View Full Version : Intermittent Ticking Noise

07-18-2006, 11:59 AM
My engine has started making a "ticking" noise. It only happens every now and then. I can crank it on the trailer and it sounds normal. Launch and run for a while and sounds normal. Run from one end of the lake and slow to idle, it will start making the ticking sound. Bring back up on plane, run a while, slow to idle and sounds normal. There doesn't seem to be a pattern to when it will do it.

Had motor rebuilt after the 2004 season and heads were supposedly reworked so it shouldn't be in the valvetrain.

Never did this until I replaced the fuel pump a couple of weeks ago. I had to change from the Indmar OEM pump to a PCM pump (because of availability issues) and also change to a PCM fuel line. The new fuel line lays really tight up against the side of the external resistor and also against the side of the distributor.

It's hard to tell where it's coming from. It's not coming from the transmission area. It doesn't seem to be up front near the water pumps. It's not really more pronounced on one side or the other. It's more like the front part of the engine under the intake manifold. I put the transmission in neutral and revved the engine a little and the ticking sped up. It's loud enough to be heard at idle with the motor box closed but not once up on plane with all the other noise. I haven't been able to look at it while it was happening enough to really be able to tell where it's coming from.

During all of this the boat runs like a champ.

Any suggestions on how to troubleshoot this? I don't want to haul it to the mechanic and then not be able to get it to happen where he can hear it.

07-18-2006, 01:25 PM
It could be an exhaust leak. That typically sounds like a tick and can come and go. I don't want you to chase your tail because if the fuel pump is what was replaced, that may be the issue, these are cam operated fuel pumps so there is linear motion. But the exhaust leak is a simple check before you go back to the mechanic. Make sure all the exhaust manifold bolts are tight, and you don't have to worry about torque specs, you will know if they are loose. Engine vibration can loosen them up and they would be pretty loose to cause a leak. Also check the valve cover bolts. Some of the bolt holes intersect with the egr cavities in the head and that can be a leak. Also check the egr plugs, they are the big plugs or bolts in the front and back of the heads, some of your front accesories may be using these holes for mounting. The egr holes are used when these heads are used in automotive applications and plugged or used for accesories on boats. On my boat, there are plugs in both heads on the back of the motor, the alternator is mounted in the front of the drivers (boat drivers side) side head, and the front of the passenger side head has a ground in it. Hope this helps.

07-18-2006, 02:27 PM
Thanks rcnjson. Any advice on how to tell if it's the fuel pump?

07-18-2006, 03:21 PM
Not that I can think of. The only thing that made me say fuel pump is that is what had changed. The mechanical fuel pumps have a follower that rides on an eccentric (or cam) which opperates the pump. If the pump is a little different, more specifically if that follower is not the same there would be a tick each time it came in contact with the eccentric. I know that there are 2 different styles of eccentrics for the 351, a 1 piece and a 2 piece. I am not sure if they have different base circles, but if they do, you would need a pump that is specific to that eccentric. I am pretty sure you have the one piece eccentric because of the age of the boat, the 2 piece eccentrics were no longer in use starting in the late 60's early 70's. Again, this is a possibility, not necessarily the answer.

07-18-2006, 03:28 PM
When you replaced the fuel line and it wound up close against the distributor and resistor and you may have a ignition short across to the resistor and distributor. Does the engine idle and run smooth or does it seem to have a slight miss.

07-18-2006, 04:52 PM
The engine runs great, even when it's "ticking". I looked for a change in performance but I couldn't tell that there was any.

The intermittent thing is what is so strange. Do you think my water pump bearings could be going bad and causing this?

07-18-2006, 05:43 PM
It seems extremely likely that the intermittent “ticking” is related to the recent fuel pump change.

When it is ticking, firmly put your hand on the new fuel line. Does the ticking go away? If so, it may be laying so tight against the resistor/distributor, that just the right vibration causes it to “tick” against whatever it is laying tight against.

Or maybe, your new fuel pump is just a little noisier than the old one, as rcnjson alluded to?

Just a couple of wild-arse guesses for you.

Good luck!

07-18-2006, 07:00 PM
Just a couple of wild-arse guesses for you.

Good luck!

Set a mouse trap in the bilge and if you catch one he may be wearing a Mickey Mouse watch, that may be doing the ticking!

07-18-2006, 10:53 PM
Shouldn't that be a Timex??

07-18-2006, 11:13 PM
Takes a lickin' and keeps on tickin'

07-19-2006, 06:56 AM
What I have done in the past, is to grab the longest breaker bar, pry-bar, screwdriver you have. Put one end touching the bone just in front of your ear, or firmly touching your ear & the other end touching whatever you think is causing the ticking. You'd be surprised how much louder it will get when you touch the right thing.

This also works when a bearing is going bad on one of your pully attachments (like Alternator, A/C, water pump, etc).

07-19-2006, 09:06 AM
I have a similar ticking sound (although a different motor) - at first I thought it was the exhaust manifold so a went 'round and tightened all the bolts a bit - didn't have an affect, now I'm thinking it's the raw water pump's bearing or something? I'll try the scewdriver/stethoscope trick and see if I can narrow it down...maybe alt. bearing? it's over on the port side up front...other than that, the motor runs great (uses oil but hey, she's 16 , sorry 17 years old)

07-19-2006, 09:44 AM
A farmer buddy of mine suggested using a length of garden hose as a "stethoscope". It's worth a try.

Thanks for the input fellas. Keep it coming!

07-19-2006, 09:51 AM
Or, a wooden dowel rod, broom handle, paint handle, cover pole, yardstick, small pvc pipe, small electrical condiut, boat paddle, boat hook, etc.

07-19-2006, 10:20 AM
A farmer buddy of mine suggested using a length of garden hose as a "stethoscope". It's worth a try.

Thanks for the input fellas. Keep it coming!

I found an exhaust leak by using this method.
My SUV had a ticking noise that only occurred at start-up. I cut a section of garden hose and found a bad gasket where the header attached to the down pipe.
I think it goes without saying but just be careful with the garden hose, or anything, around the running engine.:eek3:

07-20-2006, 11:11 AM
Could be a variety obviously from the responses your thread has received. An old mechanics trick to track ticks down is to put a long std. screwdriver against the suspect source and your ear against the handle and the process will amplify the tick like a stethoscope...if you're on the source. Caution must be taken not to come not to contact with moving parts, and watch out for loose clothing. I would start on the valve cover, as the most common source of ticks is a small piece of dirt in the oil that is plugging a hole in the hydraulic lifter and not allowing it to expand to close the pushrod gap, and hence the tick. These come and go as the piece gets dislodged and and trapped in your filter until it happens again. If the tick is confirmed from the valve cover, and the engine has just been rebuilt, I would suspect dirt in the oil. I would use a detergent additive (any auto parts store) and follow the directions for an oil change.

If the tick is from the fuel pump then something is wrong. The isn't any parts in a fuel pump that tick, so it would have to mean that the cam follower has a gap between cam and fuel pump arm. If the screwdriver confirms fuel pump, I would take it off and check the followerer and ask the parts store for another fuel pump.

Intermittent exhaust leaks usually pattern themselves with engine temp and go away when the engine is hot and are present when cold. That should be easy to sleuth out. Most exhaust leaks are not intermittent, and can be found with searching with fingers for a puff of air (when engine is running, but cold).

Last but not least is a bearing on rotating accessories, alternator for instance. They usually squeak, but occassionally will make noise intermittently when they are over loaded (belt too tight) or starting to wear.

good luck, let us know what you find.

Good luck.

07-20-2006, 04:40 PM
Thanks cwright.

Would a gap between the cam and the fuel pump arm produce a tick that comes and goes or would it be constant?

Also, is there anything in the carb that would open and close and produce a tick?

Gonna take the family to the beach next week so it'll be a couple weeks before I can put any of this good advice to work.

I'll post an update when I know more.

07-20-2006, 08:31 PM
I don't think the fuel pump cam follower would be intermittent. Did you get my email about the fuel line against your distributor?

07-21-2006, 09:56 AM
I don't think the fuel pump cam follower would be intermittent. Did you get my email about the fuel line against your distributor?

Just checked my e-mail and didn't see it. The address listed in my profile is correct. Not sure what happened. Maybe try PM? Thanks.