97 Mercruiser 5.7L Engine Knock

[cody37]

Hey guys, I bought a 97 Sea Ray with a 5.7L Mercruiser a few weeks ago as a project. Previous owner did not winterize the boat and cracked the block and one of the heads so I bought a long block to replace the motor. Previous motor had a serial number of K193942. Finished reassembling the new motor last weekend and was able to drop it in the boat. After finishing all the hookups i was able to fire it up and set the base timing to 10* BTDC and rechecked the initial carb settings so that it idles at 650 rpm. Ignition is a TB 5 without the knock sensor. It seems to idle a little rough and seems to have a few misses, I plan on rebuilding the carb. Upon acceleration I start to hear some knocking and it continues to get worse the faster it goes. I figured some lifters prolly needed to be adjusted so I was able to adjust them all to 1 turn past zero lash per the procedure in the service manual. This motor is an 87-95 roller btw with an 808 block and non Gen+ heads. I then put the covers back on and tried accelerating again, but am still getting the same noise. I have tried moving the distributor a little to see if that helped in case the timing was advanced too far which did not help. All the spark plugs are new delcos and were gapped to .035", cap and rotor have also both been replaced. I tried pulling one plug at a time to see if i could identify a cylinder and could not. I have also checked the compression and verified there is not any water getting into any of the cylinders in case there was an internal crack in the manifolds I couldn't see. All cylinders were right around 160. This motor has obviously not been broken in yet and I am afraid to take it out on the lake with it sounding like this to do so. This is my first experience with a long block so i am unsure of what it should sound like before it is broken in. I have posted a link below to a video i just shot to give you guys a better idea of what it sounds like. I'm hoping i don't have to pull it again and take it back. Any and all ideas/help is greatly appreciated! Thanks!

https://www.dropbox.com/s/6mf9z07ydd2feeb/IMG_2785.MOV?dl=0

 

[Bt Doctur]

Dont hear any loud knocking but you fried the impeller .
You are doing everything you can to blow up the new motor, so STOP.
Recheck the lifters for the correct lash, Rotate the motor until a intake valve opens and closes, adjust that cylinder, then move on to the next.
Max rpm on land is limited to your hose pressure and in most cases the rpm must not exceed 1500 or impeller damage will result.
Recheck timing at TDC #1 Compression and verify TDC with a piston stop tool or make one.Set timing to 8 BTDC

 

[cody37]

I didn't know max rpm on the hose was 1500, i have heard that others with a different setup will suck a hose flat, but that is not the case with my setup. Do you really think i fried the impeller? I was curious about the timing, the flame arrestor states 10*, but the service manual states 8*. I did notice that the 10* mark on the dampener is painted white.

 

[Bt Doctur]

the line on the harmonic balancer designates 0 TDC , you adjust this mark/line to the 8 deg notch on the indicator plate

 

[Bt Doctur]

 

[Bt Doctur]

 

[cody37]

Yes, I was just confused as to what the correct timing was 8 or 10. Here is a picture of mine. It has the plastic timing chain cover so there is just a notch (not in picture as I had put my tools away). As you can see the 10* line has been painted which matches the description on the flame arrestor cover. Maybe I'm just picky, you could hear the knock in the video?

 

[achris]

Are you using an 'advance' timing light? That or timing tape are the only ways to get the timing accurate... Someone's guess at where 10° (or 8°) are is just that, a guess.

Errr, no picture....

 

[cody37]

Yes I am using a timing light with the lead on #1 plug wire.

 

[Bt Doctur]

Did you put it in base timing mode?

 

[cody37]

Yep, purple/white wire grounded with a lead prior to turning the ignition on.

 

[achris]

Yes I am using a timing light with the lead on #1 plug wire.

No, an 'advance' timing light allows you to select the advance ('dial in'... Hate that expression)... Then you adjust the distributor until the line on the balancer and the notch on the timing chain cover line up...

Chris......

 

[cody37]

My timing light is just a normal inductive light. With the motor idling at 650 rpm, in base timing mode, i currently have the distributor adjusted so that the 10* line on the balancer is in line with the notch in my timing cover. Do you think the noise is due to incorrect ignition timing? If so what have I missed?

 

[achris]

Unless someone has put timing tape on the balancer, that line is the TDC line, not the timing (10°) line... Can you post a photo of the balancer line and the notch on the timing chain cover?

Chris.........

 

[achris]

Here's a photo of the front of my engine. Both those marks are TDC marks...



You then use an advance timing light, with 10° (or 8°) selected as the advance, and adjust the distributor until the line and the notch match up... Then you have 10° (or 8°) advance...

One of these puppies...


Or....



Or even a fully digital one....





Chris........

 

[cody37]

The light I have is just a basic one. Here is how i currently have it timed. 10* line is lined up with the notch when the timing light pulses.

 

[achris]

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

Ok, you may need to verify that the TDC mark is actually TDC. Pull #1 plug and turn the engine slowly until the piston reaches the top. Then look where the marks are. (The sounds in your video are like the timing is seriously out)

Chris....

 

[cody37]

Thanks Chris. I am on my way down to Houston to pick up a truck with a buddy. I will check that when I get back. I did verify I was on the compression stroke using a compression gauge when I set the timing but did not physically verify the piston was at TDC and matched the marks on the balancer. Like I said I have tried turning the distributor a few degrees when it was making the noise to see if that helppes in case it was too far advanced, but that didn’t seem to help.

 

[cody37]

When I pulled the plugs to check the compression and verify there wasn’t water getting in via cracked manifolds I did notice one bank was running richer than the other, I plan on rebuilding the carb, but when listening to the exhaust I can hear a miss and some light back firing when accelerating.

 

[Scott Danforth]

the other alternative that Chris mentioned is timing tape

which is what you appear to have