Water Pump and Thermostat Question

[midsized johnson]

I have an '86 70 hp Johnson with a pre-79 lower unit. I put in a water pump kit for an 86 Johnson but used a pre-79 impellor. The only difference I can see in the kits is that the upper "cup" where the impellor sits is one piece on the newer model wheras the older model is a split ring, 2 piece cup. The newer impellor has a sort of swedge key to hold it in place as opposed to the old style key. Anyway, after installing the kit and reinstalling the lower unit, my thermostat doesn't seem to be working in that water comes out of the exhaust ports like niagra almost immediately after startup. Prior to the job, water only flowed out of the ports after a few minutes at idle and, of course, when I was running under load. While I appear to have sufficient water flow, my concern is that something isn't right, causing the power head to heat up too quickly, causing the thermostat to open immediately afer startup. The power head is heating up, as it is hot to the touch after a couple minutes (or less) of idling. I replaced the thermostat with a new one, and it does the same thing. All of this makes me wonder if water flow is a problem. Conversely, I have a ton of water flow as evidenced by the water flowing out of the exhaust ports.

 

[clemsonfor]

Re: Water Pump and Thermostat Question

not sure of your entire problem but water should flow out of the exhaust ports immediatly upon start up. Your statement makes me beleive that your other pumpo was wore out! My 1970 25 flows water out of ports upon start up and after the pump job it flowed even more and the head runs cooler now. For teh head being hot you sound like you know but just to make sure your head once up to operating temp, or for that matter at any time the head should not be so hot that you can not place your hand on it for 2-5 seconds without getting burned. At idle i can leave my hand on the 25 head the whole time it is running and it not burn me. Is your motor a salt water motor maybe some corrosion broke loose in the change and clogged the cooling ports in the block or head.

-nate

 

[ob]

Re: Water Pump and Thermostat Question

Sounds like the new pump is overcoming the spring setting of the bypass feature of the T/stat/relief valve assy.Either that or the assy. is stuck /corroded open.My recommendation is to replace the relief valve and T/stat assy with all new parts.Full water flow should only relieve out of the relief ports when the engine is up to speed and the pump discharge pressure overcomes the spring tension of the T/stat.A 163 degree thermo melt stik can be got from your dealer to insure whether the engine is overheating.

 

[midsized johnson]

Re: Water Pump and Thermostat Question

I don't think I have a relief valve assembly, only a cone-shaped thermostat with a spring backer. Because both the old and new t-stats are acting the same way, it makes me wonder if I don't have some type of blockage in an inlet port causing the head to heat up too quick. Yes, it's a saltwater motor, but only for the past year, and flushed everytime I've run it. I'm going to check on the melt stick. 163 degrees is after running it, or at idle? Thanks for the input.

 

[midsized johnson]

Re: Water Pump and Thermostat Question

Okay, I'm convinced I have some blockage in the inlet port at the top of the head. I'm going to pull the head this evening and make sure it's clear. I have a repair manual that has disappeared (I had a repair manual). Anyway, can anyone give me a link to the torque sequence and specifications for this engine? '86 70 hp Johnson.
Thanks,
Allen

 

[midsized johnson]

Re: Water Pump and Thermostat Question

I pulled the cylinder head and no obvious signs of blockage. Did not pull the exhaust water jacket cover off. Replaced everything and started her up. Water comes out of peehole warm (it was moved to top of water jacket last year as per some Evinrude mod.), the water coming out of the exhaust ports is cool. The cylinder head gets extremely warm at idle. Should there be a restrictor at the water bypass at the bottom of the exhaust water jacket that feeds in under the bottom cylinder?

 

[ezeke]

Re: Water Pump and Thermostat Question

My looper (140) has always run warm at idle. Every reference that I have read here and elsewhere says this is normal for loop charged motors when the thermostats are functioning properly.

Trust the melt sticks to tell you if you have a problem, though I don't know why your alarm would not go off if you did.

 

[midsized johnson]

Re: Water Pump and Thermostat Question

It's not warm at idle, it's hot! As for the melt stick, I asked in an earlier post, is the stick melting at 163 degrees at idle speed?

 

[ezeke]

Re: Water Pump and Thermostat Question

My temp guage reads 180 at idle, but the alarm never goes off. At 1200 RPM through WOT its is 160 +/-.

It has been like that for 18 years.

 

[midsized johnson]

Re: Water Pump and Thermostat Question

Luckily, I ran into a service guy at the parts counter this morning. We got to talking about the water pump housing and he asked if I had put the rubber grommet down in the pump housing where it attaches to the inlet water tube. I gave him the old, so that's where that goes! I had put it on the tube, but above the water pump housing. No instructions on water pump kit, save for new thermostat procedures (go figure). Anyway, that was the fix, plain and simple. Thanks for the input.