8HP Won't Start

["G"]

Re: 8HP Won't Start

60 lbs of compression is not good enough. There's an issue if that's the best you have.

The tops of pistons are not where you need to look, if the rings are stuck, ring lands corroded/carboned up or pistons scored you won't get good enough compression to make this run worth a hoot.

 

[bktheking]

Re: 8HP Won't Start

60 lbs of compression is not good enough. There's an issue if that's the best you have.

The tops of pistons are not where you need to look, if the rings are stuck, ring lands corroded/carboned up or pistons scored you won't get good enough compression to make this run worth a hoot.

I guess some factors are at question, was it a screw in gauge? How many pulls on the rope when measured. I've started motors with 55 psi on the second pull, this thing should have started, 60lbs should be enough. 60 is indicative of a tired motor. After you get the head gasket back on and torqued properly take another reading. If it's still 60 and won't start, pull the plugs and point the plug holes up to the sky and put 1 tbl spoon of 2 stroke oil in each hole. Pull the starter a couple of times and put one plug back in and compression tester in the other. Take another reading, if the PSI rises then the rings are more than likely wore out. One step at a time.

 

[regulator23]

Re: 8HP Won't Start

Thank you for all the help. Once I replaced the head gasket, the exhaust manifold gasket and the thermostat assembly and cleaned everything out good, the compression jumped to 80 on both cylinders and it fired right up. I'm only getting water flow from the pee hole so it heats up pretty quickly. I am going to pull the lower end apart and see what the impellor looks like. Now that's it running, I'll run the carbon mix in the gas to see if that might even help more.

Thanks to everyone who chimed in. I had no clue on what else to try. I think this motor might have been submerged at some point in salt water. I don't think just not flushing it after salt water use could have caused this much blockage/corrosion. Thanks again

 

[bktheking]

Re: 8HP Won't Start

If it were submerged and not taken apart it would have been seized, it was not submerged this is what salt water does. It was used in salt water and not properly flushed or maintained after each use. I'm guessing that the salt had an effect on the head gasket and other powerhead gaskets lowering compression. Since it was so bad removing the lower unit and inspecting the pump and water tube is not even a discussion, it has to be done.


Glad its working for you now :, enjoy it!

 

[bktheking]

Re: 8HP Won't Start

Thermostat was a good thing to check as well.

 

[regulator23]

Re: 8HP Won't Start

I pulled the lower unit off to check the impellor and the drive shaft wouldn't come down with the lower unit. It pulled out of the gear box and is stuck in the top end. I have tried soaking (upside down) for days with PB Blaster, I've tried clamping vice grips on the shaft and tapping it out, I've tried heating the shaft. Nothing seems to be working. It's a long shaft motor, would that make a difference?

If I could get the new impellor and key in without pulling the shaft out, I would do that, but that doesn't seem possible. Help.

 

[bktheking]

Re: 8HP Won't Start

A gent or lady??? on the board known as "sweetmarie" made a puller, ran into the exact same issue on another post.

I want to make a "puller". I already took a large nut, drilled and tapped two 1/4" holes on the side of the nut so I can thread two bolts to lock onto the shaft. Then I'll take 3.5" x 6" - 1/4'' steel plate, make a hole in the center for the shaft, drill 6 holes so I can put the screws through the plate and screw them to the lower unit ( with the locked nut secured on top of the plate). Each bolt around the steel plate will have a nut (under the plate) which I will turn to lift the steel plate against the nut that's bolted to the shaft and hopefully pull the driveshaft out the crankshaft.


Cut and paste from the post, hope this helps.

 

[regulator23]

Re: 8HP Won't Start

If you heard a loud yell around 2PM EST today, it was me when I finally managed to get the drive shaft to drop. After days of PB Blaster soaking, pounding, and heat, after one hard hit today...it came out. There was a lot of crud on the splines so I've cleaned it up, installed the new impellor and seal and it runs like a clock. Thanks for all of the help. I was beginning to think it just wasn't coming out.

 

[bktheking]

Re: 8HP Won't Start

Was there a spot for an o-ring at the top of the driveshaft? I know the 9.9 has one and that's why they don't rust solid.

Glad it worked out for you.

 

[regulator23]

Re: 8HP Won't Start

It doesn't appear that there was an o-ring on the shaft. Now that it's running, I think this motor had been hanging on the back of a sailboat with the lower end in the water. Everything was blocked down below and someone must have started it, run it until it got real hot, and then shut it down and left it. Maybe the heat, coupled with the salt water, coupled with just sitting for a while caused the shaft to bind up. Who knows.

Thanks for your feedback.