Logo
FULL SITE MENU

1979 Evinrude 9.9 water restriction

K

kevinj

Advanced Contributor
I have a 1979 Evinrude 9.9 that is not pumping water properly. I installed a new water pump and flow out the pee indicator was still low. Next I removed the thermostat and found bits of rubber on the engine (inlet) side. Ah hah the culprit....or so I thought. I cleaned out the bits of rubber, tried back flush with lower unit off, and installed a new thermostat. I'm still getting low water flow. When the engine is cold I get weak flow out the indicator and once it's warm the flow completely stops and the engine starts to get hot.

My guess is that some previous owner ran it with an old water pump and filled the cooling passages with chunks of impeller. I would imagine the bits of rubber I found are just the tip of the iceberg.

My question is what parts do I need to remove so I can clear the cooling passages? It looks like the exhaust cover on the starboard side is the outlet side of after water passes through the head. So do I remove the plate on the port side of the cylinder head to look for debris? Is that the most likely place to find the junk? Finally, can this all be done with the power head in place, or am I better off to remove it to make access easier?

Thanks,
KJ
 
Unfortunately, on the 9.9-hp and 15-hp models, the upper water tube grommet is prone to failure and creates a water flow restriction... sort of a folding rubber shutoff valve scenario.

The only way to gain access to and replace that grommet is to remove both the lower unit and the power-head. It's also the only way to make sure that all water passages are open.
 
Thanks Joe. As compact as things looked I figured I would have to remove the power head. It should make for a good winter project. I have gaskets for the exhaust and cooling jackets. I'll have to order a grommet and case to exhaust housing gasket.

I don't use the motor much, but it's nice to have as a kicker motor for my fishing boat. We have several good lakes in our area that are 10 or 25 HP limit.
 
I think what I'll need is part# 324045 (upper water tube grommet) and part# 0325721 (power head to exhaust housing gasket). I have the bypass cover gasket (part# 319332) and the exhaust cover gaskets (part#0318925). Is there anything else I will need to remove the power head and flush the cooling system?

​
Thanks,
KJ

​
 
To make the job complete, not missing anything in the water passage area... while you're at it, remove the cylinder head to clean out the obvious water passages and to inspect and clean the sealing surfaces of the head and block. Possibly you've already accomplished this part.

That'll require:
1 - Head gasket... If recently new, this can be reused (Done that a few hundred times).

1 - water jacket gasket (for the plate on top of the head).... I suspect you've already replaced this when you installed a new thermostat
 
Pull the power head to remove the exhaust cover, this is where i have had blockages occurr. If any of the head bolts are super tight i'd back out, i now have a block with a head bolt snapped off in it that is impossible for me to remove.
 
So this long project is finally nearing an end. I removed the power head, inspected/blew out all cooling passages in the block and head. I removed the exhaust bypass cover and cleaned everything there too. I didn't find any big chunks in the passages. What I did find was a piece of rubber at the water inlet where the water tube mates to the block and, as Joe described, the water tube grommet was swollen and mis shapen. I can say that was a whole bunch of work for a $3 piece of rubber. UGH!!!!! :(

Here is a picture of the bad grommet.
 

Attachments

  • grommet.jpg
    grommet.jpg
    42.6 KB · Views: 361
I had a chance to test fire the motor this evening. At first I thought there were still problems because I had very little water flow out of the indicator port. I could see when the thermostat opened because there was water coming out the exhaust relief ports and I could put my fingers on the head for 10 seconds without burning my fingers. I knew it wasn't overheating but the water flow didn't seem right. Finally I took a guess and ran a wire in the indicator while the motor was running and.....bingo, a small chunk spat out and water flow was perfect.

Thank you for the great suggestions and much thanks to Joe Reeves for part numbers and suggestions. I now have a 9.9 that runs like a top.
 
Good job was ther much crap in the block? It wouldnt hurt to run it in a barrel of water with saltaway in it for about 20 minutes now you have water flowing good through it to dissolve all the corrosion. Then flush it with fresh water for a few minutes. It wouldnt hurt to pull the telltale hose off of the engine block while running and blow through the pisser both ways with high pressure air and replace the tube if it is getting hard.
 
kimcrwbr1 said:
Good job was ther much crap in the block? It wouldnt hurt to run it in a barrel of water with saltaway in it for about 20 minutes now you have water flowing good through it to dissolve all the corrosion. Then flush it with fresh water for a few minutes. It wouldnt hurt to pull the telltale hose off of the engine block while running and blow through the pisser both ways with high pressure air and replace the tube if it is getting hard.
Click to expand...
There was no corrosion really, a couple of little pieces of crud but that was about it. I ran it for about 20 minutes in a barrel before I found the small blockage in the telltale. It ran another 10 or so after I cleared that problem and it seems to be doing great now. I'll be using it Saturday and that will be a huge test. It's going to be a kicker motor on my 19' Ranger. I know it won't go fast at all, but it's a HP limit lake and the 9.9 will be faster than a trolling motor.
 
Success on the lake test!!!! As expected I didn't break any speed records pushing my Ranger with a 9.9. The GPS on my fish finder showed full throttle was a whopping 5.5MPH. Slow? Yes. Faster than a trolling motor? For Sure! Did it save my batteries for fishing? Absolutely. The little motor cranked along without any hiccups or stutters and water flowed out the telltale strong all day.

We have to make some minor modifications to the kicker bracket. When that's done I'll post pictures of the entire assembly.

KJ
 
Nice work kevinj. Has anyone ever taken a video or pictures of the steps to remove the power head ? I've been thinking about doing this to an old 9.9 I have as I think that grommet is the issue with water flow but would love to see the process before I tackle it. Anyone know where this has been layed out ?
 
I found bits of rubber in the water exhaust of the lower unit on my 1976 Evinrude 15 HP. 15655A Model. Was concerned it was the water tube o-ring, but too much rubber. Upon removing my thermostat, I realized the thermostat was very corroded but still functioned. I ordered a new one and it suggested I replace the thermostat seal....wait, the old one did not appear to have a rubber seal. I think I know the source of the rubber in the lower unit water exhaust.
 
Chunks of rubber are quite often a water pump impeller shredding. You need to pull the lower unit and inspect the impeller. If you find a shredded impeller you'll want to also pull the exhaust cover on the starboard side of the engine and make sure there are no bits of rubber blocking those channels.
 
I doubt the thermostat seal would fall apart to the point that it's not even there. My guess is the Thermostat has been replaced before and the installer forgot about that gasket.

You might be okay, but if you still aren't getting good water flow you'll want to remove the exhaust cover (#23) and make sure there is no debris in any of the channels. You'll need to order 2 of part# 0318925 (Exhaust cover gasket)when you do this.[h=1]http://www.marineengine.com/parts/j...rer=Evinrude&section=Cylinder+&+Crankcase[/h]
 
gspsrgr8 said:
I found bits of rubber in the water exhaust of the lower unit on my 1976 Evinrude 15 HP. 15655A Model. Was concerned it was the water tube o-ring, but too much rubber. Upon removing my thermostat, I realized the thermostat was very corroded but still functioned. I ordered a new one and it suggested I replace the thermostat seal....wait, the old one did not appear to have a rubber seal. I think I know the source of the rubber in the lower unit water exhaust.
Click to expand...

I would be willing to bet that the rubber you found in your lower unit is from your upper thrust mounts (motor mounts) #5 in the breakdown http://www.marineengine.com/parts/j...&manufacturer=Johnson&section=Exhaust+Housing
 
Back
Top