Noise from new 5.7 L

[kingrich]

Recently installed a new 1998 GM crate 5.7 L vortec engine in boat. Old 1997 5.7 L had 2 barrel, 12 bolt manifold(non vortec) so I went with edelbrock air gap manifold with a 600cfm edelbrock marine carb. Replaced oil pan with marine one(1 quart more capacity than stock). Pulled stock hydraulic roller cam and lifters and replaced with old marine hyd. roller cam and lifters-had to machine vortec heads for the increased lift to allow for new comp cam springs and also for clearance between top of valve guide and inside of retainer.Installed motor without alignment as the motor mount adjusters were not moved and the two rear supports only bolt in one way(1997 alpha 1 mercruiser)?<br /><br />Proceeded with breakin procedure, after 5 hours and on the 3000 rpm and occasionally rampup to 4000 for a few minutes or less I noticed a ticking/tapping noise coming from what appears to be back of compartment just behind engine. Noise increases with RPM(not louder just in sync with engine speed). Tryed a wooden dowel to locate noise but does not seem to be coming from either the side or bottom of engine. Pulled covers and adjusted valves anyways(appeared to be normal). Took boat out and noise was still there-noise dissapears when rpm is left at idle or slightly above ie.1200 RPM and under load,in gear. Not sure whats up. Next day took mechanic out for ride 1.5 hours cruising(breakin) and no noise what so ever? Next day noticed that I had timing at 8 deg ATDC rather then BTDC, adjusted and made one adjustment on carb linkage. Boat goes like a rocket compared to old 2 barrel non vortec- but noise was back again. Noise almost appears to dissapear at higher RPMS but hard to tell as engine compartment is off. Does not appear to have any effect when steering side to side or trimming up. Any ideas would be appreciated. Sorry to go on about the engine but after attending these forums when deciding to use a crate-non marine engine I found quite a bit of controversy and decided to post on progress of this conversion.<br /><br />Kingrich

 

[Scaaty]

Re: Noise from new 5.7 L

Could be a hydraulic lifter...?

 

[Dunaruna]

Re: Noise from new 5.7 L

At idle, pull one plug lead at a time. Listen for the noise to disappear. If it does, you can isolate it to a cylinder. If it doesn't, maybe the coupler?

 

[kingrich]

Re: Noise from new 5.7 L

I thought of a hydraulic lifter but not sure how to find it. The only problem is after acceleration in gear that the noise starts and when at idle or slightly above it quits-have to keep the rpm's up and in gear to hear it although it will still make the noise for a a minute when in in neutral. Will the coupler make a ticking noise-almost sound like a exhaust leak-but can not see one. Not sure if the flappers will make noise like this.

 

[Yepblaze]

Re: Noise from new 5.7 L

Grab the old siphon hose and stick one end to your ear whilst you probe for the sound with the other. It could be an exhaust leak.

 

[rbezdon]

Re: Noise from new 5.7 L

If it is exhaust it will be much louder on hard acceleration. If you get on it hard in a straight line, is the noise louder?? Same thing for a loose spark plug. Sometimes they aren't tightened all the way or loosen for the theraml cycling. This will give a ticking sound like an exhaust leak as well.

 

[Reel Poor]

Re: Noise from new 5.7 L

Exhaust flappers??????

 

[LubeDude]

Re: Noise from new 5.7 L

Originally posted by kingrich:<br /> so I went with edelbrock air gap manifold with a 600cfm edelbrock marine carb.

This may cost you a bit more fuel in the long run as the intake cant warm the Carb like it should. But if its HP you are looking for, cold fuel and carb = more HP.

 

[Scaaty]

Re: Noise from new 5.7 L

If its a sharp "crack", it might be a spark plug wire/boot shooting a spark to ground under load. New set of wires, or at least 4 to do a side (or even one or two and keep changing around will let ya know

 

[kingrich]

Re: Noise from new 5.7 L

Thanks for the replys. I will not be able to get to lake until Friday-bought stethoscope. When accelerating the noise does not get louder so much but does increase in repetition like a lifter but quieter. Last time out it even appeared to quiet down or dissapear on acceleration- but with it not doing it at all the one day out- is puzzling. It is not a sharp cracking noise like ignition wires going to ground. Is there anything behind like coupler that could make noise like this. The flywheel was in good shape and I did ensure that it was torqued down. The flappers should stay wide open on hard acceleration which is why I did not think it would be those. Will check everything on weekend with stethoscope but did use a hose last time out to no avail.

 

[rbezdon]

Re: Noise from new 5.7 L

U joints behind the coupler and they can make some "ticking" sounds when they are going south. Usually the sounds get somewhat louder when turning hard or running close to full tilt. Here sometimes the sounds can be less under acceleration due to load locking the ujoint in place and louder when not under load and if the ujoint is loose at all it can move around a bit while turning. Might be time to pull the drive and check them and do some PM on them and the gimball at the same time. Whens the last time the drive train was PMed??

 

[kingrich]

Re: Noise from new 5.7 L

The noises do not change with trimming up/down or when turning hard either way. The alpha 1 has not been PMed as long as I have owned it - 5years and boat is 8 years old. Was planning on doing impellor and u-joints this winter(fresh water boat). Did notice u-joint noise-minimal last season when trimmed up and turning but not associated with noise there now.

 

[kingrich]

Re: Noise from new 5.7 L

Finally got boat out yesterday. Stethoscope shows sound clicking/knocking coming from bellhousing area. The coupler is the triangular shaped plate with three bolts to flywheel(three rubber pads between flywheel and coupler plate).When I installed the flywheel and coupler I torqued to Man. specs and the rubber pads were in place. Can the coupler make a lifter type noise.Noise has went from intermittent to all the time.