Update on the 165hp 6 cyl. InLine tapping noise

[Skipster1]

All new lifters, pushrods, and spark plugs. Lifters adjusted using "dry" (motor not running) method. Compression check (with new gauge) indicates 130psi on cylinder #1, the rest are 140psi or a tad better. 130psi doesn't trouble me except that is where the noise SEEMS to be coming from.<br />The noise is still there.... up front and on top and a tad noisier!!!<br />I poked a magnet into each cylinder in hopes of finding some loose metal that might be causing the noise. No luck.<br />I tried to set timing with an induction light...thought it should be set at TDC or +/- 4 degrees but the engine ran much smoother and cooler at about +12-15 degrees???????? In fact when I advance the distributor up to about +15 degrees the engine pics up RPMs like mad????<br />What is the correct setting for timing on this bugger? And, does the fact that it runs better at a high setting give a clue as to the noise problem???<br />Keep in mind that this engine starts and runs beautifully and the noise has been going on for a long time....yet the engine keeps on running good?<br />And... for those of you that think this is a valve problem... I ask the same question: "How could it be a messed up valve and still run so smooth and strong?????????????"<br />Could this simply be a huge buildup of carbon???<br />Thanks y'all.... sorry to be such a pest but I want that noise outta there before I venture out into the Gulf of Mexico!!!!!!!

 

[sculbert]

Re: Update on the 165hp 6 cyl. InLine tapping noise

Your timming should be running at around 4 to 6 degrees at 700 rpm. It is normal for a system to pick up rpm as you advance the timming. The system has a centrifical advance that as your engine rpm increases it will advance the timming for you if it is working. the secondary advance would be vacum advance. I haven't seen many boats use that. You can set your advance to the optimum advance by using a vacum gage also. the process for this is to advance the timming till you just reach peak vacum then back the advance off till you drop 1.5 inches of vacum from peak. This should be the engines best operatiing range. Provides your cetrifical advance is right. The knocking you hear could be carbon. You can clear that up by use a water sray from a spray bottle and run the engine at medium rpm and spray water in the intake. "Down the throat of the carb." This is an old mechanics trick to remove carbon from engines. FYI I also have a 165hp I just installed in place of a 120hp. I can't wait to get it on the water. Almost ready!

 

[achris]

Re: Update on the 165hp 6 cyl. InLine tapping noise

When you replaced the pushrods and lifters, did you completely remove the rockers? If so, did you keep them in order and replace them on to the stud each was removed from? And did you check the rocker faces for wear?<br /><br />Just my 2c worth.<br /><br />Chris...........

 

[Skipster1]

Re: Update on the 165hp 6 cyl. InLine tapping noise

Yes... to all your questions.<br />But the noise was going on before I made all the changes. The %(&$## noise IS the reason for the new lifters, pushrods, etc... and it's still there.

 

[achris]

Re: Update on the 165hp 6 cyl. InLine tapping noise

Skiph,<br /><br />Just remembered something. Does the noise increase or decrease as the engine warms up? I had a 165 in my boat till about 10 years ago, changed to a 4.3 V6. I seem to remember a noise in mine too, now that I think about it. Turned out to be a piston pin, connecting rod small end. I think it was ok dead cold but got a bit worse as the engine warmed up. Took about a minute or two to start this light tapping noise. Nothing serious, but just, noticable. yeah. Sorry I didn't remember it earlier. Appearently it's not uncommon on those engines.<br /><br />Chris..........

 

[Skipster1]

Re: Update on the 165hp 6 cyl. InLine tapping noise

Hey Chris, thanks.... just the opposite occurs. It starts out loud and tends to get softer and come and go as the engine warms up.<br />Whew.....<br />And the noise definitely is coming from on top of the engine, near #1 or #2 piston.<br />Skip

 

[FreeBeeTony]

Re: Update on the 165hp 6 cyl. InLine tapping noise

Make sure its not the circulating pump. I have heard of these pumps going and actually rubbing on the #1 cylinder wall. It also sounds to me like you may be too far advanced. You can't time an engine by ear.....I tried the vacum gauge method on my IL6 and didn't find it too accurate. Stick with the timing light.

 

[sculbert]

Re: Update on the 165hp 6 cyl. InLine tapping noise

I tis [probably just like mine. I just installed a used 165 in my boat. I cranked it up yesterday and it was clacking for a short bit till it warmed up. The n it dissapeared. This noise is fomr one of the rockers not being fully adjusted and the lifter not pumping up real quick. You have a choice or two. if it isn't too bad and disapears after a short bit when the engine starts to warm up don't worry a bout it. The next option is to listen to it with a stepthascope and quess which cylinder it is and then readjust it the way by feeling the push rod for play and then tightning it 3/4 turns on the adjuster. I remeber on a post earlier to you one person said to tighen them 1/2 turn. that isn't correct. I double checked my mercruiser service manual and it says 3/4 turns. I just have one push rod claking just a little when cold. I am probably gogin to take my cover off and adjust it with the engine running and then cleaning up the engine afterwards. I think that is the only real good way to get one adjusted right.

 

[Skipster1]

Re: Update on the 165hp 6 cyl. InLine tapping noise

Good notions.....many thanks to both of you.<br />When I adjust it running, I just put a towel over the whole train and lift up the portion I'm working on. It works...????

 

[sculbert]

Re: Update on the 165hp 6 cyl. InLine tapping noise

Great idea. I will try that. I have automobile clips that go on the rocker arm and keep the oil from squirting out. the tool would help some also. since I only have one clacking right now it will be pretty quick to ge tthe last one right. If that is your problem also it won't take long for you to get it right either. rember to tighten till it stops and then turn another 3/4.