'86 Johnson 90 hp impeller change, then this... with video.

[Janniklindskov]

Hello there

I have just changed the impeller on my Johnson 90 hp. I bought the BRP kit with everything in it. I changed all the parts and put it back together like it was discribed in the manual that came with the kit, and i also looked in my factory manual.

Got it back together and fired the engine up, then it diden't seem to pump proberly. I then took everything apart again and put i back together. Fired her up again and then it was a little better.

Here are some videos of the engine running after the second time i got everything together....

http://youtu.be/Djm-W6NJbIs

http://youtu.be/FgZEoyTo2rs

Hope that you can see on the videos that it is like i dosen't have a steady pee....

I felt one side of the cylinders and it got more hot than the other, so hot i could't hold my hand on it. The other one i could hold my hand on.

Now my question is, why is it not pumping in a steady stream or is this stream enough?

After i had the engine on idle for a couple of minuts the rectifier suddenly caught fire

I got the rectifier of the engine and i could see that there is a large space underneath it.
Is the impeller not pumping enough water so the rectifier gets to hot? It shoud be noted that the voltmeter in the boat has been showing alot og voltage going to the battery so maybe the rectifier has been bad for some time?

Got a picture of the rectifier after the fire...

Hope some of you can help me with my problems, because the boting season is comming soon

Jannik

 

[emdsapmgr]

Re: '86 Johnson 90 hp impeller change, then this... with video.

Are you starting this engine up for the first time this year? The telltale seems to be pumping normally, even strong at idle. That is an indication that your impeller is in good shape. The water that first enters the block-feeds that telltale hose/nozzle. So, that means water is entering the powerhead. What I don't see from this engine is any water coming out of the exhaust relief ports, at the top of the midsection. They are both completely dry. This may be a problem. Once water starts to flow through the powerhead, you should see two small streams of water pouring out of those ports, as well as some watery mist. Your engine has two thermostats at the back of the engine. They are like gates that control the water flow through the block. Those stats must open when the powerhead heats up to 143 degrees. If they don't they won't let any water into or out of the block. My guess this is what happened-the top of the block was dry. When the water could not enter the block, the upper part of the block overheated and fried the watercooled regulator-which sits atop the block. [The only other thing which will fry that regulator is if you have loose connections at the battery.] I'd probably pull that thermostat housing apart and inspect it. Once it's apart, put a new pair of thermostats in. Check the nylon pressure relief valves to make sure they are not heat-deformed. One other thing: if you rev the engine slightly at idle, (maybe 1500 to 2000 rpms) the water pressure will build inside the block-usually enough to push the pressure relief valves open. Normally, that will start water flowing through the block, even if the stats are stuck shut. Go back to idle and the water flow will probably stop.

 

[boobie]

Re: '86 Johnson 90 hp impeller change, then this... with video.

Have you checked the pisser line to see if it has any dirt in it ? If the thermos check out okay you could have some bad water deflectors in the block.

 

[DougyB]

Re: '86 Johnson 90 hp impeller change, then this... with video.

I'm no expert in deflectors, but when you change your thermostats, you will find all kinds of junk in there as well. I used deep creep and bug/tar remover along with a flat screwdriver to scrape clean, and then put the hose right through the thermostat hole, and man does it flush some crap out of there.. Just gives a bit of piece of mind. Don't forget to order the gasket(s) for the housing you need to remove to access the thermostats, if you do change them

 

[Janniklindskov]

Re: '86 Johnson 90 hp impeller change, then this... with video.

Hello Guys
Thanks for all the great answers. It is the first time i start her up this season. I want to do the impeller and carb but now there are some other things as well
What emdsapmgr is talking about the rectifier is what i had in mind. I didn't know that the water flow out of the two exhaust relief ports would start at low RPM, i thought it would only come out at high RPM but i learn every day
I would really like to change the thermostat but the access is really bad and the head of the nuts are really bad. Do i really need to take the powerhead off to get good access?? or is there a smarter way?
About the rectifier, is it possible to put the old one in cut the wires and then use the old school one that is on the side of the engine because they are a lot cheaper
Thanks in advance.
Jannik

 

[emdsapmgr]

Re: '86 Johnson 90 hp impeller change, then this... with video.

I wouldn't pull the powerhead. That's a 3 hour job. You've got a flatback 90. While the access to the thermostat housing is not the best, it really beats working on the 115 engines with the bubble back exhaust housings. You may find that if you loosen up the lower cowling, that you will get some extra room to work. You should be ok if you have a 1/4 drive socket set with a swivel joint. My 1979 85 hp Johnson has power trim and the big 10 amp stator-it runs that simple rectifier (only) and it works fine.

 

[Janniklindskov]

Re: '86 Johnson 90 hp impeller change, then this... with video.

I will try to get to the thermostat by loosen up the lower cowling othervise i will have to pull the powerhead off because things have to work 100% when on the water.
The price difference is really big on the two different rectifiers and i would like to get the cheep one, do you think it will go on mine? I can see that my rectifier has four wires plus the red one and the old type only has two plus the red.
How much voltage do you get to your batteries? I'm thinking that with the unregulated system like on your engine it will kill the batteries?
Jannik

 

[Janniklindskov]

Re: '86 Johnson 90 hp impeller change, then this... with video.

I have found these on Ebay.com

The cheap on:

http://www.ebay.com/itm/New-OMC-Joh..._Accessories_Gear&vxp=mtr&hash=item4d004a94a1

The expensive one:

http://www.ebay.com/itm/Johnson-Evi..._Accessories_Gear&vxp=mtr&hash=item2eb0b55006

It would be nice to get the cheep one

Jannik

 

[emdsapmgr]

Re: '86 Johnson 90 hp impeller change, then this... with video.

The normal regulated voltage when charging may creep up to 13.5 volts. I've seen my unregulated engines run over 16 volts.

 

[Janniklindskov]

Re: '86 Johnson 90 hp impeller change, then this... with video.

Tried to get the thermostat housing of today and the bolts are totaly stuck so i went on to remove the powerhead. Got all the bolt and nuts of like it sayed in the manual and got hoisted up but it is totaly stuck..... Is there a trick to get it loose off the old gasket or will i just need a big screwdriver to pry in where the gasket is?
About the voltage, is 16 volts not a little to much for the batteries?
Jannik

 

[boobie]

Re: '86 Johnson 90 hp impeller change, then this... with video.

If you got ALL the power head bolts out try rocking the p/h from side to side with pressure on it from the hoist. You may want to pull the lower unit off of it to see if the d/s is stuck in the crankshaft splines of the p/h.

 

[Janniklindskov]

Re: '86 Johnson 90 hp impeller change, then this... with video.

I will try to rock it from side to side and see if it will surrender
I will keep you guys posted on the developement of the project...

 

[Janniklindskov]

Re: '86 Johnson 90 hp impeller change, then this... with video.

Update...

Last night i tried to get the p/h off, but 26 years of wear and tear and water had made it impossible to get off. (tried for 3 hours with every large object that i could find in my workshop).

The worst part of it is that i had to cut out a piece of the lower cowling to get to the thermostat housing. It can be put back togheter with some bolts and nuts and some rubber sealant. It is not pretty but i got the thermostats and the small plastic valves out. (the thermostat housing was also totaly stuck)

Now im waiting for my new parts, rectifier and thermokit.

Will let you guys know when im finished and gets her started up again.

Thanks for the help.

Jannik