Whatdayathink???

[jchagnard]

Engine Model: 1995 Mercury 135XL

Problem: Low oil warning - Engine will run fine for about 5-10 min. then the warning starts. Engine will only idle because control unit cuts fire to #4 &#6 cylinders. Have repeated this whether on the lake or in the driveway with water muffs on several times.

Checks performed: Pulled oil pump inspected gear on shaft and teflon worm gear inside block with a flashlight while turning the flywheel by hand - all OK( no black shavings, no corrosion, no pitting, etc.) Magnet on oil pump coupler is in place and OK. Oil tank under cowl full to the point of overflowing - OK. While engine is running; getting ~1-2volts DC (pulsing) across the blue and blue/wht lead coming off of the pump shaft sensor - I assusme this is OK. Connected a remote fuel tank 50:1 to the engine to test(3 min. @ 1500rpm) oil pump output; results 5-7.5 cc's of oil - I also assume this is within range.

Question: Would it be safe to say I narrowed it down to either the pump shaft sensor, the oil warning control unit, or both? I'm leaning towards the black box for the oil warning control.

Any input would be greatly appreciated. Thanks

 

[jchagnard]

Re: Whatdayathink???

FYI this is a complete diagnosis of the problem. Maybe it will be of help to others. Tried all that I could as a shady tree mechanic, then turned it over to the pros.

1. Bad power pack. It wasn't showing up until the motor was at normal operating temperature. That's when 3 of the cylinders lost fire.

2. Oil inj. worm gear was starting to go out. When I examined the oil pump shaft I did not find any plastic shavings. Which led me not to suspect it. The shop mechanic told me the worm gear was slipping at times. He diagnosed this by inserting the pump shaft into the block, but do not bolt on the oil pump. Let the engine idle and watch the key on the end of the shaft turn slowly. By applying slight pressure to the exposed end of the shaft with the end of a pen, the worm gear would slip on the pump shaft. So at speed, under a load, it was probably slipping more. Which meant it was only a matter of time before it stripped completely.

3. Carbs needed sync, cleaning, and adj the floats.

Motor runs like a champ now. I surely will miss my oil injection.
Regards