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Old 28-11-2018, 06:46   #46
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Re: Head removal of Perkins 4.108

While removing pan and blocking crank with a piece of wood will work and you at some point have to remove it anyway, that may be your best option, but you can also let the side of the bilge hold the end, as (hopefully) illustrated below. If the crank bolt is really stuck though, you could bend the bolts in the flywheel end, so care is needed.

You need a 24" piece of 3/4" pipe as a handle to go over your 1/2' drive T-bar for it to be used as a 'breaker bar'.

I fear that you'll be a long time with a hot air gun to get a high enough temp to do much good.

While asking around to borrow a torch, you might also ask if someone has a battery powered impact wrench along these lines, which should make short work of it...and you (probably) won't need to hold the crank.


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Old 28-11-2018, 11:53   #47
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Re: Head removal of Perkins 4.108

Before the start I cleaned the bilge this morning.
It was a kind of psychical preparation.

I did got heating gas torch and I heat the bolt for 5 min.
But still I was bending all tools.
I have on the boat also breaker bar of 5/6, but I don't have 1' 1/2" tool for it.
I will look for it tomorrow.

I decided not to use prybar in bilge because then I would look to find a solution to keep it between the bolts.
And also as you noticed I could bent bolts in flywheel.
So I went for wood to block the crank shaft.

I have on the boat air impact wrench. I hope it works. I need now to borrow air compressor.

Thank you
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Old 28-11-2018, 15:29   #48
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Re: Head removal of Perkins 4.108

Quote:
I have on the boat also breaker bar of 5/6, but I don't have 1' 1/2" tool for it.
I did got 1' 1/2" tool for breaker bar and bolt is off.

Now next.
My idler gear is rotated for 3 teeth.

How to proceed?
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Old 28-11-2018, 16:01   #49
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Re: Head removal of Perkins 4.108

Youíre certain youíre TDC?
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Old 28-11-2018, 16:31   #50
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Re: Head removal of Perkins 4.108

Those marks only line up every once and a while. When you put it back together they will line up then, but not for another 40 rev's or something. The number of teeth on the gears cause it to not line up every rev.
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Old 29-11-2018, 08:06   #51
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Re: Head removal of Perkins 4.108

Ecos is exactly right; the crank, fuel pump and cam gears are keyed or otherwise configured to only mount on their respective shafts or driven elements in one way.


The idler gear is not indexed, since there are different numbers of teeth on the other gears, the marks can't line up after one revolution after being 'timed'; the chances of them having stopped within one turn either way of being in alignment with the idler gear marks in synch with the other marks I'd think were about as good as winning the lottery (but I'm no statistician).



The number of turns required to get the marks back into alignment is specific to the particular engine model.

When you reassemble the engine, set the marks as shown in the manual and all will be well.
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Old 29-11-2018, 17:20   #52
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Re: Head removal of Perkins 4.108

Thank you..

I was in Panama city today to buy me the caliper. I was checking for spare parts options and where could find a shop for crank shaft grinding.
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Old 29-11-2018, 17:37   #53
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Re: Head removal of Perkins 4.108

Quote:
Originally Posted by pr2501 View Post
Thank you..

I was in Panama city today to buy me the caliper. I was checking for spare parts options and where could find a shop for crank shaft grinding.
If you havenít removed the crank yet how do you know it even needs to be taken down?
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Old 29-11-2018, 19:42   #54
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Re: Head removal of Perkins 4.108

Because he installed +.020 bearings in Guatemala a couple of years ago. Ivan has had some engine problems but he is intrepid.
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Old 29-11-2018, 21:15   #55
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Re: Head removal of Perkins 4.108

Ah the backstory helps for sure.
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Old 30-11-2018, 09:09   #56
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Re: Head removal of Perkins 4.108

The valve seat depth is very important. My source is the facebook page called Perkins 4108. Getting the seat depth right is big for creating exactly the right volumn of combustion chamber which has a large impact on starting and smoking. There are people on that Fbook page who can explain this better.
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Old 30-11-2018, 09:13   #57
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Re: Head removal of Perkins 4.108

Yes but it also has a relatively large tolerance .55-1.2mm is the min max for valve clearance.
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Old 30-11-2018, 10:26   #58
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Re: Head removal of Perkins 4.108

The easy way to maintain proper valve depth is just install new valves, they are not very expensive. Also when it comes to new pistons, use "class S" pistons. There are about 4 different pistons from Perkins and the "S" piston has the about the correct deck height.
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Old 30-11-2018, 15:22   #59
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Re: Head removal of Perkins 4.108

Tomorrow I am returning to crank shaft shop.
I am bringing CS (crank shaft) for inspection.

I have attached photo from manual. Can you explain me pleas, how much can values varie from regular?
(I can not figure it out from manual)

I can understand what is "undersize" (why 3 columns)
Why there is twice A ( rear journal is smaller).

But why are there always two values in manual?

Example:
A (front and center journals ) 56,85/56,86

Can you tell me if bearings in attached image are the same dimension?
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Old 30-11-2018, 17:43   #60
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Re: Head removal of Perkins 4.108

Quote:
Originally Posted by pr2501 View Post
Tomorrow I am returning to crank shaft shop.
I am bringing CS (crank shaft) for inspection.

I have attached photo from manual. Can you explain me pleas, how much can values varie from regular?
(I can not figure it out from manual)

I can understand what is "undersize" (why 3 columns)
Why there is twice A ( rear journal is smaller).

But why are there always two values in manual?

Example:
A (front and center journals ) 56,85/56,86

Can you tell me if bearings in attached image are the same dimension?
Bring the manual with you, the information contained will enable them to make sure the crank is in spec, and will enable them to grind it to the proper condition if it is not .

Can you advise why you're rebuilding the engine? I assume it's because of some top end problem because that crank looks good, as do the bearings (or at least what we can see of them). There appears to be no or almost no wear in the con rod bearings (they wear in the top) and from what we can see from the side of the mains (the wear in the bottom), they look good too. If you have a problem with low oil pressure, I'm betting it's not with the crank or bearings.

The service manual page gives dimensions for the crank.

The two numbers in the first column are the minimum/maximum dimension for the .010 oversize, for instance, 84037A is the new number for the 31132112 .010 con rod bearing, 84037B would be the .020 oversize, 84037C would be the .030 oversize.

I am not sure why there is a different dimension for the rear journal, but would be interested to find out if someone knows. I assume the slightly looser fit has something to do with oiling/stress of the journal at the flywheel end of the crank.

The 31132112 bearings are the same .010 oversize from different manufacturers.
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