Evinrude 7.5 idle

[crosbyman]

see bleeder valve on a 5.5 but… looking at the 7.5 parts I can find……… I can’t see it ? maybe the 7.5 does not have one

Joining AOMCI has priviledges 🙂

[james hobson]

You say not to add any oil in cylinder when checking compression but when a two cycle is running does it not have oil in the cylinder would that not be more realistic conditions , right now I am only getting about 35- 40 on each cylinder, is it possible to run on one cylinder and check compression on other.

[dave-bernard]

with that compression may have a blown head gasket. pull the head and check.

• This reply was modified 3 years, 3 months ago by dave-bernard.

[lloyd]

There is your answer. Low compression. Hopefully just a blown head gasket.

[billw]

Like Dave said, with those numbers, it may be a blown head gasket. 7.5s don’t have a metal ring for each cylinder, built into the gasket, like larger motors. I have a 7.5 myself, that I have to get around to doing a head gasket on. This sounds like a good thing for you to try. Be advised that when the head is off, you should check the head’s surface for machineed flatness; as they do tend to warp.

All that being said, 35 to 40 psi???? It is a miracle that the engine even starts, never mind idles badly. Is it also hard to start?

Long live American manufacturing!

[fleetwin]

Are you sure the gage reading is accurate? You might want to try a different gage…

[james hobson]

Will pull head and check , do I need to Torque head bolts to reAssemble what lbs.

[crosbyman]

see chart

Joining AOMCI has priviledges 🙂

• This reply was modified 3 years, 3 months ago by Mumbles.

[james hobson]

No not hard to start at all seems to run good just won’t idle like I said low compression 30 -35 gauge I know is accurate pulling head tonight and will get new gasket will see where that takes me

[Mumbles]

I don’t think the spring loaded shock absorber on the drive shaft below the water pump has been mentioned here yet. If the prop has hit something hard, the spring will release and allow the shock absorber to expand, dragging on the bottom of the bearing carrier located below the water pump. The motor will run in this condition but the idle quality will be compromised. Can the motor be turned over easily by hand with the spark plugs removed?

If you are going to service the impeller, it would be a perfect time to remove the carrier and inspect the bottom of it. Any contact between the two surfaces will be obvious. If a sprung shock absorber is detected, it can be pressed or pounded down to its original 6 11/16″ length. If the shock absorber is removed from the housing, the gearcase will more than likely have to be opened up to get the pinion gear back onto the shock absorber correctly. Meanwhile, let’s see what that head gasket looks like.

Here’s a shock absorber and a housing with severe signs of rubbing.

• This reply was modified 3 years, 3 months ago by Mumbles.
• This reply was modified 3 years, 3 months ago by Mumbles.

[Author]

Posts