump pushes the water through and water came pouring out where the t stat was freely so the head is unclogged along with the tube. I replaces the impeller made sure it was turning the rite way and replaced the wear plates also. I've done everything as you mentioned. Just not to sure what yal are talking about a overboard indicator. Thanks for the help

He's talking about the "pisser". Is that where you are seeing a low volume of water.

Best way to clear that is while running shoot a compressed air nozzle back up into it. Let it flow out, repeat as need.

Some people use weed whacka line while running.

fyi- The overboard indicator can be plugged solid and it will have zero effect on a properly functioning cooling system.

 

[damonlbcmiller]

Re: Low water pressure 85 johnson 40

I will try with compressed air if not today then tomorrow and let yal know what I come up with because that is where I saw the low volume. I tried the old way of blowin and suckin when I first saw it but with no luck. Is there any other way to make sure I don't run my boat hot? And thanks Again

 

[damonlbcmiller]

Re: Low water pressure 85 johnson 40

I just tried blowin the air back through it with the motor runnin and with no luck. Also there is no water coming out of the exhaust holes near the motor. Any more ideas?

 

[boobie]

Re: Low water pressure 85 johnson 40

Take the pisser elbow off once to make sure it's not blocked and look where it screws in and check for any blockage.

 

[damonlbcmiller]

Re: Low water pressure 85 johnson 40

I did that and there is no blockage. I have a feeling it's something very simple I have to be looking over considering I've replaced the water pump and I know everything is unclogged but still low pressure. I'm just not wantin to have to take it to a shop to charge me so much for something I know has to be simple. Any more ideas?

 

[daselbee]

Re: Low water pressure 85 johnson 40

I just had a Yamaha in the shop with low water pressure. Bottom line, the grommet in the top of the WP outlet was way up on the water tube, maybe an inch higher than it should be. The water tube was in the outlet properly, but the grommet was not sealing the water flow.
It was filling up the leg, as well as barely pumping water up to the head.

You have to glue those grommets in.

 

[dazk14]

Re: Low water pressure 85 johnson 40

I did that and there is no blockage. I have a feeling it's something very simple I have to be looking over considering I've replaced the water pump and I know everything is unclogged but still low pressure. I'm just not wantin to have to take it to a shop to charge me so much for something I know has to be simple. Any more ideas?

A little more fact finding....

Did you install a complete kit? The driveshaft to pump housing seal is VERY important to get meaningful water pressure. I'm wondering if the seal got shredded a bit from the sand.

Is the midsection filling up with water and leaking out in odd locations that you've never notice before.

Did you pull the lower as fishindave suggested drop in partially filled bucket and use a 1/2 drill to rotate the drive shaft and check output?

 

[damonlbcmiller]

Re: Low water pressure 85 johnson 40

I did do a kit but didn't do a new housing and I hadn't done the trick with the drill do to I have t had it off since that information. I will do it tomorrow and let yal know what I find

 

[damonlbcmiller]

Re: Low water pressure 85 johnson 40

Hey guys I took my foot off today and was gonna do the trick with the drill but my drive shaft was to big for my drill to fit over so I just hooked my muffs up to see what I could see and water came out of the water pump tube and out of where the drive shaft goes in. Is there exposed to be a gasket or something in there beside the grommet that the drive shaft tube sits on? Still stuck on this project and wanting to finish