98 770 TSL compression test results

engr146 · 10-23-2009, 03:00 PM

I finally bought tester,150# mag 0# PTO when I pulled rear plug it looked brand new,like it never fired,front was perfect also,but sighns of light use.I only started and tested ski with these plugs so it makes sense.
Would a bad head gasket have 0# in one and 150# in the other ,wishfull thinking , or am I looking @ a top end.I looked inside plug hole but could not see a hole in center,but realy could not tell.I can't pull head off now! I have to do top end job over winter.

Can I start ski just to flush,and fog without further damaging ski, has been sitting in salt water for 2 weeks, .I bought salt away and hose adapt,and all other winterize equipt.I 'am going to tow to trailer and not run ski! and pull on mon.
I'm storeing ski in my buddy's Heated mechanics garage,But I don't know If he looses heat some night.I don't want it to freeze so I would like to flush and winterize ,But not @ cost of seizing engine or breaking off more piston ect.
What do you think!!

lownrangr · 10-23-2009, 04:22 PM

next thing you need to do is pull the head. You could have a hole in the piston or it could a gasket.

engr146 · 10-23-2009, 05:12 PM

I agree,but what about flushing ,and fogging motor should I not due that first!! this is were ,I'm having the problem! Once I Tow ski, to public ramp and get it out of water and to his garage, and winterize .then should I pull head, I can always just reinstall head ,to keep moisture out ,If it ends up to be a topend job I can do over winter,
Should I open up motor @ garage after winterizing,and not be able to put it back together,rite away.leaving piston and head exposed ,to moisture.
Can I start ski w/ one piston to flush and fog,or what alternave is there.!!

Krispy · 10-23-2009, 05:25 PM

Quote:

Originally Posted by lownrangr

next thing you need to do is pull the head. You could have a hole in the piston or it could a gasket.

Wait a minute, don't pull the head. Pressure test the engine first. (I wish I would have). If you pull the head you won't know if a leak coming from the head gasket area was caused by you re-assembling or some damage.

Krispy · 10-23-2009, 05:27 PM

Quote:

Originally Posted by engr146

I agree,but what about flushing ,and fogging motor should I not due that first!! this is were ,I'm having the problem! Once I Tow ski, to public ramp and get it out of water and to his garage, and winterize .then should I pull head, I can always just reinstall head ,to keep moisture out ,If it ends up to be a topend job I can do over winter,
Should I open up motor @ garage after winterizing,and not be able to put it back together,rite away.leaving piston and head exposed ,to moisture.
Can I start ski w/ one piston to flush and fog,or what alternave is there.!!

If you have 0 psi on one pistion you know you are going to have to do some major work on the engine. I honestly wouldn't worry about foggin it. If it were me I would do the following:

1. Remove ski from water

2. Pressure test engine

3. Remove Head inspect pistion for damage

4. Coat all exposed steel parts with a water displacing / rust preventing oil.

5. Take out a loan

6. Fix the ski

Welcome to my world. It appears our 770's have each decided to fail in a similar way

engr146 · 10-23-2009, 06:19 PM

How did you end up pressure testing engine,did you buy the test plate ,I told you about!

I do know the answer to my own question!Do not run motor!! I'am just concerned,about not flushing and fogging motor! for winter after sitting in salt water.

Krispy · 10-23-2009, 06:54 PM

Quote:

Originally Posted by engr146

How did you end up pressure testing engine,did you buy the test plate ,I told you about!

I do know the answer to my own question!Do not run motor!! I'am just concerned,about not flushing and fogging motor! for winter after sitting in salt water.

Nah, The guy didn't respond to my question. I just asked him what exactly was in the package..

I may just build one, I wonder if I could just use some plate steel and some honda bond or rtv, no holes.

lownrangr · 10-24-2009, 02:44 AM

yeah i agree on pressure testing the engine first. good idea. and since you have a top end job to do, i wouldn't fog the engine either.

dank · 10-25-2009, 11:21 PM

You can make some plates out of plywood and some rubber sheeting from home supply or a old bike tube.

engr146 · 10-27-2009, 12:44 PM

I only ran oil pump and premix 50:1 on 770 for a half a tank of gas,before problem started .I don't believe this was my problem with no compression in my rear Cylinder.
when you beak in a top end or new engine your told to run same for first tank of gas rite!!