Johnson 30hp Help

DriftinMT09 said:

RaisedByWolves said:

You can rule in/out the temp sensor by disconnecting it.

Do that as a test only, definitely test the T stat and replace the impeller regardless.

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It will run without the temp sensor plugged in?

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Yes.

DriftinMT09 said:

Took the boat out yesterday, and the motor seemed to be running okay. It has always bogged down when in gear, and stalled at low rpm. It kept coughing and stalling when just idling in neutral. We ran it around around the lake at roughly 50-70% throttle with no issue. Stopped to check out if I can find the source of my water seapage into the back hull area, and when I restarted it, it would not rev out. It felt like it was hitting a limiter, or maybe only hitting on one cylinder. Just off idle, it ran fine, and smoothly. Luckily the lake wasn't too rough, and we were able to put put back to the launch.

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Did you check your spark and compression?

newyota said:

DriftinMT09 said:

Took the boat out yesterday, and the motor seemed to be running okay. It has always bogged down when in gear, and stalled at low rpm. It kept coughing and stalling when just idling in neutral. We ran it around around the lake at roughly 50-70% throttle with no issue. Stopped to check out if I can find the source of my water seapage into the back hull area, and when I restarted it, it would not rev out. It felt like it was hitting a limiter, or maybe only hitting on one cylinder. Just off idle, it ran fine, and smoothly. Luckily the lake wasn't too rough, and we were able to put put back to the launch.

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Did you check your spark and compression?

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Have not yet. I have new plugs on order. Wanted to fix the suspected impeller issue before I start tearing more apart.

After the 4th weekend, I'll have to do a compression test and see what I get for numbers. It cranked evenly (sounding) comparing it to a dead cylinder 2 stroke sound.

Pappy said:

Do NOT tear your engine apart based on guesses in this forum!!
You do need to start with the basics. Compression being a basic.
Lots of information on thermostat operation in this forum. Read up when you can.
Basically the thermostat on your engine is controlling temperature at idle and just off idle. Anything higher and the thermostat cannot provide the volume of water needed to cool the powerhead. What happens is that the bulk of cooling water then bypasses the thermostat altogether and keeps the temperature down where it needs to be.
Your engine should run around 135f or so at idle. To check you can hold the palm of your hand on the very top of the cylinder head. You should be able to hold it there for no more than 5-6 seconds. Not scientific but if you do not have a temp gun this works.

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Thanks Pappy. I do have an IR temp gun, so I will check that once I get my impeller parts, with new thermostat and gasket. COVID19 really screwed stuff up with Crowley Marine (where I ordered the parts from), and they are having large shipping delays.

Pappy said:

We are as well....probably over 60 part numbers on back order at this point. Trust me....I feel your pain! #-o

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Got my impeller replaced last night, which was all cracked up. All the blades were still intact, but cracked quite a bit. Taking the head cover off this morning, found lots of scale crap built up in the cooling jackets. Trying to remove the most of it, so I can vacuum it out. Can I flush the motor cooling jackets with CLR so I can try and maximize my cooling efficiency? Was the scale caused from overheat?

That head doesn't really look that bad. You have one place that looks real suspect that the gasket may have been leaking. The pic. isn't great, but it is suspect. Appears to have been leaking to the outside.

nccatfisher said:

That head doesn't really look that bad. You have one place that looks real suspect that the gasket may have been leaking. The pic. isn't great, but it is suspect. Appears to have been leaking to the outside.

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I agree, it looks fine.

I would however check your T-stat while youre in there.

nccatfisher said:

That head doesn't really look that bad. You have one place that looks real suspect that the gasket may have been leaking. The pic. isn't great, but it is suspect. Appears to have been leaking to the outside.

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I wasn't so much worried about the head gasket itself, but more of the head cap gasket. When I removed it, it was really scale coated and junky looking. The thermostat looked like hell.

Got the gasket and t-stat (with gasket) replaced yesterday. Replaced all the cap cover bolts as they were not very clean looking, except for the 3 upper bolts that hold around the thermostat.

Ran it, and found no water coming from pisser hole. Tore lower unit back off, and I think my water pipe wasn't in it's seat when I put it back on. Got it all aligned correctly, and once restarted, it was pumping instantly.

Now for my fuel pump rebuild kit and carb rebuild kit. Hopefully she will run like a gem.

Take the fuel pump apart very carefully. They can go together in various ways, but only 1 will work on your motor.

Pappy said:

You are definitely approaching this the right way. Nothing like peace of mind in knowing you have looked at and serviced pretty much any item that can fail and leave you at the exact farthest geographical point from your dock!

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@Pappy, do you happen to know a good starting point for the mixture screw from bottomed out?

CedarRiverScooter said:

Take the fuel pump apart very carefully. They can go together in various ways, but only 1 will work on your motor.

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I took it apart very slowly and carefully. Set everything out in the orientation it came off. Parts kit from Johnson/Evinrude had a couple one way valves that my pump did not use, but the manual forwarned of that. Other than that, just making sure the springs stayed seated was the only tricky part.

Pappy said:

Sure - Start from around 1 1/2 turns out from a lightly closed position. That should get the engine running and be on the rich side. Make small adjustments clockwise and wait for 20-30 seconds to let the engine respond. When the engine sneezes lean back the adjustment back out around a half turn or so then come back in a little if necessary.

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Maybe my idle speed is also way off. I can't really get it to run at low speed at all. Is the idle more so done with a throttle adjustment?

Pappy said:

The throttle blade should remain closed. There are calibrated orifices and a slot designed to allow enough air past to run the engine in a normal RPM range at idle. Most of your idle speed adjustment will be accomplished by advancing or retarding the mag plate and spark timing. If you have the tiller engine you may have a speed adjustment located at the tip of the throttle handle. If not then do what I asked you to do with idle mixture first as that has a lot of control over the idle speed.

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I tried the 1-1/2 turns from closed, and it just sneezed and coughed a ton. It was maybe set at 1-5/8 from closed when I reset it. The manual shows it being 2-1/2 turns out from the factory setting. Set it to that, and it's sneezing less, but smoking a lot more and it feels like it's loading up. So I'm guessing I need to lean it out a tad. What is not clear to me, is whether I need to do it with the speed adjustment on the tiller handle, threaded in or out.

Pappy said:

The speed adjustment on the tiller handle controls timing primarily. Check and make sure the throttle blade is not opening too early. There are marks that align with the throttle roller and pick-up cam telling you when the throttle should open. Make this adjustment prior to trying to adjust the mixture. Smoking too much, rough idle, and low RPM indicate a rich mixture. Adjust as necessary.

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From the service manual, I think the pick up cam was inline with the two points, when the speed adjustment was turned fully counter clockwise. The throttle plate is not opening until you really twist the handle open, or it's put in gear and the cam is allowed to move further.