97 Mercruiser 5.7L Engine Knock

[Scott Danforth]

Interesting. Never seen a marine engine with timing marks on the balancer... But....


Chris....

Chris, VP did it for years with timing tape

 

[achris]

Chris, VP did it for years with timing tape

Timing tape, yes. But actually etched into the balancer like that????

Chris.......

 

[cody37]

Outside of verifying the 0 mark on the balancer aligns with TDC of the piston what else should I be looking at? All the lifters (rollers) are new and I just reset the valve lash to one turn in last night with it running using the procedure from the service manual. Is it possible to have noisy lifters just because it has not been broke in yet? It definitely isn’t rocker arms clattering. I also didn’t see any of the rocker studs sticking out any further than the others as if one of the studs were starting to back out.

 

[achris]

That noise wasn't a 'noisy' lifter. To me, that noise was REALLY late spark. Almost like the fuel charge was still firing as the exhaust valve opened. Did you install 'anti-pump up' lifters?

Chris.....

 

[cody37]

I’ll have to ask the builder about the lifters. I bought it as a long block and they were already installed and preset when I picked it up. I would assume they are standard roller lifters but you know what assuming gets you.

 

[cody37]

Is it possible I got the wrong cap and rotor? Or if the sensor or ignition module is going bad? I have a hard time believing that the lines in the balancer may night be right, but I guess crazier things happen. Here is the cap and rotor kit I got.

 

[Scott Danforth]

dont assume that the timing tape is correct. could be timing tape for a 6" balancer on an 8" balancer.

the timing marks on the balancer themselves do not align with the timing tape, so that is a red flag

verify.

take the balancer diameter, multiply by PI (3.14159), then divide by 36. that is the lenght of distance from the 0TDC mark to the 10 degree mark using a tape measure.

 

[greno]

That noise sounds like it might be "tin" noise. Crank hitting windage tray or oil pan. Rocker arm hitting part of something in the valve cover.

 

[cody37]

One of the corners of the oil baffle did get slightly bent when I set the old motor down, I did bend it back but did not think to rotate the crank to verify none of the counter weights on the crank touched it. That could be a possibility but wouldn’t you hear that at idle?

 

[greno]

I do hear it at idle in your video at the end. It's barely audible but there.
I've had these same type of "tin" issues in some of my own engine builds.
That's why it immediately came to mind.

 

[achris]

... I have a hard time believing that the lines in the balancer may night be right,....

The rubber between the pulley and the inner section gets old and breaks down. Then the rubber slips, and the relationship between the pulley marks and the inner section is changed... Making any timing you set referencing those marks, completely wrong. Check that the TDC mark on the pulley IS at the actual TDC position of the piston...

Rubber slippage is not uncommon....

Chris.......

 

[cody37]

Update, I was able to verify that the TDC line on the balancer matches that of the piston on the compression stroke. Took it to the lake and rechecked the base mode timing with it in the water idling at 650 rpm in forward gear, confirmed it was set to 10* BTDC. Cruised around a back bay and it would not go over 2500 rpm or get on plane. With someone else driving I manually advanced and retarded the timing by moving the distributor to see if it was indeed an ignition timing issue with no change to performance. It seems to be short of fuel while under load. Carb kit came in over the weekend so I will be rebuilding this week. When I got back I removed the fuel water separator and poured contents into a clear jar, no sign of water or debris, fuel pump is a new carter electric pump. I will also be pulling the motor this week to take off the oil pan and see if a crank counter weight is contacting the oil baffle. Any other ideas or things to check while I have it out?

 

[achris]

Didn't happen to be pointing the timing light at the timing marks while your friend was driving did you?

 

[cody37]

Yes I did at idle while in forward gear to reconfirm the base mode timeing was set correctly. I did not while under way to see what the total advance was.

 

[achris]

Yes I did at idle while in forward gear to reconfirm the base mode timeing was set correctly. I did not while under way to see what the total advance was.

Would have been nice. Never mind. Next time.

 

[cody37]

Was able to pull the motor tonight. Put it on the stand and took the oil pan off. Oil baffle is nice and tight, had a friend rotate the crank while I watched, nothing touches or contacts the baffle anywhere. Flipped the motor over and took off the intake, and inspected, everything is right there as well. Any ideas what else I should check?

 

[Lou C]

I would try using a mechanic's stethoscope against the valve covers, cyl heads etc with it at a slow idle so you can really hear. Sounds like its valve train related but hard to tell on video.This engine have the old style adjustable hydraulic lifters where you turn them one turn past zero lash...question..how did you determine zero lash? because if you are turning the pushrod rather than lifting it up and down, it is possible to get it wrong. I'd go back and re-check that and also look at the rocker arms and the tips of the pushrods for wear.

 

[cody37]

Thanks Lou. This is a new long block I got so all lifters, pushrods, etc are new. Initial valve lash adjustment was set by the shop prior to receiving it. I manually checked all the push rods prior to starting and all were tight with no up and down movement. Once I had the engine in I let it warm up to operating temperature and then followed the procedure in the service manual for adjustment with it running. Backing out each rocker arm nut until it began to clatter and then slowly turning it in until the clatter stopped to find zero lash. I then slowly turned the nut in a total of 1 turn pausing to allow the lifter to adjust every 1/4 turn. I will take each lifter, rod, and arm off tonight though to visually inspect.

 

[cody37]

Update, after pulling the motor and checking both top and bottom without finding anything. I purchased a piston stop tool as suggested by achris and was able to confirm the timing marks on the balancer were spot on. I began going trough the entire ignition and electrical system. I found that the Sierra cap and rotor kit I had gotten had the correct cap, but wrong rotor. In fact the new rotor was for a 6 cylinder. Typically when I replace parts I carefully study the new vs the old to make sure it’s a match, I guess I over looked this one. Sanded the old rotor up and finished putting it back together and it runs like a top now! I appreciate all the feedback and suggestions. Thanks guys!

 

[achris]

Thanks for the feedback, and glad it wasn't an expensive fix. Was the wrong rotor marked with the right part number, or was it just the wrong part number?

Chris......