Mercruiser 5.7L Cranks but no signs of life

[MAW31]

This is somewhat of a doozy. I decided to start a new thread since the old one had moved from discovery to handled.
However, this is more like a continuation because so much has been altered.

Background: 1995 5.7L. Fairly recent purchase. For 5 months used often, now on lift in florida. Discovered hydroLock situation. Tore motor down, replaced exhaust manifold/risers, pulled intake manifold and heads. Rebuilt Carter 4BBL, reassembled motor. Thunderbolt IV ignition. Set timing to 8 deg BTDC. cranked motor over w/o plugs to get oil distributed. put plugs in, motor fired and idled, albeit roughly and with a lot of valve tapping. let motor idle for 10 min. at min rpm. checked timing, still at 8btdc. so far, very happy.

After another 10 min of idling, port side still tapping with some very noisy ones. Method used to set valve lash: at compression stroke TDC, set 8 valves. turn rod by hand while tightenning rocker nut. when could not turn rod by fingers anymore, added 3/4 additional turn. then rotate crank 1 full rotation and set other 8 valves ( 4 intake, 4 exhaust) per clymer mercruiser shop manual.

thought i could quiet the tapping by adding 1/2 turn to all rocker nuts, so pulled valve cover and did just that.

and here is where I am stumped. afterwards, motor has never fired again.
Could that little adjustment on only the port side be causal to not running at all? I"m more inclined to believe something else is afoot.

motor cranks well, 2 new healthy batteries(on a tender), timing light on #1 wire shows pulse when cranking. carb jets are working. and yet, there is not even the remotest inkling of a firing. been at it all day.

Summary: has gas, has spark, good batts, was idling earlier, timing light shows triggering, (new plugs)...and dead to the world.

By The Way...: mechanical oil guage showed good oil pressure, and water flowing fine at idle check, also engine needed very little cranking to jump to life earlier.

I am stumped.

Out of daylight for today, will test port side compression tomorrow.

 

[tpenfield]

Take them back out 1/2 turn. Also, when you are getting zero lash on the initial tightening, it should be so that the push rod can no longer wiggle up and down. That may be different than the rod no longer being able to turn.

I suspect you over tightened the rocker arms and the valves are not closing.

 

[Scott Danforth]

^+1

your too tight on lash.

 

[MAW31]

Ok. Do I still add 1/2 turn after removing up/down wiggle?

 

[harleyman1975]

I have always set lifters with engine running...but I am old school.

 

[MAW31]

update: reset all the valves using the method described by tpenfield. motor jumped to life. set timing at 8 degrees btdc.
running super rough though.
thought maybe some plugs aren't firing. so pulled #1 plug and motor slowed. (at idle). pulled #2 and nothing at all changed. What I did notice however was when I pulled the #2 plug from the distributor, i could see that at the coil, it was arcing to ground. replaced #2 wire and arcing stopped.
I now have the coil off and am cleaning surfaces.

Is there any good way to test spark plug wires? Mine are mercruiser originals, with no cracks and visually seem ok. I've seen youtube vids where peeps are using an ohm tester but gotta say... there's a lot of chucklenuts out there that really have no clue.

After cleaning surfaces am headed back to boat to see what i can see.

 

[alldodge]

Being a 95 it might could use some wires, but hey my p5 Rinker stull has the same wires. Looks are deceiving, fire the motor up at night in the dark and see if you see any arching.

With the tapping to continue I'm thinking you need new lifters or they need new seals

 

[MAW31]

Cleaned up coil neck and center wire. Here is a video i made of the motor running. Its noisy and cannot increase rpm without lots of noise.
what seems wrong? I have fully rewired 4 times now, thinking i may have a wire reversed. i used a dremel buffer to clean contacts inside distributor cap, and rotor contact. plugs r new. is it possible to have the timing 180 deg out and still run? I dont think so.

 

[alldodge]

I suggest start again with checking firing order

 

[MAW31]

The order of the wires I'm using is identical. However...immediately i see a difference. My #1 wire is where the 3 is in this diagram.
My distributor cap has a tang on it that only allows it to seat such that the stamped wire position 1 mark on the cap is where the 3 is here.
I think you've clearly identified my error! The solution is to ignore the stamped order on the cap and use this image to set the order AND position.
Thank you AllDodge: Will keep you posted. *smiling*

 

[alldodge]

The orientation of where number 1 is, does not matter, it just needs to be when 1 is at TDC. Then follow the firing order clockwise as it comes around the cap

 

[tpenfield]

you should be able to get the distributor positioned close to what is shown in the diagram. Perhaps the distributor is installed out of position to begin with.

​More importantly . . .

​When the #1 cylinder is at TDC on the compression stroke, the rotor should be pointing (or nearly so) to the #1 plug position on the distributor cap, and the wires should be connected to the cap and their respective spark plugs according to the diagram.

you will need to reset your timing once this is all sorted out.

 

[MAW31]

so I set TDC so rotor pointed toward #1 spark plug, then used the diagram AllDodge provided to set the wires at the distributor. motor started and idled. much better than before, i might add. set timing to 8deg BTDC. took video. you can see that when I attempt to rev motor even a little, i get a lot of popping back out of the carburetor. (important to note that i had purchased and installed a rebuild kit on the carb while I was doing the heads/intake.)

I am about to return to boat and check all cylinders' compression. (thinking i may still have over tightened lash, although I used the technique described by tpenfield).

what is probable cause of the popping i'm experiencing on the video?

 

[alldodge]

That sounds like a rod knocking to me, didn't hear a back fire

 

[tpenfield]

That is bad . . .

Check the procedures in the Mercruiser manual or on the Internet. I am wondering if you are adjusting each valve when its lifter is on the lower part of the cam lobe. You can do this according to the procedure outlined in the Mercruiser manual, which is what I followed when I rebuilt my engine, or you can adjust each cylinder's valves when it is at TDC of the compression stroke.

I don't think you have the valves adjusted consistently, but have improved it enough to start the engine. Probably still some valves are over tightened.

Setting the lash should be pretty much a slam-dunk.

 

[alldodge]

In the first vid I heard the same knock but was chalking it up to lifters and not paying that close attention. The second vid has the same noise

This motor was hydrolocked and the statement was tore the motor down. My assumption was it was tore all the way down and got new bearings (crank, cam, rods). If the lower end was not torn down then you have a rod knocking and possibly a bent rod

 

[tpenfield]

In the first vid I heard the same knock but was chalking it up to lifters and not paying that close attention. The second vid has the same noise

This motor was hydrolocked and the statement was tore the motor down. My assumption was it was tore all the way down and got new bearings (crank, cam, rods). If the lower end was not torn down then you have a rod knocking and possibly a bent rod

Yes, I was thinking the same thing - the lower end was re-done or at least inspected and verified OK. Perhaps the thing to do is get the valve adjustment sorted out and then run a compression test. A bent rod should reveal itself as much lower compression than the norm.

To the OP MAW31 - what is known about the condition of the lower end of the engine after the hydro-lock. Did all pistons go to the top of the deck when the engine was rotated? Was the crankshaft and connecting rods given a visual inspection?

 

[Mad Props]

I'm thinking if it was a spun bearing it would still rev up ok... leads me to believe its a valve train issue... what was your procedure to get to tdc on number 1 cylinder? It sounds like your bouncing valves off pistons...

That brings up another thing.. if it were me, I'd pop off the timing cover and make sure your cam is aligned correctly to the crank...

 

[MAW31]

on the valve lash procedure, i went to compression stroke TDC, and set 8 valves (per the clymer shop manual). loosend the nut until there was movement between rocker and rod. tightenned until no up/down rod movement and added 1/4 turn. then rotated crank 1 turn to 180deg out and set lash on other 8 valves.
I took note of the number of threads that were showing above the nut and once adjusted, there were barely 2-3 thread turns showing.

 

[QBhoy]

Second video I would say you defo aren't running on all cylinders. First one was better.
Defo sounds like a top end noise. I'd be looking at the rocker gear/valve set up again.