1990 150 HP V6 Leak Down Fail. Help!

[RBoyd1971]

Another thing, if you ever suspect a carb may have problems on a motor with multiple carbs and cylinders, don't run it. Take the carbs apart and make sure they all are clean, getting fuel, and jets are open. Running one that's not getting fuel with oil in it to a cylinder or two while running can cause major galding and scoring. If it's oil injected and you aren't mixing the fuel with oil, then that doesn't apply.

 

[RBoyd1971]

I would check the other side and if it's in similar condition, reassemble with new gaskets and run it a bit. Take compression readings so you know what's happening with it. Since it's been sitting for 8 years, after running things might improve.

 

[RBoyd1971]

One last thing, take your fingers on one hand and pull the piston over to the side to kind of lock it in place, then rock the flywheel back and forth to see it there is any slack in the wrist pins or connecting rods.

 

[racerone]

Boyd----On that motor the oil would be mixed with the gas before going into the carburetors.----No different then mixing yourself at 50:1 in your tank.----So why your last statement in post #21 ?

 

[RBoyd1971]

To be honest, I wasn't exactly sure how the oil got to the cylinder on those engines. I know some newer ones were directly injected only where it's needed, for example the eTech. I've seen these guys running their engines on starting fluid with stopped up carbs and I'm like, what the heck are you doing! I've mostly worked on the older engines without VRO etc. Mostly the smaller engines 65 hp and less.

 

[RBoyd1971]

Sorry, double post.

 

[dieffer]

One last thing, take your fingers on one hand and pull the piston over to the side to kind of lock it in place, then rock the flywheel back and forth to see it there is any slack in the wrist pins or connecting rods.

Thanks!

 

[dieffer]

Thanks everyone for all the feedback. I’m a newbie so this has been extremely helpful!

 

[dieffer]

I would pull the heads, inspect the cylinders for damage, if old gaskets are not damaged coat em with AV sealer and test run it. If compression is good 95 psi or above and close to each other. Go thru thru the carbs since it has set 8 years, replace all fule lines , flush oil tank if still has VRO...JMO

One more question about this: Would you replace ALL the fuel lines, including the little ones that run from fuel pump to solenoid, solenoid to carbs, etc, or just the main one running into the engine?