Mercruiser 3.0 harmonic balancer

[Simoniz]

Hi I have obtained a puller to remove the harmonic balancer from the front of the crankshaft of my 2001 year Mercruised 3.0l engine.

The bolts supplied with the puller are metric and so dont fit the threaded holes in the harmonic balancer which I assume are an inch based thread (AF, BSF or similar).

I want to buy the correct bolts and also a tap to clean up the threads in the HB which are a bit rusty.

Does anyone know the size and type of threads used in the HB? They are similar (but not the same as) M8 fine ie fine thread approx 8mm outside dia.

Many thanks.

 

[rodbolt]

Re: Mercruiser 3.0 harmonic balancer

bolt size is 3/8ths x 24 or 3/8 UNF pick your poison, I would use a grade 8, identified by 5 dsh lines on the bolt head.
dont ask about installing the balancer, starts to many arguments

 

[ron7000]

Re: Mercruiser 3.0 harmonic balancer

grade 8 for pulling the crankshaft pulley ?

why not grade... any bolt that's metal?
It came right off when I did mine, and i used home depot junk bolts.

 

[rodbolt]

Re: Mercruiser 3.0 harmonic balancer

cause as its a press fit and press only, no retaining bolt, a few are on rather tight. break one off and come chat.
they wont ever break unles engine box clearence dictates that the engine has to be removed for drilling.
grade 8 isnt any more expensive than grade 5,most home depot junk, just added insurance that the job proceeds as planned.

 

[achris]

Re: Mercruiser 3.0 harmonic balancer

grade 8 for pulling the crankshaft pulley ?

why not grade... any bolt that's metal?

It's called CYA... Don't risk bending/breaking a bolt just for the sake of a few cents.

It came right off when I did mine, and i used home depot junk bolts.

Consider yourself lucky.... Or maybe the crank was a bit undersize... Maybe if the balancer was that loose I'd be a bit concerned.

Use the high tensiles, Simon....

Chris.............

 

[Simoniz]

Re: Mercruiser 3.0 harmonic balancer

Rodbolt, very many thanks indeed!

bolt size is 3/8ths x 24 or 3/8 UNF pick your poison

Just to be sure, are these 2 thread specs 1 and the same or is there a possibility that it could be either?

 

[achris]

Re: Mercruiser 3.0 harmonic balancer

3/8"-24 is 3/8"UNF

Chris...........

 

[rodbolt]

Re: Mercruiser 3.0 harmonic balancer

yep, pick your poison.
but if ya really wanna jack up the parts counter guy, ask for a 1/4" straight pipe tap

 

[achris]

Re: Mercruiser 3.0 harmonic balancer

yep, pick your poison.
but if ya really wanna jack up the parts counter guy, ask for a 1/4" straight pipe tap

Would you be asking for NPT or BSPP?

 

[rodbolt]

Re: Mercruiser 3.0 harmonic balancer

actually its 1/4 NPTS
S designates its a straight thread not a standard taper pipe thread
only thing I use them on now is old merc gimbal assys

 

[ron7000]

Re: Mercruiser 3.0 harmonic balancer

It's called CYA... Don't risk bending/breaking a bolt just for the sake of a few cents.

cover your butt? c'mon are you serious?

we are talking about the 3 bolts that would screw into crankshaft pulley, a.k.a. harmonic dampener or balancer pulley?


if you are pulling on the pulley with a puller tool, you have 3 bolts screwed into the pulley. What is the strength (proof load, tensile strength, whatever) of a common 3/8 bolt? It's a couple thousand pounds at least, and you are using three of them, you would break the pulley apart and off the crankshaft long before you would ever bend any sort of bolt screwed into the pulley.

And aren't the bolts that come with a puller set grade 5 at best anyway?

to say you have to use grade 8 or give the impression if you don't that you'll have problems is absurd.

 

[achris]

Re: Mercruiser 3.0 harmonic balancer

Hey Ron,

I guess you're right.. We don't need high tensile bolts for pullers. I guess the puller manufacturers are all wrong too. Ever puller kit I've ever bought (I don't buy cheap rubbish) has had grade 8 bolts... Now I wonder why that is????

I also have a piece of 1/2" plate in the workshop that I will drill if I don't have a puller to fit the job I'm doing... Guess what bolts I use when I'm doing that??? Nope, wrong... not grade 5s... High tensile....

I agree with you about the straight pull load, but bolts on pullers are also subject to high lateral loads too. That's what I'm looking at that will break the bolts..

Chris............

 

[ron7000]

Re: Mercruiser 3.0 harmonic balancer

high lateral loads using a puller?

 

[JCF350]

Re: Mercruiser 3.0 harmonic balancer

bolt size is 3/8ths x 24 or 3/8 UNF pick your poison, I would use a grade 8, identified by 5 dsh lines on the bolt head.

5 dash lines is grade seven 6 dash lines is grade 8

dont ask about installing the balancer, starts to many arguments

Why not? There is already one about which grade to use.

 

[achris]

Re: Mercruiser 3.0 harmonic balancer

high lateral loads using a puller?

Lateral means sideways... When you start to tighten the forcing screw, that's the one on the middle that you turn, the puller starts to turn in the same direction, putting high side loads on the bolts. Soft bolts = bent bolts. After the metal reaches it's maximum elasticity, they break... Use high tensile and you reduce the likelihood of broken bolts...

If I hung you over a 1000' cliff with a piece of rope and told you that you had a choice of the rope that we are pretty sure will hold your weight, or a rope that we know is rated at three times your weight, which one would you choose?

Chris............

 

[Bondo]

Re: Mercruiser 3.0 harmonic balancer

If I hung you over a 1000' cliff with a piece of rope and told you that you had a choice of the rope that we are pretty sure will hold your weight, or a rope that we know is rated at three times your weight, which one would you choose?

Ayuh,.........

Personally,......
I'd want 10,000lb. rated Rope holding My 160lb. AZZ......................................



Btw,......
The "Home Owner's" grade of Bolts sold at my local Home Depot are only Gr.2.........
The Gr.8s are Extremely Cheap insurance.........

 

[ziggy]

Re: Mercruiser 3.0 harmonic balancer

i find this disagreement funny because it's about pocket change diff. in price..... if ya got to buy new bolts for yer puller. why not got grade 8. i hate broke off bolts....they cause a major challenge sometimes to get them removed. i agree with the lateral load too. if yer puller aint square with what yer pulling. side load does exist. i've bent puller bolts before with side load. fortunetly, i stoped and readjusted the puller prior to them breaking off...... grade 8 for me too..... oh, and when i start to come off center with grade 8 bolts, i stop and readj. them too.... did i comment on how i dislike removeing broke bolts.... oh yeah, said that....... better safe than sorry....

as fer yer rope guys..... hum. i ain't hangin over a 1000' cliff with any rope....... that's for younger folks to test out...... ever see that movie cliffhanger? yikes...... equipment can fail.......

 

[ron7000]

Re: Mercruiser 3.0 harmonic balancer

Lateral means sideways... When you start to tighten the forcing screw, that's the one on the middle that you turn, the puller starts to turn in the same direction, putting high side loads on the bolts. Soft bolts = bent bolts. After the metal reaches it's maximum elasticity, they break... Use high tensile and you reduce the likelihood of broken bolts...

dude what kind of puller are you using? Are you lubing the puller threads? A puller does not put a high side load on the bolts going to the pulley. The whole purpose of the puller is to pull, that's why it's called a puller. The threads of the puller are cut so that it transforms your rotational motion into linear motion. It doesn't put a high lateral load on the bolts, unless your definition of high is 20, 30 or 100 pounds. How much lateral loading do you think is being put on it? And if your pulley were to be really stuck on or the puller was crap and the puller threads had so much friction that your rotational force into the puller was kept as rotational force you would start turning the crankshaft anyway.
and soft bolts, wtf kind of implication is that. at least if you were using soft bolts you would see them start to bend first unless you're really a turd and just turn wrenches until things either pop off or break off.

If I hung you over a 1000' cliff with a piece of rope and told you that you had a choice of the rope that we are pretty sure will hold your weight, or a rope that we know is rated at three times your weight, which one would you choose?

first, you would not be hanging me over a cliff. I would have thrown you off the cliff, with both your ropes and your grade 8 bolts. I would even go find your garage, get your puller, and throw that down after you too.
great rationalization skills there outback jack

 

[tommays]

Re: Mercruiser 3.0 harmonic balancer

Play nice



Tommays

 

[John_S]

Re: Mercruiser 3.0 harmonic balancer

FWIW: Last spring, I went for the no cost puller rental from Autozone. They gave me a brand new one, but it looked like the quality of something you get from Harbor Frieght. Removed the harmonic balancer on my 350. It was on there very tight. While I didn't bend or break the three outer bolts, I did gall the the threads on the main inner one. It became a one-time use puller. Glad it didn't cost me anything, but would have been extremely angry if one of the bolts snapped. If buying one, don't go this low end.

The free rental of the installer went much better! But, we can't talk about that!