Motor mounts

[nelsonsmoody]

Hello all,

How can I tell if I need my motor mounts replaced on 4-108 Perkins 1989?
Nelson

[Pblais]

Some ways are easier to tell than others.

If any of them are broken you need all new ones and the engine realinged. You don't replace just one or two. If they break you waited too long. This can also throw the alignment off. You can do this in the water but if you need to replace them it's good to check the shaft and cutlass bearing at the same time. Poor mounts can contribute to poor alignment and to scoring on the shaft extra stress on the cutlass bearing. If it's a 1989 boat I would expect to have replaced the mounts at least few times if not more. They do wear out.

Given the boat is a 1989 it would be a good idea to go over the whole setup if you replace mounts since it requires realignmnet of the shaft. Alignment is a job you want as perfect as possible. Getting it to .0015 inches is possible even though specs may be as much as .003. Getting it that close will be something you can notice and hear. Not every mechanic can do it that close.

[Chief Engineer]

15 ten thousandths????

'mkay

[Pblais]

15 ten thousandths????

Yup, my last shaft was that tight. I didn't do it myself.

[Chief Engineer]

It is possible.....tedious....but possible

[nelsonsmoody]

what???????
No way!
can't be.
going to look this weekend and fill in with info.
sorry for short note m working off cell phone.
ps.
you guys r making me scare!!
nelson

[Chief Engineer]

I have a customer that sends me e-mails from his Farkleberry or whatever they call it.

I wnt 2 let u know tha eng is rng fn np but wud liek 2 kno f u cn b here fri am 10.

I respond Bill Ip op ork, lgak zbb bzz foppa corn ole dkwad.

Sorry, even some of us that have degrees can't unnerstanwhatchersayin

[Ex-Calif]

I am not going to disagree with previous posters but as a jet engine guy I can tell you that the high pressure rotor in a modern jet engine is rarely aligned with better than a .002 FIR. The rotor weighs a couple thousand pounds and thse bad boys spin at 19,000 RPM. Getting a prop shaft to .0015 is pretty magical.