Mercruiser 3.0 with noisy valves

[brewern]

I recently purchased a 1980 Rinkerbuilt with a Mercruiser 3.0, aka GM Straight 4 140 HP, aka the "Iron Duke".
On our last trip to the lake the valves started being noisy so when we got home, I did my research and found this video:

I did the valve adjustment with no problems and replaced the valve cover gasket. I also bought and used Nyloc nuts instead of the cheap crimped nuts that were on it.
When we got out on the lake this weekend, the valves were still a little noisy, but much better. But, by the end of the weekend, they were loud and noisy again.

The video said to do 3/4ths of a turn on the nut at zero lash. I did exactly that, but maybe my older engine needs more?

Any advice would be welcome. Thanks!

 

[tpenfield]

Re: Mercruiser 3.0 with noisy valves

Nyloc nuts on the rocker arm studs ???

What happened to them when they got hot ??? You are better off with the crimp nuts.

 

[Bt Doctur]

Re: Mercruiser 3.0 with noisy valves

what is the oil pressure when cold and hot?
what weight oil are you using?
3/4 should be fine
tp is correct, nylocs could be even worse, besides if they were cheap as you called them I`m sure aircraft would not be using them either.
nylocs are used where there is no heat condition, crimped nuts are used where there is a heat condition.

 

[oldjeep]

Re: Mercruiser 3.0 with noisy valves

Could just be sticky lifters. When I had my 80's bayliner I had a couple lifters go bad, no amount of adjusting them would help. Wound up just replacing them all.

x3 on the nylocks - not a good idea, should be using standard chevy stover nuts.

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

what is the oil pressure when cold and hot?
what weight oil are you using?
3/4 should be fine
tp is correct, nylocs could be even worse, besides if they were cheap as you called them I`m sure aircraft would not be using them either.
nylocs are used where there is no heat condition, crimped nuts are used where there is a heat condition.

Hmmm, I was told by the previous owner to use Nylocs. But with everyone here saying to switch back, I'll switch back to the crimped nuts tonight.
I didn't notice the oil pressure, so I'll make sure I take note of that next time we're out.
I'm using 10W30 for the oil.

Would it hurt to do a full turn instead of 3/4ths? I'm getting real good at taking the fuel lines and valve cover off, so I could always do this adjustment right on the water in under 30 minutes I think.

 

[oldjeep]

Re: Mercruiser 3.0 with noisy valves

Hmmm, I was told by the previous owner to use Nylocs. But with everyone here saying to switch back, I'll switch back to the crimped nuts tonight.
I didn't notice the oil pressure, so I'll make sure I take note of that next time we're out.
I'm using 10W30 for the oil.

Would it hurt to do a full turn instead of 3/4ths? I'm getting real good at taking the fuel lines and valve cover off, so I could always do this adjustment right on the water in under 30 minutes I think.

10W30???? Well there is your problem. 25W40 is what you should be running

 

[kd7isf]

Re: Mercruiser 3.0 with noisy valves

That engine is NOT the Iron Duke. The Iron Duke is a slightly newer, so called "improvement" over this engine. It never made it to the marine market because the cylinder walls are soo much thiner.. The marine GM I-4 is a Chevy Stovebolt engine.

That said, your problem came back because your nylock nuts are not made for heat and they simply backed off or melted when they got hot. Go back to the crimped nuts -- they're there for a reason....

If 3/4 doesn't work (and this assumes use of proper oil -- 25W40 or HD40 depending on your climate) then I agree with the above -- replace lifters... They don't cost much...

Hope this helps..

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

That engine is NOT the Iron Duke. The Iron Duke is a slightly newer, so called "improvement" over this engine. It never made it to the marine market because the cylinder walls are soo much thiner.. The marine GM I-4 is a Chevy Stovebolt engine.

That said, your problem came back because your nylock nuts are not made for heat and they simply backed off or melted when they got hot. Go back to the crimped nuts -- they're there for a reason....

If 3/4 doesn't work (and this assumes use of proper oil -- 25W40 or HD40 depending on your climate) then I agree with the above -- replace lifters... They don't cost much...

Hope this helps..

Good to know!
It seems the previous owner was misinformed on several counts. Ok, I'll change back to the crimped nuts, switch to 25W40, and buy new lifters if the noise continues.

The only local marine store is not open on Monday's and I have a hard time leaving work to go on other days. If I were to call a car parts store, would they have the correct lifters for this engine?

Thanks!

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

Ok, crimped nuts replaced. The nylocks came off real easy too! They obviously heated up and backed off.
While removing the valve cover, I noticed an insulated pipe just to the right of the valve cover, on the left hand side of the carburator. I noticed it was loose, and looked like it should feed into a small tube on the top of the engine. The small tube is easily removed and has obvious exhaust build up on it. See pics for clarification. Can anyone tell me what that is, and should it be hooked up? Or what's the deal? I'm happy to start a new thread if needed.

Thanks!

 

[Fishermark]

Re: Mercruiser 3.0 with noisy valves

That tube is simply a heat tube for your choke.

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

Is that anything I should hook back up? Or just not worry about it?

 

[fishrdan]

Re: Mercruiser 3.0 with noisy valves

You can get the rocker stud nuts from an auto parts store, it's one of the few parts that you can get for your "marine" engine at an auto parts store. Tell them you have a 68 Chevy II with a 153 4 cylinder engine. You have a GM 181, but the 153 is the closest auto equivalent engine.

If you decide to install new lifters, you'll need to break them in like a new cam, 15-20 minutes at 1500-2000RPM

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

Thanks all! We took her out again this weekend and it still makes the noise. So, I'm definitely leaning towards the lifters. I also double checked some other readings. WOT pegged out at 3000 RPM and the oil pressure gauge read 40 consistantly. I have a compression tester at home now, so I'll get to that compression test soon. First I need to heal up some. While at the campsite we were throwing a frisbee around, and I sprinted to chase one that was rolling away. Well, my 40 year old body doesn't react like it used to! There was an audible 'pop' in my left calf. Maybe a tendon? I'm headed to the Instant Care place in the morning. Growing old sucks!

Anyway, we went to Burside Island State Park over the last 4 days. Enjoyed it a lot, and it wasn't terribly busy! It rained a little, but mostly held off until we were headed back home. Here's some pics of Lake Cumberland in case you need lake pics.

(You can see why I named the boat "A Dog's Life")

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

Well, summer is wrapping up, and it's time to get the garage ready to store the boat for the winter. We moved into this house 2 years ago and luckily, it has a two car garage. But, the previous owner added two walls in the garage to create, what I guess was, a 'man cave'! This effectively cut the garage in 2, and made it into a 1 car garage. Well, today my son and I grabbed a crow bar and a hammer and ripped out the walls. Now, I think we can fit the boat (if it's on a cradle) and a vehicle into the garage.
With that, I can work on the motor, and hopefully fix up the canoe. It should be a fun winter!

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

The new boat garage renovation continues. Got a little more done today. Still plenty more to go. Where did I get all this crap? I need to have a yard sale!

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

Unfortunately, I didn't get the garage quite ready before the rains came. The boat was sitting out getting soaked so I pushed everything to the edges and moved it in! It's TIGHT, but at least it's inside.

Soon I'll place it on a couple of cradles and move the trailer outside and cover it while I put powder and lipstick on the ol' girl.

So, here's the sardine in her can:

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

First things first, dry it all out:



I think my first project will be fixing all those wires hanging down on the starboard side. Easy fix and should make it look better immediately. I also plan on reupholstering all the side panel. I may also re-carpet everything. I don't think I want to, or can afford, snap in carpeting.



Once everything is out and dry, I'll reevaluate fixing the lifters. I'm not sure I want to pull the motor unless I have to. And I think my minor oil leak is coming from the side plate, which will get fixed when I fix the lifters...

I guess we'll see! But for now, she's inside, which means I can sit in her, have a few beers and pick my projects.
This is the first winter I've looked forward to in a while!

 

[888]

Re: Mercruiser 3.0 with noisy valves

First things first, dry it all out:

View attachment 168816View attachment 168818View attachment 168819

I think my first project will be fixing all those wires hanging down on the starboard side. Easy fix and should make it look better immediately. I also plan on reupholstering all the side panel. I may also re-carpet everything. I don't think I want to, or can afford, snap in carpeting.

View attachment 168820View attachment 168817

Once everything is out and dry, I'll reevaluate fixing the lifters. I'm not sure I want to pull the motor unless I have to. And I think my minor oil leak is coming from the side plate, which will get fixed when I fix the lifters...

I guess we'll see! But for now, she's inside, which means I can sit in her, have a few beers and pick my projects.
This is the first winter I've looked forward to in a while!

Have a feeling your gonna find a wiped cam lobe or the beginnings of it.It happens a lot when you don't use oil with zinc additives.

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

Have a feeling your gonna find a wiped cam lobe or the beginnings of it.It happens a lot when you don't use oil with zinc additives.

I hate that news... but I love your banner. Stealing it!

 

[NetDoc]

Re: Mercruiser 3.0 with noisy valves

I just chased a bunch of noises from my 3.0. At the end, the clatter wasn't rhythmic enough to be lifter related. The only thing I could come up with was loose flywheel bolts. Wow. I was right and I replaced the bolts and torqued them down to 65lb/ft[SUP]2[/SUP]. It's been quiet ever since.

Unlike yourself, I am gearing up for a season of diving and hunting. The heat is breaking and the seas are flat calm today. It should be fun.