What The @#$% Now?

[steiner]

Long story but I will give background and things I have done;

So went on a small trip last week. Trails were not setup as it was warm (6c or 20f). Sled seemed to use more fuel than usual. Fuel light came on at 70 miles which is odd usually comes on around 90+ miles. During the ride noticed an odd exhaust sound. Sounded like exhaust donuts but I run the copper ones so probably I broke the exhaust collector pipe , again. Tore it down. Found the 2 exhausts gasket at the rear of the headers were toast and also one flex pipe was broken. Repaired all the exhaust. Fired it up and all sounded good. Did the rag test long enough to almost stall the motor. Maybe this was the cause of the higher than normal fuel usage?
After all that I then noticed coolant at the rear of the sled. Turns out the rear exchanger had been rubbed thru by the tunnel protector. Sourced a good used one and installed it. Leak fixed.
While everything was apart I checked the plugs. Took #1 and #2 out. They looked good so back in they went and did not bother looking at #3 and#4.
Got everything put back together and fire up the sled again. It won't fire up instantly like usual. Try again and it stumbles to life but there is a loud sharp knocking sound present. Sounds like a collapsed lifter on a 350 Chevy. I hit the kill switch. Check if there is oil in the tank. Yup, full as I did an oil change just before the ride last week. Look to see if I can spot anything at of the norm. All looks good. Out comes the stethoscope. Fired it up again. It has a hard time starting but does eventually stay running. Can't pinpoint the issue. Remove the primary clutch as that is rattling like a sob. Start it gain and noise is still there. Check around with the steth and the noise goes away.
Now I am super paranoid. What was that noise?? Install the primary and fire it up. Now the primary rattles like my old Vector did. Pull the sparkplugs. 1, 2 and 4 are black sooted and 3 is clean. Change plugs. Same result. Clean plugs and swap coil 3 for coil 1. Still runs and idles the same. Ohm out all the coils. All read the same. Fire it up again and unplug each coil one at a time. This is the result.
Unplug cyl #1 = Dies instantly
Unplug cyl#2 = Dies instantly
Unplug cyl #3 = No change noticeable change in rpm but dies in 6 seconds.
Unplug cyl #4 = No change noticeable change in rpm but dies in 6 seconds.

All ground blocks have been removed, wires soldered and sealed. No visible rub thru's in the harness.
Gas is fresh. Battery has excellent voltage and is kept on a battery maintainer in the off season.
As of now it will start and idle. Sounds like a Vector. It will rev up and sound like a normal Apex.
Idles like crap and does not respond to changing the idle speed setting.
What am I missing????

 

[Redbeard]

Have you looked inside the airbox for blockage?

May also want to do a compression test to rule out a bigger issue, which I hope isn't the case for you.

 

[steiner]

Was going to do a compression test but my automotive tester does not have a small enough adaptor.
The sharp ticking sound that it had at first is still a large concern.
I had the opened the airbox to check for oil accumulation, which was minimal.

 

[steiner]

This is really pissing me off as I listen to sleds ripping down the trail 200 yards from my house.

 

[74Nitro]

How low was the coolant?

 

[steiner]

How low was the coolant?

Coolant tank was about a 1/4 full.

 

[sideshowBob]

As you know...Apex engines don't tick or knock unless something is stuck or broken. I think a compression test will be necessary for diagnosis...hopefully its good but sounds like a valve issue to me.
But maybe, if you are lucky, its just real crappy fuel causing rough running and noise from misfiring ect.

 

[steiner]

Played for an hour trying to build a rig to test the compression. Got frustrated and just plugged each hole with a coil. Cyl #1, #2 and #4 shot the coil pack up. Cyl#3 didn't move it at all.

 

[steiner]

Anyone have a You tube vid on removing the valve cover?

 

[CaptCaper]

I'd drain the fuel completely just to be sure and re do with fuel from another source. This happened to me with my 22 hp lawn tractor. Bad fuel out there in so many places.

 

[74Nitro]

I'd drain the fuel completely just to be sure and re do with fuel from another source. This happened to me with my 22 hp lawn tractor. Bad fuel out there in so many places.

If number three has no compression, I think we can rule out fuel.

 

[kinger]

wow i was going to say check the wiring on #3 but that compression test is interesting. It may have dropped a valve. Mine did that once. Valve cover should be a easy removal. Good luck !

 

[steiner]

I removed the valve cover. Blew compressed air into #3 and it came out of #4. Blew air into #4 and it came out of #3. So now the head is coming off. Must be the Head gasket.
Anyone have any pro tips that are not mentioned in the manual?

 

[steiner]

Ok. Was hoping it was the head gasket because of the way the air was blowing from one to the other cyl but.... no.
This is what I found.

 

[74Nitro]

Rod bearing fail