Lifter replacement all or one??

[SHickey]

Hello again,

In my quest to constantly improve the "old girl" 1976 straight six Mercrusier 165 HP MC-1, I have been trying to track down a ticking sound in the back of the motor. My mechanic neighbor and I have come to the conclusion one of the lifters is bad and that I can probably get rid of the tick if I replace it.

My questions are #1 How do lifters go bad in the first place? Oil starvation or just regular wear. #2 Can I replace the lifters through the access cover on the Lt side of the motor without too much trouble? #3 Since I need to replace one bad lifter, should I get a set and replace all of them or should I leave the other lifters alone and concentrate on the failed one??

Thanks again for your input!!

 

[Bondo]

Ayuh,.... Have ya tried adjustin' the loose one,..??

Cams, 'n lifters wear together,....

I wouldn't replace just one lifter, 'n if ya replace the whole set, you could wipe out the cam,...

 

[SHickey]

Yes,
I have tried adjusting the valve riser nuts a number of times and I keep getting this light persistent tick in the back of the motor. My mechanic buddy told me this ticking situation can go on forever if I do nothing due to the age of the motor. I am not a perfectionist, but I would like to extend the life of my motor for as long as I can and if I can prevent valve and pushrod damage, I would be willing to replace the lifters if need be. Or should I just leave well enough alone considering I have heard this tick for the last 4 years I have owned the boat.

Can anyone tell me why a set of new lifters would damage the cam?? Sorry if it is a stupid question.

 

[GA_Boater]

Over time the cam and lifters establish a wear pattern. If you change to a new lifter, the wear on the cam can be accelerated, wiping out the cam lobe.

The reason for this is the lifters and push rods rotate and sometimes a new lifter won't rotate on an old cam because the wear patterns has been disrupted.

Are you absolutely sure the tick is caused by a lifter? Ticks are caused by other things as well.

 

[SHickey]

Thanks for responding.

Nothing is 100% about this motor or it's diagnosis but my mechanic buddy and I were able to determine the tick was coming from one of the risers on the last cylinder at the back of the motor with a stethoscope. He says let it go and if or when it fails, I will lose that cylinder but be able to limp home as long as i am not in the middle of Lake Ontario.

From what I am gathering, a new set of lifters or just a replacement will most likely ruin the cam lobes and accelerate the demise of my old gal and that would be a pity.

What would you guys do if you were in my shoes?? Bare in mind, I do not race or abuse my boats or motors to the best of my ability.

Thanks again for the input

 

[GA_Boater]

If you take off the valve cover and start the motor, you can put a thumb or finger on the lash adjustment nuts one at a time. The ticking sound will stop or change on the valve needing adjustment.

 

[SHickey]

Yes,

We have adjusted the riser nuts numerous times and the ticking sound just does not get resolved. Mind you it is not loud ticking but a low annoying tick tick tick that just does not go away under any adjustment to that last cylinder valve set. We can adjust the other riser nuts and get all kinds of sounds and lack of motor performance so we have set the valves adjustments to their optimal setting and diagnosed a lifter failure situation

Again thanks for the responses

 

[Bondo]

Nothing is 100% about this motor or it's diagnosis but my mechanic buddy and I were able to determine the tick was coming from one of the risers on the last cylinder at the back of the motor with a stethoscope.

Ayuh,... A likely culprit causin' a Clickin' sound 'round the aft of the motor is,...
The Exhaust Shutters, located at the top of the down-pipe,....

If the motor ever ran without water flow, it burns the rubber coatin' off the shutters, causin' the clickin' sound,.....

If it Is a lifter, I'd just adjust it, 'n live with it,...

 

[SHickey]

Thanks for the response.

Could the exhaust shutters be replaced at the top of the down pipe if they are burned and melted?? Is it possible to visually inspect these shutters before determining they are the problem??

It would be fantastic if this was the source of the clicking sound and not the valves and lifters!!

 

[Silvertip]

If the lifter can't be adjusted, break out a set of feeler gauges. Select the .010 gauge and slip it between the tip of the offending valve and its rocker arm. Noise goes away you are not adjusting properly. But I suspect the lifter is not the problem in the first place as you should be able to turn down the adjusting nut to silence any valve whether the lifter is actually working or not. It may not make a smooth running engine but the noise would be gone and in that case you either have a flat cam lobe or bad lifter. I also disagree on the new lifter automatically destroying the cam lobe. A close look at the old lifter base will show either very little wear but with a ghtslit dish and if there is no unusual pattern a new lifter can be used. Obviously the best outcome is to replace the cam and lifters but under the circumstances, that is simply not necessary until you prove there is actually a cam/lifter problem. If there is scoring on the bottom of the lifter then the lobe is already damaged.

 

[Bondo]

Could the exhaust shutters be replaced at the top of the down pipe if they are burned and melted?? Is it possible to visually inspect these shutters before determining they are the problem??

Ayuh,.... You'll have to pull the riser off the manifold, 'n the down-pipe to see into the down-pipe,.....

There's very little space 'tween 'em under that rubber coupler,....

Speakin' of the rubber coupler, get yerself a Hose Pick, before ya try takin' it apart,....
The Hose Pick will make it much easier to loosen the rubber, 'n slide it down the pipe,....

 

[SHickey]

Can I easily remove the lifter I believe is bad from behind the push rod cover without too much trouble or special tools to inspect it?? As far as the exhaust shutters go, are they designed as a kind of "check valve" letting water out and not letting it return back into the down pipe? Can they be replaced if they are not functioning properly??

This ticking situation gets better by the hour and thanks for all of the responses!!

 

[harleyman1975]

I'm with everybody else. I don't think the lifter is bad...I think you have burned exhaust shutters. A lifter tick can be adjusted away...it may return...but it can be adjusted away at least for a few seconds.

 

[SHickey]

If new exhaust shutters are the culprit, are they difficult to fix?? I replaced the manifold last year so most every item on the top of the motor (raiser) can be easily removed if I need to work on the exhaust shutters.

Thanks again for the input!!

 

[Bondo]

are they difficult to fix??

Ayuh,..... On a scale of 1 to 10, it can fall anywhere 'tween 2, 'n 9,..... depends on how much "Boat" is in the way,.....

Search up the replacements here at iboats, usin' yer serial numbers, 'n get the set, along with Gaskets for the riser/ manifold,....
'n get yerself a Hose Pick,....

Once ya get to where they live, it's a piece of cake, swappin' the old for new,...

 

[SHickey]

Yes,

I looked up the part diagram on marineengine and I can see where there will be some difficulty in replacing the shutter. From the diagram, I believe the shutter is located in the exhaust elbow assembly underneath the exhaust bellows. Removing the raiser and the bellow should not be a problem but removing the exhaust bellow from the exhaust elbow will be a different story. So now I understand why Moderator Bondo has recommended a hose pick investment.

I think I will take the whole thing apart and see if the shutter is bad and go from there. If this is the source of my annoying ticking problem I will be most happy, excited and thankful for all the help I received today.

Thanks again for all of the input!!

 

[Silvertip]

The only time a lifter noise would not be able to be adjusted out is if the rocker stud is gradually pulling out of the head. Some engines have studs that are screwed into the head, some are pressed in. On a low reving engine like yours, a stud that is pulling out is unlikely. In fact I've never seen it on an I-6 but I've seen plenty of them on V8's. Mechanical fuel pumps with bad/weak return springs can also cause a noise not much like a rod knock but that would be low and at the front of the engine.

 

[SHickey]

Wow!!

I never heard of the rocker studs gradually loosening and pulling out of the heads. I imagine anything is possible and thanks for giving me a heads up surrounding this situation. I have no idea whether or not the rocker studs are pressed or screwed into the I-6 head.

You guys give me so much to think about it makes sleeping a difficult proposition some nights.

Again thanks for the input!!

 

[Mohawkmtrs]

Use your stethoscope to determine if the noise is coming from the shutter before tearing anything apart.

 

[SHickey]

That is a great idea considering that shutter is in the exhaust elbow assembly way in the back of the boat. Not a lot of room to work in as I remember.

Thanks again for the input!!