1974 Chrysler 135 hp limping

[WinnerCougar74]

OK, yesterday the motor was running the best it ever did since I owned it. I had about a 15 minute run back to the dock and about 10 minutes is I heard a small pop and the engine slowed way down. It started up but I could only get it up to about 2000 rpms so we limped back to the dock. Today I pulled the plugs and they looked ok, checked the fuel pump diaphragm and it was ok, pulled the float bowls and caught the fuel in a container and almost identical amount in both, Then ran compression, #1-140, #2-140, #3-90 (ran it 3 times, all the same) #4-140. Hand turned the flywheel while holding a screw driver against each piston and all 4 pistons had zero play in the assembly. #3 seems normal. I have not looked inside the cylinder. My best guess so far is a blown head gasket.

 

[WinnerCougar74]

If you have any thoughts please chime in. Thx

 

[jerryjerry05]

Look at the post, explains the Starting Fluid Test.

#3 cyl is the port that runs the fuel pump. Inspect that.

 

[WinnerCougar74]

Both float bowls were full so seems like fuel is correct. Pump diaphragm was ok. It seems like the question is, what causes a difference on one cylinder by 50psi. Since the piston, bearings and crank seem tight what could it be, broken ring? cracked piston? or blown head gasket?

 

[WinnerCougar74]

Also, there seems to be conflicting opinions on the fuel pump causing low compression on the #3 cylinder. Does anyone know for sure?

 

[WinnerCougar74]

plugs pulled yesterday, from right to left 1-4, #1&2 insulator tip white, #3&4 insulator tip dark, what would cause the bottom two cylinders to run rich, would it have something to do with the fuel pump attached to the #3 intake cover?

 

[racerone]

Remove bypass cover for #3 and post pictures of piston rings / skirt.

 

[jerryjerry05]

If the pump was OK?? do what Racerone suggested.
Remove the cover and push on the rings and see if they are loose or stuck.

 

[WinnerCougar74]

The autopsy has begun. Here are some images of cylinder #3.

 

[racerone]

Pictures really do not make things clear to me.

 

[WinnerCougar74]

All are cylinder #3 on the exhaust side
#0021 right side of the picture is the piston wall, left side is head.
#0038 is the same area from a different angle.
#0040 is the same area
#0042 is another gouge
here is another picture showing both gouges #0035

So this doesn't look that bad?

 

[WinnerCougar74]

 

[WinnerCougar74]

Another picture showing some of the top of the piston and the 2 gouges

 

[racerone]

Simple.-----Motor has to come apart.-----Something let go inside the motor !

 

[WinnerCougar74]

Thank You, racerone, for your opinion. The pitted pistons have been like that since I got it, now #3 is a little worse, prolly a chunk broke off. It's not grenaded but definitely would have to be resleeved, new pistons, rings and a new head and on and on.

 

[WinnerCougar74]

I learned so much from you. Thx! Prolly moving on to a looper evinrude with an oil pump. I do a lot of trolling and would really like to only have one motor hanging off the back. Boat is a very nice 1974 Winner Cougar 19 ft fiberglass (pic in my profile). When the chrysler was running well it would push it to 38 mph. I'm thinking about a 1990's or 2000's Evinrude 70 hp with a trolling flap and selling the 9.9 trolling motor. The factory catalog for the Winner says the 70 hp will push the boat to 30 mph. I rarely go 30. I troll a lot and search for fish and bait a lot so tons of hours at low speeds. Top speed is not that big of a deal. What would you think of downsizing. The total number of people in the boat is 4 plus fishing gear.

 

[racerone]

Find a 1985 to 1998 V-4 Evinrude / Johnson crossflow for cheap.----Rebuild it with 4 new WISECO pistons and enjoy boating for 20 years.

 

[roscoe]

Find a 1985 to 1998 V-4 Evinrude / Johnson crossflow for cheap.----Rebuild it with 4 new WISECO pistons and enjoy boating for 20 years.

This makes more sense than a 70.

 

[WinnerCougar74]

Can a Evinrude crossflow idle all day without fouling plugs. I'm not going through that again.

 

[racerone]

They will idle all day long and the next day !!-----This concept of plugs fouling is not well understood in my opinion.-----I trolled with a 235 HP V-6 crossflow for hrs at a time.